Pettit exercises on the CEVIS

NASA Image and Video Library

2012-03-07

ISS030-E-132541 (7 March 2012) --- NASA astronaut Don Pettit, Expedition 30 flight engineer, performs a VO2max experiment while using the Cycle Ergometer with Vibration Isolation System (CEVIS) in the Destiny laboratory of the International Space Station. VO2max uses the Portable Pulmonary Function System (PPFS), CEVIS, Pulmonary Function System (PFS) gas cylinders and mixing bag system, plus multiple other pieces of hardware to measure oxygen uptake and cardiac output.

Pulse transit time measured by photoplethysmography improves the accuracy of heart rate as a surrogate measure of cardiac output, stroke volume and oxygen uptake in response to graded exercise.

PubMed

Pollonini, L; Padhye, N S; Re, R; Torricelli, A; Simpson, R J; Dacso, C C

2015-05-01

Heart rate (HR) is a valuable and widespread measure for physical training programs, although its description of conditioning is limited to the cardiac response to exercise. More comprehensive measures of exercise adaptation include cardiac output (Q̇), stroke volume (SV) and oxygen uptake (V̇O2), but these physiological parameters can be measured only with cumbersome equipment installed in clinical settings. In this work, we explore the ability of pulse transit time (PTT) to represent a valuable pairing with HR for indirectly estimating Q̇, SV and V̇O2 non-invasively. PTT was measured as the time interval between the peak of the electrocardiographic (ECG) R-wave and the onset of the photoplethysmography (PPG) waveform at the periphery (i.e. fingertip) with a portable sensor. Fifteen healthy young subjects underwent a graded incremental cycling protocol after which HR and PTT were correlated with Q̇, SV and V̇O2 using linear mixed models. The addition of PTT significantly improved the modeling of Q̇, SV and V̇O2 at the individual level ([Formula: see text] for SV, 0.548 for Q̇, and 0.771 for V̇O2) compared to predictive models based solely on HR ([Formula: see text] for SV, 0.503 for Q̇, and 0.745 for V̇O2). While challenges in sensitivity and artifact rejection exist, combining PTT with HR holds potential for development of novel wearable sensors that provide exercise assessment largely superior to HR monitors.

Effects of high-intensity interval training on central haemodynamics and skeletal muscle oxygenation during exercise in patients with chronic heart failure.

PubMed

Spee, Ruud F; Niemeijer, Victor M; Wijn, Pieter F; Doevendans, Pieter A; Kemps, Hareld M

2016-12-01

Background High-intensity interval training (HIT) improves exercise capacity in patients with chronic heart failure (CHF). Moreover, HIT was associated with improved resting cardiac function. However, the extent to which these improvements actually contribute to training-induced changes in exercise capacity remains to be elucidated. Therefore, we evaluated the effects of HIT on exercising central haemodynamics and skeletal muscle oxygenation. Methods Twenty-six CHF patients were randomised to a 12-week 4 × 4 minute HIT program at 85-95% of peak VO 2 or usual care. Patients performed maximal and submaximal cardiopulmonary exercise testing with simultaneous assessment of cardiac output and skeletal muscle oxygenation by near infrared spectroscopy, using the amplitude of the tissue saturation index (TSIamp). Results Peak workload increased by 11% after HIT ( p between group = 0.01) with a non-significant increase in peak VO 2 (+7%, p between group = 0.19). Cardiac reserve increased by 37% after HIT ( p within group = 0.03, p between group = 0.08); this increase was not related to improvements in peak workload. Oxygen uptake recovery kinetics after submaximal exercise were accelerated by 20% ( p between group = 0.02); this improvement was related to a decrease in TSIamp ( r = 0.71, p = 0.03), but not to changes in cardiac output kinetics. Conclusion HIT induced improvements in maximal exercise capacity and exercising haemodynamics at peak exercise. Improvements in recovery after submaximal exercise were associated with attenuated skeletal muscle deoxygenation during submaximal exercise, but not with changes in cardiac output kinetics, suggesting that the effect of HIT on submaximal exercise capacity is mediated by improved microvascular oxygen delivery-to-utilisation matching.

Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution During Hemorrhagic Shock and Resuscitation in Adult Swine.

PubMed

Berlin, David A; Peprah-Mensah, Harrison; Manoach, Seth; Heerdt, Paul M

2017-02-01

The study tests the hypothesis that noninvasive cardiac output monitoring based upon bioreactance (Cheetah Medical, Portland, OR) has acceptable agreement with intermittent bolus thermodilution over a wide range of cardiac output in an adult porcine model of hemorrhagic shock and resuscitation. Prospective laboratory animal investigation. Preclinical university laboratory. Eight ~ 50 kg Yorkshire swine with a femoral artery catheter for blood pressure measurement and a pulmonary artery catheter for bolus thermodilution. With the pigs anesthetized and mechanically ventilated, 40 mL/kg of blood was removed yielding marked hypotension and a rise in plasma lactate. After 60 minutes, pigs were resuscitated with shed blood and crystalloid. Noninvasive cardiac output monitoring and intermittent thermodilution cardiac output were simultaneously measured at nine time points spanning baseline, hemorrhage, and resuscitation. Simultaneous noninvasive cardiac output monitoring and thermodilution measurements of cardiac output were compared by Bland-Altman analysis. A plot was constructed using the difference of each paired measurement expressed as a percentage of the mean of the pair plotted against the mean of the pair. Percent bias was used to scale the differences in the measurements for the magnitude of the cardiac output. Method concordance was assessed from a four-quadrant plot with a 15% zone of exclusion. Overall, noninvasive cardiac output monitoring percent bias was 1.47% (95% CI, -2.5 to 5.4) with limits of agreement of upper equal to 33.4% (95% CI, 26.5-40.2) and lower equal to -30.4% (95% CI, -37.3 to -23.6). Trending analysis demonstrated a 97% concordance between noninvasive cardiac output monitoring and thermodilution cardiac output. Over the wide range of cardiac output produced by hemorrhage and resuscitation in large pigs, noninvasive cardiac output monitoring has acceptable agreement with thermodilution cardiac output.

Comparison Between Doppler-Echocardiography and Uncalibrated Pulse Contour Method for Cardiac Output Measurement: A Multicenter Observational Study.

PubMed

Scolletta, Sabino; Franchi, Federico; Romagnoli, Stefano; Carlà, Rossella; Donati, Abele; Fabbri, Lea P; Forfori, Francesco; Alonso-Iñigo, José M; Laviola, Silvia; Mangani, Valerio; Maj, Giulia; Martinelli, Giampaolo; Mirabella, Lucia; Morelli, Andrea; Persona, Paolo; Payen, Didier

2016-07-01

Echocardiography and pulse contour methods allow, respectively, noninvasive and less invasive cardiac output estimation. The aim of the present study was to compare Doppler echocardiography with the pulse contour method MostCare for cardiac output estimation in a large and nonselected critically ill population. A prospective multicenter observational comparison study. The study was conducted in 15 European medicosurgical ICUs. We assessed cardiac output in 400 patients in whom an echocardiographic evaluation was performed as a routine need or for cardiocirculatory assessment. None. One echocardiographic cardiac output measurement was compared with the corresponding MostCare cardiac output value per patient, considering different ICU admission categories and clinical conditions. For statistical analysis, we used Bland-Altman and linear regression analyses. To assess heterogeneity in results of individual centers, Cochran Q, and the I statistics were applied. A total of 400 paired echocardiographic cardiac output and MostCare cardiac output measures were compared. MostCare cardiac output values ranged from 1.95 to 9.90 L/min, and echocardiographic cardiac output ranged from 1.82 to 9.75 L/min. A significant correlation was found between echocardiographic cardiac output and MostCare cardiac output (r = 0.85; p < 0.0001). Among the different ICUs, the mean bias between echocardiographic cardiac output and MostCare cardiac output ranged from -0.40 to 0.45 L/min, and the percentage error ranged from 13.2% to 47.2%. Overall, the mean bias was -0.03 L/min, with 95% limits of agreement of -1.54 to 1.47 L/min and a relative percentage error of 30.1%. The percentage error was 24% in the sepsis category, 26% in the trauma category, 30% in the surgical category, and 33% in the medical admission category. The final overall percentage error was 27.3% with a 95% CI of 22.2-32.4%. Our results suggest that MostCare could be an alternative to echocardiography to assess cardiac output in ICU patients with a large spectrum of clinical conditions.

Cardiac sarcoidosis demonstrated by Tl-201 and Ga-67 SPECT imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taki, J.; Nakajima, K.; Bunko, H.

1990-09-01

Ga-67 and Tl-201 SPECT was performed to evaluate cardiac sarcoidosis in a 15-year-old boy. Tl-201 SPECT imaging showed decreased uptake in the inferior to lateral wall and Ga-67 accumulation in the area of decreased Tl-201 uptake. These findings suggested cardiac sarcoidosis, and cardiac biopsy confirmed this diagnosis. After corticosteroid therapy, myocardial uptake of Ga-67 disappeared and myocardial TI-201 uptake became more homogeneous.

Glutaredoxin-2 is required to control oxidative phosphorylation in cardiac muscle by mediating deglutathionylation reactions.

PubMed

Mailloux, Ryan J; Xuan, Jian Ying; McBride, Skye; Maharsy, Wael; Thorn, Stephanie; Holterman, Chet E; Kennedy, Christopher R J; Rippstein, Peter; deKemp, Robert; da Silva, Jean; Nemer, Mona; Lou, Marjorie; Harper, Mary-Ellen

2014-05-23

Glutaredoxin-2 (Grx2) modulates the activity of several mitochondrial proteins in cardiac tissue by catalyzing deglutathionylation reactions. However, it remains uncertain whether Grx2 is required to control mitochondrial ATP output in heart. Here, we report that Grx2 plays a vital role modulating mitochondrial energetics and heart physiology by mediating the deglutathionylation of mitochondrial proteins. Deletion of Grx2 (Grx2(-/-)) decreased ATP production by complex I-linked substrates to half that in wild type (WT) mitochondria. Decreased respiration was associated with increased complex I glutathionylation diminishing its activity. Tissue glucose uptake was concomitantly increased. Mitochondrial ATP output and complex I activity could be recovered by restoring the redox environment to that favoring the deglutathionylated states of proteins. Grx2(-/-) hearts also developed left ventricular hypertrophy and fibrosis, and mice became hypertensive. Mitochondrial energetics from Grx2 heterozygotes (Grx2(+/-)) were also dysfunctional, and hearts were hypertrophic. Intriguingly, Grx2(+/-) mice were far less hypertensive than Grx2(-/-) mice. Thus, Grx2 plays a vital role in modulating mitochondrial metabolism in cardiac muscle, and Grx2 deficiency leads to pathology. As mitochondrial ATP production was restored by the addition of reductants, these findings may be relevant to novel redox-related therapies in cardiac disease. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Muscle oxygen transport and utilization in heart failure: implications for exercise (in)tolerance.

PubMed

Poole, David C; Hirai, Daniel M; Copp, Steven W; Musch, Timothy I

2012-03-01

The defining characteristic of chronic heart failure (CHF) is an exercise intolerance that is inextricably linked to structural and functional aberrations in the O(2) transport pathway. CHF reduces muscle O(2) supply while simultaneously increasing O(2) demands. CHF severity varies from moderate to severe and is assessed commonly in terms of the maximum O(2) uptake, which relates closely to patient morbidity and mortality in CHF and forms the basis for Weber and colleagues' (167) classifications of heart failure, speed of the O(2) uptake kinetics following exercise onset and during recovery, and the capacity to perform submaximal exercise. As the heart fails, cardiovascular regulation shifts from controlling cardiac output as a means for supplying the oxidative energetic needs of exercising skeletal muscle and other organs to preventing catastrophic swings in blood pressure. This shift is mediated by a complex array of events that include altered reflex and humoral control of the circulation, required to prevent the skeletal muscle "sleeping giant" from outstripping the pathologically limited cardiac output and secondarily impacts lung (and respiratory muscle), vascular, and locomotory muscle function. Recently, interest has also focused on the dysregulation of inflammatory mediators including tumor necrosis factor-α and interleukin-1β as well as reactive oxygen species as mediators of systemic and muscle dysfunction. This brief review focuses on skeletal muscle to address the mechanistic bases for the reduced maximum O(2) uptake, slowed O(2) uptake kinetics, and exercise intolerance in CHF. Experimental evidence in humans and animal models of CHF unveils the microvascular cause(s) and consequences of the O(2) supply (decreased)/O(2) demand (increased) imbalance emblematic of CHF. Therapeutic strategies to improve muscle microvascular and oxidative function (e.g., exercise training and anti-inflammatory, antioxidant strategies, in particular) and hence patient exercise tolerance and quality of life are presented within their appropriate context of the O(2) transport pathway.

Validation of cardiac output studies from the Mostcare compared to a pulmonary artery catheter in septic patients.

PubMed

Gopal, S; Do, T; Pooni, J S; Martinelli, G

2014-03-01

The Mostcare monitor is a non-invasive cardiac output monitor. It has been well validated in cardiac surgical patients but there is limited evidence on its use in patients with severe sepsis and septic shock. The study included the first 22 consecutive patients with severe sepsis and septic shock in whom the floatation of a pulmonary artery catheter was deemed necessary to guide clinical management. Cardiac output measurements including cardiac output, cardiac index and stroke volume were simultaneously calculated and recorded from a thermodilution pulmonary artery catheter and from the Mostcare monitor respectively. The two methods of measuring cardiac output were compared by Bland-Altman statistics and linear regression analysis. A percentage error of less than 30% was defined as acceptable for this study. Bland-Altman analysis for cardiac output showed a Bias of 0.31 L.min-1, precision (=SD) of 1.97 L.min-1 and a percentage error of 62.54%. For Cardiac Index the bias was 0.21 L.min-1.m-2, precision of 1.10 L.min-1.m-2 and a percentage error of 64%. For stroke volume the bias was 5 mL, precision of 24.46 mL and percentage error of 70.21%. Linear regression produced a correlation coefficient r2 for cardiac output, cardiac index, and stroke volume, of 0.403, 0.306, and 0.3 respectively. Compared to thermodilution cardiac output, cardiac output studies obtained from the Mostcare monitor have an unacceptably high error rate. The Mostcare monitor demonstrated to be an unreliable monitoring device to measure cardiac output in patients with severe sepsis and septic shock on an intensive care unit.

External cardiac compression may be harmful in some scenarios of pulseless electrical activity.

PubMed

Hogan, T S

2012-10-01

Pulseless electrical activity occurs when organised or semi-organised electrical activity of the heart persists but the product of systemic vascular resistance and the increase in systemic arterial flow generated by the ejection of the left venticular stroke volume is not sufficient to produce a clinically detectable pulse. Pulseless electrical activity encompasses a very heterogeneous variety of severe circulatory shock states ranging in severity from pseudo-cardiac arrest to effective cardiac arrest. Outcomes of cardiopulmonary resuscitation for pulseless electrical activity are generally poor. Impairment of cardiac filling is the limiting factor to cardiac output in many scenarios of pulseless electrical activity, including extreme vasodilatory shock states. There is no evidence that external cardiac compression can increase cardiac output when impaired cardiac filling is the limiting factor to cardiac output. If impaired cardiac filling is the limiting factor to cardiac output and the heart is effectively ejecting all the blood returning to it, then external cardiac compression can only increase cardiac output if it increases venous return and cardiac filling. Repeated cardiac compression asynchronous with the patient's cardiac cycle and raised mean intrathoracic pressure due to chest compression can be expected to reduce rather than to increase cardiac filling and therefore to reduce rather than to increase cardiac output in such circumstances. The hypothesis is proposed that the performance of external cardiac compression will have zero or negative effect on cardiac output in pulseless electrical activity when impaired cardiac filling is the limiting factor to cardiac output. External cardiac compression may be both directly and indirectly harmful to significant sub-groups of patients with pulseless electrical activity. We have neither evidence nor theory to provide comfort that external cardiac compression is not harmful in many scenarios of pulseless electrical activity. Investigation using a variety of animal models of pulseless electrical activity produced by different shock-inducing mechanisms is required to provide an evidence base for resuscitation guidelines. Copyright © 2012 Elsevier Ltd. All rights reserved.

Increased cardiac output and maximal oxygen uptake in response to ten sessions of high intensity interval training.

PubMed

Astorino, Todd A; Edmunds, Ross M; Clark, Amy; King, Leesa; Gallant, Rachael M; Namm, Samantha; Fischer, Anthony; Wood, Kimi A

2018-01-01

Increases in maximal oxygen uptake (VO2max) are widely reported in response to completion of high intensity interval training (HIIT), yet the mechanism explaining this result is poorly understood. This study examined changes in VO2max and cardiac output (CO) in response to 10 sessions of low-volume HIIT. Participants included 30 active men and women (mean age and VO2max=22.9±5.4 years and 39.6±5.6 mL/kg/min) who performed HIIT and 30 men and women (age and VO2max=25.7±4.5 years and 40.7±5.2 mL/kg/min) who served as non-exercising controls (CON). High intensity interval training consisted of 6-10 s bouts of cycling per session at 90-110 percent peak power output (PPO) interspersed with 75 s recovery. Before and after training, progressive cycling to exhaustion was completed during which CO, stroke volume (SV), and heart rate (HR) were estimated using thoracic impedance. To confirm VO2max attainment, a verification test was completed after progressive cycling at a work rate equal to 110%PPO. Data demonstrated significant improvements in VO2max (2.71±0.63 L/min to 2.86±0.63 L/min, P<0.001) and COmax (20.0±3.1 L/min to 21.7±3.2 L/min, P=0.04) via HIIT that were not exhibited in CON. Maximal SV was increased in HIIT (P=0.04) although there was no change in maximal HR (P=0.57). The increase in VO2max seen in response to ten sessions of HIIT is due to improvements in oxygen delivery.

Immediate ventilatory response to sudden changes in venous return in humans.

PubMed Central

Cummin, A R; Iyawe, V I; Jacobi, M S; Mehta, N; Patil, C P; Saunders, K B

1986-01-01

We changed venous return transiently by postural manoeuvres, and by lower body positive pressure, to see what happened simultaneously to ventilation. Cardiac output was measured by a Doppler technique. In seven subjects, after inflation of a pressure suit to 80 and 40 mmHg at 30 deg head-up tilt, both cardiac output and ventilation increased. Ventilation increased rapidly to a peak in the first 5 s, cardiac output more slowly to a steady state in about 20 s, at 80 mmHg inflation. After inflation to 80 mmHg in six subjects at 12.5 deg head-up and 30 deg head-down tilt, cardiac output did not change in the first, and fell in the second case. There were no significant changes in ventilation. On release of pressure there were transient increases in both cardiac output and ventilation, with ventilation lagging behind cardiac output, in contrast to (2) above. In five subjects, elevation of the legs at 30 deg head-up tilt caused a rise in both cardiac output and ventilation, but in two subjects neither occurred. In all seven subjects there was a transient increase in cardiac output and ventilation when the legs were lowered. Ventilation and cardiac output changes were approximately in phase. We were therefore unable to dissociate entirely increasing cardiac output from increasing ventilation. The relation between them was certainly not a simple proportional one. PMID:3612571

Mathematics and the Heart: Understanding Cardiac Output

ERIC Educational Resources Information Center

Champanerkar, Jyoti

2013-01-01

This paper illustrates a biological application of the concepts of relative change and area under a curve, from mathematics. We study two biological measures "relative change in cardiac output" and "cardiac output", which are predictors of heart blockages and other related ailments. Cardiac output refers to the quantity of…

123I-MIBG cardiac uptake and smell identification in parkinsonian patients with LRRK2 mutations.

PubMed

Valldeoriola, Francesc; Gaig, Carles; Muxí, Africa; Navales, Ignacio; Paredes, Pilar; Lomeña, Francisco; De la Cerda, Andres; Buongiorno, Mariateresa; Ezquerra, Mario; Santacruz, Pilar; Martí, Maria Jose; Tolosa, Eduardo

2011-06-01

Reduced uptake of (123)I- metaiodobenzylguanidine (MIBG) on cardiac gammagraphy and impaired odor identification are markers of neurodegenerative diseases with Lewy bodies (LB) as a pathological hallmark, such as idiopathic Parkinson's disease (IPD). LRRK2 patients present with a clinical syndrome indistinguishable from IPD, but LB have not been found in some cases. Patients with such mutations could behave differently than patients with IPD with respect to MIBG cardiac uptake and olfaction. We studied 14 LRRK2 patients, 14 IPD patients matched by age, gender, disease duration and severity, and 13 age and gender matched control subjects. Olfaction was analyzed through the University of Pennsylvania Smell Identification Test (UPSIT). MIBG cardiac uptake was evaluated through the H/M ratio. The late H/M was 1.44 ± 0.31 for LRRK2 patients, 1.19 ± 0.15 for PD patients, and 1.67 ± 0.16 for control subjects. LRRK2 patients presented lower but not statistically significant MIBG cardiac uptake than controls (p = 0.08) and significant higher uptake than PD patients (p = 0.04). UPSIT mean scores were 21.5 ± 7.3 for LRRK2 patients, 18.7 ± 6.2 for IPD patients and 29.7 ± 5.7 for control subjects. UPSIT score was lower in both LRRK2 and PD than in controls. In LRRK2 patients a positive correlation was found between myocardial MIBG uptake and UPSIT scores, (R = 0.801, p < 0.001). In LRRK2 patients, MIBG cardiac uptake was less impaired than in PD; a positive correlation between MIBG cardiac uptake and UPSIT scores was observed. As MIBG cardiac reduced uptake and impaired odor identification are markers of LB pathology, this findings may represent neuropathological heterogeneity among LRRK2 patients.

Early 4-week cardiac rehabilitation exercise training in elderly patients after heart surgery.

PubMed

Eder, Barbara; Hofmann, Peter; von Duvillard, Serge P; Brandt, Dieter; Schmid, Jean-Paul; Pokan, Rochus; Wonisch, Manfred

2010-01-01

The aim of this study was to assess the effects on exercise performance of supplementing a standard cardiac rehabilitation program with additional exercise programming compared to the standard cardiac rehabilitation program alone in elderly patients after heart surgery. In this prospective, randomized controlled trial, 60 patients (32 men and 28 women, mean age 73.1 +/- 4.7 years) completed cardiac rehabilitation (initiated 12.2 +/- 4.9 days postsurgery). Subjects were assigned to either a control group (CG, standard cardiac rehabilitation program [n = 19]), or an intervention group (IG, additional walking [n = 19], or cycle ergometry training [n = 22]). A symptom limited cardiopulmonary exercise test and 6-minute walk test (6MWT) were performed before and after 4 weeks of cardiac rehabilitation. The MacNew questionnaire was used to assess quality of life (QOL). At baseline, no significant differences for peak oxygen uptake ((.)VO2), maximal power output, or the 6MWT were detected between IG and CG. Global QOL was significantly higher in IG. After 4 weeks of cardiac rehabilitation, patients significantly improved in absolute values of the cardiopulmonary exercise test, 6MWT, and QOL scores. Significant differences between groups were found for peak (.)VO2 (IG: 18.2 +/- 3.1 mL x kg x min vs. CG: 16.5 +/- 2.2 mL x kg x min, P < .05); maximal power output (IG: 72.2 +/- 16 W vs. CG: 60.7 +/- 15 W, P < .05); 6MWT (IG: 454.8 +/- 76.3 m vs. CG: 400.5 +/- 75.5 m, P < .05); and QOL global (IG: 6.5 +/- 0.5 vs. CG: 6.3 +/- 0.6, P < .05). The supplementation of additional walking or cycle exercise training to standard cardiac rehabilitation programming compared to standard cardiac rehabilitation alone in elderly patients after heart surgery leads to significantly better exercise tolerance.

Economic and Social Impact of Increasing Uptake of Cardiac Rehabilitation Services--A Cost Benefit Analysis.

PubMed

De Gruyter, Elaine; Ford, Greg; Stavreski, Bill

2016-02-01

Cardiac rehabilitation can reduce mortality, improve cardiac risk factor profile and reduce readmissions; yet uptake remains low at 30%. This research aims to investigate the social and economic impact of increasing the uptake of cardiac rehabilitation in Victoria, Australia using cost benefit analysis (CBA). Cost benefit analysis has been undertaken over a 10-year period to analyse three scenarios: (1) Base Case: 30% uptake; (2) Scenario 1: 50% uptake; and (3) Scenario 2: 65% uptake. Impacts considered include cardiac rehabilitation program costs, direct inpatient costs, other healthcare costs, burden of disease, productivity losses, informal care costs and net deadweight loss. There is a net financial saving of $46.7-$86.7 million under the scenarios. Compared to the Base Case, an additional net benefit of $138.9-$227.2 million is expected. This results in a Benefit Cost Ratio of 5.6 and 6.8 for Scenarios 1 and 2 respectively. Disability Adjusted Life Years were 21,117-37,565 years lower than the Base Case. Greater uptake of cardiac rehabilitation can reduce the burden of disease, directly translating to benefits for society and the economy. This research supports the need for greater promotion, routine referral to be made standard practice and implementation of reforms to boost uptake. Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

An oil-based model of inhalation anesthetic uptake and elimination.

PubMed

Loughlin, P J; Bowes, W A; Westenskow, D R

1989-08-01

An oil-based model was developed as a physical simulation of inhalation anesthetic uptake and elimination. It provides an alternative to animal models in testing the performance of anesthesia equipment. A 7.5-1 water-filled manometer simulates pulmonary mechanics. Nitrogen and carbon dioxide flowing into the manometer simulate oxygen consumption and carbon dioxide production. Oil-filled chambers (180 ml and 900 ml) simulate the uptake and washout of halothane by the vessel-rich and muscle tissue groups. A 17.2-1 air-filled chamber simulates uptake by the lung group. Gas circulates through the chambers (3.7, 13.8, and 25 l/min) to simulate the transport of anesthetic to the tissues by the circulatory system. Results show that during induction and washout, the rate of rise in endtidal halothane fraction simulated by the model parallels that measured in patients. The model's end-tidal fraction changes correctly with changes in cardiac output and alveolar ventilation. The model has been used to test anesthetic controllers and to evaluate gas sensors, and should be useful in teaching principles underlying volatile anesthetic uptake.

Iodine-123 metaiodobenzylguanidine imaging of the heart in idiopathic congestive cardiomyopathy and cardiac transplants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glowniak, J.V.; Turner, F.E.; Gray, L.L.

1989-07-01

Iodine-123 metaiodobenzylguanidine ((/sup 123/I)MIBG) is a norepinephrine analog which can be used to image the sympathetic innervation of the heart. In this study, cardiac imaging with (/sup 123/I)MIBG was performed in patients with idiopathic congestive cardiomyopathy and compared to normal controls. Initial uptake, half-time of tracer within the heart, and heart to lung ratios were all significantly reduced in patients compared to normals. Uptake in lungs, liver, salivary glands, and spleen was similar in controls and patients with cardiomyopathy indicating that decreased MIBG uptake was not a generalized abnormality in these patients. Iodine-123 MIBG imaging was also performed in cardiacmore » transplant patients to determine cardiac nonneuronal uptake. Uptake in transplants was less than 10% of normals in the first 2 hr and nearly undetectable after 16 hr. The decreased uptake of MIBG suggests cardiac sympathetic nerve dysfunction while the rapid washout of MIBG from the heart suggests increased cardiac sympathetic nerve activity in idiopathic congestive cardiomyopathy.« less

Mechanisms Regulating the Cardiac Output Response to Cyanide Infusion, a Model of Hypoxia

PubMed Central

Liang, Chang-seng; Huckabee, William E.

1973-01-01

When tissue metabolic changes like those of hypoxia were induced by intra-aortic infusion of cyanide in dogs, cardiac output began to increase after 3 to 5 min, reached a peak (220% of the control value) at 15 min, and returned to control in 40 min. This pattern of cardiac output rise was not altered by vagotomy with or without atropine pretreatment. However, this cardiac output response could be differentiated into three phases by pretreating the animals with agents that block specific activities of the sympatho-adrenal system. First, ganglionic blockade produced by mecamylamine or sympathetic nerve blockade by bretylium abolished the middle phase of the cardiac output seen in the untreated animal, but early and late phases still could be discerned. Second, beta-adrenergic receptor blockade produced by propranolol shortened the total duration of the cardiac output rise by abolishing the late phase. Third, when given together, propranolol and mecamylamine (or bretylium) prevented most of the cardiac output rise that follows the early phase. When cyanide was given to splenectomized dogs, the duration of the cardiac output response was not shortened, but the response became biphasic, resembling that seen after chemical sympathectomy. A similar biphasic response of the cardiac output also resulted from splenic denervation; sham operation or nephrectomy had no effect on the monophasic pattern of the normal response. Splenic venous blood obtained from cyanide-treated dogs, when infused intraportally, caused an increase in cardiac output in recipient dogs; similar infusion of arterial blood had no effects. These results suggest that the cardiac output response to cyanide infusion consists of three components: an early phase, related neither to the autonomic nervous system nor to circulating catecholamines; a middle phase, caused by a nonadrenergic humoral substance released from the spleen by sympathetic stimulation; and a late phase, dependent upon adrenergic receptors but not upon sympathetic transmission. PMID:4750445

Cardiorespiratory collapse at high temperature in swimming adult sockeye salmon

PubMed Central

Eliason, Erika J.; Clark, Timothy D.; Hinch, Scott G.; Farrell, Anthony P.

2013-01-01

Elevated summer river temperatures are associated with high in-river mortality in adult sockeye salmon (Oncorhynchus nerka) during their once-in-a-lifetime spawning migration up the Fraser River (British Columbia, Canada). However, the mechanisms underlying the decrease in whole-animal performance and cardiorespiratory collapse above optimal temperatures for aerobic scope (Topt) remain elusive for aquatic ectotherms. This is in part because all the relevant cardiorespiratory variables have rarely been measured directly and simultaneously during exercise at supra-optimal temperatures. Using the oxygen- and capacity-limited thermal tolerance hypothesis as a framework, this study simultaneously and directly measured oxygen consumption rate (MO2), cardiac output , heart rate (fH), and cardiac stroke volume (Vs), as well as arterial and venous blood oxygen status in adult sockeye salmon swimming at temperatures that bracketed Topt to elucidate possible limitations in oxygen uptake into the blood or internal delivery through the oxygen cascade. Above Topt, the decline in MO2max and aerobic scope was best explained by a cardiac limitation, triggered by reduced scope for fH. The highest test temperatures were characterized by a negative scope for fH, dramatic decreases in maximal and maximal Vs, and cardiac dysrhythmias. In contrast, arterial blood oxygen content and partial pressure were almost insensitive to supra-optimal temperature, suggesting that oxygen delivery to and uptake by the gill were not a limiting factor. We propose that the high-temperature-induced en route mortality in migrating sockeye salmon may be at least partly attributed to physiological limitations in aerobic performance due to cardiac collapse via insufficient scope for fH. Furthermore, this improved mechanistic understanding of cardiorespiratory collapse at high temperature is likely to have broader application to other salmonids and perhaps other aquatic ectotherms. PMID:27293592

Cardiorespiratory collapse at high temperature in swimming adult sockeye salmon.

PubMed

Eliason, Erika J; Clark, Timothy D; Hinch, Scott G; Farrell, Anthony P

2013-01-01

Elevated summer river temperatures are associated with high in-river mortality in adult sockeye salmon (Oncorhynchus nerka) during their once-in-a-lifetime spawning migration up the Fraser River (British Columbia, Canada). However, the mechanisms underlying the decrease in whole-animal performance and cardiorespiratory collapse above optimal temperatures for aerobic scope (T opt) remain elusive for aquatic ectotherms. This is in part because all the relevant cardiorespiratory variables have rarely been measured directly and simultaneously during exercise at supra-optimal temperatures. Using the oxygen- and capacity-limited thermal tolerance hypothesis as a framework, this study simultaneously and directly measured oxygen consumption rate (MO2), cardiac output [Formula: see text], heart rate (f H), and cardiac stroke volume (V s), as well as arterial and venous blood oxygen status in adult sockeye salmon swimming at temperatures that bracketed T opt to elucidate possible limitations in oxygen uptake into the blood or internal delivery through the oxygen cascade. Above T opt, the decline in MO2max and aerobic scope was best explained by a cardiac limitation, triggered by reduced scope for f H. The highest test temperatures were characterized by a negative scope for f H, dramatic decreases in maximal [Formula: see text] and maximal V s, and cardiac dysrhythmias. In contrast, arterial blood oxygen content and partial pressure were almost insensitive to supra-optimal temperature, suggesting that oxygen delivery to and uptake by the gill were not a limiting factor. We propose that the high-temperature-induced en route mortality in migrating sockeye salmon may be at least partly attributed to physiological limitations in aerobic performance due to cardiac collapse via insufficient scope for f H. Furthermore, this improved mechanistic understanding of cardiorespiratory collapse at high temperature is likely to have broader application to other salmonids and perhaps other aquatic ectotherms.

Simultaneous determination of dynamic cardiac metabolism and function using PET/MRI.

PubMed

Barton, Gregory P; Vildberg, Lauren; Goss, Kara; Aggarwal, Niti; Eldridge, Marlowe; McMillan, Alan B

2018-05-01

Cardiac metabolic changes in heart disease precede overt contractile dysfunction. However, metabolism and function are not typically assessed together in clinical practice. The purpose of this study was to develop a cardiac positron emission tomography/magnetic resonance (PET/MR) stress test to assess the dynamic relationship between contractile function and metabolism in a preclinical model. Following an overnight fast, healthy pigs (45-50 kg) were anesthetized and mechanically ventilated. 18 F-fluorodeoxyglucose ( 18 F-FDG) solution was administered intravenously at a constant rate of 0.01 mL/s for 60 minutes. A cardiac PET/MR stress test was performed using normoxic gas (F I O 2  = .209) and hypoxic gas (F I O 2  = .12). Simultaneous cardiac imaging was performed on an integrated 3T PET/MR scanner. Hypoxic stress induced a significant increase in heart rate, cardiac output, left ventricular (LV) ejection fraction (EF), and peak torsion. There was a significant decline in arterial SpO 2 , LV end-diastolic and end-systolic volumes in hypoxia. Increased LV systolic function was coupled with an increase in myocardial FDG uptake (Ki) during hypoxic stress. PET/MR with continuous FDG infusion captures dynamic changes in both cardiac metabolism and contractile function. This technique warrants evaluation in human cardiac disease for assessment of subtle functional and metabolic abnormalities.

Levosimendan versus milrinone in neonates and infants after corrective open-heart surgery: a pilot study.

PubMed

Lechner, Evelyn; Hofer, Anna; Leitner-Peneder, Gabriele; Freynschlag, Roland; Mair, Rudolf; Weinzettel, Robert; Rehak, Peter; Gombotz, Hans

2012-09-01

Low cardiac output syndrome commonly complicates the postoperative course after open-heart surgery in children. To prevent low cardiac output syndrome, prophylactic administration of milrinone after cardiopulmonary bypass is commonly used in small children. The aim of this study was to compare the effect of prophylactically administered levosimendan and milrinone on cardiac index in neonates and infants after corrective open-heart surgery. Prospective, single-center, double-blind, randomized pilot study. Tertiary care center, postoperative pediatric cardiac intensive care unit. After written informed consent, 40 infants undergoing corrective open-heart surgery were included. At weaning from cardiopulmonary bypass, either a 24-hr infusion of 0.1 μg/kg/min levosimendan or of 0.5 μg/kg/min milrinone were administered. Cardiac output was evaluated at 2, 6, 9, 12, 18, 24, and 48 hrs after cardiopulmonary bypass using a transesophageal Doppler technique (Cardio-QP, Deltex Medical, Chichester, UK). Cardiac index was calculated from cardiac output and the patients' respective body surface area. Intention-to-treat data of 39 patients (19 in the levosimendan and 20 in the milrinone group) were analyzed using analysis of variance for repeated measurements for statistics. Analysis of variance revealed for both, cardiac index and cardiac output, similar results with no significant differences of the factors group and time. A significant interaction for cardiac output (p = .005) and cardiac index (p = .007) was found, which indicates different time courses of cardiac index in the two groups. Both drugs were well tolerated; no death or serious adverse event occurred. In our small study, postoperative cardiac index over time was similar in patients with prophylactically administered levosimendan and patients with prophylactically given milrinone. We observed an increase in cardiac output and cardiac index over time in the levosimendan group, whereas cardiac output and cardiac index remained stable in the milrinone group. This pilot study has primarily served to obtain experience using the new drug levosimendan in neonates and infants and to initiate further multicenter trials in pediatric patients.

β-Adrenergic or parasympathetic inhibition, heart rate and cardiac output during normoxic and acute hypoxic exercise in humans

PubMed Central

Hopkins, Susan R; Bogaard, Harm J; Niizeki, Kyuichi; Yamaya, Yoshiki; Ziegler, Michael G; Wagner, Peter D

2003-01-01

Acute hypoxia increases heart rate (HR) and cardiac output () at a given oxygen consumption () during submaximal exercise. It is widely believed that the underlying mechanism involves increased sympathetic activation and circulating catecholamines acting on cardiac β receptors. Recent evidence indicating a continued role for parasympathetic modulation of HR during moderate exercise suggests that increased parasympathetic withdrawal plays a part in the increase in HR and during hypoxic exercise. To test this, we separately blocked the β-sympathetic and parasympathetic arms of the autonomic nervous system (ANS) in six healthy subjects (five male, one female; mean ± s.e.m. age = 31.7 ± 1.6 years, normoxic maximal () = 3.1 ± 0.3 l min−1) during exercise in conditions of normoxia and acute hypoxia (inspired oxygen fraction = 0.125) to . Data were collected on different days under the following conditions: (1)control, (2) after 8.0 mg propranolol I.V. and (3) after 0.8 mg glycopyrrolate I.V. was measured using open-circuit acetylene uptake. Hypoxia increased venous [adrenaline] and [noradrenaline] but not [dopamine] at a given (P < 0.05, P < 0.01 and P = 0.2, respectively). HR/ and / increased during hypoxia in all three conditions (P < 0.05). Unexpectedly, the effects of hypoxia on HR and were not significantly different from control with either β-sympathetic or parasympathetic inhibition. These data suggest that although acute exposure to hypoxia increases circulating [catecholamines], the effects of hypoxia on HR and do not necessarily require intact cardiac muscarinic and β receptors. It may be that cardiac α receptors play a primary role in elevating HR and during hypoxic exercise, or perhaps offer an alternative mechanism when other ANS pathways are blocked. PMID:12766243

Cardiorespiratory performance during prolonged swimming tests with salmonids: a perspective on temperature effects and potential analytical pitfalls.

PubMed

Farrell, A P

2007-11-29

A prolonged swimming trial is the most common approach in studying steady-state changes in oxygen uptake, cardiac output and tissue oxygen extraction as a function of swimming speed in salmonids. The data generated by these sorts of studies are used here to support the idea that a maximum oxygen uptake is reached during a critical swimming speed test. Maximum oxygen uptake has a temperature optimum. Potential explanations are advanced to explain why maximum aerobic performance falls off at high temperature. The valuable information provided by critical swimming tests can be confounded by non-steady-state swimming behaviours, which typically occur with increasing frequency as salmonids approach fatigue. Two major concerns are noted. Foremost, measurements of oxygen uptake during swimming can considerably underestimate the true cost of transport near critical swimming speed, apparently in a temperature-dependent manner. Second, based on a comparison with voluntary swimming ascents in a raceway, forced swimming trials in a swim tunnel respirometer may underestimate critical swimming speed, possibly because fish in a swim tunnel respirometer are unable to sustain a ground speed.

Cardiac sympathetic denervation and dementia in de novo Parkinson's disease: A 7-year follow-up study.

PubMed

Choi, Mun Hee; Yoon, Jung Han; Yong, Suk Woo

2017-10-15

Postganglionic cardiac sympathetic denervation is evident in patients with early-stage Parkinson's disease (PD). Cardiac iodine-123-meta-iodobenzylguanidine (MIBG) uptake is correlated with the non-motor symptoms of PD, suggesting that low cardiac MIBG uptake may reflect wider alpha-synuclein pathology. In addition, low cardiac MIBG could be related to orthostatic hypotension in PD, which may affect cognition. However, the prognostic validity of baseline MIBG scintigraphy in terms of the risk of subsequent dementia remains unclear. We investigated whether cardiac MIBG uptake was associated with a later risk of dementia. We retrospectively enrolled 93 drug-naive patients with de novo PD who underwent MIBG scanning on initial evaluation. The patients visited our outpatient clinic every 3-6months and were followed-up for a minimum of 4years from the time they were begun on dopaminergic medication. The predictive powers of baseline MIBG cardiac scintigraphic data in terms of dementia development were evaluated using Cox's proportional hazard models. During a mean follow-up period of 6.7years, 27 patients with PD (29.0%) developed dementia. These patients had less baseline MIBG uptake than did others (delayed H/M ratios: 1.19 vs. 1.31). Multivariate Cox's proportional hazard modeling revealed that both MIBG uptake (hazard ratio [HR] 3.40; p=0.004) and age (HR 1.08, p=0.01) significantly predicted dementia development. A reduction in cardiac MIBG uptake by PD patients may be associated with a subsequent risk of dementia; reduced uptake may reflect wider extension of alpha-synuclein pathology in PD. Copyright © 2017 Elsevier B.V. All rights reserved.

Mild hypothermia increases pulmonary anti-inflammatory response during protective mechanical ventilation in a piglet model of acute lung injury.

PubMed

Cruces, Pablo; Erranz, Benjamín; Donoso, Alejandro; Carvajal, Cristóbal; Salomón, Tatiana; Torres, María Fernanda; Díaz, Franco

2013-11-01

The effects of mild hypothermia (HT) on acute lung injury (ALI) are unknown in species with metabolic rate similar to that of humans, receiving protective mechanical ventilation (MV). We hypothesized that mild hypothermia would attenuate pulmonary and systemic inflammatory responses in piglets with ALI managed with a protective MV. Acute lung injury (ALI) was induced with surfactant deactivation in 38 piglets. The animals were then ventilated with low tidal volume, moderate positive end-expiratory pressure (PEEP), and permissive hypercapnia throughout the experiment. Subjects were randomized to HT (33.5°C) or normothermia (37°C) groups over 4 h. Plasma and tissue cytokines, tissue apoptosis, lung mechanics, pulmonary vascular permeability, hemodynamic, and coagulation were evaluated. Lung interleukin-10 concentrations were higher in subjects that underwent HT after ALI induction than in those that maintained normothermia. No difference was found in other systemic and tissue cytokines. HT did not induce lung or kidney tissue apoptosis or influence lung mechanics or markers of pulmonary vascular permeability. Heart rate, cardiac output, oxygen uptake, and delivery were significantly lower in subjects that underwent HT, but no difference in arterial lactate, central venous oxygen saturation, and coagulation test was observed. Mild hypothermia induced a local anti-inflammatory response in the lungs, without affecting lung function or coagulation, in this piglet model of ALI. The HT group had lower cardiac output without signs of global dysoxia, suggesting an adaptation to the decrease in oxygen uptake and delivery. Studies are needed to determine the therapeutic role of HT in ALI. © 2013 John Wiley & Sons Ltd.

Ga-67 cardiac uptake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, D.S.; Tipton, R.E.

1983-12-01

A case of positive Ga-67 image due to tuberculous pericarditis is presented. The pattern and distribution of the uptake suggested that the concentration of the activity was mainly in the inflamed pericardium. The known causes of Ga-67 cardiac uptake were reviewed, and a differential diagnosis is given.

Serum cortisol concentration with exploratory cut-off values do not predict the effects of hydrocortisone administration in children with low cardiac output after cardiac surgery.

PubMed

Verweij, E J; Hogenbirk, Karin; Roest, Arno A W; van Brempt, Ronald; Hazekamp, Mark G; de Jonge, Evert

2012-10-01

Low cardiac output syndrome is common after paediatric cardiac surgery. Previous studies suggested that hydrocortisone administration may improve haemodynamic stability in case of resistant low cardiac output syndrome in critically ill children. This study was set up to test the hypothesis that the effects of hydrocortisone on haemodynamics in children with low cardiac output syndrome depend on the presence of (relative) adrenal insufficiency. A retrospective study was done on paediatric patients who received hydrocortisone when diagnosed with resistant low cardiac output syndrome after paediatric cardiac surgery in the period from 1 November 2005 to 31 December 2008. We studied the difference in effects of treatment with hydrocortisone administration between patients with adrenal insufficiency defined as an exploratory cut-off value of total cortisol of <100 nmol/l and patients with a serum total cortisol of ≥ 100 nmol/l. A total of 62 of patients were enrolled, meeting the inclusion criteria for low cardiac output syndrome. Thirty-two patients were assigned to Group 1 (<100 nmol/l) and 30 were assigned to Group 2 (≥ 100 nmol/l). Haemodynamics improved after hydrocortisone administration, with an increase in blood pressure, a decrease in administered vasopressors and inotropic drugs, an increase in urine production and a decrease in plasma lactate concentrations. The effects of treatment with hydrocortisone in children with low cardiac output after cardiac surgery was similar in patients with a low baseline serum cortisol concentration and those with normal baseline cortisol levels. A cortisol value using an exploratory cut-off value of 100 nmol/l for adrenal insufficiency should not be used as a criterion to treat these patients with hydrocortisone.

Influence of simulated microgravity on the sympathetic response to exercise

NASA Technical Reports Server (NTRS)

Woodman, C. R.; Kregel, K. C.; Tipton, C. M.

1997-01-01

Rats exposed to simulated conditions of microgravity exhibit reductions in aerobic exercise capacity that may be due to an impaired ability of the sympathetic nervous system (SNS) to mediate an increase in cardiac output and to redistribute blood flow. The purpose of this study was to quantify the sympathetic response to exercise in rats after exposure to 14 days of simulated microgravity or control conditions. To achieve this aim, rats were exposed to 14 days of head-down suspension (HDS) or cage control (CC) conditions. On day 14, norepinephrine (NE) synthesis was blocked with alpha-methyl-p-tyrosine, and the rate of NE depletion after synthesis blockade was used to estimate SNS activity in the left ventricle, spleen, and soleus muscle during treadmill exercise at 75% of maximal oxygen uptake. When compared with CC rats, the sympathetic response to exercise in HDS rats was characterized by a lower rate of NE depletion in the left ventricle (-82%) and spleen (-42%). The rate of NE depletion in the soleus muscle was 47% higher. These differences could contribute to the decrement in aerobic capacity of HDS rats by impairing their ability to augment cardiac output and to redirect blood flow to actively contracting skeletal muscle during exercise.

First experience of simultaneous PET/MRI for the early detection of cardiac involvement in patients with Anderson-Fabry disease.

PubMed

Nappi, Carmela; Altiero, Michele; Imbriaco, Massimo; Nicolai, Emanuele; Giudice, Caterina Anna; Aiello, Marco; Diomiaiuti, Claudio Tommaso; Pisani, Antonio; Spinelli, Letizia; Cuocolo, Alberto

2015-06-01

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with severe multiorgan dysfunction and premature death. Early diagnosis and treatment strategies play a key role in patient outcome. We investigated the potential role of hybrid PET/MR imaging in the assessment of early cardiac involvement in AFD patients. Thirteen AFD patients without cardiac symptoms and with normal left ventricular function underwent simultaneous cardiac PET/MR imaging after administration of (18)F-FDG. Cardiac FDG uptake was quantified by measuring the standardized uptake value in 17 myocardial segments in each subject. The coefficient of variation (COV, i.e. the standard deviation divided by the average) of the uptake of the 17 segments was calculated as an index of heterogeneity in the heart. Six patients exhibited focal late gadolinium enhancement (LGE) indicating intramyocardial fibrosis, and four of these also had positive short inversion time inversion recovery (STIR) sequences. All patients with LGE and positive STIR MR images showed focal FDG uptake in the corresponding myocardial segments indicating inflammation. Of the seven patients with negative LGE and STIR images, five showed homogeneous FDG cardiac uptake and two showed heterogeneous FDG uptake. The COV was significantly greater in patients with focal FDG uptake (0.25 ± 0.02) than in those without (0.14 ± 0.07, p < 0.01). PET/MR imaging is clinically feasible for the early detection of cardiac involvement in patients with AFD. Further studies evaluating the role of hybrid PET/MR imaging in management of the disease in larger patient populations are warranted.

Cardiovascular and Muscular Consequences of Work-Matched Interval-Type of Concentric and Eccentric Pedaling Exercise on a Soft Robot.

PubMed

Flück, Martin; Bosshard, Rebekka; Lungarella, Max

2017-01-01

Eccentric types of endurance exercise are an acknowledged alternative to conventional concentric types of exercise rehabilitation for the cardiac patient, because they reduce cardiorespiratory strain due to a lower metabolic cost of producing an equivalent mechanical output. The former contention has not been tested in a power- and work-matched situation of interval-type exercise under identical conditions because concentric and eccentric types of exercise pose specific demands on the exercise machinery, which are not fulfilled in current practice. Here we tested cardiovascular and muscular consequences of work-matched interval-type of leg exercise (target workload of 15 sets of 1-min bipedal cycles of knee extension and flexion at 30 rpm with 17% of maximal concentric power) on a soft robotic device in healthy subjects by concomitantly monitoring respiration, blood glucose and lactate, and power during exercise and recovery. We hypothesized that interval-type of eccentric exercise lowers strain on glucose-related aerobic metabolism compared to work-matched concentric exercise, and reduces cardiorespiratory strain to levels being acceptable for the cardiac patient. Eight physically active male subjects (24.0 years, 74.7 kg, 3.4 L O2 min -1 ), which power and endurance performance was extensively characterized, completed the study, finalizing 12 sets on average. Average performance was similar during concentric and eccentric exercise ( p = 0.75) but lower than during constant load endurance exercise on a cycle ergometer at 75% of peak aerobic power output (126 vs. 188 Watt) that is recommended for improving endurance capacity. Peak oxygen uptake (-17%), peak ventilation (-23%), peak cardiac output (-16%), and blood lactate (-37%) during soft robotic exercise were lower during eccentric than concentric exercise. Glucose was 8% increased after eccentric exercise when peak RER was 12% lower than during concentric exercise. Muscle power and RFD were similarly reduced after eccentric and concentric exercise. The results highlight that the deployed interval-type of eccentric leg exercise reduces metabolic strain of the cardiovasculature and muscle compared to concentric exercise, to recommended levels for cardio-rehabilitation (i.e., 50-70% of peak heart rate). Increases in blood glucose concentration indicate that resistance to contraction-induced glucose uptake after the deployed eccentric protocol is unrelated to muscle fatigue.

Cardiovascular and Muscular Consequences of Work-Matched Interval-Type of Concentric and Eccentric Pedaling Exercise on a Soft Robot

PubMed Central

Flück, Martin; Bosshard, Rebekka; Lungarella, Max

2017-01-01

Eccentric types of endurance exercise are an acknowledged alternative to conventional concentric types of exercise rehabilitation for the cardiac patient, because they reduce cardiorespiratory strain due to a lower metabolic cost of producing an equivalent mechanical output. The former contention has not been tested in a power- and work-matched situation of interval-type exercise under identical conditions because concentric and eccentric types of exercise pose specific demands on the exercise machinery, which are not fulfilled in current practice. Here we tested cardiovascular and muscular consequences of work-matched interval-type of leg exercise (target workload of 15 sets of 1-min bipedal cycles of knee extension and flexion at 30 rpm with 17% of maximal concentric power) on a soft robotic device in healthy subjects by concomitantly monitoring respiration, blood glucose and lactate, and power during exercise and recovery. We hypothesized that interval-type of eccentric exercise lowers strain on glucose-related aerobic metabolism compared to work-matched concentric exercise, and reduces cardiorespiratory strain to levels being acceptable for the cardiac patient. Eight physically active male subjects (24.0 years, 74.7 kg, 3.4 L O2 min−1), which power and endurance performance was extensively characterized, completed the study, finalizing 12 sets on average. Average performance was similar during concentric and eccentric exercise (p = 0.75) but lower than during constant load endurance exercise on a cycle ergometer at 75% of peak aerobic power output (126 vs. 188 Watt) that is recommended for improving endurance capacity. Peak oxygen uptake (−17%), peak ventilation (−23%), peak cardiac output (−16%), and blood lactate (−37%) during soft robotic exercise were lower during eccentric than concentric exercise. Glucose was 8% increased after eccentric exercise when peak RER was 12% lower than during concentric exercise. Muscle power and RFD were similarly reduced after eccentric and concentric exercise. The results highlight that the deployed interval-type of eccentric leg exercise reduces metabolic strain of the cardiovasculature and muscle compared to concentric exercise, to recommended levels for cardio-rehabilitation (i.e., 50–70% of peak heart rate). Increases in blood glucose concentration indicate that resistance to contraction-induced glucose uptake after the deployed eccentric protocol is unrelated to muscle fatigue. PMID:28912726

Atlas-derived perfusion correlates of white matter hyperintensities in patients with reduced cardiac output.

PubMed

Jefferson, Angela L; Holland, Christopher M; Tate, David F; Csapo, Istvan; Poppas, Athena; Cohen, Ronald A; Guttmann, Charles R G

2011-01-01

Reduced cardiac output is associated with increased white matter hyperintensities (WMH) and executive dysfunction in older adults, which may be secondary to relations between systemic and cerebral perfusion. This study preliminarily describes the regional distribution of cerebral WMH in the context of a normal cerebral perfusion atlas and aims to determine if these variables are associated with reduced cardiac output. Thirty-two participants (72 ± 8 years old, 38% female) with cardiovascular risk factors or disease underwent structural MRI acquisition at 1.5T using a standard imaging protocol that included FLAIR sequences. WMH distribution was examined in common anatomical space using voxel-based morphometry and as a function of normal cerebral perfusion patterns by overlaying a single photon emission computed tomography (SPECT) atlas. Doppler echocardiogram data was used to dichotomize the participants on the basis of low (n=9) and normal (n=23) cardiac output. Global WMH count and volume did not differ between the low and normal cardiac output groups; however, atlas-derived SPECT perfusion values in regions of hyperintensities were reduced in the low versus normal cardiac output group (p<0.001). Our preliminary data suggest that participants with low cardiac output have WMH in regions of relatively reduced perfusion, while normal cardiac output participants have WMH in regions with relatively higher regional perfusion. This spatial perfusion distribution difference for areas of WMH may occur in the context of reduced systemic perfusion, which subsequently impacts cerebral perfusion and contributes to subclinical or clinical microvascular damage. Copyright © 2009 Elsevier Inc. All rights reserved.

Uptake of Predictive Genetic Testing and Cardiac Evaluation for Children at Risk for an Inherited Arrhythmia or Cardiomyopathy.

PubMed

Christian, Susan; Atallah, Joseph; Clegg, Robin; Giuffre, Michael; Huculak, Cathleen; Dzwiniel, Tara; Parboosingh, Jillian; Taylor, Sherryl; Somerville, Martin

2018-02-01

Predictive genetic testing in minors should be considered when clinical intervention is available. Children who carry a pathogenic variant for an inherited arrhythmia or cardiomyopathy require regular cardiac screening and may be prescribed medication and/or be told to modify their physical activity. Medical genetics and pediatric cardiology charts were reviewed to identify factors associated with uptake of genetic testing and cardiac evaluation for children at risk for long QT syndrome, hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy. The data collected included genetic diagnosis, clinical symptoms in the carrier parent, number of children under 18 years of age, age of children, family history of sudden cardiac arrest/death, uptake of cardiac evaluation and if evaluated, phenotype for each child. We identified 97 at risk children from 58 families found to carry a pathogenic variant for one of these conditions. Sixty six percent of the families pursued genetic testing and 73% underwent cardiac screening when it was recommended. Declining predictive genetic testing was significantly associated with genetic specialist recommendation (p < 0.001) and having an asymptomatic carrier father (p = 0.006). Cardiac evaluation was significantly associated with uptake of genetic testing (p = 0.007). This study provides a greater understanding of factors associated with uptake of genetic testing and cardiac evaluation in children at risk of an inherited arrhythmia or cardiomyopathy. It also identifies a need to educate families about the importance of cardiac evaluation even in the absence of genetic testing.

Validity of cardiac output measurement by the thermodilution method in the presence of acute tricuspid regurgitation.

PubMed

Boerboom, L E; Kinney, T E; Olinger, G N; Hoffmann, R G

1993-10-01

Evaluation of patients with acute tricuspid insufficiency may include assessment of cardiac output by the thermodilution method. The accuracy of estimates of thermodilution-derived cardiac output in the presence of tricuspid insufficiency has been questioned. This study was designed to determine the validity of the thermodilution technique in a canine model of acute reversible tricuspid insufficiency. Cardiac output as measured by thermodilution and electromagnetic flowmeter was compared at two grades of regurgitation. The relationship between these two methods (thermodilution/electromagnetic) changed significantly from a regression slope of 1.01 +/- 0.18 (mean +/- standard deviation) during control conditions to a slope of 0.86 +/- 0.23 (p < 0.02) during severe regurgitation. No significant change was observed between control and mild regurgitation or between the initial control value and a control measurement repeated after tricuspid insufficiency was reversed at the termination of the study. This study shows that in a canine model of severe acute tricuspid regurgitation the thermodilution method underestimates cardiac output by an amount that is proportional to the level of cardiac output and to the grade of regurgitation.

F-18 sodium fluoride PET/CT does not effectively image myocardial inflammation due to suspected cardiac sarcoidosis.

PubMed

Weinberg, Richard L; Morgenstern, Rachelle; DeLuca, Albert; Chen, Jennifer; Bokhari, Sabahat

2017-12-01

Sarcoidosis is an inflammatory disorder of unknown etiology that can involve the heart. While effective in imaging cardiac sarcoidosis, F-18 fluorodeoxyglucose (FDG) PET/CT often shows non-specific myocardial uptake. F-18 sodium fluoride (NaF) has been used to image inflammation in coronary artery plaques and has low background myocardial uptake. Here, we evaluated whether F-18 NaF can image myocardial inflammation due to clinically suspected cardiac sarcoidosis. We performed a single institution pilot study testing if F-18 NaF PET/CT can detect myocardial inflammation in patients with suspected cardiac sarcoidosis. Patients underwent cardiac PET/CT with F-18 FDG as part of their routine care and subsequently received an F-18 NaF PET/CT scan. Three patients underwent F-18 FDG and F-18 NaF imaging. In all patients, there was F-18 FDG uptake consistent with cardiac sarcoidosis. The F-18 NaF PET/CT scans showed no myocardial uptake. In this small preliminary study, PET/CT scan using F-18 NaF does not appear to detect myocardial inflammation caused by suspected cardiac sarcoidosis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gertz, M.A.; Brown, M.L.; Hauser, M.F.

Thirty-four patients with amyloidosis proved by biopsy specimen were studied using technetium Tc 99m pyrophosphate scintigraphy to assess its utility in the diagnosis of amyloid heart involvement. Of 14 patients studied retrospectively, only three had intense uptake judged to be diagnostic of cardiac amyloidosis. In a prospective analysis of 20 patients with amyloidosis, all of whom had evidence of cardiac involvement by two-dimensional echocardiography, 17 had abnormal scans. Fourteen of the 17 scans had only 1+ or 2+ uptake, a finding that also was present in 15 of the 20 control patients (without amyloid heart disease). Only three of themore » 20 patients with cardiac amyloidosis had intense uptake that was considered unequivocal and diagnostic of amyloidosis. Of the five patients with biopsy specimen proof of endomyocardial amyloidosis, only one had intense uptake and one had no uptake. When intense uptake of technetium Tc 99m pyrophosphate is found in the heart of a patient, amyloidosis is highly likely. The technique, however, is not sufficiently sensitive to warrant routine screening of patients with amyloidosis or cardiomyopathies. Cross-sectional echocardiography is superior to pyrophosphate scintigraphy for recognition of cardiac amyloidosis.« less

Use of the single-breath method of estimating cardiac output during exercise-stress testing.

NASA Technical Reports Server (NTRS)

Buderer, M. C.; Rummel, J. A.; Sawin, C. F.; Mauldin, D. G.

1973-01-01

The single-breath cardiac output measurement technique of Kim et al. (1966) has been modified for use in obtaining cardiac output measurements during exercise-stress tests on Apollo astronauts. The modifications involve the use of a respiratory mass spectrometer for data acquisition and a digital computer program for data analysis. The variation of the modified method for triplicate steady-state cardiac output measurements was plus or minus 1 liter/min. The combined physiological and methodological variation seen during a set of three exercise tests on a series of subjects was 1 to 2.5 liter/min. Comparison of the modified method with the direct Fick technique showed that although the single-breath values were consistently low, the scatter of data was small and the correlation between the two methods was high. Possible reasons for the low single-breath cardiac output values are discussed.

A model analysis of arterial oxygen desaturation during apnea in preterm infants.

PubMed

Sands, Scott A; Edwards, Bradley A; Kelly, Vanessa J; Davidson, Malcolm R; Wilkinson, Malcolm H; Berger, Philip J

2009-12-01

Rapid arterial O(2) desaturation during apnea in the preterm infant has obvious clinical implications but to date no adequate explanation for why it exists. Understanding the factors influencing the rate of arterial O(2) desaturation during apnea (Sa(O)₂) is complicated by the non-linear O(2) dissociation curve, falling pulmonary O(2) uptake, and by the fact that O(2) desaturation is biphasic, exhibiting a rapid phase (stage 1) followed by a slower phase when severe desaturation develops (stage 2). Using a mathematical model incorporating pulmonary uptake dynamics, we found that elevated metabolic O(2) consumption accelerates Sa(O)₂throughout the entire desaturation process. By contrast, the remaining factors have a restricted temporal influence: low pre-apneic alveolar P(O)₂causes an early onset of desaturation, but thereafter has little impact; reduced lung volume, hemoglobin content or cardiac output, accelerates Sa(O)₂during stage 1, and finally, total blood O(2) capacity (blood volume and hemoglobin content) alone determines Sa(O)₂during stage 2. Preterm infants with elevated metabolic rate, respiratory depression, low lung volume, impaired cardiac reserve, anemia, or hypovolemia, are at risk for rapid and profound apneic hypoxemia. Our insights provide a basic physiological framework that may guide clinical interpretation and design of interventions for preventing sudden apneic hypoxemia.

Jack Reeves and his science.

PubMed

Moore, Lorna G; Grover, Robert F

2006-04-28

John T. (Jack) Reeves' science is reviewed across the 37 years of his research career at the University of Colorado Health Sciences Center, a period which occupied approximately half his remarkable life. His contributions centered on understanding the inter-relatedness as well as the underlying mechanisms controlling the various components of the O(2) transport system. We review here his studies on exercise performance; these encompassed about half his scientific output with the other half being devoted to the study of hypoxic pulmonary hypertension. Early studies concerned cardiac output, showing how it was a balance between O(2) uptake and O(2) extraction, and that cardiac output during exercise at high altitude was reduced, most likely because of decreased plasma volume and left ventricular filling. Jack's many studies addressed virtually every aspect of the O(2) transport system -- adding significantly to our understanding of the syndromes of altitude illness, the mechanisms by which ventilatory sensitivity to hypoxia and hypercapnia influenced ventilatory acclimatization, and the contributions of the various limbs of the autonomic nervous system on systemic blood pressure, vascular resistance and substrate utilization. His scientific career ended abruptly in 2004 when struck by a car while biking to work, but his legacy remains in his more than 385+ research articles or chapters, the 40+ fellows he trained, and the countless number of younger (and older) scientists for whom he served as a role model for learning how to scrutinize their data and present their findings in clear and sometimes bold prose. An integral man, he is sorely missed.

Noninvasive aortic bloodflow by Pulsed Doppler Echocardiography (PDE) compared to cardiac output by the direct Fick procedure

NASA Technical Reports Server (NTRS)

1980-01-01

Left ventricular stroke volume was estimated from the systolic velocity integral in the ascending aorta by pulsed Doppler Echocardiography (PDE) and the cross sectional area of the aorta estimated by M mode echocardiography on 15 patients with coronary disease undergoing right catheterization for diagnostic purposes. Cardiac output was calculated from stroke volume and heart volume using the PDE method as well as the Fick procedure for comparison. The mean value for the cardiac output via the PDE method (4.42 L/min) was only 6% lower than for the cardiac output obtained from the Fick procedure (4.69 L/min) and the correlation between the two methods was excellent (r=0.967, p less than .01). The good agreement between the two methods demonstrates that the PDE technique offers a reliable noninvasive alternative for estimating cardiac output, requiring no active cooperation by the subject. It was concluded that the Doppler method is superior to the Fick method in that it provides beat by beat information on cardiac performance.

Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements.

PubMed

Ma, Irene W Y; Caplin, Joshua D; Azad, Aftab; Wilson, Christina; Fifer, Michael A; Bagchi, Aranya; Liteplo, Andrew S; Noble, Vicki E

2017-12-01

Non-invasive measures that can accurately estimate cardiac output may help identify volume-responsive patients. This study seeks to compare two non-invasive measures (corrected carotid flow time and carotid blood flow) and their correlations with invasive reference measurements of cardiac output. Consenting adult patients (n = 51) at Massachusetts General Hospital cardiac catheterization laboratory undergoing right heart catheterization between February and April 2016 were included. Carotid ultrasound images were obtained concurrently with cardiac output measurements, obtained by the thermodilution method in the absence of severe tricuspid regurgitation and by the Fick oxygen method otherwise. Corrected carotid flow time was calculated as systole time/√cycle time. Carotid blood flow was calculated as π × (carotid diameter) 2 /4 × velocity time integral × heart rate. Measurements were obtained using a single carotid waveform and an average of three carotid waveforms for both measures. Single waveform measurements of corrected flow time did not correlate with cardiac output (ρ = 0.25, 95% CI -0.03 to 0.49, p = 0.08), but an average of three waveforms correlated significantly, although weakly (ρ = 0.29, 95% CI 0.02-0.53, p = 0.046). Carotid blood flow measurements correlated moderately with cardiac output regardless of if single waveform or an average of three waveforms were used: ρ = 0.44, 95% CI 0.18-0.63, p = 0.004, and ρ = 0.41, 95% CI 0.16-0.62, p = 0.004, respectively. Carotid blood flow may be a better marker of cardiac output and less subject to measurements issues than corrected carotid flow time.

[Measurement of cardiac output by thermodilution with a diode as a temperature sensor].

PubMed

Díaz Fernández, A; Benítez, D; Sánchez Tello, G; Márquez, L A

1979-01-01

An area integrator for the thermodilution curve in cardiac output measurement is described. A new temperature sensor is used, a diode with some advantages over the thermistor normally used. The main advantages are: easy calibration and replacement, and broad range of linearity. The cardiac output values obtained in dog with the integrator follow a linear relationship with those of the flowmeter. In simultaneous measurements the correlation is R = 0.96. Using a diode as temperature sensor a modification of the Steward Hamilton equation (used for thermistor) is necessary. With this new equation a monogram is performed to calculate the cardiac output from the area given by the numerical integrator.

Metabolism and acetylation contribute to leucine-mediated inhibition of cardiac glucose uptake.

PubMed

Renguet, Edith; Ginion, Audrey; Gélinas, Roselle; Bultot, Laurent; Auquier, Julien; Robillard Frayne, Isabelle; Daneault, Caroline; Vanoverschelde, Jean-Louis; Des Rosiers, Christine; Hue, Louis; Horman, Sandrine; Beauloye, Christophe; Bertrand, Luc

2017-08-01

High plasma leucine levels strongly correlate with type 2 diabetes. Studies of muscle cells have suggested that leucine alters the insulin response for glucose transport by activating an insulin-negative feedback loop driven by the mammalian target of rapamycin/p70 ribosomal S6 kinase (mTOR/p70S6K) pathway. Here, we examined the molecular mechanism involved in leucine's action on cardiac glucose uptake. Leucine was indeed able to curb glucose uptake after insulin stimulation in both cultured cardiomyocytes and perfused hearts. Although leucine activated mTOR/p70S6K, the mTOR inhibitor rapamycin did not prevent leucine's inhibitory action on glucose uptake, ruling out the contribution of the insulin-negative feedback loop. α-Ketoisocaproate, the first metabolite of leucine catabolism, mimicked leucine's effect on glucose uptake. Incubation of cardiomyocytes with [ 13 C]leucine ascertained its metabolism to ketone bodies (KBs), which had a similar negative impact on insulin-stimulated glucose transport. Both leucine and KBs reduced glucose uptake by affecting translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Finally, we found that leucine elevated the global protein acetylation level. Pharmacological inhibition of lysine acetyltransferases counteracted this increase in protein acetylation and prevented leucine's inhibitory action on both glucose uptake and GLUT4 translocation. Taken together, these results indicate that leucine metabolism into KBs contributes to inhibition of cardiac glucose uptake by hampering the translocation of GLUT4-containing vesicles via acetylation. They offer new insights into the establishment of insulin resistance in the heart. NEW & NOTEWORTHY Catabolism of the branched-chain amino acid leucine into ketone bodies efficiently inhibits cardiac glucose uptake through decreased translocation of glucose transporter 4 to the plasma membrane. Leucine increases protein acetylation. Pharmacological inhibition of acetylation reverses leucine's action, suggesting acetylation involvement in this phenomenon.Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/leucine-metabolism-inhibits-cardiac-glucose-uptake/. Copyright © 2017 the American Physiological Society.

The relationship between cardiac output and dynamic cerebral autoregulation in humans.

PubMed

Deegan, B M; Devine, E R; Geraghty, M C; Jones, E; Ólaighin, G; Serrador, J M

2010-11-01

Cerebral autoregulation adjusts cerebrovascular resistance in the face of changing perfusion pressures to maintain relatively constant flow. Results from several studies suggest that cardiac output may also play a role. We tested the hypothesis that cerebral blood flow would autoregulate independent of changes in cardiac output. Transient systemic hypotension was induced by thigh-cuff deflation in 19 healthy volunteers (7 women) in both supine and seated positions. Mean arterial pressure (Finapres), cerebral blood flow (transcranial Doppler) in the anterior (ACA) and middle cerebral artery (MCA), beat-by-beat cardiac output (echocardiography), and end-tidal Pco(2) were measured. Autoregulation was assessed using the autoregulatory index (ARI) defined by Tiecks et al. (Tiecks FP, Lam AM, Aaslid R, Newell DW. Stroke 26: 1014-1019, 1995). Cerebral autoregulation was better in the supine position in both the ACA [supine ARI: 5.0 ± 0.21 (mean ± SE), seated ARI: 3.9 ± 0.4, P = 0.01] and MCA (supine ARI: 5.0 ± 0.2, seated ARI: 3.8 ± 0.3, P = 0.004). In contrast, cardiac output responses were not different between positions and did not correlate with cerebral blood flow ARIs. In addition, women had better autoregulation in the ACA (P = 0.046), but not the MCA, despite having the same cardiac output response. These data demonstrate cardiac output does not appear to affect the dynamic cerebral autoregulatory response to sudden hypotension in healthy controls, regardless of posture. These results also highlight the importance of considering sex when studying cerebral autoregulation.

Clinical usefulness of the definitions for defining characteristics of activity intolerance, excess fluid volume and decreased cardiac output in decompensated heart failure: a descriptive exploratory study.

PubMed

de Souza, Vanessa; Zeitoun, Sandra Salloum; Lopes, Camila Takao; de Oliveira, Ana Paula Dias; Lopes, Juliana de Lima; de Barros, Alba Lucia Bottura Leite

2015-09-01

To assess the clinical usefulness of the operational definitions for the defining characteristics of the NANDA International nursing diagnoses, activity intolerance, decreased cardiac output and excess fluid volume, and the concomitant presence of those diagnoses in patients with decompensated heart failure. Content validity of the operational definitions for the defining characteristics of activity intolerance, excess fluid volume and decreased cardiac output have been previously validated by experts. Their clinical usefulness requires clinical validation. This was a descriptive exploratory study. Two expert nurses independently assessed 25 patients with decompensated heart failure for the presence or absence of 29 defining characteristics. Interrater reliability was analysed using the Kappa coefficient as a measure of clinical usefulness. The Fisher's exact test was used to test the association of the defining characteristics of activity intolerance and excess fluid volume in the presence of decreased cardiac output, and the correlation between the three diagnoses. Assessments regarding the presence of all defining characteristics reached 100% agreement, except with anxiety. Five defining characteristics of excess fluid volume were significantly associated with the presence of decreased cardiac output. Concomitant presence of the three diagnoses occurred in 80% of the patients. However, there was no significant correlation between the three diagnoses. The operational definitions for the diagnoses had strong interrater reliability, therefore they were considered clinically useful. Only five defining characteristics were representative of the association between excess fluid volume and decreased cardiac output. Therefore, excess fluid volume is related to decreased cardiac output, although these diagnoses are not necessarily associated with activity intolerance. The operational definitions may favour early recognition of the sequence of responses to decompensation, guiding the choice of common interventions to improve or resolve excess fluid volume and decreased cardiac output. © 2015 John Wiley & Sons Ltd.

Rodent Studies of Cardiovascular Deconditioning

NASA Technical Reports Server (NTRS)

Shoukas, Artin A.

1999-01-01

Changes in blood pressure can occur for two reasons: 1) A decrease in cardiac output resulting from the altered contractility of the heart or through changes in venous filling pressure via the Frank Starling mechanism or; 2) A change in systemic vascular resistance. The observed changes in cardiac output and blood pressure after long term space flight cannot be entirely explained through changes in contractility or heart rate alone. Therefore, alterations in filling pressure mediated through changes in systemic venous capacitance and arterial resistance function may be important determinants of cardiac output and blood pressure after long term space flight. Our laboratory and previous studies have shown the importance of veno-constriction mediated by the carotid sinus baroreceptor reflex system on overall circulatory homeostasis and in the regulation of cardiac output. Our proposed experiments test the overall hypothesis that alterations in venous capacitance function and arterial resistance by the carotid sinus baroreceptor reflex system are an important determinant of the cardiac output and blood pressure response seen in astronauts after returning to earth from long term exposure to microgravity. This hypothesis is important to our overall understanding of circulatory adjustments made during long term space flight. It also provides a framework for investigating counter measures to reduce the incidence of orthostatic hypotension caused by an attenuation of cardiac output. We continue to use hind limb unweighted (HLU) rat model to simulate the patho physiological effects as they relate to cardiovascular deconditioning in microgravity. We have used this model to address the hypothesis that microgravity induced cardiovascular deconditioning results in impaired vascular responses and that these impaired vascular responses result from abnormal alpha-1 AR signaling. The impaired vascular reactivity results in attenuated blood pressure and cardiac output responses to an orthostatic challenge. We have used in vitro vascular reactivity assays to explore abnormalities in vascular responses in vessels from HLU animals and, cardiac output (CO), blood pressure (BP) and heart rate (HR) measurements to characterize changes in hemodynamics following HLU.

Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

PubMed

Drescher, U; Mookerjee, S; Steegmanns, A; Knicker, A; Hoffmann, U

2017-06-01

To evaluate the effects of exercise velocity (60, 150, 240deg∙s -1 ) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO 2 ) following high-intensity concentric-eccentric isokinetic exercise. Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t 1/2 ) for oxygen uptake (V˙O 2 pulm), carbon dioxide output (V˙CO 2 pulm), and ventilation (V˙ E ). Significant differences of the t 1/2 values were identified between 60 and 150deg∙s -1 . Significant differences in the t 1/2 values were observed between V˙O 2 pulm and V˙CO 2 pulm and between V˙CO 2 pulm and V˙ E . The time to attain the first avDO 2 -peak showed significant differences between arm and leg exercise. The present study illustrates, that V˙O 2 pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O 2 pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases. Copyright © 2017 Elsevier B.V. All rights reserved.

Cardiac Remodeling in Response to 1 Year of Intensive Endurance Training

PubMed Central

Arbab-Zadeh, Armin; Perhonen, Merja; Howden, Erin; Peshock, Ronald M.; Zhang, Rong; Adams-Huet, Beverly; Haykowsky, Mark J.; Levine, Benjamin D.

2017-01-01

Background It is unclear whether, and to what extent, the striking cardiac morphological manifestations of endurance athletes are a result of exercise training or a genetically determined characteristic of talented athletes. We hypothesized that prolonged and intensive endurance training in previously sedentary healthy young individuals could induce cardiac remodeling similar to that observed cross-sectionally in elite endurance athletes. Methods and Results Twelve previously sedentary subjects (aged 29±6 years; 7 men and 5 women) trained progressively and intensively for 12 months such that they could compete in a marathon. Magnetic resonance images for assessment of right and left ventricular mass and volumes were obtained at baseline and after 3, 6, 9, and 12 months of training. Maximum oxygen uptake (V̇o2 max) and cardiac output at rest and during exercise (C2H2 rebreathing) were measured at the same time periods. Pulmonary artery catheterization was performed before and after 1 year of training, and pressure-volume and Starling curves were constructed during decreases (lower body negative pressure) and increases (saline infusion) in cardiac volume. Mean V̇o2 max rose from 40.3±1.6 to 48.7±2.5 mL/kg per minute after 1 year (P<0.00001), associated with an increase in both maximal cardiac output and stroke volume. Left and right ventricular mass increased progressively with training duration and intensity and reached levels similar to those observed in elite endurance athletes. In contrast, left ventricular volume did not change significantly until 6 months of training, although right ventricular volume increased progressively from the outset; Starling and pressure-volume curves approached but did not match those of elite athletes. Conclusions One year of prolonged and intensive endurance training leads to cardiac morphological adaptations in previously sedentary young subjects similar to those observed in elite endurance athletes; however, it is not sufficient to achieve similar levels of cardiac compliance and performance. Contrary to conventional thinking, the left ventricle responds to exercise with initial concentric but not eccentric remodeling during the first 6 to 9 months after commencement of endurance training depending on the duration and intensity of exercise. Thereafter, the left ventricle dilates and restores the baseline mass-to-volume ratio. In contrast, the right ventricle responds to endurance training with eccentric remodeling at all levels of training. PMID:25281664

Diabetic db/db mice do not develop heart failure upon pressure overload: a longitudinal in vivo PET, MRI, and MRS study on cardiac metabolic, structural, and functional adaptations.

PubMed

Abdurrachim, Desiree; Nabben, Miranda; Hoerr, Verena; Kuhlmann, Michael T; Bovenkamp, Philipp; Ciapaite, Jolita; Geraets, Ilvy M E; Coumans, Will; Luiken, Joost J F P; Glatz, Jan F C; Schäfers, Michael; Nicolay, Klaas; Faber, Cornelius; Hermann, Sven; Prompers, Jeanine J

2017-08-01

Heart failure is associated with altered myocardial substrate metabolism and impaired cardiac energetics. Comorbidities like diabetes may influence the metabolic adaptations during heart failure development. We quantified to what extent changes in substrate preference, lipid accumulation, and energy status predict the longitudinal development of hypertrophy and failure in the non-diabetic and the diabetic heart. Transverse aortic constriction (TAC) was performed in non-diabetic (db/+) and diabetic (db/db) mice to induce pressure overload. Magnetic resonance imaging, 31P magnetic resonance spectroscopy (MRS), 1H MRS, and 18F-fluorodeoxyglucose-positron emission tomography (PET) were applied to measure cardiac function, energy status, lipid content, and glucose uptake, respectively. In vivo measurements were complemented with ex vivo techniques of high-resolution respirometry, proteomics, and western blotting to elucidate the underlying molecular pathways. In non-diabetic mice, TAC induced progressive cardiac hypertrophy and dysfunction, which correlated with increased protein kinase D-1 (PKD1) phosphorylation and increased glucose uptake. These changes in glucose utilization preceded a reduction in cardiac energy status. At baseline, compared with non-diabetic mice, diabetic mice showed normal cardiac function, higher lipid content and mitochondrial capacity for fatty acid oxidation, and lower PKD1 phosphorylation, glucose uptake, and energetics. Interestingly, TAC affected cardiac function only mildly in diabetic mice, which was accompanied by normalization of phosphorylated PKD1, glucose uptake, and cardiac energy status. The cardiac metabolic adaptations in diabetic mice seem to prevent the heart from failing upon pressure overload, suggesting that restoring the balance between glucose and fatty acid utilization is beneficial for cardiac function. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.

Relationship between cardiac function and resting cerebral blood flow: MRI measurements in healthy elderly subjects.

PubMed

Henriksen, Otto M; Jensen, Lars T; Krabbe, Katja; Larsson, Henrik B W; Rostrup, Egill

2014-11-01

Although both impaired cardiac function and reduced cerebral blood flow are associated with ageing, current knowledge of the influence of cardiac function on resting cerebral blood flow (CBF) is limited. The aim of this study was to investigate the potential effects of cardiac function on CBF. CBF and cardiac output were measured in 31 healthy subjects 50-75 years old using magnetic resonance imaging techniques. Mean values of CBF, cardiac output and cardiac index were 43.6 ml per 100 g min(-1), 5.5 l min(-1) and 2.7 l min(-1) m(-2), respectively, in males, and 53.4 ml per 100 g min(-1), 4.3 l min(-1) and 2.4 l min(-1) m(-2), respectively, in females. No effects of cardiac output or cardiac index on CBF or structural signs of brain ageing were observed. However, fractional brain flow defined as the ratio of total brain flow to cardiac output was inversely correlated with cardiac index (r(2) = 0.22, P = 0.008) and furthermore lower in males than in females (8.6% versus 12.5%, P = 0.003). Fractional brain flow was also inversely correlated with cerebral white matter lesion grade, although this effect was not significant when adjusted for age. Frequency analysis of heart rate variability showed a gender-related inverse association of increased low-to-high-frequency power ratio with CBF and fractional brain flow. The findings do not support a direct effect of cardiac function on CBF, but demonstrates gender-related differences in cardiac output distribution. We propose fractional brain flow as a novel index that may be a useful marker of adequate brain perfusion in the context of ageing as well as cardiovascular disease. © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Cardiac function and exercise adaptation in 8 children with LPIN1 mutations.

PubMed

Legendre, Antoine; Khraiche, Diala; Ou, Phalla; Mauvais, François-Xavier; Madrange, Marine; Guemann, Anne-Sophie; Jais, Jean-Philippe; Bonnet, Damien; Hamel, Yamina; de Lonlay, Pascale

2018-03-01

Lipin-1 deficiency is a major cause of rhabdomyolysis that are precipitated by febrile illness. The prognosis is poor, with one-third of patients dying from cardiac arrest during a crisis episode. Apart from acute rhabdomyolysis, most patients are healthy, showing normal clinical and cardiac ultrasound parameters. We report cardiac and exercise examinations of 8 children carrying two LPIN1 mutations. The examinations were performed outside of a myolysis episode, but one patient presented with fever during one examination. All but one patient displayed normal resting cardiac function, as determined by echocardiography. One patient exhibited slight left ventricular dysfunction at rest and a lack of increased stroke volume during cycle ramp exercise. During exercise, peripheral muscle adaptation was impaired in 2 patients compared to healthy controls: they presented an abnormal increase in cardiac output relative to oxygen uptake: dQ/dVO 2 =8.2 and 9.5 (>2DS of controls population). One patient underwent 2 exercise tests; during one test, the patient was febrile, leading to acute rhabdomyolysis in the following hours. He exhibited changes in recovery muscle reoxygenation parameters and an increased dQ/dVO 2 during exercise compared with that under normothermia (7.9 vs 6), which did not lead to acute rhabdomyolysis. The four patients assessed by cardiac 1 H-magnetic resonance spectroscopy exhibited signs of intracardiac steatosis. We observed abnormal haemodynamic profiles during exercise in 3/8 patients with lipin-1 deficiency, suggesting impaired muscle oxidative phosphorylation during exercise. Fever appeared to be an aggravating factor. One patient exhibited moderate cardiac dysfunction, which was possibly related to intracardiac stored lipid toxicity. Copyright © 2018 Elsevier Inc. All rights reserved.

Postoperative Hydrocortisone Infusion Reduces the Prevalence of Low Cardiac Output Syndrome After Neonatal Cardiopulmonary Bypass.

PubMed

Robert, Stephen M; Borasino, Santiago; Dabal, Robert J; Cleveland, David C; Hock, Kristal M; Alten, Jeffrey A

2015-09-01

Neonatal cardiac surgery with cardiopulmonary bypass is often complicated by morbidity associated with inflammation and low cardiac output syndrome. Hydrocortisone "stress dosing" is reported to provide hemodynamic benefits in some patients with refractory shock. Development of cardiopulmonary bypass-induced adrenal insufficiency may provide further rationale for postoperative hydrocortisone administration. We sought to determine whether prophylactic, postoperative hydrocortisone infusion could decrease prevalence of low cardiac output syndrome after neonatal cardiac surgery with cardiopulmonary bypass. Double-blind, randomized control trial. Pediatric cardiac ICU and operating room in tertiary care center. Forty neonates undergoing cardiac surgery with cardiopulmonary bypass were randomized (19 hydrocortisone and 21 placebo). Demographics and known risk factors were similar between groups. After cardiopulmonary bypass separation, bolus hydrocortisone (50 mg/m²) or placebo was administered, followed by continuous hydrocortisone infusion (50 mg/m²/d) or placebo tapered over 5 days. Adrenocorticotropic hormone stimulation testing (1 μg) was performed before and after cardiopulmonary bypass, prior to steroid administration. Blood was collected for cytokine analysis before and after cardiopulmonary bypass. Subjects receiving hydrocortisone were less likely to develop low cardiac output syndrome (5/19, 26% vs 12/21, 57%; p = 0.049). Hydrocortisone group had more negative net fluid balance at 48 hours (-114 vs -64 mL/kg; p = 0.01) and greater urine output at 0-24 hours (2.7 vs 1.2 mL/kg/hr; p = 0.03). Hydrocortisone group weaned off catecholamines and vasopressin sooner than placebo, with a difference in inotrope-free subjects apparent after 48 hours (p = 0.033). Five placebo subjects (24%) compared with no hydrocortisone subjects required rescue steroids (p = 0.02). Thirteen (32.5%) had adrenal insufficiency after cardiopulmonary bypass. Patients with adrenal insufficiency randomized to receive hydrocortisone had lower prevalence of low cardiac output syndrome compared with patients with adrenal insufficiency randomized to placebo (1/6 vs 6/7, respectively; p = 0.02). Hydrocortisone significantly reduced proinflammatory cytokines. Ventilator-free days, hospital length of stay, and kidney injury were similar. Prophylactic, postoperative hydrocortisone reduces low cardiac output syndrome, improves fluid balance and urine output, and attenuates inflammation after neonatal cardiopulmonary bypass surgery. Further studies are necessary to show if these benefits lead to improvements in more important clinical outcomes.

Heterogeneous response of cardiac sympathetic function to cardiac resynchronization therapy in heart failure documented by 11[C]-hydroxy-ephedrine and PET/CT.

PubMed

Capitanio, Selene; Nanni, Cristina; Marini, Cecilia; Bonfiglioli, Rachele; Martignani, Cristian; Dib, Bassam; Fuccio, Chiara; Boriani, Giuseppe; Picori, Lorena; Boschi, Stefano; Morbelli, Silvia; Fanti, Stefano; Sambuceti, Gianmario

2015-11-01

Cardiac resynchronization therapy (CRT) is an accepted treatment in patients with end-stage heart failure. PET permits the absolute quantification of global and regional homogeneity in cardiac sympathetic innervation. We evaluated the variation of cardiac adrenergic activity in patients with idiopathic heart failure (IHF) disease (NYHA III-IV) after CRT using (11)C-hydroxyephedrine (HED) PET/CT. Ten IHF patients (mean age = 68; range = 55-81; average left ventricular ejection fraction 26 ± 4%) implanted with a resynchronization device underwent three HED PET/CT studies: PET 1 one week after inactive device implantation; PET 2, one week after PET 1 under stimulated rhythm; PET 3, at 3 months under active CRT. A dedicated software (PMOD 3.4 version) was used to estimate global and regional cardiac uptake of HED through 17 segment polar maps. At baseline, HED uptake was heterogeneously distributed throughout the left ventricle with a variation coefficient of 18 ± 5%. This variable markedly decreased after three months CRT (12 ± 5%, p < 0.01). Interestingly, subdividing the 170 myocardial segments (17 segments of each patient multiplied by the number of patients) into two groups, according to the median value of tracer uptake expressed as % of maximal myocardial uptake (76%), we observed a different behaviour depending on baseline innervation: HED uptake significantly increased only in segments with "impaired innervation" (SUV 2.61 ± 0.92 at PET1 and 3.05 ± 1.67 at three months, p < 0.01). As shown by HED PET/CT uptake and distribution, improvement in homogeneity of myocardial neuronal function reflected a selective improvement of tracer uptake in regions with more severe neuronal damage. These finding supported the presence of a myocardial regional variability in response of cardiac sympathetic system to CRT and a systemic response involving remote tissues with rich adrenergic innervation. This work might contribute to identify imaging parameters that could predict the response to CRT therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

Infused cardioplegia index: A new tool to improve myocardial protection. A cohort study.

PubMed

Jiménez Rivera, J J; Llanos Jorge, C; Iribarren Sarrías, J L; Brouard Martín, M; Lacalzada Almeida, J; Pérez Vela, J L; Avalos Pinto, R; Pérez Hernández, R; Ramos de la Rosa, S; Yanes Bowden, G; Martínez Sanz, R

2018-05-19

Strategies for cardio-protection are essential in coronary artery bypass graft surgery. The authors explored the relationship between cardioplegia volume, left ventricular mass index and ischemia time by means of the infused cardioplegia index and its relationship with post-operative low cardiac output syndrome. All patients undergoing coronary artery bypass graft surgery between January 2013 and December 2015 were included. Low cardiac output syndrome was defined according to criteria of the SEMICYUC's consensus document. The perioperative factors associated with low cardiac output syndrome were estimated, and using a ROC curve, the optimum cut-off point for the infused cardioplegia index to predict the absence of low cardiac output syndrome was calculated. Of 360 patients included, 116 (32%) developed low cardiac output syndrome. The independent risk predictors were: New York Heart Association Functional Classification (OR 1.8 [95% CI=1.18-2.55]), left ventricle ejection fraction (OR 0.95 (95% CI=0.93-0.98]), ICI (OR 0.99 [95% CI=0.991-0.996]) and retrograde cardioplegia (OR 1.2 [95% CI=1.03-1.50]). The infused cardioplegia index showed an area under the ROC curve of 0.77 (0.70-0.83; P<.001) for the absence of postoperative low cardiac output syndrome using the optimum cut-off point of 23.6ml·min -1 (100g/m 2 of LV) -1 . The infused cardioplegia index presents an inverse relationship with the development of post-operative low cardiac output syndrome. This index could form part of new strategies aimed at optimising cardio-protection. The total volume of intermittent cardioplegia, especially that of maintenance, should probably be individualised, adjusting for ischemia time and left ventricle mass index. Copyright © 2018 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Focal Reduction in Cardiac 123I-Metaiodobenzylguanidine Uptake in Patients With Anderson-Fabry Disease.

PubMed

Yamamoto, Saori; Suzuki, Hideaki; Sugimura, Koichiro; Tatebe, Shunsuke; Aoki, Tatsuo; Miura, Masanobu; Yaoita, Nobuhiro; Sato, Haruka; Kozu, Katuya; Ota, Hideki; Takanami, Kentaro; Takase, Kei; Shimokawa, Hiroaki

2016-11-25

It remains to be elucidated whether cardiac sympathetic nervous activity is impaired in patients with Anderson-Fabry disease (AFD).Methods and Results:We performed 123 I-meta-iodobenzylguanidine (MIBG) scintigraphy and gadolinium-enhanced cardiovascular magnetic resonance (CMR) in 5 AFD patients. MIBG uptake in the inferolateral wall, where wall thinning and delayed enhancement were noted on CMR, was significantly lower compared with the anteroseptal wall. The localized reduction in MIBG uptake was also noted in 2 patients with no obvious abnormal findings on CMR. Cardiac sympathetic nervous activity is impaired in AFD before development of structural myocardial abnormalities. (Circ J 2016; 80: 2550-2551).

Heart Performance Determination by Visualization in Larval Fishes: Influence of Alternative Models for Heart Shape and Volume

PubMed Central

Perrichon, Prescilla; Grosell, Martin; Burggren, Warren W.

2017-01-01

Understanding cardiac function in developing larval fishes is crucial for assessing their physiological condition and overall health. Cardiac output measurements in transparent fish larvae and other vertebrates have long been made by analyzing videos of the beating heart, and modeling this structure using a conventional simple prolate spheroid shape model. However, the larval fish heart changes shape during early development and subsequent maturation, but no consideration has been made of the effect of different heart geometries on cardiac output estimation. The present study assessed the validity of three different heart models (the “standard” prolate spheroid model as well as a cylinder and cone tip + cylinder model) applied to digital images of complete cardiac cycles in larval mahi-mahi and red drum. The inherent error of each model was determined to allow for more precise calculation of stroke volume and cardiac output. The conventional prolate spheroid and cone tip + cylinder models yielded significantly different stroke volume values at 56 hpf in red drum and from 56 to 104 hpf in mahi. End-diastolic and stroke volumes modeled by just a simple cylinder shape were 30–50% higher compared to the conventional prolate spheroid. However, when these values of stroke volume multiplied by heart rate to calculate cardiac output, no significant differences between models emerged because of considerable variability in heart rate. Essentially, the conventional prolate spheroid shape model provides the simplest measurement with lowest variability of stroke volume and cardiac output. However, assessment of heart function—especially if stroke volume is the focus of the study—should consider larval heart shape, with different models being applied on a species-by-species and developmental stage-by-stage basis for best estimation of cardiac output. PMID:28725199

Correlations between near-infrared spectroscopy, perfusion index, and cardiac outputs in extremely preterm infants in the first 72 h of life.

PubMed

Janaillac, Marie; Beausoleil, Thierry P; Barrington, Keith J; Raboisson, Marie-Josée; Karam, Oliver; Dehaes, Mathieu; Lapointe, Anie

2018-04-01

Haemodynamic assessment during the transitional period in preterm infants is challenging. We aimed to describe the relationships between cerebral regional tissue oxygen saturation (CrSO 2 ), perfusion index (PI), echocardiographic, and clinical parameters in extremely preterm infants in their first 72 h of life. Twenty newborns born at < 28 weeks of gestation were continuously monitored with CrSO 2 and preductal PI. Cardiac output was measured at H6, H24, H48, and H72. The median gestational age and birth weight were 25.0 weeks (24-26) and 750 g (655-920), respectively. CrSO 2 and preductal PI had r values < 0.35 with blood gases, lactates, haemoglobin, and mean blood pressure. Cardiac output significantly increased over the 72 h of the study period. Fifteen patients had at least one episode of low left and/or right ventricular output (RVO), during which there was a strong correlation between CrSO 2 and superior vena cava (SVC) flow (at H6 (r = 0.74) and H24 (r = 0.86)) and between PI and RVO (at H6 (r = 0.68) and H24 (r = 0.92)). Five patients had low SVC flow (≤ 40 mL/kg/min) at H6, during which PI was strongly correlated with RVO (r = 0.98). CrSO 2 and preductal PI are strongly correlated with cardiac output during low cardiac output states. What is Known: • Perfusion index and near-infrared spectroscopy are non-invasive tools to evaluate haemodynamics in preterm infants. • Pre- and postductal perfusion indexes strongly correlate with left ventricular output in term infants, and near-infrared spectroscopy has been validated to assess cerebral oxygenation in term and preterm infants. What is New: • Cerebral regional tissue oxygen saturation and preductal perfusion index were strongly correlated with cardiac output during low cardiac output states. • The strength of the correlation between cerebral regional tissue oxygen saturation, preductal perfusion index, and cardiac output varied in the first 72 h of life, reflecting the complexity of the transitional physiology.

Odour identification test and its relation to cardiac 123I‐metaiodobenzylguanidine in patients with drug induced parkinsonism

PubMed Central

Lee, Phil Hyu; Yeo, Seung Hyeon; Yong, Seok Woo; Kim, Yun Joong

2007-01-01

We investigated olfactory function and its relation to cardiac 123I‐metaiodobenzylguanidine (MIBG) uptake in 15 patients with drug induced parkinsonism (DIP). The mean Cross Cultural Smell Identification (CCSI) score was significantly greater in patients with DIP than in those with Parkinson's disease (PD: 6.9 (1.6) vs 4.4 (2.2); p<0.001); however, the mean CCSI score in patients with DIP was not significantly different from controls. One patient with DIP, whose CCSI score was significantly reduced, also exhibited decreased cardiac MIBG uptake. DIP patients with CCSI scores within the normal range had normal cardiac MIBG uptake. Our study suggests that an olfactory function test may be a useful tool for detecting DIP unrelated to PD and for identifying patients with DIP who have subclinical PD. PMID:17557797

Intracoronary glucagon-like peptide 1 preferentially augments glucose uptake in ischemic myocardium independent of changes in coronary flow.

PubMed

Moberly, Steven P; Berwick, Zachary C; Kohr, Meredith; Svendsen, Mark; Mather, Kieren J; Tune, Johnathan D

2012-03-01

We examined the acute dose-dependent effects of intracoronary glucagon-like peptide (GLP)-1 (7-36) on coronary vascular tone, cardiac contractile function and metabolism in normal and ischemic myocardium. Experiments were conducted in open chest, anesthetized dogs at coronary perfusion pressures (CPP) of 100 and 40 mmHg before and during intracoronary GLP-1 (7-36) infusion (10 pmol/L to 1 nmol/L). Isometric tension studies were also conducted in isolated coronary arteries. Cardiac and coronary expression of GLP-1 receptors (GLP-1R) was assessed by Western blot and immunohistochemical analysis. GLP-1R was present in the myocardium and the coronary vasculature. The tension of intact and endothelium-denuded coronary artery rings was unaffected by GLP-1. At normal perfusion pressure (100 mmHg), intracoronary GLP-1 (7-36) (targeting plasma concentration 10 pmol/L to 1 nmol/L) did not affect blood pressure, coronary blood flow or myocardial oxygen consumption (MVO(2)); however, there were modest reductions in cardiac output and stroke volume. In untreated control hearts, reducing CPP to 40 mmHg produced marked reductions in coronary blood flow (0.50 ± 0.10 to 0.17 ± 0.03 mL/min/g; P < 0.001) and MVO(2) (27 ± 2.3 to 15 ± 2.7 μL O(2)/min/g; P < 0.001). At CPP = 40 mmHg, GLP-1 had no effect on coronary blood flow, MVO(2) or regional shortening, but dose-dependently increased myocardial glucose uptake from 0.11 ± 0.02 μmol/min/g at baseline to 0.17 ± 0.04 μmol/min/g at 1 nmol/L GLP-1 (P < 0.001). These data indicate that acute, intracoronary administration of GLP-1 (7-36) preferentially augments glucose metabolism in ischemic myocardium, independent of effects on cardiac contractile function or coronary blood flow.

Non-invasive cardiac output trending during exercise recovery on a bathroom-scale-based ballistocardiograph.

PubMed

Inan, O T; Etemadi, M; Paloma, A; Giovangrandi, L; Kovacs, G T A

2009-03-01

Cardiac ejection of blood into the aorta generates a reaction force on the body that can be measured externally via the ballistocardiogram (BCG). In this study, a commercial bathroom scale was modified to measure the BCGs of nine healthy subjects recovering from treadmill exercise. During the recovery, Doppler echocardiogram signals were obtained simultaneously from the left ventricular outflow tract of the heart. The percentage changes in root-mean-square (RMS) power of the BCG were strongly correlated with the percentage changes in cardiac output measured by Doppler echocardiography (R(2) = 0.85, n = 275 data points). The correlation coefficients for individually analyzed data ranged from 0.79 to 0.96. Using Bland-Altman methods for assessing agreement, the mean bias was found to be -0.5% (+/-24%) in estimating the percentage changes in cardiac output. In contrast to other non-invasive methods for trending cardiac output, the unobtrusive procedure presented here uses inexpensive equipment and could be performed without the aid of a medical professional.

Comparative evaluation of 18F-FLT and 18F-FDG for detecting cardiac and extra-cardiac thoracic involvement in patients with newly diagnosed sarcoidosis.

PubMed

Norikane, Takashi; Yamamoto, Yuka; Maeda, Yukito; Noma, Takahisa; Dobashi, Hiroaki; Nishiyama, Yoshihiro

2017-08-29

18 F-FDG PET has been used in sarcoidosis for diagnosis and determination of the extent of the disease. However, assessing inflammatory lesions in cardiac sarcoidosis using 18 F-FDG can be challenging because it accumulates physiologically in normal myocardium. Another radiotracer, 3'-deoxy-3'- 18 F-fluorothymidine ( 18 F-FLT), has been investigated as a promising PET tracer for evaluating tumor proliferative activity. In contrast to 18 F-FDG, 18 F-FLT uptake in the normal myocardium is low. The purpose of this retrospective study was to compare the uptake of 18 F-FLT and 18 F-FDG in the evaluation of cardiac and extra-cardiac thoracic involvement in patients with newly diagnosed sarcoidosis. Data for 20 patients with newly diagnosed sarcoidosis were examined. 18 F-FLT and 18 F-FDG PET/CT studies had been performed at 1 h after each radiotracer injection. The patients had fasted for at least 18 h before 18 F-FDG PET/CT but were given no special dietary instructions regarding the period before 18 F-FLT PET/CT. Uptake of 18 F-FLT and 18 F-FDG was examined visually and semiquantitatively using maximal standardized uptake value (SUVmax). Two patients had cardiac sarcoidosis, 7 had extra-cardiac thoracic sarcoidosis, and 11 had both cardiac and extra-cardiac thoracic sarcoidosis. On visual analysis for diagnosis of cardiac sarcoidosis, 4/20 18 F-FDG scans were rated as inconclusive because the 18 F-FDG pattern was diffuse, whereas no FLT scans were rated as inconclusive. The sensitivity of 18 F-FDG PET/CT for detection of cardiac sarcoidosis was 85%; specificity, 100%; and accuracy, 90%. The corresponding values for 18 F-FLT PET/CT were 92, 100, and 95%, respectively. Using semiquantitative analysis of cardiac sarcoidosis, the mean 18 F-FDG SUVmax was significantly higher than the mean 18 F-FLT SUVmax (P < 0.005). Both 18 F-FDG and 18 F-FLT PET/CT studies detected all 24 extra-cardiac lesions. Using semiquantitative analysis of extra-cardiac sarcoidosis, the mean 18 F-FDG SUVmax was significantly higher than the mean 18 F-FLT SUVmax (P < 0.001). The results of this preliminary study suggest that 18 F-FLT PET/CT can detect cardiac and extra-cardiac thoracic involvement in patients with newly diagnosed sarcoidosis as well as 18 F-FDG PET/CT, although uptake of 18 F-FLT in lesions was significantly lower than that of 18 F-FDG. However, 18 F-FLT PET/CT may be easier to perform since it requires neither prolonged fasting nor a special diet prior to imaging.

Oxygen removal from water versus arterial oxygen delivery: calibrating the Fick equation in Pacific salmon.

PubMed

Farrell, Anthony P; Eliason, Erika J; Clark, Timothy D; Steinhausen, Maria F

2014-10-01

While it is well known that O2 is directly removed from the water by skin and gill tissues of fish, the mismatch between O2 removal from water (O2 uptake; [Formula: see text]) and the O2 delivered to tissues by the primary circulation (O2 consumption; [Formula: see text]) has never been measured directly. Using data from four recent studies that simultaneously measured [Formula: see text] and [Formula: see text] in 2-5 kg Pacific salmon, our analysis revealed that sockeye salmon can remove an additional 12-48 % more O2 from the water than the primary circulation delivers to the systemic tissues. This percentage did not change significantly during swimming activity, a result that contradicts an earlier prediction that the difference should decrease when [Formula: see text] increases during exercise. In resting Chinook salmon, a similar percentage difference in simultaneously measured [Formula: see text] and [Formula: see text] was observed, yet the difference tended to disappear during acute heat stress to a near lethal temperature. These results emphasize that caution should be exercised when using the Fick equation to estimate cardiac output because the overestimate of cardiac output that results from using the Fick equation in Pacific salmon is not small, may not be fixed and may exist in other teleosts.

21 CFR 870.1220 - Electrode recording catheter or electrode recording probe.

Code of Federal Regulations, 2010 CFR

2010-04-01

... electrocardiogram, or to detect cardiac output or left-to-right heart shunts. The device may be unipolar or... a special indicator for cardiac output or left-to-right heart shunt determinations. (b...

21 CFR 870.1220 - Electrode recording catheter or electrode recording probe.

Code of Federal Regulations, 2011 CFR

2011-04-01

... electrocardiogram, or to detect cardiac output or left-to-right heart shunts. The device may be unipolar or... a special indicator for cardiac output or left-to-right heart shunt determinations. (b...

21 CFR 870.1220 - Electrode recording catheter or electrode recording probe.

Code of Federal Regulations, 2012 CFR

2012-04-01

... electrocardiogram, or to detect cardiac output or left-to-right heart shunts. The device may be unipolar or... a special indicator for cardiac output or left-to-right heart shunt determinations. (b...

21 CFR 870.1220 - Electrode recording catheter or electrode recording probe.

Code of Federal Regulations, 2013 CFR

2013-04-01

... electrocardiogram, or to detect cardiac output or left-to-right heart shunts. The device may be unipolar or... a special indicator for cardiac output or left-to-right heart shunt determinations. (b...

21 CFR 870.1220 - Electrode recording catheter or electrode recording probe.

Code of Federal Regulations, 2014 CFR

2014-04-01

... electrocardiogram, or to detect cardiac output or left-to-right heart shunts. The device may be unipolar or... a special indicator for cardiac output or left-to-right heart shunt determinations. (b...

Determination of Cardiac Output and Ejection Fraction with the Dual Cardiac Probe

PubMed Central

Cardenas, Carlos G.; Depuey, E. Gordon; Thompson, Wayne L.; Garcia, Efrain; Burdine, John A.

1983-01-01

Cardiac output and left ventricular ejection fraction were determined noninvasively at the bedside in 26 patients by using a dual scintillation probe. The probe is a nonimaging detector that records a high frequency time-activity curve of the passage of an intravenously injected radioactive bolus through the heart. Results were correlated with ejection fraction measured by biplane cineangiography (r = 0.80) and cardiac output determined by green dye dilution (R = 0.86). It is concluded that the dual probe provides an accurate noninvasive means of measuring these parameters, and that it may be particularly applicable to serial measurements in patients in the intensive care unit. Images PMID:15227151

Characteristics of patients with a relatively greater minimum VE/VCO2 against peak VO2% and impaired exercise tolerance.

PubMed

Nakade, Taisuke; Adachi, Hitoshi; Murata, Makoto; Oshima, Shigeru

2018-05-14

Cardiopulmonary exercise testing (CPX) is used to evaluate functional capacity and assess prognosis in cardiac patients. Ventilatory efficiency (VE/VCO 2 ) reflects ventilation-perfusion mismatch; the minimum VE/VCO 2 value (minVE/VCO 2 ) is representative of pulmonary arterial blood flow in individuals without pulmonary disease. Usually, minVE/VCO 2 has a strong relationship with the peak oxygen uptake (VO 2 ), but dissociation can occur. Therefore, we investigated the relationship between minVE/VCO 2 and predicted peak VO 2 (peak VO 2 %) and evaluated the parameters associated with a discrepancy between these two parameters. A total of 289 Japanese patients underwent CPX using a cycle ergometer with ramp protocols between 2013 and 2014. Among these, 174 patients with a peak VO 2 % lower than 70% were enrolled. Patients were divided into groups based on their minVE/VCO 2 [Low group: minVE/VCO 2  < mean - SD (38.8-5.6); High group: minVE/VCO 2  > mean + SD (38.8 + 5.6)]. The characteristics and cardiac function at rest, evaluated using echocardiography, were compared between groups. The High group had a significantly lower ejection fraction, stroke volume, and cardiac output, and higher brain natriuretic peptide, tricuspid regurgitation pressure gradient, right ventricular systolic pressure, and peak early diastolic LV filling velocity/peak atrial filling velocity ratio compared with the Low group (p's < 0.01). In addition, the Low group had a significantly higher prevalence of pleural effusion than did the High group (26 vs 11%, p < 0.01). Patients with a relatively greater minVE/VCO 2 in comparison with peak VO 2 had impaired cardiac output as well as restricted pulmonary blood flow increase during exercise, partly due to accumulated pleural effusion.

5'-AMP-activated protein kinase increases glucose uptake independent of GLUT4 translocation in cardiac myocytes.

PubMed

Lee, Christopher T; Ussher, John R; Mohammad, Askar; Lam, Anna; Lopaschuk, Gary D

2014-04-01

Glucose uptake and glycolysis are increased in the heart during ischemia, and this metabolic alteration constitutes an important contributing factor towards ischemic injury. Therefore, it is important to understand glucose uptake regulation in the ischemic heart. There are primarily 2 glucose transporters controlling glucose uptake into cardiac myocytes: GLUT1 and GLUT4. In the non-ischemic heart, insulin stimulates GLUT4 translocation to the sarcolemmal membrane, while both GLUT1 and GLUT4 translocation can occur following AMPK stimulation. Using a newly developed technique involving [(3)H]2-deoxyglucose, we measured glucose uptake in H9c2 ventricular myoblasts, and demonstrated that while insulin has no detectable effect on glucose uptake, phenformin-induced AMPK activation increases glucose uptake 2.5-fold. Furthermore, insulin treatment produced no discernible effect on either Akt serine 473 phosphorylation or AMPKα threonine 172 phosphorylation, while treatment with phenformin results in an increase in AMPKα threonine 172 phosphorylation, and a decrease in Akt serine 473 phosphorylation. Visualization of a dsRed-GLUT4 fusion construct in H9c2 cells by laser confocal microscopy showed that unlike insulin, AMPK activation did not redistribute GLUT4 to the sarcolemmal membrane, suggesting that AMPK may regulate glucose uptake via another glucose transporter. These studies suggest that AMPK is a major regulator of glucose uptake in cardiac myocytes.

Functional impairment of skeletal muscle oxidative metabolism during knee extension exercise after bed rest.

PubMed

Salvadego, Desy; Lazzer, Stefano; Marzorati, Mauro; Porcelli, Simone; Rejc, Enrico; Simunic, Bostjan; Pisot, Rado; di Prampero, Pietro Enrico; Grassi, Bruno

2011-12-01

A functional evaluation of skeletal muscle oxidative metabolism during dynamic knee extension (KE) incremental exercises was carried out following a 35-day bed rest (BR) (Valdoltra 2008 BR campaign). Nine young male volunteers (age: 23.5 ± 2.2 yr; mean ± SD) were evaluated. Pulmonary gas exchange, heart rate and cardiac output (by impedance cardiography), skeletal muscle (vastus lateralis) fractional O(2) extraction, and brain (frontal cortex) oxygenation (by near-infrared spectroscopy) were determined during incremental KE. Values at exhaustion were considered "peak". Peak heart rate (147 ± 18 beats/min before vs. 146 ± 17 beats/min after BR) and peak cardiac output (17.8 ± 3.3 l/min before vs. 16.1 ± 1.8 l/min after BR) were unaffected by BR. As expected, brain oxygenation did not decrease during KE. Peak O(2) uptake was lower after vs. before BR, both when expressed as liters per minute (0.99 ± 0.17 vs. 1.26 ± 0.27) and when normalized per unit of quadriceps muscle mass (46.5 ± 6.4 vs. 56.9 ± 11.0 ml·min(-1)·100 g(-1)). Skeletal muscle peak fractional O(2) extraction, expressed as a percentage of the maximal values obtained during a transient limb ischemia, was lower after (46.3 ± 12.1%) vs. before BR (66.5 ± 11.2%). After elimination, by the adopted exercise protocol, of constraints related to cardiovascular O(2) delivery, a decrease in peak O(2) uptake and muscle peak capacity of fractional O(2) extraction was found after 35 days of BR. These findings suggest a substantial impairment of oxidative function at the muscle level, "downstream" with respect to bulk blood flow to the exercising muscles, that is possibly at the level of blood flow distribution/O(2) utilization inside the muscle, peripheral O(2) diffusion, and intracellular oxidative metabolism.

The effect of lifelong exercise dose on cardiovascular function during exercise

PubMed Central

Carrick-Ranson, Graeme; Hastings, Jeffrey L.; Bhella, Paul S.; Fujimoto, Naoki; Shibata, Shigeki; Palmer, M. Dean; Boyd, Kara; Livingston, Sheryl; Dijk, Erika

2014-01-01

An increased “dose” of endurance exercise training is associated with a greater maximal oxygen uptake (V̇o2max), a larger left ventricular (LV) mass, and improved heart rate and blood pressure control. However, the effect of lifelong exercise dose on metabolic and hemodynamic response during exercise has not been previously examined. We performed a cross-sectional study on 101 (69 men) seniors (60 yr and older) focusing on lifelong exercise frequency as an index of exercise dose. These included 27 who had performed ≤2 exercise sessions/wk (sedentary), 25 who performed 2–3 sessions/wk (casual), 24 who performed 4–5 sessions/wk (committed) and 25 who performed ≥6 sessions/wk plus regular competitions (Masters athletes) over at least the last 25 yr. Oxygen uptake and hemodynamics [cardiac output, stroke volume (SV)] were collected at rest, two levels of steady-state submaximal exercise, and maximal exercise. Doppler ultrasound measures of LV diastolic filling were assessed at rest and during LV loading (saline infusion) to simulate increased LV filling. Body composition, total blood volume, and heart rate recovery after maximal exercise were also examined. V̇o2max increased in a dose-dependent manner (P < 0.05). At maximal exercise, cardiac output and SV were largest in committed exercisers and Masters athletes (P < 0.05), while arteriovenous oxygen difference was greater in all trained groups (P < 0.05). At maximal exercise, effective arterial elastance, an index of ventricular-arterial coupling, was lower in committed exercisers and Masters athletes (P < 0.05). Doppler measures of LV filling were not enhanced at any condition, irrespective of lifelong exercise frequency. These data suggest that performing four or more weekly endurance exercise sessions over a lifetime results in significant gains in V̇o2max, SV, and heart rate regulation during exercise; however, improved SV regulation during exercise is not coupled with favorable effects on LV filling, even when the heart is fully loaded. PMID:24458750

[The predictive value of plasma B-type natriuretic peptide levels on outcome in children with pulmonary hypertension undergoing congenital heart surgery].

PubMed

Baysal, Ayse; Saşmazel, Ahmet; Yildirim, Ayse; Ozyaprak, Buket; Gundogus, Narin; Kocak, Tuncer

2014-01-01

In children undergoing congenital heart surgery, plasma brain natriuretic peptide levels may have a role in development of low cardiac output syndrome that is defined as a combination of clinical findings and interventions to augment cardiac output in children with pulmonary hypertension. In a prospective observational study, fifty-one children undergoing congenital heart surgery with preoperative echocardiographic study showing pulmonary hypertension were enrolled. The plasma brain natriuretic peptide levels were collected before operation, 12, 24 and 48h after operation. The patients enrolled into the study were divided into two groups depending on: (1) Development of LCOS which is defined as a combination of clinical findings or interventions to augment cardiac output postoperatively; (2) Determination of preoperative brain natriuretic peptide cut-off value by receiver operating curve analysis for low cardiac output syndrome. The secondary end points were: (1) duration of mechanical ventilation ≥72h, (2) intensive care unit stay >7days, and (3) mortality. The differences in preoperative and postoperative brain natriuretic peptide levels of patients with or without low cardiac output syndrome (n=35, n=16, respectively) showed significant differences in repeated measurement time points (p=0.0001). The preoperative brain natriuretic peptide cut-off value of 125.5pgmL-1 was found to have the highest sensitivity of 88.9% and specificity of 96.9% in predicting low cardiac output syndrome in patients with pulmonary hypertension. A good correlation was found between preoperative plasma brain natriuretic peptide level and duration of mechanical ventilation (r=0.67, p=0.0001). In patients with pulmonary hypertension undergoing congenital heart surgery, 91% of patients with preoperative plasma brain natriuretic peptide levels above 125.5pgmL-1 are at risk of developing low cardiac output syndrome which is an important postoperative outcome. Copyright © 2013 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Impedance cardiography: a comparison of cardiac output vs waveform analysis for assessing left ventricular systolic dysfunction.

PubMed

DeMarzo, Arthur P; Kelly, Russell F; Calvin, James E

2007-01-01

Early detection of asymptomatic left ventricular systolic dysfunction (LVSD) is beneficial in managing heart failure. Recent studies have cast doubt on the usefulness of cardiac output as an indicator of LVSD. In impedance cardiography (ICG), the dZ/dt waveform has a systolic wave called the E wave. This study looked at measurements of the amplitude and area of the E wave compared with ICG-derived cardiac output, stroke volume, cardiac index, and stroke index as methods of assessing LVSD. ICG data were obtained from patients (n=26) admitted to a coronary care unit. Clinical LVSD severity was stratified into 4 groups (none, mild, moderate, and severe) based on echocardiography data and standard clinical assessment by a cardiologist blinded to ICG data. Statistical analysis showed that the E wave amplitude and area were better indicators of the level of LVSD than cardiac output, stroke volume, cardiac index, or stroke index. ICG waveform analysis has potential as a simple point-of-care test for detecting LVSD in asymptomatic patients at high risk for developing heart failure and for monitoring LVSD in patients being treated for heart failure.

Spontaneous Reduction in Abnormal Myocardial Uptake of Fluorine-18 Fluorodeoxygluose in a Patient with Cardiac Sarcoidosis.

PubMed

Terasaki, Fumio; Fujita, Shu-Ichi; Kanzaki, Yumiko; Hirose, Yoshinobu; Ishizaka, Nobukazu

2018-05-30

Fluorine-18 fluorodeoxygluose ( 18 F-FDG) positron emission tomography (PET) is a useful tool for evaluating disease activity in sarcoidosis including cardiac involvement. A 67-year-old patient who developed atrioventricular block requiring permanent pacemaker implantation was diagnosed with cardiac sarcoidosis. The patient did not undergo steroid or immunosuppressive therapy but underwent serial 18 F-FDG PET examination, which showed spontaneous reduction in the myocardial FDG uptake, indicating the remission of immune-inflammatory activity. Although the global systolic function remained preserved, thinning of the septal wall emerged during the clinical course of follow-up, which is characteristic for cardiac sarcoidosis.

Influence of protein ingestion on human splanchnic and whole-body oxygen consumption, blood flow, and blood temperature.

PubMed

Brundin, T; Wahren, J

1994-05-01

Splanchnic and whole-body oxygen uptake, blood flow, and blood temperature were studied in 10 healthy subjects before and during 2 hours after oral ingestion of 900 kJ of fish protein. Indirect calorimetry and catheter techniques were used, including blood thermometry in arterial, pulmonary arterial, and hepatic venous blood. After the meal, pulmonary oxygen uptake increased from a basal value of 272 +/- 11 to 332 +/- 23 mL/min. During the first postprandial hour, splanchnic oxygen uptake increased from 62 +/- 5 to 93 +/- 9 mL/min (+50%, P < .05), thereby accounting for 62% +/- 17% of the simultaneous increase in whole-body oxygen consumption. During the second postprandial hour, splanchnic oxygen uptake increased no further, whereas in the extrasplanchnic tissues the oxygen consumption increased, now accounting for the entire simultaneous increase in pulmonary oxygen uptake. Cardiac output increased from basal 6.4 +/- 0.4 to 7.5 +/- 0.5 L/min. Splanchnic blood flow changed little while the arteriohepatic venous oxygen difference increased from 46 +/- 3 to 54 +/- 4 mL/L. Arterial and hepatic venous blood temperatures increased by almost 0.3 degrees C, reflecting a considerable accumulation of heat, indicating a conversion into a positive thermal balance. It is concluded that after protein ingestion, (1) oxygen uptake increases mainly in the splanchnic organs during the first hour, and thereafter exclusively in the extrasplanchnic tissues; (2) the blood flow increases mainly in extrasplanchnic tissues; and (3) the blood temperature increases almost linearly, indicating an upward adjustment of the temperature setpoint in the central thermosensors.

Evaluation of concordance among three cardiac output measurement techniques in adult patients during cardiovascular surgery postoperative care.

PubMed

Muñoz, L; Velandia, A; Reyes, L E; Arevalo-Rodríguez, I; Mejía, C; Asprilla, D; Uribe, D V; Arevalo, J J

2017-12-01

The standard method for cardiac output measuring is thermodilution although it is an invasive technique. Transesophageal Echocardiography (TEE) offers a dynamic and functional alternative to thermodilution. Analyze concordance between two TEE methods and thermodilution for cardiac output assessment. Observational concordance study in cardiovascular surgery patients that required pulmonary artery catheter. TEE cardiac output measurement at both mitral annulus (MA) and left ventricle outflow tract (LVOT) were performed. Results were compared with thermodilution. Correlation was evaluated by Lin's concordance correlation coefficient and Bland-Altman analysis. Statistical analysis was undertaken in STATA 13.0. Twenty-five patients were enrolled. Fifty two percent of patients were male, median age and ejection fraction was 63 years and 35% respectively. Median thermodilution, LVOT and MA -measured cardiac output was 3.25 L/min, 3.46 L/min and 8.4 L/min respectively. Different values between thermodilution and MA measurements were found (Lin concordance=0.071; Confidence Interval 95%=-0.009 to 0.151; Spearman's correlation=0.22) as values between thermodilution and LVOT (Lin concordance=0.232; Confidence Interval 95%=-0.12 a 0.537; Spearman's correlation 0.28). Bland-Altman analysis showed greater difference between MA measurements and thermodilution (DM=-0.408; Bland-Altman Limits=-0.809 to -0.007), than the other echocardiographic findings (DM=0.007; Bland-Altman Limits=-0.441 to 0.428). Results from cardiac output measurement by doppler and 2D-TEE on both MA and LVOT do not correlate with those obtained by thermodilution. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Cardiac output monitoring using indicator-dilution techniques: basics, limits, and perspectives.

PubMed

Reuter, Daniel A; Huang, Cecil; Edrich, Thomas; Shernan, Stanton K; Eltzschig, Holger K

2010-03-01

The ability to monitor cardiac output is one of the important cornerstones of hemodynamic assessment for managing critically ill patients at increased risk for developing cardiac complications, and in particular in patients with preexisting cardiovascular comorbidities. For >30 years, single-bolus thermodilution measurement through a pulmonary artery catheter for assessment of cardiac output has been widely accepted as the "clinical standard" for advanced hemodynamic monitoring. In this article, we review this clinical standard, along with current alternatives also based on the indicator-dilution technique, such as the transcardiopulmonary thermodilution and lithium dilution techniques. In this review, not only the underlying technical principles and the unique features but also the limitations of each application of indicator dilution are outlined.

The effect of perhexiline on myocardial protection during coronary artery surgery: a two-centre, randomized, double-blind, placebo-controlled trial

PubMed Central

Drury, Nigel E.; Howell, Neil J.; Calvert, Melanie J.; Weber, Ralf J.M.; Senanayake, Eshan L.; Lewis, Michael E.; Hyde, Jonathan A.J.; Green, David H.; Mascaro, Jorge G.; Wilson, Ian C.; Graham, Timothy R.; Rooney, Stephen J.; Viant, Mark R.; Freemantle, Nick; Frenneaux, Michael P.; Pagano, Domenico

2015-01-01

OBJECTIVES Perhexiline is thought to modulate metabolism by inhibiting mitochondrial carnitine palmitoyltransferase-1, reducing fatty acid uptake and increasing carbohydrate utilization. This study assessed whether preoperative perhexiline improves markers of myocardial protection in patients undergoing coronary artery bypass graft surgery and analysed its effect on the myocardial metabolome. METHODS In a prospective, randomized, double-blind, placebo-controlled trial, patients at two centres were randomized to receive either oral perhexiline or placebo for at least 5 days prior to surgery. The primary outcome was a low cardiac output episode in the first 6 h. All pre-specified analyses were conducted according to the intention-to-treat principle with a statistical power of 90% to detect a relative risk of 0.5 and a conventional one-sided α-value of 0.025. A subset of pre-ischaemic left ventricular biopsies was analysed using mass spectrometry-based metabolomics. RESULTS Over a 3-year period, 286 patients were randomized, received the intervention and were included in the analysis. The incidence rate of a low cardiac output episode in the perhexiline arm was 36.7% (51/139) vs 34.7% (51/147) in the control arm [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.56–1.50, P = 0.74]. Perhexiline was associated with a reduction in the cardiac index at 6 h [difference in means 0.19, 95% CI 0.07–0.31, P = 0.001] and an increase in inotropic support in the first 12 h (OR 0.55, 95% CI 0.34–0.89, P = 0.015). There were no significant differences in myocardial injury with troponin-T or electrocardiogram, reoperation, renal dysfunction or length of stay. No difference in the preischaemic left ventricular metabolism was identified between groups on metabolomics analysis. CONCLUSIONS Preoperative perhexiline does not improve myocardial protection in patients undergoing coronary surgery and in fact reduced perioperative cardiac output, increasing the need for inotropic support. Perhexiline has no significant effect on the mass spectrometry-visible polar myocardial metabolome in vivo in humans, supporting the suggestion that it acts via a pathway that is independent of myocardial carnitine palmitoyltransferase inhibition and may explain the lack of clinical benefit observed following surgery. ClinicalTrials.Gov ID NCT00845364. PMID:24948413

The effect of perhexiline on myocardial protection during coronary artery surgery: a two-centre, randomized, double-blind, placebo-controlled trial.

PubMed

Drury, Nigel E; Howell, Neil J; Calvert, Melanie J; Weber, Ralf J M; Senanayake, Eshan L; Lewis, Michael E; Hyde, Jonathan A J; Green, David H; Mascaro, Jorge G; Wilson, Ian C; Graham, Timothy R; Rooney, Stephen J; Viant, Mark R; Freemantle, Nick; Frenneaux, Michael P; Pagano, Domenico

2015-03-01

Perhexiline is thought to modulate metabolism by inhibiting mitochondrial carnitine palmitoyltransferase-1, reducing fatty acid uptake and increasing carbohydrate utilization. This study assessed whether preoperative perhexiline improves markers of myocardial protection in patients undergoing coronary artery bypass graft surgery and analysed its effect on the myocardial metabolome. In a prospective, randomized, double-blind, placebo-controlled trial, patients at two centres were randomized to receive either oral perhexiline or placebo for at least 5 days prior to surgery. The primary outcome was a low cardiac output episode in the first 6 h. All pre-specified analyses were conducted according to the intention-to-treat principle with a statistical power of 90% to detect a relative risk of 0.5 and a conventional one-sided α-value of 0.025. A subset of pre-ischaemic left ventricular biopsies was analysed using mass spectrometry-based metabolomics. Over a 3-year period, 286 patients were randomized, received the intervention and were included in the analysis. The incidence rate of a low cardiac output episode in the perhexiline arm was 36.7% (51/139) vs 34.7% (51/147) in the control arm [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.56-1.50, P = 0.74]. Perhexiline was associated with a reduction in the cardiac index at 6 h [difference in means 0.19, 95% CI 0.07-0.31, P = 0.001] and an increase in inotropic support in the first 12 h (OR 0.55, 95% CI 0.34-0.89, P = 0.015). There were no significant differences in myocardial injury with troponin-T or electrocardiogram, reoperation, renal dysfunction or length of stay. No difference in the preischaemic left ventricular metabolism was identified between groups on metabolomics analysis. Preoperative perhexiline does not improve myocardial protection in patients undergoing coronary surgery and in fact reduced perioperative cardiac output, increasing the need for inotropic support. Perhexiline has no significant effect on the mass spectrometry-visible polar myocardial metabolome in vivo in humans, supporting the suggestion that it acts via a pathway that is independent of myocardial carnitine palmitoyltransferase inhibition and may explain the lack of clinical benefit observed following surgery. NCT00845364. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.

Transesophageal Echocardiography, 3-Dimensional and Speckle Tracking Together as Sensitive Markers for Early Outcome in Patients With Left Ventricular Dysfunction Undergoing Cardiac Surgery.

PubMed

Kumar, Alok; Puri, Goverdhan Dutt; Bahl, Ajay

2017-10-01

Speckle tracking, when combined with 3-dimensional (3D) left ventricular ejection fraction, might prove to be a more sensitive marker for postoperative ventricular dysfunction. This study investigated early outcomes in a cohort of patients with left ventricular dysfunction undergoing cardiac surgery. Prospective, blinded, observational study. University hospital; single institution. The study comprised 73 adult patients with left ventricular ejection fraction <50% undergoing cardiac surgery using cardiopulmonary bypass. Routine transesophageal echocardiography before and after bypass. Global longitudinal strain using speckle tracking and 3D left ventricular ejection fraction were computed using transesophageal echocardiography. Mean prebypass global longitudinal strain and 3D left ventricle ejection fraction were significantly lower in patients with postoperative low-cardiac-output syndrome compared with patients who did not develop low cardiac output (global longitudinal strain -7.5% v -10.7% and 3D left ventricular ejection fraction 29% v 39%, respectively; p < 0.0001). The cut-off value of global longitudinal strain predicting postoperative low-cardiac-output syndrome was -6%, with 95% sensitivity and 68% specificity; and 3D left ventricular ejection fraction was 19% with 98% sensitivity and 81% specificity. Preoperative left ventricular global longitudinal strain (-6%) and 3D left ventricular ejection fraction (19%) together could act as predictor of postoperative low-cardiac-output states with high sensitivity (99.9%) in patients undergoing cardiac surgery. Copyright © 2017 Elsevier Inc. All rights reserved.

Measurement of cardiac output using improved chromatographic analysis of sulfur hexafluoride (SF6).

PubMed

Klocke, F J; Roberts, D L; Farhi, E R; Naughton, B J; Sekovski, B; Klocke, R A

1977-06-01

A constant current variable frequency pulsed electron capture detector has been incorporated into the gas chromatographic analysis of trace amounts of sulfur hexafluoride (SF6) in water and blood. The resulting system offers a broader effective operating range than more conventional electron capture units and has been utilized for measurements of cardiac output employing constant-rate infusion of dissolved SF6. The SF6 technique has been validated against direct volumetric measurements of cardiac output in a canine right-heart bypass preparation and used subsequently for rapidly repeated measurements in conscious animals and man.

Cerebral oxygen saturation and cardiac output during anaesthesia in sitting position for neurosurgical procedures: a prospective observational study.

PubMed

Schramm, P; Tzanova, I; Hagen, F; Berres, M; Closhen, D; Pestel, G; Engelhard, K

2016-10-01

Neurosurgical operations in the dorsal cranium often require the patient to be positioned in a sitting position. This can be associated with decreased cardiac output and cerebral hypoperfusion, and possibly, inadequate cerebral oxygenation. In the present study, cerebral oxygen saturation was measured during neurosurgery in the sitting position and correlated with cardiac output. Perioperative cerebral oxygen saturation was measured continuously with two different monitors, INVOS ® and FORE-SIGHT ® . Cardiac output was measured at eight predefined time points using transoesophageal echocardiography. Forty patients were enrolled, but only 35 (20 female) were eventually operated on in the sitting position. At the first time point, the regional cerebral oxygen saturation measured with INVOS ® was 70 (sd 9)%; thereafter, it increased by 0.0187% min -1 (P<0.01). The cerebral tissue oxygen saturation measured with FORE-SIGHT ® started at 68 (sd 13)% and increased by 0.0142% min -1 (P<0.01). The mean arterial blood pressure did not change. Cardiac output was between 6.3 (sd 1.3) and 7.2 (1.8) litre min -1 at the predefined time points. Cardiac output, but not mean arterial blood pressure, showed a positive and significant correlation with cerebral oxygen saturation. During neurosurgery in the sitting position, the cerebral oxygen saturation slowly increases and, therefore, this position seems to be safe with regard to cerebral oxygen saturation. Cerebral oxygen saturation is stable because of constant CO and MAP, while the influence of CO on cerebral oxygen saturation seems to be more relevant. NCT01275898. © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Improving Diagnosis of Sepsis After Burn Injury Using a Portable Sepsis Alert System

DTIC Science & Technology

vital signs of heart rate variability, regional tissue oxygenation, and noninvasive cardiac output can diagnose burn sepsis earlier, reducing...morbidity and mortality. Rationale: Heart Rate Variability (HRV), regional Tissue Oxygenation, and non-invasive Cardiac Output (CO), have shown promise in

Validation and application of single breath cardiac output determinations in man

NASA Technical Reports Server (NTRS)

Loeppky, J. A.; Fletcher, E. R.; Myhre, L. G.; Luft, U. C.

1986-01-01

The results of a procedure for estimating cardiac output by a single-breath technique (Qsb), obtained in healthy males during supine rest and during exercise on a bicycle ergometer, were compared with the results on cardiac output obtained by the direct Fick method (QF). The single breath maneuver consisted of a slow exhalation to near residual volume following an inspiration somewhat deeper than normal. The Qsb calculations incorporated an equation of the CO2 dissociation curve and a 'moving spline' sequential curve-fitting technique to calculate the instantaneous R from points on the original expirogram. The resulting linear regression equation indicated a 24-percent underestimation of QF by the Qsb technique. After applying a correction, the Qsb-QF relationship was improved. A subsequent study during upright rest and exercise to 80 percent of VO2(max) in 6 subjects indicated a close linear relationship between Qsb and VO2 for all 95 values obtained, with slope and intercept close to those in published studies in which invasive cardiac output measurements were used.

Comparison of pulsed Doppler and thermodilution methods for measuring cardiac output in critically ill patients.

PubMed

Donovan, K D; Dobb, G J; Newman, M A; Hockings, B E; Ireland, M

1987-09-01

We obtained 145 consecutive cardiac output measurements in 38 critically ill patients, using the invasive thermodilution and the noninvasive pulsed Doppler methods. The mean thermodilution cardiac output (TDCO) was 5.7 +/- 1.87 L/min and the mean pulsed Doppler cardiac output (PDCO) was 5.16 +/- 1.66 L/min. The mean difference between the two measurements was 0.51 L/min with an SD greater than 1.6 L/min, reflecting the scattering of results. The overall correlation coefficient was .58. The intercepts were large and the regression equation some way from the line of equal values (TDCO = 2.28 + 0.66 PDCO). When the results were analyzed according to diagnosis or by group experience, there were some differences in the bias of the estimate; however, the SD of the difference between methods was greater than one liter/min in all groups. Thus, the pulsed Doppler method failed to estimate accurately TDCO in critically ill patients.

Haemodynamic effects of a selective adenosine A2A receptor agonist, CGS 21680, in chronic heart failure in anaesthetized rats.

PubMed

Nekooeian, A A; Tabrizchi, R

1998-10-01

1. Recently we demonstrated that the administration of an A2A adenosine receptor agonist, CGS 21680, to anaesthetized rats with acute heart failure (1 h post-coronary artery ligation) resulted in an increase in cardiac output. In the present investigation, the effects of CGS 21680 on cardiac output, vascular resistance, heart rate, blood pressure and mean circulatory filling pressure (Pmcf) were investigated in anaesthetized rats with chronic heart failure (8 weeks post-coronary artery ligation). 2. Experiments were conducted in five groups (n = 6) of animals: sham-operated vehicle-treated (0.9% NaCl; 0.037 mL kg(-1) min(-1)) animals in which the occluder was placed but not pulled to ligate the coronary artery; coronary artery-ligated vehicle-treated animals; and coronary artery-ligated CGS 21680-treated (0.1. 0.3 or 1.0 microg kg(-1) min(-1)) animals. 3. Baseline blood pressure, cardiac output and rate of rise in left ventricular pressure (+dP/dt) were significantly reduced in animals with coronary artery ligation when compared to sham-operated animals. Coronary artery ligation resulted in a significant increase in left ventricular end-diastolic pressure, Pmcf and venous resistance when compared to sham-operated animals. 4. Administration of CGS 21680 at 0.3 and 1.0 microg kg(-1) min(-1) significantly (n = 6; P<0.05) increased cardiac output by 19+/-4% and 39+/-5%, and heart rate by 14+/-2% and 15+/-1%, respectively, when compared to vehicle treatment in coronary artery-ligated animals. Administration of CGS 21680 also significantly reduced blood pressure and arterial resistance when compared to coronary artery-ligated vehicle-treated animals. Infusion of CGS 21680 also significantly reduced venous resistance when compared to vehicle-treated coronary artery-ligated animals. 5. The results show that heart failure is characterized by reduced cardiac output, and increased left ventricular end-diastolic pressure, venous resistance and Pmcf. Acute treatment with CGS 21680 in animals with chronic heart failure decreased left ventricular end-diastolic pressure and increased cardiac output. This increase in cardiac output was the result of reduced arterial and venous resistances and increased heart rate.

The Higher the Insulin Resistance the Lower the Cardiac Output in Men with Type 1 Diabetes During the Maximal Exercise Test.

PubMed

Niedzwiecki, Pawel; Naskret, Dariusz; Pilacinski, Stanislaw; Pempera, Maciej; Uruska, Aleksandra; Adamska, Anna; Zozulinska-Ziolkiewicz, Dorota

2017-06-01

The aim of this study was to assess the hemodynamic parameters analyzed in bioimpedance cardiography during maximal exercise in patients with type 1 diabetes differing in insulin resistance. The study group consisted of 40 men with type 1 diabetes. Tissue sensitivity to insulin was assessed on the basis of the glucose disposal rate (GDR) analyzed during hyperinsulinemic-euglycemic clamp. Patients were divided into groups with GDR <4.5 mg/kg/min (G1 group-lower insulin sensitivity) and GDR ≥4.5 mg/kg/min (G2 group-higher insulin sensitivity). During the exercise test, the heart rate, systolic volume, cardiac output, cardiac index were measured by the impedance meter (PhysioFlow). Compared with the G2 group, the G1 group had a lower cardiac output (CO): during exercise 8.6 (IQR 7.7-10.0) versus 12.8 (IQR 10.8-13.7) L/min; P < 0.0001, at the maximal effort 13.1 (IQR 12.2-16.7) versus 18.6 (IQR 16.9-20.2) L/min; P = 0.001, and during observation after exercise 8.4 (IQR 6.3-9.6) versus 11.9 (IQR 10.1-13.1) L/min; P < 0.0001. We noticed a positive correlation of GDR and cardiac output: during the exercise test (r = 0.63, P = 0.0002), at the maximal effort (Rs 0.56, P = 0.001), and during observation after the exercise test (r = 0.72, P < 0.0001). In multivariate logistic regression, cardiac output during exercise and during observation was associated with high GDR, regardless of the age and duration of diabetes [OR: 1.98 (95% CI 1.10-3.56), P = 0.02 and OR: 1.91 (95% CI 1.05-3.48), P = 0.03; respectively]. In nonobese subjects with type 1 diabetes, with good metabolic control, insulin resistance is associated with cardiac hemodynamic parameters assessed during and after exercise. The higher the insulin resistance the lower the cardiac output during maximal exercise in men with type 1 diabetes.

The human female heart incorporates glucose more efficiently than the male heart.

PubMed

Kakinuma, Yoshihiko; Okada, Shoshiro; Nogami, Munenobu; Kumon, Yoshitaka

2013-10-03

Oestrogen is known to play a cardioprotective role in cardiovascular diseases, as demonstrated in a number of animal studies. However, few human studies have investigated sex-based differences with regard to cardiac glucose uptake using (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT). Therefore, we evaluated healthy male and female subjects who underwent FDG-PET/CT examination to determine whether there was a sex-related difference in cardiac glucose uptake with age. In females, the prevalence of maximal FDG uptake (PET score 2) demonstrated a convex pattern with ageing, and it peaked at age 51-60 years in the females, gradually decreasing to a minimum at age >70 years. In contrast, the prevalence of maximal FDG uptake by age in males was a mirror image of that in females, i.e. it formed a concave pattern with a nadir at 61-70 years, followed by an increase in the prevalence. These findings suggest that female hearts depend more on glucose as an energy substrate as they age, however, efficient glucose uptake is attenuated with increasing age. In contrast, the male heart sustains its glucose uptake capacity at age >70 years. This characteristic sex-based difference in cardiac glucose uptake might be related to the female predominance of Takotsubo cardiomyopathy. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Bioimpedance cardiography in pregnancy: A longitudinal cohort study on hemodynamic pattern and outcome.

PubMed

Andreas, Martin; Kuessel, Lorenz; Kastl, Stefan P; Wirth, Stefan; Gruber, Kathrin; Rhomberg, Franziska; Gomari-Grisar, Fatemeh A; Franz, Maximilian; Zeisler, Harald; Gottsauner-Wolf, Michael

2016-06-01

Pregnancy associated cardiovascular pathologies have a significant impact on outcome for mother and child. Bioimpedance cardiography may provide additional outcome-relevant information early in pregnancy and may also be used as a predictive instrument for pregnancy-associated diseases. We performed a prospective longitudinal cohort trial in an outpatient setting and included 242 pregnant women. Cardiac output and concomitant hemodynamic data were recorded from 11(th)-13(th) week of gestation every 5(th) week as well as at two occasions post partum employing bioimpedance cardiography. Cardiac output increased during pregnancy and peaked early in the third trimester. A higher heart rate and a decreased systemic vascular resistance were accountable for the observed changes. Women who had a pregnancy-associated disease during a previous pregnancy or developed hypertension or preeclampsia had a significantly increased cardiac output early in pregnancy. Furthermore, an effect of cardiac output on birthweight was found in healthy pregnancies and could be confirmed with multiple linear regression analysis. Cardiovascular adaptation during pregnancy is characterized by distinct pattern described herein. These may be altered in women at risk for preeclampsia or reduced birthweigth. The assessment of cardiac parameters by bioimpedance cardiography could be performed at low costs without additional risks.

Beat by beat stroke volume assessment by PDE in upright and supine exercise

NASA Technical Reports Server (NTRS)

1980-01-01

A 3.0 MHz pulse Doppler echocardiograph was used to estimate instantaneous stroke volume and cardiac output in 8 men during steady state supine and upright exercise at 300 kpm/min which were compared with other studies utilizing invasive procedures. The mean transients in heart rate and stroke volume and cardiac output for the first 20 sec of exercise in each posture were then determined. Centerline blood velocities were obtained in the ascending aorta with the transducer positioned manually in the suprasternal notch. Mean supine values for stroke volume and cardiac output at rest and exercise were 111 (6.4) and 112 ml (9.7 L/min), respectively, for supine. The corresponding results for upright were 76 (5.6) and 92 ml (8.4 L/min). These values compare favorably with prior studies. The transient response of cardiac output following the onset of upright was about twice as fast as in S because of the rapid and almost immediate upsurge in stroke volume. In supine, only heart rate served to augment cardiac output as stroke volume initially fell. The faster initial aortic flow in upright must represent the rapid mobilization of pooled venous blood from the leg veins which more than accounts for the additional volume (184 ml) of blood passing through the aorta during upright compared with supine in the first 20 sec.

Clinical Validation of Non-Invasive Cardiac Output Monitoring in Healthy Pregnant Women.

PubMed

McLaughlin, Kelsey; Wright, Stephen P; Kingdom, John C P; Parker, John D

2017-11-01

Non-invasive hemodynamic monitoring has the potential to be a valuable clinical tool for the screening and management of hypertensive disorders of pregnancy. The objective of this study was to validate the clinical utility of the non-invasive cardiac output monitoring (NICOM) system in pregnant women. Twenty healthy pregnant women with a singleton pregnancy at 22 to 26 weeks' gestation were enrolled in this study. Measures of heart rate, stroke volume, and cardiac output were obtained through NICOM and compared with Doppler echocardiography. NICOM significantly overestimated measures of both stroke volume and cardiac output compared with Doppler echocardiography (95 ± 4 vs. 73 ± 4 mL, P < 0.0001; and 7.4 ± 0.2 vs. 5.6 ± 0.2 L/min, P < 0.0001; respectively). There is no gold standard for the measurement of cardiac output in the setting of pregnancy. However, once normal values have been established, NICOM has the potential to be a useful clinical tool for monitoring maternal hemodynamics in pregnant women. Further investigation regarding the validity of NICOM is required in larger populations of healthy and hypertensive pregnant women to determine whether this device is appropriate for maternal hemodynamic assessment during pregnancy. Copyright © 2017 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada. Published by Elsevier Inc. All rights reserved.

Clinical review: Positive end-expiratory pressure and cardiac output

PubMed Central

Luecke, Thomas; Pelosi, Paolo

2005-01-01

In patients with acute lung injury, high levels of positive end-expiratory pressure (PEEP) may be necessary to maintain or restore oxygenation, despite the fact that 'aggressive' mechanical ventilation can markedly affect cardiac function in a complex and often unpredictable fashion. As heart rate usually does not change with PEEP, the entire fall in cardiac output is a consequence of a reduction in left ventricular stroke volume (SV). PEEP-induced changes in cardiac output are analyzed, therefore, in terms of changes in SV and its determinants (preload, afterload, contractility and ventricular compliance). Mechanical ventilation with PEEP, like any other active or passive ventilatory maneuver, primarily affects cardiac function by changing lung volume and intrathoracic pressure. In order to describe the direct cardiocirculatory consequences of respiratory failure necessitating mechanical ventilation and PEEP, this review will focus on the effects of changes in lung volume, factors controlling venous return, the diastolic interactions between the ventricles and the effects of intrathoracic pressure on cardiac function, specifically left ventricular function. Finally, the hemodynamic consequences of PEEP in patients with heart failure, chronic obstructive pulmonary disease and acute respiratory distress syndrome are discussed. PMID:16356246

Exercise starts and ends in the brain.

PubMed

Kayser, Bengt

2003-10-01

Classically the limit to endurance of exercise is explained in terms of metabolic capacity. Cardio-respiratory capacity and muscle fatigue are thought to set the limit and the majority of studies on factors limiting endurance exercise discuss issues such as maximal oxygen uptake (VO2max), aerobic enzyme capacity, cardiac output, glycogen stores, etc. However, this paradigm does not explain the limitation to endurance exercise with large muscle groups at altitude, when at exhaustion exercise is ended without limb locomotor muscle fatigue and with sub-maximal cardiac output. A simple fact provides a basis for an explanation. Voluntary exercise starts and ends in the brain. It starts with spatial and temporal recruitment of motor units and ends with their de-recruitment. A conscious decision precedes a voluntary effort. The end of effort is again volitional and a forced conscious decision to stop precedes it, but it is unknown what forces the off-switch of recruitment at exhaustion although sensation of exertion certainly plays a role. An alternative model explaining the limitation of exercise endurance thus proposes that the central nervous system integrates input from various sources all related to the exercise and limits the intensity and duration of recruitment of limb skeletal muscle to prevent jeopardizing the integrity of the organism. This model acknowledges the cardio-respiratory and muscle metabolic capacities as prime actors on the performance scene, while crediting the central nervous system for its pivotal role as the ultimate site where exercise starts and ends.

Ephedrine fails to accelerate the onset of neuromuscular block by vecuronium.

PubMed

Komatsu, Ryu; Nagata, Osamu; Ozaki, Makoto; Sessler, Daniel I

2003-08-01

The onset time of neuromuscular blocking drugs is partially determined by circulatory factors, including muscle blood flow and cardiac output. We thus tested the hypothesis that a bolus of ephedrine accelerates the onset of vecuronium neuromuscular block by increasing cardiac output. A prospective, randomized study was conducted in 53 patients scheduled for elective surgery. After the induction of anesthesia, the ulnar nerve was stimulated supramaximally every 10 s, and the evoked twitch response of the adductor pollicis was recorded with accelerometry. Patients were maintained under anesthesia with continuous infusion of propofol for 10 min and then randomly assigned to ephedrine 210 microg/kg (n = 27) or an equivalent volume of saline (n = 26). The test solution was given 1 min before the administration of 0.1 mg/kg of vecuronium. Cardiac output was monitored with impedance cardiography. Ephedrine, but not saline, increased cardiac index (17%; P = 0.003). Nonetheless, the onset of 90% neuromuscular block was virtually identical in the patients given ephedrine (183 +/- 41 s) and saline (181 +/- 47 s). There was no correlation between cardiac index and onset of the blockade. We conclude that the onset of the vecuronium-induced neuromuscular block is primarily determined by factors other than cardiac output. The combination of ephedrine and vecuronium thus cannot be substituted for rapid-acting nondepolarizing muscle relaxants. Ephedrine increased cardiac index but failed to speed onset of neuromuscular block with vecuronium. We conclude that ephedrine administration does not shorten the onset time of vecuronium.

Recombinant glucagon-like peptide-1 increases myocardial glucose uptake and improves left ventricular performance in conscious dogs with pacing-induced dilated cardiomyopathy.

PubMed

Nikolaidis, Lazaros A; Elahi, Dariush; Hentosz, Teresa; Doverspike, Aaron; Huerbin, Rhonda; Zourelias, Lee; Stolarski, Carol; Shen, You-tang; Shannon, Richard P

2004-08-24

The failing heart demonstrates a preference for glucose as its metabolic substrate. Whether enhancing myocardial glucose uptake favorably influences left ventricular (LV) contractile performance in heart failure remains uncertain. Glucagon-like peptide-1 (GLP-1) is a naturally occurring incretin with potent insulinotropic effects the action of which is attenuated when glucose levels fall below 4 mmol. We examined the impact of recombinant GLP-1 (rGLP-1) on LV and systemic hemodynamics and myocardial substrate uptake in conscious dogs with advanced dilated cardiomyopathy (DCM) as a mechanism for overcoming myocardial insulin resistance and enhancing myocardial glucose uptake. Thirty-five dogs were instrumented and studied in the fully conscious state. Advanced DCM was induced by 28 days of rapid pacing. Sixteen dogs with advanced DCM received a 48-hour infusion of rGLP-1 (1.5 pmol x kg(-1) x min(-1)). Eight dogs with DCM served as controls and received 48 hours of a saline infusion (3 mL/d). Infusion of rGLP-1 was associated with significant (P<0.02) increases in LV dP/dt (98%), stroke volume (102%), and cardiac output (57%) and significant decreases in LV end-diastolic pressure, heart rate, and systemic vascular resistance. rGLP-1 increased myocardial insulin sensitivity and myocardial glucose uptake. There were no significant changes in the saline control group. rGLP-1 dramatically improved LV and systemic hemodynamics in conscious dogs with advanced DCM induced by rapid pacing. rGLP-1 has insulinomimetic and glucagonostatic properties, with resultant increases in myocardial glucose uptake. rGLP-1 may be a useful metabolic adjuvant in decompensated heart failure.

Exercise cardiac output following Skylab missions - The second manned Skylab mission

NASA Technical Reports Server (NTRS)

Buderer, M. C.; Mauldin, D. G.; Rummel, J. A.; Michel, E. L.; Sawin, C. F.

1976-01-01

Cardiac output was measured during preflight and postflight exercise-stress tests on the Skylab astronauts. In the postflight tests immediately following the 28-, 59-, and 84-d earth orbital missions, the astronauts exhibited an approximate 30% decrease in cardiac output coupled with an approximate 50% decrease in cardiac stroke volume during exercise. These changes were accompanied by elevated heart rates and significant increases in total systemic peripheral vascular resistance. Mean arterial pressure was unchanged. All parameters returned to normal preflight values within 30 d of the end of the orbital period. Duration of the zero-G exposure did not appear to influence either the magnitude of the hemodynamic changes or the time-course of their return to normal. These results are discussed in relation to other cardiovascular findings and possible mechanisms responsible for the observations are outlined.

Effect of specific activity on cardiac uptake of iodine-123-MIBG.

PubMed

Farahati, J; Bier, D; Scheubeck, M; Lassmann, M; Schelper, L F; Grelle, I; Hanscheid, H; Biko, J; Graefe, K H; Reiners, C

1997-03-01

Radioiodinated meta-iodobenzylguanidine (MIBG), an analog of norepinephrine, has been used to assess myocardial sympathetic innervation. Recent in vivo studies predict enhanced cardiac uptake of this radiopharmaceutical with high specific activity. To clarify the effect of specific activity on cardiac uptake of radioiodinated MIBG, the distribution and kinetics of no-carrier-added [123I]MIBG (> or = 7.4 TBq/mumol) were compared with those of commercial [123I]MIBG (approximately 74 MBq/mumol) in three healthy volunteers by serial imaging and blood sampling. Higher specific activity result in higher uptake of radioiodinated MIBG in all volunteers in the heart (p < 0.05) and liver (p < 0.05) but not in the lung (p = 0.26). Due to rapid deiodination, a more pronounced accumulation of radioactivity was present in plasma after no-carrier-added MIBG than commercial [123I]MIBG, resulting in higher background and thyroid activity after administration of the former. Calculated heart-to-liver (p = 0.96) and heart-to-lung (p = 0.42) count ratios in all volunteers revealed no significant improvement in cardiac imaging with no-carrier-added [123I]MIBG compared to commercial [123I]MIBG. This study highlights the appreciably higher in vivo deiodination of no-carrier-added [123I]MIBG compared to commercial preparation of [123I]MIBG in humans. Cardiac images acquired with no-carrier-added [123I]MIBG do not seem to be superior to those obtained with commercial MIBG.

Thromboresistant surface coatings for the measurement of cardiac output through continuous low flow peripheral A-V shunts.

PubMed Central

Deeb, G M; Borovetz, H S; Griffith, B P; Hardesty, R L

1980-01-01

The dilution technique for determining cardiac output using indocyanine green dye is limited in patients weighing less than 20 kg because of the obligatory volume loss. Reproducible achieved using the green dye dilution method by the establishment of a low flow peripheral arteriovenous shunt. The shunt materials were treated with thromboresistant agents--TDMAC (7%) and albumin (1 g/dl)--to facilitate the use of this technique without heparin. For A-V shunt flow rates of 8-30 cc/min reproducible values of cardiac output were obtained for up to 38 hours which were in good agreement with determinations made using the conventional technique of dye dilution. PMID:6986120

Metabonomics Indicates Inhibition of Fatty Acid Synthesis, β-Oxidation, and Tricarboxylic Acid Cycle in Triclocarban-Induced Cardiac Metabolic Alterations in Male Mice.

PubMed

Xie, Wenping; Zhang, Wenpeng; Ren, Juan; Li, Wentao; Zhou, Lili; Cui, Yuan; Chen, Huiming; Yu, Wenlian; Zhuang, Xiaomei; Zhang, Zhenqing; Shen, Guolin; Li, Haishan

2018-02-14

Triclocarban (TCC) has been identified as a new environmental pollutant that is potentially hazardous to human health; however, the effects of short-term TCC exposure on cardiac function are not known. The aim of this study was to use metabonomics and molecular biology techniques to systematically elucidate the molecular mechanisms of TCC-induced effects on cardiac function in mice. Our results show that TCC inhibited the uptake, synthesis, and oxidation of fatty acids, suppressed the tricarboxylic acid (TCA) cycle, and increased aerobic glycolysis levels in heart tissue after short-term TCC exposure. TCC also inhibited the nuclear peroxisome proliferator-activated receptor α (PPARα), confirming its inhibitory effects on fatty acid uptake and oxidation. Histopathology and other analyses further confirm that TCC altered mouse cardiac physiology and pathology, ultimately affecting normal cardiac metabolic function. We elucidate the molecular mechanisms of TCC-induced harmful effects on mouse cardiac metabolism and function from a new perspective, using metabonomics and bioinformatics analysis data.

WE-FG-202-06: The Use of Hybrid PET MRI for Identifying the Presence of Cardiac Inflammation Following External Beam Irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Sherif, O; Xhaferllari, I; Battista, J

Purpose: To monitor the evolution of radiation-induced cardiac inflammation in a canine model using hybrid positron emission tomography (PET/magnetic resonance imaging (MRI). Methods: Research ethics approval was obtained for a longitudinal imaging study of 5 canines after cardiac irradiation. Animals were imaged at baseline, 3 months, 6 months, and 12 months post cardiac irradiation using a hybrid PET-MRI system (Biograph mMR, Siemens Healthcare). The imaging protocol was designed to assess changes in cardiac inflammation using {sup 18}F-fluorodeoxyglucose ({sup 18}F-FDG) PET tracer. In order to image cardiac inflammation, the normal myocardial uptake of glucose was suppressed prior to the injection ofmore » {sup 18}F-FDG. The suppression of glycolysis was achieved through; fasting (16–21 hours prior to the start of imaging) and an intravenous injection of heparin immediately followed by a 20% lipid infusion 20 min prior to the injection of {sup 18}F-FDG. The standard uptake value (SUV) obtained from 17 myocardial regions were used to compare FDG scans. All animals received a simulation CT scan (GE Medical Systems) for radiation treatment planning. Radiation treatment plans were created using the Pinncale3 treatment planning system (Philips Radiation Oncology Systems) and designed to resemble the typical cardiac exposure during left-sided breast cancer radiotherapy. Cardiac irradiations were performed in a single fraction using a TrueBeam linear accelerator (Varian Medical Systems). Results: The delivered dose (mean ± standard error) to heart, left ventricle, and left anterior descending artery were 1.7±0.1 Gy, 2.7±0.1 Gy, and 5.5±0.3 Gy respectively. At these doses, a significant increase in {sup 18}F-FDG uptake within the entire heart relative to baseline (1.1±0.02 g/ml) uptake was observed. {sup 18}F-FDG uptake at 3 months, 6 months, and 12 months post irradiation were 1.8±0.03 g/ml, 2.4±0.06 g/ml, and 2.6±0.11 g/ml respectively. Conclusion: Low doses of limited cardiac irradiation show evidence of a persistent global inflammatory response that can be detected using {sup 18}F-FDG PET imaging. This work was supported through the Translational Breast Cancer Studentship award, funded in part by the Breast Cancer Society of Canada. Additional financial support is provided by the London Regional Cancer Program Catalyst Grant and the Thames Valley Veterinary Services.« less

Comparison of an Endotracheal Cardiac Output Monitor to a Pulmonary Artery Catheter

DTIC Science & Technology

2017-12-04

of a FDA approved device, the CONMED endotracheal cardiac output monitor (ECOM) ™ apparatus, by comparing it to the Edwards Vig ilance II monitor...and Use Committee (FWH 20140100A). Results Using GraphPad Prism® to conduct non-linear fit analyses comparing the slopes of the curves for ECOM

Decreased 2,3-diphosphoglycerate concentration in low cardiac output patients and its influence on the determination of in vivo p50.

PubMed

Piccioni, Marilde A; Cestari, Idágene A; Strunz, Célia M C; Auler, José O

2003-08-01

We investigated whether 2,3-diphosphoglycerate (2,3-DPG) is altered in patients with low cardiac output and the influence of its concentration on the calculation of in vivo P(50). Biochemical and blood gas analysis were performed along with the measurement of cardiac output and body temperature in 13 patients submitted to cardiopulmonary bypass surgeries without the use of donor blood. In vivo P(50) was calculated using the measured (P(50m)) and the estimated 2,3-DPG (P(50e)). 2,3-DPG concentration was lower in these patients when compared to the values obtained in normal volunteers (6.9 +/- 2.2 vs. 11.9 +/- 2.4 microm/gHb). P(50m) was lower than P(50e) (21.6 +/- 1.1 vs. 30.1 +/- 1.2 mm Hg) at all time points. Our data show that in patients with low cardiac output, 2,3-DPG concentration is reduced. Therefore, in these patients, the use of standard values for this variable may introduce an error in the calculation of in vivo P(50).

Effects of nifedipine and captopril on vascular capacitance of ganglion-blocked anesthetized dogs.

PubMed

Ogilvie, R I; Zborowska-Sluis, D

1990-03-01

The hemodynamic effects of nifedipine and captopril at doses producing similar reductions in arterial pressure were studied in pentobarbital-anesthetized ventilated dogs after splenectomy during ganglion blockade with hexamethonium. Mean circulatory filling pressure (Pmcf) was determined during transient circulatory arrest induced by acetylcholine at baseline circulating blood volumes and after increases of 5 and 10 mL/kg. Central blood volumes (pulmonary artery to aortic root) were determined from transit times, and separately determined cardiac outputs (right atrium to pulmonary artery) were estimated by thermodilution. Nifedipine (n = 5) increased Pmcf at all circulating blood volumes and reduced total vascular capacitance without a change in total vascular compliance. Central blood volume, right atrial pressure, and cardiac output were increased with induced increases in circulating blood volume. In contrast, captopril (n = 5) did not alter total vascular capacitance, central blood volume, right atrial pressure, or cardiac output at baseline or with increased circulating volume. Thus, at doses producing similar reductions in arterial pressure, nifedipine but not captopril increased venous return and cardiac output in ganglion-blocked dogs.

Cardiovascular dynamics associated with tolerance to lower body negative pressure

NASA Technical Reports Server (NTRS)

Sather, T. M.; Goldwater, D. J.; Montgomery, L. D.; Convertino, V. A.

1986-01-01

The purpose of this investigation was to identify cardiovascular responses associated with tolerance to lower body negative pressure (LBNP). Eighteen men, ages 29-51 years, were categorized as high (HT) or low (LT) LBNP-tolerant based on a graded presyncopal-limited LBNP exposure criterion of -60 mm Hg relative to ambient pressure. Groups were matched for physical characteristics and pre-LBNP cardiovascular measurements, with the exceptions of greater (p less than 0.05) end-diastolic volume and cardiac output in the HT group. During peak LBNP, cardiac output was similar in both groups, although the HT group displayed a greater heart rate (p less than 0.05). In both groups, venous return appeared to limit cardiac output resulting in decreased arterial pressure. Tolerance to LBNP did not appear solely dependent on the absolute amount of blood pooled in the legs since the HT group demonstrated a greater (p less than 0.05) peak LBNP-induced increase in midthigh-leg volume. Greater tolerance to LBNP was associated with a larger pre-LBNP cardiac output reserve and higher compensatory increases in heart rate and peripheral resistance.

Investigation of a continuous heating/cooling technique for cardiac output measurement.

PubMed

Ehlers, K C; Mylrea, K C; Calkins, J M

1987-01-01

Cardiac output is frequently measured to assess patient hemodynamic status in the operating room and intensive care unit. Current research for measuring cardiac output includes continuous sinusoidal heating and synchronous detection of thermal signals. This technique is limited by maximum heating element temperatures and background thermal noise. A continuous heating and cooling technique was investigated in vitro to determine if greater thermal signal magnitudes could be obtained. A fast responding thermistor was employed to measure consecutive ejected temperature plateaus in the thermal signal. A flow bath and mechanical ventricle were used to simulate the cardiovascular system. A thermoelectric module was used to apply heating and cooling energy to the flow stream. Trials encompassing a range of input power, input frequency, and flow rate were conducted. By alternating heating and cooling, thermal signal magnitude can be increased when compared to continuous heating alone. However, the increase was not sufficient to allow for recording in all patients over the expected normal range of cardiac output. Consecutive ejected temperature plateaus were also measured on the thermal signal and ejection fraction calculations were made.

Beat-by-beat analysis of cardiac output and blood pressure responses to short-term barostimulation in different body positions

NASA Astrophysics Data System (ADS)

Hildebrandt, Wulf; Schütze, Harald; Stegemann, J.

Rapid quantification of the human baro-reflex control of heart rate has been achieved on a beat-by-beat basis using a neck-chamber with quick ECG-triggered pressure changes. Referring to recent findings on heart rate and stroke volume, the present study uses this technique to compare cardiac output as well as blood pressure changes in supine and upright position to investigate feedback effects and to confirm postural reflex modifications not revealed by RR-interval changes. A suction profile starting at +40 mmHg and running 7 steps of pressure decrease down to -65 mmHg was examined in 0° and 90° tilting position while beat-by-beat recordings were done of heart rate, stroke volume (impedance-cardiography) and blood pressure (Finapres tm) (n=16). The percentual heart rate decrease failed to be significantly different between positions. A suction-induced stroke volume increase led to a cardiac output almost maintained when supine and significantly increased when upright. A decrease in all blood pressure values was found during suction, except for systolic values in upright position which increased. Conclusively, (a) it is confirmed that different inotropy accounts for the seen gravitational effect on the cardiac output not represented by heart rate; (b) identical suction levels in different positions lead to different stimuli at the carotid receptor. This interference has to be considered in microgravity studies by beat-by-beat measurement of cardiac output and blood pressure.

Cardiac output and systemic vascular resistance: Clinical assessment compared with a noninvasive objective measurement in children with shock.

PubMed

Razavi, Asma; Newth, Christopher J L; Khemani, Robinder G; Beltramo, Fernando; Ross, Patrick A

2017-06-01

To evaluate physician assessment of cardiac output and systemic vascular resistance in patients with shock compared with an ultrasonic cardiac output monitor (USCOM). To explore potential changes in therapy decisions if USCOM data were available using physician intervention answers. Double-blinded, prospective, observational study in a tertiary hospital pediatric intensive care unit. Forty children (<18years) admitted with shock, requiring ongoing volume resuscitation or inotropic support. Two to 3 physicians clinically assessed cardiac output and systemic vascular resistance, categorizing them as high, normal, or low. An investigator simultaneously measured cardiac index (CI) and systemic vascular resistance index (SVRI) with USCOM categorized as high, normal, or low. Overall agreement between physician and USCOM for CI (48.5% [κ = 0.18]) and SVRI (45.9% [κ = 0.16]) was poor. Interobserver agreement was also poor for CI (58.7% [κ = 0.33]) and SVRI (52.3% [κ = 0.28]). Comparing theoretical physician interventions to "acceptable" or "unacceptable" clinical interventions, based on USCOM measurement, 56 (21%) physician interventions were found to be "unacceptable." There is poor agreement between physician-assessed CI and SVRI and USCOM, with significant interobserver variability among physicians. Objective measurement of CI and SVRI may reduce variability and improve diagnostic accuracy. Copyright © 2016 Elsevier Inc. All rights reserved.

Cardiac changes induced by immersion and breath-hold diving in humans.

PubMed

Marabotti, Claudio; Scalzini, Alessandro; Cialoni, Danilo; Passera, Mirko; L'Abbate, Antonio; Bedini, Remo

2009-01-01

To evaluate the separate cardiovascular response to body immersion and increased environmental pressure during diving, 12 healthy male subjects (mean age 35.2 +/- 6.5 yr) underwent two-dimensional Doppler echocardiography in five different conditions: out of water (basal); head-out immersion while breathing (condition A); fully immersed at the surface while breathing (condition B) and breath holding (condition C); and breath-hold diving at 5-m depth (condition D). Heart rate, left ventricular volumes, stroke volume, and cardiac output were obtained by underwater echocardiography. Early (E) and late (A) transmitral flow velocities, their ratio (E/A), and deceleration time of E (DTE) were also obtained from pulsed-wave Doppler, as left ventricular diastolic function indexes. The experimental protocol induced significant reductions in left ventricular volumes, left ventricular stroke volume (P < 0.05), cardiac output (P < 0.001), and heart rate (P < 0.05). A significant increase in E peak (P < 0.01) and E/A (P < 0.01) and a significant reduction of DTE (P < 0.01) were also observed. Changes occurring during diving (condition D) accounted for most of the changes observed in the experimental series. In particular, cardiac output at condition D was significantly lower compared with each of the other experimental conditions, E/A was significantly higher during condition D than in conditions A and C. Finally, DTE was significantly shorter at condition D than in basal and condition C. This study confirms a reduction of cardiac output in diving humans. Since most of the changes were observed during diving, the increased environmental pressure seems responsible for this hemodynamic rearrangement. Left ventricular diastolic function changes suggest a constrictive effect on the heart, possibly accounting for cardiac output reduction.

Alteration in mitochondrial Ca(2+) uptake disrupts insulin signaling in hypertrophic cardiomyocytes.

PubMed

Gutiérrez, Tomás; Parra, Valentina; Troncoso, Rodrigo; Pennanen, Christian; Contreras-Ferrat, Ariel; Vasquez-Trincado, César; Morales, Pablo E; Lopez-Crisosto, Camila; Sotomayor-Flores, Cristian; Chiong, Mario; Rothermel, Beverly A; Lavandero, Sergio

2014-11-07

Cardiac hypertrophy is characterized by alterations in both cardiac bioenergetics and insulin sensitivity. Insulin promotes glucose uptake by cardiomyocytes and its use as a substrate for glycolysis and mitochondrial oxidation in order to maintain the high cardiac energy demands. Insulin stimulates Ca(2+) release from the endoplasmic reticulum, however, how this translates to changes in mitochondrial metabolism in either healthy or hypertrophic cardiomyocytes is not fully understood. In the present study we investigated insulin-dependent mitochondrial Ca(2+) signaling in normal and norepinephrine or insulin like growth factor-1-induced hypertrophic cardiomyocytes. Using mitochondrion-selective Ca(2+)-fluorescent probes we showed that insulin increases mitochondrial Ca(2+) levels. This signal was inhibited by the pharmacological blockade of either the inositol 1,4,5-triphosphate receptor or the mitochondrial Ca(2+) uniporter, as well as by siRNA-dependent mitochondrial Ca(2+) uniporter knockdown. Norepinephrine-stimulated cardiomyocytes showed a significant decrease in endoplasmic reticulum-mitochondrial contacts compared to either control or insulin like growth factor-1-stimulated cells. This resulted in a reduction in mitochondrial Ca(2+) uptake, Akt activation, glucose uptake and oxygen consumption in response to insulin. Blocking mitochondrial Ca(2+) uptake was sufficient to mimic the effect of norepinephrine-induced cardiomyocyte hypertrophy on insulin signaling. Mitochondrial Ca(2+) uptake is a key event in insulin signaling and metabolism in cardiomyocytes.

Haemodynamic effects of a selective adenosine A2A receptor agonist, CGS 21680, in chronic heart failure in anaesthetized rats

PubMed Central

Nekooeian, Ali A; Tabrizchi, Reza

1998-01-01

Recently we demonstrated that the administration of an A2A adenosine receptor agonist, CGS 21680, to anaesthetized rats with acute heart failure (1 h post-coronary artery ligation) resulted in an increase in cardiac output. In the present investigation, the effects of CGS 21680 on cardiac output, vascular resistance, heart rate, blood pressure and mean circulatory filling pressure (Pmcf) were investigated in anaesthetized rats with chronic heart failure (8 weeks post-coronary artery ligation).Experiments were conducted in five groups (n=6) of animals: sham-operated vehicle-treated (0.9% NaCl; 0.037 mL kg−1 min−1) animals in which the occluder was placed but not pulled to ligate the coronary artery; coronary artery-ligated vehicle-treated animals; and coronary artery-ligated CGS 21680-treated (0.1, 0.3 or 1.0 μg kg−1 min−1) animals.Baseline blood pressure, cardiac output and rate of rise in left ventricular pressure (+dP/dt) were significantly reduced in animals with coronary artery ligation when compared to sham-operated animals. Coronary artery ligation resulted in a significant increase in left ventricular end-diastolic pressure, Pmcf and venous resistance when compared to sham-operated animals.Administration of CGS 21680 at 0.3 and 1.0 μg kg−1 min−1 significantly (n=6; P<0.05) increased cardiac output by 19±4% and 39±5%, and heart rate by 14±2% and 15±1%, respectively, when compared to vehicle treatment in coronary artery-ligated animals. Administration of CGS 21680 also significantly reduced blood pressure and arterial resistance when compared to coronary artery-ligated vehicle-treated animals. Infusion of CGS 21680 also significantly reduced venous resistance when compared to vehicle-treated coronary artery-ligated animals.The results show that heart failure is characterized by reduced cardiac output, and increased left ventricular end-diastolic pressure, venous resistance and Pmcf. Acute treatment with CGS 21680 in animals with chronic heart failure decreased left ventricular end-diastolic pressure and increased cardiac output. This increase in cardiac output was the result of reduced arterial and venous resistances and increased heart rate. PMID:9831898

Optimal pacing modes after cardiac transplantation: is synchronisation of recipient and donor atria beneficial?

PubMed Central

Parry, Gareth; Malbut, Katie; Dark, John H; Bexton, Rodney S

1992-01-01

Objective—To investigate the response of the transplanted heart to different pacing modes and to synchronisation of the recipient and donor atria in terms of cardiac output at rest. Design—Doppler derived cardiac output measurements at three pacing rates (90/min, 110/min and 130/min) in five pacing modes: right ventricular pacing, donor atrial pacing, recipient-donor synchronous pacing, donor atrial-ventricular sequential pacing, and synchronous recipient-donor atrial-ventricular sequential pacing. Patients—11 healthy cardiac transplant recipients with three pairs of epicardial leads inserted at transplantation. Results—Donor atrial pacing (+11% overall) and donor atrial-ventricular sequential pacing (+8% overall) were significantly better than right ventricular pacing (p < 0·001) at all pacing rates. Synchronised pacing of recipient and donor atrial segments did not confer additional benefit in either atrial or atrial-ventricular sequential modes of pacing in terms of cardiac output at rest at these fixed rates. Conclusions—Atrial pacing or atrial-ventricular sequential pacing appear to be appropriate modes in cardiac transplant recipients. Synchronisation of recipient and donor atrial segments in this study produced no additional benefit. Chronotropic competence in these patients may, however, result in improved exercise capacity and deserves further investigation. PMID:1389737

A randomized controlled trial of levosimendan to reduce mortality in high-risk cardiac surgery patients (CHEETAH): Rationale and design.

PubMed

Zangrillo, Alberto; Alvaro, Gabriele; Pisano, Antonio; Guarracino, Fabio; Lobreglio, Rosetta; Bradic, Nikola; Lembo, Rosalba; Gianni, Stefano; Calabrò, Maria Grazia; Likhvantsev, Valery; Grigoryev, Evgeny; Buscaglia, Giuseppe; Pala, Giovanni; Auci, Elisabetta; Amantea, Bruno; Monaco, Fabrizio; De Vuono, Giovanni; Corcione, Antonio; Galdieri, Nicola; Cariello, Claudia; Bove, Tiziana; Fominskiy, Evgeny; Auriemma, Stefano; Baiocchi, Massimo; Bianchi, Alessandro; Frontini, Mario; Paternoster, Gianluca; Sangalli, Fabio; Wang, Chew-Yin; Zucchetti, Maria Chiara; Biondi-Zoccai, Giuseppe; Gemma, Marco; Lipinski, Michael J; Lomivorotov, Vladimir V; Landoni, Giovanni

2016-07-01

Patients undergoing cardiac surgery are at risk of perioperative low cardiac output syndrome due to postoperative myocardial dysfunction. Myocardial dysfunction in patients undergoing cardiac surgery is a potential indication for the use of levosimendan, a calcium sensitizer with 3 beneficial cardiovascular effects (inotropic, vasodilatory, and anti-inflammatory), which appears effective in improving clinically relevant outcomes. Double-blind, placebo-controlled, multicenter randomized trial. Tertiary care hospitals. Cardiac surgery patients (n = 1,000) with postoperative myocardial dysfunction (defined as patients with intraaortic balloon pump and/or high-dose standard inotropic support) will be randomized to receive a continuous infusion of either levosimendan (0.05-0.2 μg/[kg min]) or placebo for 24-48 hours. The primary end point will be 30-day mortality. Secondary end points will be mortality at 1 year, time on mechanical ventilation, acute kidney injury, decision to stop the study drug due to adverse events or to start open-label levosimendan, and length of intensive care unit and hospital stay. We will test the hypothesis that levosimendan reduces 30-day mortality in cardiac surgery patients with postoperative myocardial dysfunction. This trial is planned to determine whether levosimendan could improve survival in patients with postoperative low cardiac output syndrome. The results of this double-blind, placebo-controlled randomized trial may provide important insights into the management of low cardiac output in cardiac surgery. Copyright © 2016 Elsevier Inc. All rights reserved.

Assessment of cardiac function using myocardial perfusion imaging technique on SPECT with 99mTc sestamibi

NASA Astrophysics Data System (ADS)

Gani, M. R. A.; Nazir, F.; Pawiro, S. A.; Soejoko, D. S.

2016-03-01

Suspicion on coronary heart disease can be confirmed by observing the function of left ventricle cardiac muscle with Myocardial Perfusion Imaging techniques. The function perfusion itself is indicated by the uptake of radiopharmaceutical tracer. The 31 patients were studied undergoing the MPI examination on Gatot Soebroto Hospital using 99mTc-sestamibi radiopharmaceutical with stress and rest conditions. Stress was stimulated by physical exercise or pharmacological agent. After two hours, the patient did rest condition on the same day. The difference of uptake percentage between stress and rest conditions will be used to determine the malfunction of perfusion due to ischemic or infarct. Degradation of cardiac function was determined based on the image-based assessment of five segments of left ventricle cardiac. As a result, 8 (25.8%) patients had normal myocardial perfusion and 11 (35.5%) patients suspected for having partial ischemia. Total ischemia occurred to 8 (25.8%) patients with reversible and irreversible ischemia and the remaining 4 (12.9%) patients for partial infarct with characteristic the percentage of perfusion ≤50%. It is concluded that MPI technique of image-based assessment on uptake percentage difference between stress and rest conditions can be employed to predict abnormal perfusion as complementary information to diagnose the cardiac function.

V̇O2,max: what do we know, and what do we still need to know?

PubMed Central

Levine, Benjamin D

2008-01-01

Maximal oxygen uptake is a physiological characteristic bounded by the parametric limits of the Fick equation: (left ventricular (LV) end-diastolic volume − LV end-systolic volume) × heart rate × arterio-venous oxygen difference. ‘Classical’ views of emphasize its critical dependence on convective oxygen transport to working skeletal muscle, and recent data are dispositive, proving convincingly that such limits must and do exist. ‘Contemporary’ investigations into the mechanisms underlying peripheral muscle fatigue due to energetic supply/demand mismatch are clarifying the local mediators of fatigue at the skeletal muscle level, though the afferent signalling pathways that communicate these environmental conditions to the brain and the sites of central integration of cardiovascular and neuromotor control are still being worked out. Elite endurance athletes have a high due primarily to a high cardiac output from a large compliant cardiac chamber (including the myocardium and pericardium) which relaxes quickly and fills to a large end-diastolic volume. This large capacity for LV filling and ejection allows preservation of blood pressure during extraordinary rates of muscle blood flow and oxygen transport which support high rates of sustained oxidative metabolism. The magnitude and mechanisms of cardiac phenotype plasticity remain uncertain and probably involve underlying genetic factors, as well as the length, duration, type, intensity and age of initiation of the training stimulus PMID:18006574

Ability to work in anaerobic condition is associated with physical performance on the six-minute walk test in older patients receiving cardiac rehabilitation.

PubMed

Pasquini, Guido; Vannetti, Federica; Molino-Lova, Raffaele

2015-05-01

During maximal incremental exercise, the ability to work in the anaerobic condition, expressed by the respiratory exchange ratio, is associated with physical performance. Further, peak respiratory exchange ratio is regarded as the best non-invasive measure of a patient's actual exercise effort. This study examined whether ability to work in the anaerobic condition is also associated with physical performance in submaximal constant work rate exercise. A total of 75 older patients (51 men, 24 women), mean age 71.1 years (standard deviation 6.7 years), who had recently undergone cardiac surgery, performed cardiopulmonary exercise testing in a 6-min walk test before and after rehabilitation. The distance walked, steady-state oxygen uptake, carbon dioxide output and respiratory exchange ratio increased significantly after rehabilitation (p < 0.001 for all). In multivariable models predicting the distance walked before and after rehabilitation, higher steady-state respiratory exchange ratio was independently associated with longer distance (p < 0.001 for both). In older patients receiving post-acute cardiac rehabilitation the ability to work in the anaerobic condition is associated with physical performance in submaximal constant work rate exercises. Thus the steady-state respiratory exchange ratio might be regarded as a measure of the patient's actual exercise effort. This information may prove useful in customizing exercise prescription and assessing the effects of rehabilitation.

Autonomic Cardiovascular Control and Executive Function in Chronic Hypotension.

PubMed

Duschek, Stefan; Hoffmann, Alexandra; Reyes Del Paso, Gustavo A; Ettinger, Ulrich

2017-06-01

Chronic low blood pressure (hypotension) is characterized by complaints such as fatigue, reduced drive, dizziness, and cold limbs. Additionally, deficits in attention and memory have been observed. Autonomic dysregulation is considered to be involved in the origin of this condition. The study explored autonomic cardiovascular control in the context of higher cognitive processing (executive function) in hypotension. Hemodynamic recordings were performed in 40 hypotensive and 40 normotensive participants during execution of four classical executive function tasks (number-letter task, n-back task, continuous performance test, and flanker task). Parameters of cardiac sympathetic control, i.e., stroke volume, cardiac output, pre-ejection period, total peripheral resistance, and parasympathetic control, i.e., respiratory sinus arrhythmia and baroreflex sensitivity, were obtained. The hypotensive group exhibited lower stroke volume and cardiac output, as well as higher pre-ejection period and baroreflex sensitivity during task execution. Increased error rates in hypotensive individuals were observed in the n-back and flanker tasks. In the total sample, there were positive correlations of error rates with pre-ejection period, baroreflex sensitivity and respiratory sinus arrhythmia, and negative correlations with cardiac output. Group differences in stroke volume, cardiac output, and pre-ejection period suggest diminished beta-adrenergic myocardial drive during executive function processing in hypotension, in addition to increased baroreflex function. Although further research is warranted to quantify the extent of executive function impairment in hypotension, the results from correlation analysis add evidence to the notion that higher sympathetic inotropic influences and reduced parasympathetic cardiac influences are accompanied by better cognitive performance.

Evaluation of noninvasive cardiac output methods during exercise

NASA Technical Reports Server (NTRS)

Moore, Alan D.; Barrows, Linda H.; Rashid, Michael; Siconolfi, Steven F.

1992-01-01

Noninvasive techniques to estimate cardiac output (Qc) will be used during future space flight. This retrospective literature survey compared the Qc techniques of carbon dioxide rebreathing (CO2-R), CO2 single breath (CO2-S), Doppler (DOP), impedance (IM), and inert gas (IG: acetylene or nitrous oxide) to direct (DIR) assessments measured at rest and during exercise.

Sarcomeric protein modification during adrenergic stress enhances cross-bridge kinetics and cardiac output

PubMed Central

Gresham, Kenneth S.; Mamidi, Ranganath; Li, Jiayang; Kwak, Hyerin

2017-01-01

Molecular adaptations to chronic neurohormonal stress, including sarcomeric protein cleavage and phosphorylation, provide a mechanism to increase ventricular contractility and enhance cardiac output, yet the link between sarcomeric protein modifications and changes in myocardial function remains unclear. To examine the effects of neurohormonal stress on posttranslational modifications of sarcomeric proteins, mice were administered combined α- and β-adrenergic receptor agonists (isoproterenol and phenylephrine, IPE) for 14 days using implantable osmotic pumps. In addition to significant cardiac hypertrophy and increased maximal ventricular pressure, IPE treatment accelerated pressure development and relaxation (74% increase in dP/dtmax and 14% decrease in τ), resulting in a 52% increase in cardiac output compared with saline (SAL)-treated mice. Accelerated pressure development was maintained when accounting for changes in heart rate and preload, suggesting that myocardial adaptations contribute to enhanced ventricular contractility. Ventricular myocardium isolated from IPE-treated mice displayed a significant reduction in troponin I (TnI) and myosin-binding protein C (MyBP-C) expression and a concomitant increase in the phosphorylation levels of the remaining TnI and MyBP-C protein compared with myocardium isolated from saline-treated control mice. Skinned myocardium isolated from IPE-treated mice displayed a significant acceleration in the rate of cross-bridge (XB) detachment (46% increase) and an enhanced magnitude of XB recruitment (43% increase) at submaximal Ca2+ activation compared with SAL-treated mice but unaltered myofilament Ca2+ sensitivity of force generation. These findings demonstrate that sarcomeric protein modifications during neurohormonal stress are molecular adaptations that enhance in vivo ventricular contractility through accelerated XB kinetics to increase cardiac output. NEW & NOTEWORTHY Posttranslational modifications to sarcomeric regulatory proteins provide a mechanism to modulate cardiac function in response to stress. In this study, we demonstrate that neurohormonal stress produces modifications to myosin-binding protein C and troponin I, including a reduction in protein expression within the sarcomere and increased phosphorylation of the remaining protein, which serve to enhance cross-bridge kinetics and increase cardiac output. These findings highlight the importance of sarcomeric regulatory protein modifications in modulating ventricular function during cardiac stress. PMID:27909224

Sarcomeric protein modification during adrenergic stress enhances cross-bridge kinetics and cardiac output.

PubMed

Gresham, Kenneth S; Mamidi, Ranganath; Li, Jiayang; Kwak, Hyerin; Stelzer, Julian E

2017-03-01

Molecular adaptations to chronic neurohormonal stress, including sarcomeric protein cleavage and phosphorylation, provide a mechanism to increase ventricular contractility and enhance cardiac output, yet the link between sarcomeric protein modifications and changes in myocardial function remains unclear. To examine the effects of neurohormonal stress on posttranslational modifications of sarcomeric proteins, mice were administered combined α- and β-adrenergic receptor agonists (isoproterenol and phenylephrine, IPE) for 14 days using implantable osmotic pumps. In addition to significant cardiac hypertrophy and increased maximal ventricular pressure, IPE treatment accelerated pressure development and relaxation (74% increase in dP/d t max and 14% decrease in τ), resulting in a 52% increase in cardiac output compared with saline (SAL)-treated mice. Accelerated pressure development was maintained when accounting for changes in heart rate and preload, suggesting that myocardial adaptations contribute to enhanced ventricular contractility. Ventricular myocardium isolated from IPE-treated mice displayed a significant reduction in troponin I (TnI) and myosin-binding protein C (MyBP-C) expression and a concomitant increase in the phosphorylation levels of the remaining TnI and MyBP-C protein compared with myocardium isolated from saline-treated control mice. Skinned myocardium isolated from IPE-treated mice displayed a significant acceleration in the rate of cross-bridge (XB) detachment (46% increase) and an enhanced magnitude of XB recruitment (43% increase) at submaximal Ca 2+ activation compared with SAL-treated mice but unaltered myofilament Ca 2+ sensitivity of force generation. These findings demonstrate that sarcomeric protein modifications during neurohormonal stress are molecular adaptations that enhance in vivo ventricular contractility through accelerated XB kinetics to increase cardiac output. NEW & NOTEWORTHY Posttranslational modifications to sarcomeric regulatory proteins provide a mechanism to modulate cardiac function in response to stress. In this study, we demonstrate that neurohormonal stress produces modifications to myosin-binding protein C and troponin I, including a reduction in protein expression within the sarcomere and increased phosphorylation of the remaining protein, which serve to enhance cross-bridge kinetics and increase cardiac output. These findings highlight the importance of sarcomeric regulatory protein modifications in modulating ventricular function during cardiac stress. Copyright © 2017 the American Physiological Society.

VA/Q distribution during heavy exercise and recovery in humans: implications for pulmonary edema

NASA Technical Reports Server (NTRS)

Schaffartzik, W.; Poole, D. C.; Derion, T.; Tsukimoto, K.; Hogan, M. C.; Arcos, J. P.; Bebout, D. E.; Wagner, P. D.

1992-01-01

Ventilation-perfusion (VA/Q) inequality has been shown to increase with exercise. Potential mechanisms for this increase include nonuniform pulmonary vasoconstriction, ventilatory time constant inequality, reduced large airway gas mixing, and development of interstitial pulmonary edema. We hypothesized that persistence of VA/Q mismatch after ventilation and cardiac output subside during recovery would be consistent with edema; however, rapid resolution would suggest mechanisms related to changes in ventilation and blood flow per se. Thirteen healthy males performed near-maximal cycle ergometry at an inspiratory PO2 of 91 Torr (because hypoxia accentuates VA/Q mismatch on exercise). Cardiorespiratory variables and inert gas elimination patterns were measured at rest, during exercise, and between 2 and 30 min of recovery. Two profiles of VA/Q distribution behavior emerged during heavy exercise: in group 1 an increase in VA/Q mismatch (log SDQ of 0.35 +/- 0.02 at rest and 0.44 +/- 0.02 at exercise; P less than 0.05, n = 7) and in group 2 no change in VA/Q mismatch (n = 6). There were no differences in anthropometric data, work rate, O2 uptake, or ventilation during heavy exercise between groups. Group 1 demonstrated significantly greater VA/Q inequality, lower vital capacity, and higher forced expiratory flow at 25-75% of forced vital capacity for the first 20 min during recovery than group 2. Cardiac index was higher in group 1 both during heavy exercise and 4 and 6 min postexercise. However, both ventilation and cardiac output returned toward baseline values more rapidly than did VA/Q relationships. Arterial pH was lower in group 1 during exercise and recovery. We conclude that greater VA/Q inequality in group 1 and its persistence during recovery are consistent with the hypothesis that edema occurs and contributes to the increase in VA/Q inequality during exercise. This is supported by observation of greater blood flows and acidosis and, presumably therefore, higher pulmonary vascular pressures in such subjects.

Cardiac Expression of Microsomal Triglyceride Transfer Protein Is Increased in Obesity and Serves to Attenuate Cardiac Triglyceride Accumulation

PubMed Central

Bartels, Emil D.; Nielsen, Jan M.; Hellgren, Lars I.; Ploug, Thorkil; Nielsen, Lars B.

2009-01-01

Obesity causes lipid accumulation in the heart and may lead to lipotoxic heart disease. Traditionally, the size of the cardiac triglyceride pool is thought to reflect the balance between uptake and β-oxidation of fatty acids. However, triglycerides can also be exported from cardiomyocytes via secretion of apolipoproteinB-containing (apoB) lipoproteins. Lipoprotein formation depends on expression of microsomal triglyceride transfer protein (MTP); the mouse expresses two isoforms of MTP, A and B. Since many aspects of the link between obesity-induced cardiac disease and cardiac lipid metabolism remain unknown, we investigated how cardiac lipoprotein synthesis affects cardiac expression of triglyceride metabolism-controlling genes, insulin sensitivity, and function in obese mice. Heart-specific ablation of MTP-A in mice using Cre-loxP technology impaired upregulation of MTP expression in response to increased fatty acid availability during fasting and fat feeding. This resulted in cardiac triglyceride accumulation but unaffected cardiac insulin-stimulated glucose uptake. Long-term fat-feeding of male C57Bl/6 mice increased cardiac triglycerides, induced cardiac expression of triglyceride metabolism-controlling genes and attenuated heart function. Abolishing cardiac triglyceride accumulation in fat-fed mice by overexpression of an apoB transgene in the heart prevented the induction of triglyceride metabolism-controlling genes and improved heart function. The results suggest that in obesity, the physiological increase of cardiac MTP expression serves to attenuate cardiac triglyceride accumulation albeit without major effects on cardiac insulin sensitivity. Nevertheless, the data suggest that genetically increased lipoprotein secretion prevents development of obesity-induced lipotoxic heart disease. PMID:19390571

Evaluation of a low-carbohydrate diet-based preparation protocol without fasting for cardiac PET/MR imaging.

PubMed

Nensa, Felix; Tezgah, E; Schweins, K; Goebel, J; Heusch, P; Nassenstein, K; Schlosser, T; Poeppel, T D

2017-06-01

Assessment of increased glucose uptake in inflammatory or malignant myocardial disease using PET/MRI relies on uptake suppression in normal myocardium. We evaluated the efficacy of a ≥24 hours high-fat, low-carbohydrate, and protein-permitted diet (HFLCPP) in combination with unfractionated heparin for suppression of "physiologic" myocardial glucose uptake. PET/MRI was successfully performed in 89 patients. HFLCPP was started ≥24 hours prior to PET/MRI. All patients received i.v. injection of unfractionated heparin (50 IU·kg -1 ) 15 minutes prior to FDG administration. Left ventricular FDG uptake was visually evaluated by two readers. Diffuse myocardial uptake exceeding liver uptake, isolated uptake in the lateral wall, or diffuse uptake in the entire circumference of the heart base were defined as failed suppression. Homogeneous myocardial uptake below liver uptake with/without focal uptake was defined as successful suppression. Success rate was 84%. Suppression was unsuccessful in 14 patients. No significant influence of gender (P = .40) or age (P = .21) was found. However, insufficient suppression was more common in patients younger than 45 years (20% vs 7%). PET/MR imaging completion rate was >97%. A HFLCPP diet in combination with unfractionated heparin was successfully implemented for cardiac PET/MRI and resulted in a sufficient suppression of myocardial FDG uptake in 84% of patients.

Pyruvate transport in isolated cardiac mitochondria from two species of amphibian exhibiting dissimilar aerobic scope: Bufo marinus and Rana catesbeiana.

PubMed

Duerr, Jeffrey M; Tucker, Kristina

2007-08-01

Cardiac mitochondria were isolated from Bufo marinus and Rana catesbeiana, two species of amphibian whose cardiovascular systems are adapted to either predominantly aerobic or glycolytic modes of locomotion. Mitochondrial oxidative capacity was compared using VO2 max and respiratory control ratios in the presence of a variety of substrates including pyruvate, lactate, oxaloacetate, beta-hydroxybutyrate, and octanoyl-carnitine. B. marinus cardiac mitochondria exhibited VO2 max values twice that of R. catesbeiana cardiac mitochondria when oxidizing carbohydrate substrates. Pyruvate transport was measured via a radiolabeled-tracer assay in isolated B. marinus and R. catesbeiana cardiac mitochondria. Time-course experiments described both alpha-cyano-4-hydroxycinnamate-sensitive (MCT-like) and phenylsuccinate-sensitive pyruvate uptake mechanisms in both species. Pyruvate uptake by the MCT-like transporter was enhanced in the presence of a pH gradient, whereas the phenylsuccinate-sensitive transporter was inhibited. Notably, anuran cardiac mitochondria exhibited activities of lactate dehydrogenase and pyruvate carboxylase. The presence of both transporters on the inner mitochondrial membrane affords the net uptake of monocarboxylates including pyruvate, beta-hydroxybutyrate, and lactate; the latter potentially indicating the presence of a lactate/pyruvate shuttle allowing oxidation of extramitochondrial NADH. Intramitochondrial lactate dehydrogenase and pyruvate carboxylase enables lactate to be oxidized to pyruvate or converted to anaplerotic oxaloacetate. Kinetics of the MCT-like transporter differed significantly between the two species, suggesting differences in aerobic scope may be in part attributable to differences in mitochondrial carbohydrate utilization. (c) 2007 Wiley-Liss, Inc.

Cerebral and somatic oxygen saturations after repair of tetralogy of Fallot: effects of extubation on regional blood flow.

PubMed

Bronicki, Ronald A; Checchia, Paul A; Anas, Nick G; Adams, Gerald J; Penny, Daniel J; Bleiweis, Mark S; Shekerdemian, Lara S

2013-02-01

After repair of tetralogy of Fallot, some patients experience a low cardiac output state owing to right ventricular diastolic failure. Negative-pressure ventilation has been shown to improve cardiac output in these patients. What has not been evaluated is the effect of extubation and loading of the respiratory muscles on the distribution of cardiac output after repair of tetralogy of Fallot. In 23 consecutive patients undergoing repair of tetralogy of Fallot, standard hemodynamic variables, central venous oxygen saturations, and near infrared spectroscopy of the brain, mesenteric, and renal circulations were monitored for 30 minutes before and after extubation. With extubation, the systolic blood pressure increased significantly from 96 ± 11 to 106 ± 15 mm Hg (p = 0.002) while the heart rate remained unchanged. With extubation, the central venous oxygen saturation increased significantly from 65% ± 7% to 70% ± 10% (p = 0.003). Cerebral oxygen saturations increased significantly from 67% ± 10% to 72% ± 9% (p = 0.0001), whereas mesenteric oxygenation fell significantly from 74% ± 15% to 72% ± 15% (p = 0.04). Renal oxygenation was unaffected by extubation. Cardiac output and cerebral oxygenation increased significantly during spontaneous respiration, the latter suggesting that the brain was in or approaching an oxygen supply-dependent state before extubation. Despite the increase in cardiac output, the presumed increase in respiratory pump perfusion, as well as the concurrent increase in cerebral perfusion, came at the expense of mesenteric perfusion. Renal oxygenation remained unchanged with extubation. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Revision of gonadal radiation dose to man from thallium-201

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosain, P.; Hosain, F.

1981-06-01

Thallium-201 as thallous chloride is now routinely used for myocardial imaging. We observed a biological translocation of T1-201 leading to a gradual increase in the concentration of radioactivity in the testes which facilitated testicular imaging. The initial distribution of intravenously injected tracer dose is greatly dependent on the distribution of cardiac output, but its metabolic fate is analogous to the potassium ion. We have extensively studied the kinetics of thallium in rats, and also carried out limited comparative studies in different species. An attempt was also made to compare the uptake values that could be obtained in dogs by quantitativemore » imaging and by autopsy. Separation of scrotum, epididymis and testes revealed that the increase in uptake occurred predominantly in the testes. The uptake increased with time for about 1 day, and after 2 days it declined with a biological half-life of approximately 2 days. The later phase of testicular clearance was similar to the rate of clearance from other organs. The testicular uptake of T1-201 was highest in rats: the initial value at 10 to 15 min was 0.48 +- 0.09% of the injected dose which increased to 1.77 +- 0.20% by 1 day. The initial uptake in mice was low (0.18 +- 0.06%) but it increased to about 4 folds by 1 day. Values in human, extrapolated from limited quantitative imaging, was similar to mice. These studies indicated the need for the revision of the gonadal radiation dose to man. Calculations show, contrary to the accepted value of about 0.5 rads/mCi, an approximate value of 1.5 rads/mCi is more realistic.« less

Ventilatory and circulatory responses at the onset of exercise in man following heart or heart-lung transplantation.

PubMed Central

Banner, N; Guz, A; Heaton, R; Innes, J A; Murphy, K; Yacoub, M

1988-01-01

1. Ventilatory and cardiovascular responses to the onset of voluntary and electrically induced leg exercise were studied in six patients following heart transplantation and five following heart-lung transplantation; the results were compared between the patient groups and also with responses from a group of normal subjects. 2. Oxygen consumption, carbon dioxide production and ventilation and its components were measured over two 30 s periods prior to, and two 30 s periods following, the onset of exercise. Relative changes in stroke volume and cardiac output were derived from ensemble-averaged Doppler measurements of ascending aortic blood velocity over the same 30 s periods. 3. None of the groups of subjects showed any significant differences in responses to voluntary exercise compared to electrically induced exercise of similar work pattern and intensity. 4. Compared to normal controls, the transplanted subjects showed higher resting heart rates which did not increase at the onset of exercise; stroke volume increased, but less than in the normal subjects. The resulting cardiac output increases in the transplanted subjects were minimal compared to the normal subjects. 5. Ventilation and oxygen uptake increased immediately and with similar magnitude in all three groups. 6. These results show that in the same individual it is possible to have an appropriate ventilatory response to the onset of exercise in the presumed absence of a normal corticospinal input to the exercising muscles (electrically induced exercise) and afferent neural information from the lungs and heart, and in the absence of a normal circulatory response to exercise. The mechanisms underlying this ventilatory response remain undetermined. PMID:3136247

Hyperventilation accelerates the rise of arterial blood concentrations of desflurane in gynecologic patients.

PubMed

Lu, Chih-Cherng; Lin, Tso-Chou; Hsu, Che-Hao; Yu, Mu-Hsien; Chen, Ta-Liang; Chen, Ruei-Ming; Ku, Chih-Hung; Ho, Shung-Tai

2012-09-01

Under a constant inspired concentration, the uptake of a volatile anesthetic into the arterial blood should mainly be governed by alveolar ventilation, according to the assumption that the patient's cardiac output remains stable during anesthesia. We investigated whether ventilation volume affects the rate of desflurane uptake by examining arterial blood concentrations. Thirty female patients were randomly allocated into the following three groups: hyperventilation, normal ventilation and hypoventilation. Hemodynamic variables were measured using a Finometer, inspiratory and end-tidal concentrations of desflurane were measured by infrared analysis, and the desflurane concentration in the arterial blood (Ades) was analyzed by gas chromatography. During the first 10 minutes after the administration of desflurane, the Ades was highest in the hyperventilation group, and this value was significantly different from those obtained for the normal and hypoventilation groups. In addition, hyperventilation significantly increased the slope of Ades-over-time during the first 5 minutes compared with patients experiencing normal ventilation and hypoventilation, but there were no differences in these slopes during the periods from 5-10, 10-20 and 20-40 minutes after the administration of desflurane. This finding indicates that there were no differences in desflurane uptake between the three groups after the first 5 minutes within desflurane administration. Hyperventilation accelerated the rate of the rise in Ades following desflurane administration, which was time-dependent with respect to different alveolar ventilations levels.

Hyperventilation accelerates the rise of arterial blood concentrations of desflurane in gynecologic patients

PubMed Central

Lu, Chih-Cherng; Lin, Tso-Chou; Hsu, Che-Hao; Yu, Mu-Hsien; Chen, Ta-Liang; Chen, Ruei-Ming; Ku, Chih-Hung; Ho, Shung-Tai

2012-01-01

OBJECTIVES: Under a constant inspired concentration, the uptake of a volatile anesthetic into the arterial blood should mainly be governed by alveolar ventilation, according to the assumption that the patient's cardiac output remains stable during anesthesia. We investigated whether ventilation volume affects the rate of desflurane uptake by examining arterial blood concentrations. METHOD: Thirty female patients were randomly allocated into the following three groups: hyperventilation, normal ventilation and hypoventilation. Hemodynamic variables were measured using a Finometer, inspiratory and end-tidal concentrations of desflurane were measured by infrared analysis, and the desflurane concentration in the arterial blood (Ades) was analyzed by gas chromatography. RESULTS: During the first 10 minutes after the administration of desflurane, the Ades was highest in the hyperventilation group, and this value was significantly different from those obtained for the normal and hypoventilation groups. In addition, hyperventilation significantly increased the slope of Ades-over-time during the first 5 minutes compared with patients experiencing normal ventilation and hypoventilation, but there were no differences in these slopes during the periods from 5-10, 10-20 and 20-40 minutes after the administration of desflurane. This finding indicates that there were no differences in desflurane uptake between the three groups after the first 5 minutes within desflurane administration. CONCLUSIONS: Hyperventilation accelerated the rate of the rise in Ades following desflurane administration, which was time-dependent with respect to different alveolar ventilations levels. PMID:23018299

Transport and biotransformation of the new cytostatic complex cis-diammineplatinum(II)-chlorocholylglycinate (Bamet-R2) by the rat liver.

PubMed

Macias, R I; Monte, M J; El-Mir, M Y; Villanueva, G R; Marin, J J

1998-09-01

Rat liver uptake and bile output of the cytostatic complex cis-diammineplatinum(II)-chlorocholylglycinate (Bamet-R2) were studied. Up to 100 microM, Bamet-R2 uptake by rat hepatocytes in primary culture followed saturation kinetics (Vmax = 0.65 +/- 0.12 nmol/5 min per mg protein; K(M) = 45.2 +/- 10.7 microM). Bamet-R2 uptake was lower than that of cholylglycinate (CG) but higher than that of cisplatin. Replacement of 116 mM NaCl by 116 mM choline chloride did not significantly reduce Bamet-R2 uptake. Addition of 500 microM CG, cholic acid, estrone sulfate, or ouabain to 50 microM Bamet-R2-containing incubation media inhibited Bamet-R2 uptake. No liver biotransformation of Bamet-R2 occurred, as indicated by HPLC analysis of bile collected from anesthetized rats after intravenous administration of the drug. Bamet-R2 uptake and secretion into bile by isolated rat livers exceeded those of cisplatin but were lower than those of CG. Differences between Bamet-R2 and CG were more marked for bile output than for liver uptake. Thus, higher Bamet-R2 than CG or cisplatin liver content was found. Co-administration of Bamet-R2 and CG revealed that CG induced a slight reduction in Bamet-R2 uptake and a marked inhibition in Bamet-R2 bile output. By contrast, Bamet-R2 had no effect on CG on either liver uptake or bile output. In sum, the present data indicate that Bamet-R2 is efficiently taken up and secreted into bile by the rat liver by mechanisms shared in part by natural bile acids.

Anesthesia in a Combat Environment

DTIC Science & Technology

1981-09-25

infusion in those patients where disruption of iliac vei~ns or inferior vena cava is a possibility (pelvic, abdominal, or chest trauima), A cathetor...minimal or no decrease in cardiac output, stroke volume, left -ventricular work, stroke work, and mean arterial pressure (5). Halothane, fluroxene, and...healthy young male volunteers to preserve cardiac output unchanged, decrease stroke volume, arterial pressure, peripheral resistance, 02 and left

[The adrenergic mechanisms are involved in the pulmonary hemodynamics changes following experimental myocardial ischemia in rabbits].

PubMed

Evlakhov, V I; Poiasov, I Z

2012-05-01

In acute experiments in anesthetized rabbits the changes of the pulmonary hemodynamics following myocardial ischemia in the region of the descendent left coronary artery were studied in control animals and after the blockade of alpha-adrenoreceptors by phentolamine or N-cholinoreceptors of autonomic ganglia by hexamethonium. Following myocardial ischemia in control animals the pulmonary artery pressure and flow decreased, the pulmonary vascular resistance was elevated not significantly, the cardiac output decreased more than pulmonary artery flow. Following myocardial ischemia after the blockade of alpha-adrenoreceptors the pulmonary artery flow and cardiac output decreased in the same level and the pulmonary vascular resistance was decreased. In these conditions the pulmonary artery pressure decreased more than in control animals, meanwhile the pulmonary artery flow was decreased in the same level as in the last case. Following myocardial ischemia after the blockade of N-cholinoreceptors the pulmonary hemodynamics changes were the same as they were following myocardial ischemia in the control rabbits, the cardiac output decreased more than pulmonary artery flow. The disbalance of the cardiac output and pulmonary artery flow changes in the case of myocardial ischemia was caused by the pulmonary vessel reactions following activations of the humoral adrenergic mechanisms.

Identification of prognostic markers in transthyretin and AL cardiac amyloidosis.

PubMed

Damy, Thibaud; Jaccard, Arnaud; Guellich, Aziz; Lavergne, David; Galat, Arnault; Deux, Jean-François; Hittinger, Luc; Dupuis, Jehan; Frenkel, Valérie; Rigaud, Charlotte; Plante-Bordeneuve, Violaine; Bodez, Diane; Mohty, Dania

2016-09-01

The prognosis of amyloidosis is known to depend heavily on cardiac function and may be improved by identifying patients at highest risk for adverse cardiac events. Identify predictors of mortality in patients with cardiac light-chain amyloidosis (AL), hereditary transthyretin amyloidosis (m-TTR), or wild-type transthyretin amyloidosis (WT-TTR) to prompt physician to refer these patients to dedicated centers. Observational study. About 266 patients referred for suspected cardiac amyloidosis (CA) in two French university centers were included. About 198 patients had CA (AL = 118, m-TTR = 57, and WT-TTR = 23). Their median (25th-75th percentile) age, NT-proBNP left ventricular ejection fraction were, respectively, 68 years (59-76), 2339 pg mL -1 (424-5974), and 60% (48-66). About 31% were in NYHA class III-IV. Interventricular septal thickness was greater in the m-TTR and WT-TTR groups than in the AL group (p < 0.0001). Median follow-up in survivor was 26 months (15-44) and 87 (44%) patients died. By multivariate analysis, independent predictors of mortality for AL amyloidosis were the following: age, cardiac output and NT-proBNP; for TTR amyloidosis was: NT-proBNP. When all amyloidosis were combined NT-proBNP, low cardiac output and pericardial effusion were independently associated with mortality. NT-proBNP is a strong prognosticator in the three types of cardiac amyloidosis. High NT-proBNP, low cardiac output, and pericardial effusion at the time of screening should prompt physician to refer the patients to amyloidosis referral center.

Oxygen transport and cardiovascular function at extreme altitude: lessons from Operation Everest II

NASA Technical Reports Server (NTRS)

Sutton, J. R.; Reeves, J. T.; Groves, B. M.; Wagner, P. D.; Alexander, J. K.; Hultgren, H. N.; Cymerman, A.; Houston, C. S.

1992-01-01

Operation Everest II was designed to examine the physiological responses to gradual decompression simulating an ascent of Mt Everest (8,848 m) to an inspired PO2 of 43 mmHg. The principal studies conducted were cardiovascular, respiratory, muscular-skeletal and metabolic responses to exercise. Eight healthy males aged 21-31 years began the "ascent" and six successfully reached the "summit", where their resting arterial blood gases were PO2 = 30 mmHg and PCO2 = 11 mmHg, pH = 7.56. Their maximal oxygen uptake decreased from 3.98 +/- 0.2 L/min at sea level to 1.17 +/- 0.08 L/min at PIO2 43 mmHg. The principal factors responsible for oxygen transport from the atmosphere to tissues were (1) Alveolar ventilation--a four fold increase. (2) Diffusion from the alveolus to end capillary blood--unchanged. (3) Cardiac function (assessed by hemodynamics, echocardiography and electrocardiography)--normal--although maximum cardiac output and heart rate were reduced. (4) Oxygen extraction--maximal with PvO2 14.8 +/- 1 mmHg. With increasing altitude maximal blood and muscle lactate progressively declined although at any submaximal intensity blood and muscle lactate was higher at higher altitudes.

Hormonal changes in antiorthostatic rats

NASA Technical Reports Server (NTRS)

Popovic, V.; Popovic, P.; Honeycutt, C.

1982-01-01

Hypokinesia, especially hypokinesia with negative tilt ('antiorthostatic hypokinesia'), mimics some of the effects of weightlessness. It is shown that cardiac output is increased during early exposure of rats to antiorthostatic hypokinesia. The increase of the stroke volume and of the cardiac output observed in the antiorthostatic hypokinetic rats is probably the consequence of a blood volume shift toward the chest brought forth by head-down positioning of the animals. It is also possible that struggling of the animals to escape from the harness and an increased metabolism contribute to the elevation of cardiac output. In order to study this hypothesis 'stress hormones' were measured in the antiorthostatic rats. Plasma levels of ACTH, corticosterone and prolactin were measured in the arterial blood (0.3 ml) sampled before, during and after hypokinesia from chronic aortic cannulas of the rats.

Glucose oxidation positively regulates glucose uptake and improves cardiac function recovery after myocardial reperfusion.

PubMed

Li, Tingting; Xu, Jie; Qin, Xinghua; Hou, Zuoxu; Guo, Yongzheng; Liu, Zhenhua; Wu, Jianjiang; Zheng, Hong; Zhang, Xing; Gao, Feng

2017-11-01

Myocardial reperfusion decreases glucose oxidation and uncouples glucose oxidation from glycolysis. Therapies that increase glucose oxidation lessen myocardial ischemia-reperfusion (I/R) injury. However, the regulation of glucose uptake during reperfusion remains poorly understood. We found that glucose uptake was remarkably diminished in the myocardium following reperfusion in Sprague-Dawley rats as detected by 18 F-labeled and fluorescent-labeled glucose analogs, even though GLUT1 was upregulated by threefold and GLUT4 translocation remained unchanged compared with those of sham-treated rats. The decreased glucose uptake was accompanied by suppressed glucose oxidation. Interestingly, stimulating glucose oxidation by inhibition of pyruvate dehydrogenase kinase 4 (PDK4), a rate-limiting enzyme for glucose oxidation, increased glucose uptake and alleviated I/R injury. In vitro data in neonatal myocytes showed that PDK4 overexpression decreased glucose uptake, whereas its knockdown increased glucose uptake, suggesting that PDK4 has a role in regulating glucose uptake. Moreover, inhibition of PDK4 increased myocardial glucose uptake with concomitant enhancement of cardiac insulin sensitivity following myocardial I/R. These results showed that the suppressed glucose oxidation mediated by PDK4 contributes to the reduced glucose uptake in the myocardium following reperfusion, and enhancement of glucose uptake exerts cardioprotection. The findings suggest that stimulating glucose oxidation via PDK4 could be an efficient approach to improve recovery from myocardial I/R injury. Copyright © 2017 the American Physiological Society.

The left ventricle as a mechanical engine: from Leonardo da Vinci to the echocardiographic assessment of peak power output-to-left ventricular mass.

PubMed

Dini, Frank L; Guarini, Giacinta; Ballo, Piercarlo; Carluccio, Erberto; Maiello, Maria; Capozza, Paola; Innelli, Pasquale; Rosa, Gian M; Palmiero, Pasquale; Galderisi, Maurizio; Razzolini, Renato; Nodari, Savina

2013-03-01

The interpretation of the heart as a mechanical engine dates back to the teachings of Leonardo da Vinci, who was the first to apply the laws of mechanics to the function of the heart. Similar to any mechanical engine, whose performance is proportional to the power generated with respect to weight, the left ventricle can be viewed as a power generator whose performance can be related to left ventricular mass. Stress echocardiography may provide valuable information on the relationship between cardiac performance and recruited left ventricular mass that may be used in distinguishing between adaptive and maladaptive left ventricular remodeling. Peak power output-to-mass, obtained during exercise or pharmacological stress echocardiography, is a measure that reflects the number of watts that are developed by 100 g of left ventricular mass under maximal stimulation. Power output-to-mass may be calculated as left ventricular power output per 100 g of left ventricular mass: 100× left ventricular power output divided by left ventricular mass (W/100 g). A simplified formula to calculate power output-to-mass is as follows: 0.222 × cardiac output (l/min) × mean blood pressure (mmHg)/left ventricular mass (g). When the integrity of myocardial structure is compromised, a mismatch becomes apparent between maximal cardiac power output and left ventricular mass; when this occurs, a reduction of the peak power output-to-mass index is observed.

[New methods for determining the relative load due to physical effort of the human body].

PubMed

Szubert, Józef; Szubert, Sławomir; Koszada-Włodarczyk, Wiesława; Bortkiewicz, Alicja

2014-01-01

The relative physical load (% VO2max) is the quotient of oxygen uptake (Vo2) during physical effort and maximum oxygen uptake (VO2max) by the human body. For this purpose the stress test must be performed. The relative load shows a high correlation with minute ventilation, cardiac output, heart rate, stroke volume, increased concentrations of catecholamines in the blood, inner temperature, weight, height and human body surface area. The relative load is a criterion for the maximum workloads admissible for healthy and sick workers. Besides, the classification of effort can be more precise when based on the relative load than on the energy output. Based on our own and international empirical evidence and the laws of heat transfer and fluid mechanics, a model of temperature control system has been developed, involving the elements of human cardiovascular and respiratory systems. Using this model, we have been able to develop our own methods of determining the relative load, applying only the body core temperature (Tw) or heart rate within one minute (HR), body mass (m), height (H), and body surface area (AD) instead of VO,max. The values of the relative physical load (% VO2max) obtained by using our own methods do not differ significantly from those obtained by other methods and by other researchers. The developed methods for determining the relative physical load (% VO2max) do not require the exercise test to be performed, therefore, they may be considered (after verification in an experimental study) a feasible alternative to current methods.

Ischemic preconditioning of the muscle improves maximal exercise performance but not maximal oxygen uptake in humans.

PubMed

Crisafulli, Antonio; Tangianu, Flavio; Tocco, Filippo; Concu, Alberto; Mameli, Ombretta; Mulliri, Gabriele; Caria, Marcello A

2011-08-01

Brief episodes of nonlethal ischemia, commonly known as "ischemic preconditioning" (IP), are protective against cell injury induced by infarction. Moreover, muscle IP has been found capable of improving exercise performance. The aim of the study was the comparison of standard exercise performances carried out in normal conditions with those carried out following IP, achieved by brief muscle ischemia at rest (RIP) and after exercise (EIP). Seventeen physically active, healthy male subjects performed three incremental, randomly assigned maximal exercise tests on a cycle ergometer up to exhaustion. One was the reference (REF) test, whereas the others were performed after the RIP and EIP sessions. Total exercise time (TET), total work (TW), and maximal power output (W(max)), oxygen uptake (VO(2max)), and pulmonary ventilation (VE(max)) were assessed. Furthermore, impedance cardiography was used to measure maximal heart rate (HR(max)), stroke volume (SV(max)), and cardiac output (CO(max)). A subgroup of volunteers (n = 10) performed all-out tests to assess their anaerobic capacity. We found that both RIP and EIP protocols increased in a similar fashion TET, TW, W(max), VE(max), and HR(max) with respect to the REF test. In particular, W(max) increased by ∼ 4% in both preconditioning procedures. However, preconditioning sessions failed to increase traditionally measured variables such as VO(2max), SV(max,) CO(max), and anaerobic capacity(.) It was concluded that muscle IP improves performance without any difference between RIP and EIP procedures. The mechanism of this effect could be related to changes in fatigue perception.

Pattern of myocardial 99mTc-HMDP uptake and impact on myocardial function in patients with transthyretin cardiac amyloidosis.

PubMed

Pradel, Sarah; Brun, Stéphanie; Victor, Gérard; Pascal, Pierre; Fournier, Pauline; Ribes, David; Lavie-Badie, Yoan; Galinier, Michel; Carrié, Didier; Berry, Isabelle; Lairez, Olivier

2018-06-07

The purpose of the study was to describe the pattern of 99m Tc-labeled phosphate agents myocardial uptake by scintigraphy and explore its impact on left ventricular (LV) functions in transthyretin cardiac amyloidosis (TTR-CA). Fifty patients with TTR-CA underwent 99m Tc- hydroxymethylene-diphosphonate ( 99m Tc-HMDP) scintigraphy and echocardiography with measure of LV thickness, longitudinal strain (LS), systolic and diastolic functions. Cardiac retention by scintigraphy was assessed by visual scoring and the heart/whole body (H/WB) ratio was calculated by dividing counts in the heart by counts in late whole-body images. The mean population age was 79 ± 10 years. Mean H/WB ratio was 12 ± 7. Myocardial 99m Tc-HMDP uptake on segments 5, 6, 7, 8, 11, 12, 13, 14, 16, and 17 was correlated with H/WB ratio. Mean LVEF and global LS were 51 ± 10% and - 10 ± 3%, respectively. H/WB ratio was correlated with global LS (R = 0.408, P = .003), Ea (R = - 0.566, P < .001) and mean left ventricular wall thickness (R = 0.476, P < .001) but not with LVEF (R = - 0.109, P = .453). Segmental myocardial uptake was slightly correlated with segmental LS (R = 0.152, P < .001). H/WB ratio was not correlated with NT-proBNP levels (R = 0.219, P = .148) neither E/Ea ratio (R = 0.204, P = .184). These findings show the relationship between bone tracer myocardial uptake and LV functions in patients with TTR cardiac amyloidosis.

Maternal hemodynamics: a method to classify hypertensive disorders of pregnancy.

PubMed

Ferrazzi, Enrico; Stampalija, Tamara; Monasta, Lorenzo; Di Martino, Daniela; Vonck, Sharona; Gyselaers, Wilfried

2018-01-01

The classification of hypertensive disorders of pregnancy is based on the time at the onset of hypertension, proteinuria, and other associated complications. Maternal hemodynamic interrogation in hypertensive disorders of pregnancy considers not only the peripheral blood pressure but also the entire cardiovascular system, and it might help to classify the different clinical phenotypes of this syndrome. This study aimed to examine cardiovascular parameters in a cohort of patients affected by hypertensive disorders of pregnancy according to the clinical phenotypes that prioritize fetoplacental characteristics and not the time at onset of hypertensive disorders of pregnancy. At the fetal-maternal medicine unit of Ziekenhuis Oost-Limburg (Genk, Belgium), maternal cardiovascular parameters were obtained through impedance cardiography using a noninvasive continuous cardiac output monitor with the patients placed in a standing position. The patients were classified as pregnant women with hypertensive disorders of pregnancy who delivered appropriate- and small-for-gestational-age fetuses. Normotensive pregnant women with an appropriate-for-gestational-age fetus at delivery were enrolled as the control group. The possible impact of obesity (body mass index ≥30 kg/m 2 ) on maternal hemodynamics was reassessed in the same groups. Maternal age, parity, body mass index, and blood pressure were not significantly different between the hypertensive disorders of pregnancy/appropriate-for-gestational-age and hypertensive disorders of pregnancy/small-for-gestational-age groups. The mean uterine artery pulsatility index was significantly higher in the hypertensive disorders of pregnancy/small-for-gestational-age group. The cardiac output and cardiac index were significantly lower in the hypertensive disorders of pregnancy/small-for-gestational-age group (cardiac output 6.5 L/min, cardiac index 3.6) than in the hypertensive disorders of pregnancy/appropriate-for-gestational-age group (cardiac output 7.6 L/min, cardiac index 3.9) but not between the hypertensive disorders of pregnancy/appropriate-for-gestational-age and control groups (cardiac output 7.6 L/min, cardiac index 4.0). Total vascular resistance was significantly higher in the hypertensive disorders of pregnancy/small-for-gestational-age group than in the hypertensive disorders of pregnancy/appropriate-for-gestational-age group and the control group. All women with hypertensive disorders of pregnancy showed signs of central arterial dysfunction. The cardiovascular parameters were not influenced by gestational age at the onset of hypertensive disorders of pregnancy, and no difference was observed between the women with appropriate-for-gestational-age fetuses affected by preeclampsia or by gestational hypertension with appropriate-for-gestational-age fetuses. Women in the obese/hypertensive disorders of pregnancy/appropriate-for-gestational-age and obese/hypertensive disorders of pregnancy/small-for-gestational-age groups showed a significant increase in cardiac output, as well as significant changes in other parameters, compared with the nonobese/hypertensive disorders of pregnancy/appropriate-for-gestational-age and nonobese/hypertensive disorders of pregnancy/small-for-gestational-age groups. Significantly low cardiac output and high total vascular resistance characterized the women with hypertensive disorders of pregnancy associated with small for gestational age due to placental insufficiency, independent of the gestational age at the onset of hypertension. The cardiovascular parameters were not significantly different in the women with appropriate-for-gestational-age or small-for-gestational-age fetuses affected by preeclampsia or gestational hypertension. These findings support the view that maternal hemodynamics may be a candidate diagnostic tool to identify hypertensive disorders in pregnancies associated with small-for-gestational-age fetuses. This additional tool matches other reported evidence provided by uterine Doppler velocimetry, low vascular growth factors in the first trimester, and placental pathology. Obesity is associated with a significantly higher cardiac output and outweighs other determinants of hemodynamics in pregnancy; therefore, in future studies on hypertensive disorders, obesity should be studied as an additional disease and not simply as a demographic characteristic. Copyright © 2017 Elsevier Inc. All rights reserved.

Whole plant based treatment of hypercholesterolemia with Crataegus laevigata in a zebrafish model.

PubMed

Littleton, Robert M; Miller, Matthew; Hove, Jay R

2012-07-23

Consumers are increasingly turning to plant-based complementary and alternative medicines to treat hypercholesterolemia. Many of these treatments are untested and their efficacy is unknown. This multitude of potential remedies necessitates a model system amenable to testing large numbers of organisms that maintains similarity to humans in both mode of drug administration and overall physiology. Here we develop the larval zebrafish (4-30 days post fertilization) as a vertebrate model of dietary plant-based treatment of hypercholesterolemia and test the effects of Crataegus laevigata in this model. Larval zebrafish were fed high cholesterol diets infused with fluorescent sterols and phytomedicines. Plants were ground with mortar and pestle into a fine powder before addition to food. Fluorescent sterols were utilized to optically quantify relative difference in intravascular cholesterol levels between groups of fish. We utilized the Zeiss 7-Live Duo high-speed confocal platform in order to both quantify intravascular sterol fluorescence and to capture video of the heart beat for determination of cardiac output. In this investigation we developed and utilized a larval zebrafish model to investigate dietary plant-based intervention of the pathophysiology of hypercholesterolemia. We found BODIPY-cholesterol effectively labels diet-introduced intravascular cholesterol levels (P < 0.05, Student's t-test). We also established that zebrafish cardiac output declines as cholesterol dose increases (difference between 0.1% and 8% (w/w) high cholesterol diet-treated cardiac output significant at P < 0.05, 1-way ANOVA). Using this model, we found hawthorn leaves and flowers significantly reduce intravascular cholesterol levels (P < 0.05, 1-way ANOVA) and interact with cholesterol to impact cardiac output in hypercholesterolemic fish (2-way ANOVA, P < 0.05 for interaction effect). The results of this study demonstrate that the larval zebrafish has the potential to become a powerful model to test plant based dietary intervention of hypercholesterolemia. Using this model we have shown that hawthorn leaves and flowers have the potential to affect cardiac output as well as intravascular cholesterol levels. Further, our observation that hawthorn leaves and flowers interact with cholesterol to impact cardiac output indicates that the physiological effects of hawthorn may depend on diet.

Maximal muscular vascular conductances during whole body upright exercise in humans

PubMed Central

Calbet, J A L; Jensen-Urstad, M; van Hall, G; Holmberg, H -C; Rosdahl, H; Saltin, B

2004-01-01

That muscular blood flow may reach 2.5 l kg−1 min−1 in the quadriceps muscle has led to the suggestion that muscular vascular conductance must be restrained during whole body exercise to avoid hypotension. The main aim of this study was to determine the maximal arm and leg muscle vascular conductances (VC) during leg and arm exercise, to find out if the maximal muscular vasodilatory response is restrained during maximal combined arm and leg exercise. Six Swedish elite cross-country skiers, age (mean ± s.e.m.) 24 ± 2 years, height 180 ± 2 cm, weight 74 ± 2 kg, and maximal oxygen uptake (V̇O2,max) 5.1 ± 0.1 l min−1 participated in the study. Femoral and subclavian vein blood flows, intra-arterial blood pressure, cardiac output, as well as blood gases in the femoral and subclavian vein, right atrium and femoral artery were determined during skiing (roller skis) at ∼76% of V̇O2,max and at V̇O2,max with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise) and leg skiing (predominantly leg exercise). During submaximal exercise cardiac output (26–27 l min−1), mean blood pressure (MAP) (∼87 mmHg), systemic VC, systemic oxygen delivery and pulmonary V̇O2 (∼4 l min−1) attained similar values regardless of exercise mode. The distribution of cardiac output was modified depending on the musculature engaged in the exercise. There was a close relationship between VC and V̇O2 in arms (r = 0.99, P < 0.001) and legs (r = 0.98, P < 0.05). Peak arm VC (63.7 ± 5.6 ml min−1 mmHg−1) was attained during double poling, while peak leg VC was reached at maximal exercise with the diagonal technique (109.8 ± 11.5 ml min−1 mmHg−1) when arm VC was 38.8 ± 5.7 ml min−1 mmHg−1. If during maximal exercise arms and legs had been vasodilated to the observed maximal levels then mean arterial pressure would have dropped at least to 75–77 mmHg in our experimental conditions. It is concluded that skeletal muscle vascular conductance is restrained during whole body exercise in the upright position to avoid hypotension. PMID:15121799

Effect of hypokinesia on cardiac contractile function and nervous regulation of the heart

NASA Technical Reports Server (NTRS)

Meyerson, F. Z.; Kapelko, V. I.; Gorina, M. S.; Shchegolkov, A. N.; Larinov, N. P.

1980-01-01

Longterm hypokinesia caused cardiac deadaptation in rabbits, which resulted in the diminishing of the left ventricular rate of contraction and relaxation, joined later by decreased vascular resistance. As a results, the ejection rate as well as stroke volume and cardiac output were normal. The decrease of the relaxation speed was more obvious at a high heart rate and results in shortening of the diastolic pause and diminishing of cardiac output. Hearts of the hypokinetic animals were characterized by normal maximal pressure developed by a unit of muccardial mass aorta clamping, decreased adrenoreactivity, and increased cholinoreactivity. This complex of changes is contrary to changes observed in adaptation to exercise, but is similar to changes observed in compensatory hypertrophy of the heart.

Neuregulin-1β promotes glucose uptake via PI3K/Akt in neonatal rat cardiomyocytes.

PubMed

Pentassuglia, Laura; Heim, Philippe; Lebboukh, Sonia; Morandi, Christian; Xu, Lifen; Brink, Marijke

2016-05-01

Nrg1β is critically involved in cardiac development and also maintains function of the adult heart. Studies conducted in animal models showed that it improves cardiac performance under a range of pathological conditions, which led to its introduction in clinical trials to treat heart failure. Recent work also implicated Nrg1β in the regenerative potential of neonatal and adult hearts. The molecular mechanisms whereby Nrg1β acts in cardiac cells are still poorly understood. In the present study, we analyzed the effects of Nrg1β on glucose uptake in neonatal rat ventricular myocytes and investigated to what extent mTOR/Akt signaling pathways are implicated. We show that Nrg1β enhances glucose uptake in cardiomyocytes as efficiently as IGF-I and insulin. Nrg1β causes phosphorylation of ErbB2 and ErbB4 and rapidly induces the phosphorylation of FAK (Tyr(861)), Akt (Thr(308) and Ser(473)), and its effector AS160 (Thr(642)). Knockdown of ErbB2 or ErbB4 reduces Akt phosphorylation and blocks the glucose uptake. The Akt inhibitor VIII and the PI3K inhibitors LY-294002 and Byl-719 abolish Nrg1β-induced phosphorylation and glucose uptake. Finally, specific mTORC2 inactivation after knockdown of rictor blocks the Nrg1β-induced increases in Akt-p-Ser(473) but does not modify AS160-p-Thr(642) or the glucose uptake responses to Nrg1β. In conclusion, our study demonstrates that Nrg1β enhances glucose uptake in cardiomyocytes via ErbB2/ErbB4 heterodimers, PI3Kα, and Akt. Furthermore, although Nrg1β activates mTORC2, the resulting Akt-Ser(473) phosphorylation is not essential for glucose uptake induction. These new insights into pathways whereby Nrg1β regulates glucose uptake in cardiomyocytes may contribute to the understanding of its regenerative capacity and protective function in heart failure. Copyright © 2016 the American Physiological Society.

Influence of body position on hemodynamics in patients with ischemic heart disease undergoing cardiac surgery.

PubMed

Mekis, Dusan; Kamenik, Mirt

2010-05-01

The cardiovascular response to decreased or increased preload in high-risk patients with ischemic heart disease enables us to understand the physiologic response to hemorrhage and its treatment. Although numerous studies have failed to show its effectiveness, the head-down position is still widely used to treat patients with hypotension and shock. The aim of our study was to evaluate the influence of body position on hemodynamics in high-risk patients undergoing coronary artery bypass graft surgery. In 16 patients with ischemic hearth disease and poor left ventricular function undergoing coronary artery bypass graft surgery, we measured cardiac output with thermodilution, arterial pressure, central venous pressure (CVP), pulmonary artery wedge pressure (PAWP) and heart rate in three different body positions: the horizontal position, 20 degrees head-up position, 20 degrees head-down position and back in the horizontal position. The measurements were made before and after cardiac surgery. Before skin incision the change from horizontal to 20 degrees head-up position led to a nonsignificant decrease in cardiac output and a significant decrease in mean arterial pressure, CVP and PAWP. The change from 20 degrees head-up to 20 degrees head-down position led to a significant increase in cardiac output, mean arterial pressure, CVP and PAWP. After skin closure the change from horizontal to 20 degrees head-up position led to a nonsignificant decrease in cardiac output and mean arterial pressure and a significant decrease CVP and PAWP. The change from 20 degrees head-up to 20 degrees head-down position led to a nonsignificant increase in cardiac output and a significant increase in mean arterial pressure, CVP and PAWP. There were no significant changes in heart rate during the changes in position before or after surgery. The results of our study showed a hemodynamic response similar to hemorrhage after placing the patients in a 20 degrees head-up position and improving hemodynamics in the head-down position in mechanically ventilated patients undergoing coronary artery bypass graft surgery.

Measurement of cardiac output from dynamic pulmonary circulation time CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yee, Seonghwan, E-mail: Seonghwan.Yee@Beaumont.edu; Scalzetti, Ernest M.

Purpose: To introduce a method of estimating cardiac output from the dynamic pulmonary circulation time CT that is primarily used to determine the optimal time window of CT pulmonary angiography (CTPA). Methods: Dynamic pulmonary circulation time CT series, acquired for eight patients, were retrospectively analyzed. The dynamic CT series was acquired, prior to the main CTPA, in cine mode (1 frame/s) for a single slice at the level of the main pulmonary artery covering the cross sections of ascending aorta (AA) and descending aorta (DA) during the infusion of iodinated contrast. The time series of contrast changes obtained for DA,more » which is the downstream of AA, was assumed to be related to the time series for AA by the convolution with a delay function. The delay time constant in the delay function, representing the average time interval between the cross sections of AA and DA, was determined by least square error fitting between the convoluted AA time series and the DA time series. The cardiac output was then calculated by dividing the volume of the aortic arch between the cross sections of AA and DA (estimated from the single slice CT image) by the average time interval, and multiplying the result by a correction factor. Results: The mean cardiac output value for the six patients was 5.11 (l/min) (with a standard deviation of 1.57 l/min), which is in good agreement with the literature value; the data for the other two patients were too noisy for processing. Conclusions: The dynamic single-slice pulmonary circulation time CT series also can be used to estimate cardiac output.« less

Effects of commonly used inotropes on myocardial function and oxygen consumption under constant ventricular loading conditions

PubMed Central

DeWitt, Elizabeth S.; Black, Katherine J.; Thiagarajan, Ravi R.; DiNardo, James A.; Colan, Steven D.; McGowan, Francis X.

2016-01-01

Inotropic medications are routinely used to increase cardiac output and arterial blood pressure during critical illness. However, few comparative data exist between these medications, particularly independent of their effects on venous capacitance and systemic vascular resistance. We hypothesized that an isolated working heart model that maintained constant left atrial pressure and aortic blood pressure could identify load-independent differences between inotropic medications. In an isolated heart preparation, the aorta and left atrium of Sprague Dawley rats were cannulated and placed in working mode with fixed left atrial and aortic pressure. Hearts were then exposed to common doses of a catecholamine (dopamine, epinephrine, norepinephrine, or dobutamine), milrinone, or triiodothyronine (n = 10 per dose per combination). Cardiac output, contractility (dP/dtmax), diastolic performance (dP/dtmin and tau), stroke work, heart rate, and myocardial oxygen consumption were compared during each 10-min infusion to an immediately preceding baseline. Of the catecholamines, dobutamine increased cardiac output, contractility, and diastolic performance more than clinically equivalent doses of norepinephrine (second most potent), dopamine, or epinephrine (P < 0.001). The use of triiodothyronine and milrinone was not associated with significant changes in cardiac output, contractility or diastolic function, either alone or added to a baseline catecholamine infusion. Myocardial oxygen consumption was closely related to dP/dtmax (r2 = 0.72), dP/dtmin (r2 = 0.70), and stroke work (r2 = 0.53). In uninjured, isolated working rodent hearts under constant ventricular loading conditions, dobutamine increased contractility and cardiac output more than clinically equivalent doses of norepinephrine, dopamine, and epinephrine; milrinone and triiodothyronine did not have significant effects on contractility. PMID:27150829

Nonuniform cardiac denervation observed by 11C-meta-hydroxyephedrine PET in 6-OHDA-treated monkeys.

PubMed

Joers, Valerie; Seneczko, Kailie; Goecks, Nichole C; Kamp, Timothy J; Hacker, Timothy A; Brunner, Kevin G; Engle, Jonathan W; Barnhart, Todd E; Nickles, R Jerome; Holden, James E; Emborg, Marina E

2012-01-01

Parkinson's disease presents nonmotor complications such as autonomic dysfunction that do not respond to traditional anti-parkinsonian therapies. The lack of established preclinical monkey models of Parkinson's disease with cardiac dysfunction hampers development and testing of new treatments to alleviate or prevent this feature. This study aimed to assess the feasibility of developing a model of cardiac dysautonomia in nonhuman primates and preclinical evaluations tools. Five rhesus monkeys received intravenous injections of 6-hydroxydopamine (total dose: 50 mg/kg). The animals were evaluated before and after with a battery of tests, including positron emission tomography with the norepinephrine analog (11)C-meta-hydroxyephedrine. Imaging 1 week after neurotoxin treatment revealed nearly complete loss of specific radioligand uptake. Partial progressive recovery of cardiac uptake found between 1 and 10 weeks remained stable between 10 and 14 weeks. In all five animals, examination of the pattern of uptake (using Logan plot analysis to create distribution volume maps) revealed a persistent region-specific significant loss in the inferior wall of the left ventricle at 10 (P<0.001) and 14 weeks (P<0.01) relative to the anterior wall. Blood levels of dopamine, norepinephrine (P<0.05), epinephrine, and 3,4-dihydroxyphenylacetic acid (P<0.01) were notably decreased after 6-hydroxydopamine at all time points. These results demonstrate that systemic injection of 6-hydroxydopamine in nonhuman primates creates a nonuniform but reproducible pattern of cardiac denervation as well as a persistent loss of circulating catecholamines, supporting the use of this method to further develop a monkey model of cardiac dysautonomia.

Role of cardiac output and the autonomic nervous system in the antinatriuretic response to acute constriction of the thoracic superior vena cava.

NASA Technical Reports Server (NTRS)

Schrier, R. W.; Humphreys, M. H.; Ufferman, R. C.

1971-01-01

Study of the differential characteristics of hepatic congestion and decreased cardiac output in terms of potential afferent stimuli in the antinatriuretic effect of acute thoracic inferior vena cava (TIVC) constriction. An attempt is made to see if the autonomic nervous system is involved in the antinatriuretic effect of acute TIVC or thoracic superior vena cava constriction.

Mechanisms of decreased left ventricular preload during continuous positive pressure ventilation in ARDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhainaut, J.F.; Devaux, J.Y.; Monsallier, J.F.

1986-07-01

Continuous positive pressure ventilation is associated with a reduction in left ventricular preload and cardiac output, but the mechanisms responsible are controversial. The decrease in left ventricular preload may result exclusively from a decreased systemic venous return due to increased pleural pressure, or from an additional effect such as decreased left ventricular compliance. To determine the mechanisms responsible, we studied the changes in cardiac output induced by continuous positive pressure ventilation in eight patients with the adult respiratory distress syndrome. We measured cardiac output by thermodilution, and biventricular ejection fraction by equilibrium gated blood pool scintigraphy. Biventricular end-diastolic volumes weremore » then calculated by dividing stroke volume by ejection fraction. As positive end-expiratory pressure increased from 0 to 20 cm H/sub 2/O, stroke volume and biventricular end-diastolic volumes fell about 25 percent, and biventricular ejection fraction remained unchanged. At 20 cm H/sub 2/O positive end-expiratory pressure, volume expansion for normalizing cardiac output restored biventricular end-diastolic volumes without markedly changing biventricular end-diastolic transmural pressures. The primary cause of the reduction in left ventricular preload with continuous positive pressure ventilation appears to be a fall in venous return and hence in right ventricular stroke volume, without evidence of change in left ventricular diastolic compliance.« less

Cardiac output increases prior to development of pulmonary edema after re-expansion of spontaneous pneumothorax.

PubMed

Tan, H C; Mak, K H; Johan, A; Wang, Y T; Poh, S C

2002-06-01

Pulmonary edema following reexpansion of spontaneous pneumothorax is an uncommon complication. The underlying mechanism of this condition is unclear. We report the hemodynamic characteristics in a series of 7 male patients with spontaneous large (>50%) pneumothoraces of > or = 24 h and correlate the changes with reexpansion pulmonary edema (REPE). A pulmonary artery floatation catheter was inserted and hemodynamic data were obtained before therapeutic chest tube insertion, 1 h after chest tube insertion and the following day. Four (57%) patients developed REPE. There was a tendency for larger pneumothorax to develop REPE. Capillary wedge pressure did not change significantly 1 h after the insertion of chest tube in all our patients. Cardiac output increased significantly in patients who developed REPE compared to those who did not (+ 1.06 l/min vs -0.27 l/min; P = 0.03) 1 h after insertion of chest tube. One patient did not develop pulmonary edema despite having a large (> 80%) pneumothorax. His cardiac output did not rise 1 h after chest tube insertion. REPE is not an uncommon complication following chest tube drainage in patients with large and long-standing pneumothorax. The increase in cardiac output after chest tube insertion may be associated with subsequent development of REPE.

Pulmonary circulation and gas exchange at exercise in Sherpas at high altitude.

PubMed

Faoro, Vitalie; Huez, Sandrine; Vanderpool, Rebecca; Groepenhoff, Herman; de Bisschop, Claire; Martinot, Jean-Benot; Lamotte, Michel; Pavelescu, Adriana; Guénard, Hervé; Naeije, Robert

2014-04-01

Tibetans have been reported to present with a unique phenotypic adaptation to high altitude characterized by higher resting ventilation and arterial oxygen saturation, no excessive polycythemia, and lower pulmonary arterial pressures (Ppa) compared with other high-altitude populations. How this affects exercise capacity is not exactly known. We measured aerobic exercise capacity during an incremental cardiopulmonary exercise test, lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) at rest, and mean Ppa (mPpa) and cardiac output by echocardiography at rest and at exercise in 13 Sherpas and in 13 acclimatized lowlander controls at the altitude of 5,050 m in Nepal. In Sherpas vs. lowlanders, arterial oxygen saturation was 86 ± 1 vs. 83 ± 2% (mean ± SE; P = nonsignificant), mPpa at rest 19 ± 1 vs. 23 ± 1 mmHg (P < 0.05), DL(CO) corrected for hemoglobin 61 ± 4 vs. 37 ± 2 ml · min(-1) · mmHg(-1) (P < 0.001), DL(NO) 226 ± 18 vs. 153 ± 9 ml · min(-1) · mmHg(-1) (P < 0.001), maximum oxygen uptake 32 ± 3 vs. 28 ± 1 ml · kg(-1) · min(-1) (P = nonsignificant), and ventilatory equivalent for carbon dioxide at anaerobic threshold 40 ± 2 vs. 48 ± 2 (P < 0.001). Maximum oxygen uptake was correlated directly to DL(CO) and inversely to the slope of mPpa-cardiac index relationships in both Sherpas and acclimatized lowlanders. We conclude that Sherpas compared with acclimatized lowlanders have an unremarkable aerobic exercise capacity, but with less pronounced pulmonary hypertension, lower ventilatory responses, and higher lung diffusing capacity.

Gymnasium-based unsupervised exercise maintains benefits in oxygen uptake kinetics obtained following supervised training in type 2 diabetes.

PubMed

Macananey, Oscar; O'Shea, Donal; Warmington, Stuart A; Green, Simon; Egaña, Mikel

2012-08-01

Supervised exercise (SE) in patients with type 2 diabetes improves oxygen uptake kinetics at the onset of exercise. Maintenance of these improvements, however, has not been examined when supervision is removed. We explored if potential improvements in oxygen uptake kinetics following a 12-week SE that combined aerobic and resistance training were maintained after a subsequent 12-week unsupervised exercise (UE). The involvement of cardiac output (CO) in these improvements was also tested. Nineteen volunteers with type 2 diabetes were recruited. Oxygen uptake kinetics and CO (inert gas rebreathing) responses to constant-load cycling at 50% ventilatory threshold (V(T)), 80% V(T), and mid-point between V(T) and peak workload (50% Δ) were examined at baseline (on 2 occasions) and following each 12-week training period. Participants decided to exercise at a local gymnasium during the UE. Thirteen subjects completed all the interventions. The time constant of phase 2 of oxygen uptake was significantly faster (p < 0.05) post-SE and post-UE compared with baseline at 50% V(T) (17.3 ± 10.7 s and 17.5 ± 5.9 s vs. 29.9 ± 10.7 s), 80% V(T) (18.9 ± 4.7 and 20.9 ± 8.4 vs. 34.3 ± 12.7s), and 50% Δ (20.4 ± 8.2 s and 20.2 ± 6.0 s vs. 27.6 ± 3.7 s). SE also induced faster heart rate kinetics at all 3 intensities and a larger increase in CO at 30 s in relation to 240 s at 80% V(T); and these responses were maintained post-UE. Unsupervised exercise maintained benefits in oxygen uptake kinetics obtained during a supervised exercise in subjects with diabetes, and these benefits were associated with a faster dynamic response of heart rate after training.

Lithotomy versus jack-knife position on haemodynamic parameters assessed by impedance cardiography during anorectal surgery under low dose spinal anaesthesia: a randomized controlled trial.

PubMed

Borodiciene, Jurgita; Gudaityte, Jurate; Macas, Andrius

2015-05-06

Although the prone position providing better exposure for anorectal surgery is required it can cause a reduction of cardiac output and cardiac index. The goal was to compare haemodynamic changes assessed by impedance cardiography during anorectal surgery under low-dose spinal anaesthesia in lithotomy and jack-knife position. The prospective randomized controlled study included 104, ASA I-II adult patients admitted for elective minor anorectal surgery, assigned to be performed in lithotomy (groupL, n = 52) or jack-knife position (groupJ, n = 52). After arrival to operating room the standard monitoring, impedance cardiography device was connected to the patient, and the following variables were recorded: cardiac output, cardiac index, systemic vascular resistance, stroke index at times of arrival to operating room, placement for, start and end of surgery and placement to bed. Spinal block was made in the sitting position with 4 mg of 0.5% hyperbaric bupivacaine and 10 μg of Fentanyl injected over 2 min. Comparison was based on haemodynamic changes between and inside groups over time. Student's t, chi square tests were used for statistical analysis with p < 0.05 regarded as statistically significant. The reduction of cardiac output was statistically significant after placement of the patient into the prone position: from baseline 7.4+/-1.6 to 4.9+/-1.2 after placement for and 4.7+/-1.2 at the start and end of surgery (mean +/-SD l/min). The difference of cardiac output between groups was 2.0 l/min after positioning for and the start of surgery and 1.5 l/min at the end of surgery (p < 0.05). Mean cardiac index reduced from baseline 3.9+/-0.8 to 2.6+/-0.7 and 2.4+/-0.6 (mean+/-SD l/min/m(2)) in groupJ and between groups: by 1.0 l/min/m(2) after placement for, 1.1 at the start and 0.8 at the end of surgery (p < 0.05). Systemic vascular resistance increased from baseline 1080+/-338 to 1483+/-479 after placement for, 1523+/-481 at the start and 1525+/-545 at the end of surgery in groupJ (mean+/-SD dynes/sec/cm(-5), p < 0.05). According to impedance cardiography, jack-knife position after low-dose spinal anaesthesia produces transitory, but statistically significant reduction of cardiac output and cardiac index with increase of systemic vascular resistance, compared to insignificant changes in lithotomy position. Clinical Trials NCT02115178.

Retention Kinetics of the 18F-Labeled Sympathetic Nerve PET Tracer LMI1195: Comparison with 11C-Hydroxyephedrine and 123I-MIBG.

PubMed

Werner, Rudolf A; Rischpler, Christoph; Onthank, David; Lapa, Constantin; Robinson, Simon; Samnick, Samuel; Javadi, Mehrbod; Schwaiger, Markus; Nekolla, Stephan G; Higuchi, Takahiro

2015-09-01

(18)F-N-[3-bromo-4-(3-fluoro-propoxy)-benzyl]-guanidine ((18)F-LMI1195) is a new PET tracer designed for noninvasive assessment of sympathetic innervation of the heart. The (18)F label facilitates the imaging advantages of PET over SPECT technology while allowing centralized manufacturing. Highly specific neural uptake of (18)F-LMI1195 has previously been established, but the retention kinetics are not yet fully understood. Healthy New Zealand White rabbits were studied with (18)F-LMI1195 using a small-animal PET system. Dynamic 40-min chest scans were started just before intravenous bolus injection of (18)F-LMI1195. Imaging was performed under norepinephrine transport inhibition with desipramine pretreatment, a 1.5 mg/kg desipramine chase administered 10 min after tracer injection, and saline treatment of controls. As a reference, cardiac uptake of (11)C-hydroxyephedrine and (123)I-metaiodobenzylguanidine ((123)I-MIBG) was examined by PET and planar scintigraphy, respectively. Cardiac uptake of all 3 tracers was inhibited by pretreatment with desipramine. Stable cardiac tracer retention was delineated by dynamic PET in control rabbits for (11)C-hydroxyephedrine (washout rate, 0.42% ± 0.57%/min) and (18)F-LMI1195 (washout rate, 0.058% ± 0.28%/min). A desipramine chase increased (11)C-hydroxyephedrine washout from the heart (2.43% ± 0.15%/min, P < 0.001), whereas (18)F-LMI1195 washout was not influenced (0.059% ± 0.11%/min, not statistically significant). Additionally, a desipramine chase did not change the cardiac (123)I-MIBG uptake (delayed heart-to-mediastinum ratio, 1.99 ± 0.12 (desipramine chase) vs. 2.05 ± 0.16 (controls), not statistically significant). In vivo norepinephrine transporter (NET) blockade with desipramine confirmed specific neural uptake of (18)F-LMI1195, (11)C-hydroxyephedrine, and (123)I-MIBG in rabbit hearts. (11)C-hydroxyephedrine cardiac retention was sensitive to a NET inhibitor chase, indicating a cycle of continuous NET uptake and release at the nerve terminals. In contrast, (18)F-LMI1195 and (123)I-MIBG demonstrated stable storage at the nerve terminal with resistance to a NET inhibitor chase, mimicking physiologic norepinephrine turnover. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

(99m)Tc-pyrophosphate scintigraphy for differentiating light-chain cardiac amyloidosis from the transthyretin-related familial and senile cardiac amyloidoses.

PubMed

Bokhari, Sabahat; Castaño, Adam; Pozniakoff, Ted; Deslisle, Susan; Latif, Farhana; Maurer, Mathew S

2013-03-01

Differentiating immunoglobulin light-chain (AL) from transthyretin-related cardiac amyloidoses (ATTR) is imperative given implications for prognosis, therapy, and genetic counseling. We validated the discriminatory ability of (99m)Tc-pyrophosphate ((99m)Tc-PYP) scintigraphy in AL versus ATTR. Forty-five subjects (12 AL, 16 ATTR wild type, and 17 ATTR mutants) underwent (99m)Tc-PYP planar and single-photon positive emission computed tomography cardiac imaging. Scans were performed by experienced nuclear cardiologists blinded to the subjects' cohort assignment. Cardiac retention was assessed with both a semiquantitative visual score (range, 0; no uptake to 3, diffuse uptake) and by quantitative analysis by drawing a region of interest over the heart corrected for contralateral counts and calculating a heart-to-contralateral ratio. Subjects with ATTR cardiac amyloid had a significantly higher semiquantitative cardiac visual score than the AL cohort (2.9±0.06 versus 0.8±0.27; P<0.0001) as well as a higher quantitative score (1.80±0.04 versus 1.21±0.04; P<0.0001). Using a heart-to-contralateral ratio >1.5 consistent with intensely diffuse myocardial tracer retention had a 97% sensitivity and 100% specificity with area under the curve 0.992, P<0.0001 for identifying ATTR cardiac amyloidosis. (99m)Tc-PYP cardiac imaging distinguishes AL from ATTR cardiac amyloidosis and may be a simple, widely available method for identifying subjects with ATTR cardiac amyloidosis, which should be studied in a larger prospective manner.

Diesel Exhaust Inhalation Increases Cardiac Output, Bradyarrhythmias, and Parasympathetic Tone in Aged Heart Failure-Prone Rats

EPA Science Inventory

Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance...

An Implantable Extracardiac Soft Robotic Device for the Failing Heart: Mechanical Coupling and Synchronization.

PubMed

Payne, Christopher J; Wamala, Isaac; Abah, Colette; Thalhofer, Thomas; Saeed, Mossab; Bautista-Salinas, Daniel; Horvath, Markus A; Vasilyev, Nikolay V; Roche, Ellen T; Pigula, Frank A; Walsh, Conor J

2017-09-01

Soft robotic devices have significant potential for medical device applications that warrant safe synergistic interaction with humans. This article describes the optimization of an implantable soft robotic system for heart failure whereby soft actuators wrapped around the ventricles are programmed to contract and relax in synchrony with the beating heart. Elastic elements integrated into the soft actuators provide recoiling function so as to aid refilling during the diastolic phase of the cardiac cycle. Improved synchronization with the biological system is achieved by incorporating the native ventricular pressure into the control system to trigger assistance and synchronize the device with the heart. A three-state electro-pneumatic valve configuration allows the actuators to contract at different rates to vary contraction patterns. An in vivo study was performed to test three hypotheses relating to mechanical coupling and temporal synchronization of the actuators and heart. First, that adhesion of the actuators to the ventricles improves cardiac output. Second, that there is a contraction-relaxation ratio of the actuators which generates optimal cardiac output. Third, that the rate of actuator contraction is a factor in cardiac output.

Improved Accuracy of Automated Estimation of Cardiac Output Using Circulation Time in Patients with Heart Failure.

PubMed

Dajani, Hilmi R; Hosokawa, Kazuya; Ando, Shin-Ichi

2016-11-01

Lung-to-finger circulation time of oxygenated blood during nocturnal periodic breathing in heart failure patients measured using polysomnography correlates negatively with cardiac function but possesses limited accuracy for cardiac output (CO) estimation. CO was recalculated from lung-to-finger circulation time using a multivariable linear model with information on age and average overnight heart rate in 25 patients who underwent evaluation of heart failure. The multivariable model decreased the percentage error to 22.3% relative to invasive CO measured during cardiac catheterization. This improved automated noninvasive CO estimation using multiple variables meets a recently proposed performance criterion for clinical acceptability of noninvasive CO estimation, and compares very favorably with other available methods. Copyright © 2016 Elsevier Inc. All rights reserved.

Xenobiotic Kinetics and Toxicity Among Fish and Mammals.

DTIC Science & Technology

1993-03-31

across the gill epithelium is rapid (assuming that much of the clearance is due to branchial elimination) and controlled by cardiac output. Paraoxon and...might be due to the plasma free fraction, which combined with the moderate lipophilicity allows significant branchial excretion in trout, a pathway...2.89 liter/hr/kg) was similar to the cardiac output (1.8 liter/hr/kg) suggesting significant branchial excretion in trout. Compared with the rat, the

Determination of the precision error of the pulmonary artery thermodilution catheter using an in vitro continuous flow test rig.

PubMed

Yang, Xiao-Xing; Critchley, Lester A; Joynt, Gavin M

2011-01-01

Thermodilution cardiac output using a pulmonary artery catheter is the reference method against which all new methods of cardiac output measurement are judged. However, thermodilution lacks precision and has a quoted precision error of ± 20%. There is uncertainty about its true precision and this causes difficulty when validating new cardiac output technology. Our aim in this investigation was to determine the current precision error of thermodilution measurements. A test rig through which water circulated at different constant rates with ports to insert catheters into a flow chamber was assembled. Flow rate was measured by an externally placed transonic flowprobe and meter. The meter was calibrated by timed filling of a cylinder. Arrow and Edwards 7Fr thermodilution catheters, connected to a Siemens SC9000 cardiac output monitor, were tested. Thermodilution readings were made by injecting 5 mL of ice-cold water. Precision error was divided into random and systematic components, which were determined separately. Between-readings (random) variability was determined for each catheter by taking sets of 10 readings at different flow rates. Coefficient of variation (CV) was calculated for each set and averaged. Between-catheter systems (systematic) variability was derived by plotting calibration lines for sets of catheters. Slopes were used to estimate the systematic component. Performances of 3 cardiac output monitors were compared: Siemens SC9000, Siemens Sirecust 1261, and Philips MP50. Five Arrow and 5 Edwards catheters were tested using the Siemens SC9000 monitor. Flow rates between 0.7 and 7.0 L/min were studied. The CV (random error) for Arrow was 5.4% and for Edwards was 4.8%. The random precision error was ± 10.0% (95% confidence limits). CV (systematic error) was 5.8% and 6.0%, respectively. The systematic precision error was ± 11.6%. The total precision error of a single thermodilution reading was ± 15.3% and ± 13.0% for triplicate readings. Precision error increased by 45% when using the Sirecust monitor and 100% when using the Philips monitor. In vitro testing of pulmonary artery catheters enabled us to measure both the random and systematic error components of thermodilution cardiac output measurement, and thus calculate the precision error. Using the Siemens monitor, we established a precision error of ± 15.3% for single and ± 13.0% for triplicate reading, which was similar to the previous estimate of ± 20%. However, this precision error was significantly worsened by using the Sirecust and Philips monitors. Clinicians should recognize that the precision error of thermodilution cardiac output is dependent on the selection of catheter and monitor model.

Suppression of Arrhythmia by Enhancing Mitochondrial Ca2+ Uptake in Catecholaminergic Ventricular Tachycardia Models.

PubMed

Schweitzer, Maria K; Wilting, Fabiola; Sedej, Simon; Dreizehnter, Lisa; Dupper, Nathan J; Tian, Qinghai; Moretti, Alessandra; My, Ilaria; Kwon, Ohyun; Priori, Silvia G; Laugwitz, Karl-Ludwig; Storch, Ursula; Lipp, Peter; Breit, Andreas; Mederos Y Schnitzler, Michael; Gudermann, Thomas; Schredelseker, Johann

2017-12-01

Cardiovascular disease-related deaths frequently arise from arrhythmias, but treatment options are limited due to perilous side effects of commonly used antiarrhythmic drugs. Cardiac rhythmicity strongly depends on cardiomyocyte Ca 2+ handling and prevalent cardiac diseases are causally associated with perturbations in intracellular Ca 2+ handling. Therefore, intracellular Ca 2+ transporters are lead candidate structures for novel and safer antiarrhythmic therapies. Mitochondria and mitochondrial Ca 2+ transport proteins are important regulators of cardiac Ca 2+ handling. Here we evaluated the potential of pharmacological activation of mitochondrial Ca 2+ uptake for the treatment of cardiac arrhythmia. To this aim,we tested substances that enhance mitochondrial Ca 2+ uptake for their ability to suppress arrhythmia in a murine model for ryanodine receptor 2 (RyR2)-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT) in vitro and in vivo and in induced pluripotent stem cell-derived cardiomyocytes from a CPVT patient. In freshly isolated cardiomyocytes of RyR2 R4496C/WT mice efsevin, a synthetic agonist of the voltage-dependent anion channel 2 (VDAC2) in the outer mitochondrial membrane, prevented the formation of diastolic Ca 2+ waves and spontaneous action potentials. The antiarrhythmic effect of efsevin was abolished by blockade of the mitochondrial Ca 2+ uniporter (MCU), but could be reproduced using the natural MCU activator kaempferol. Both mitochondrial Ca 2+ uptake enhancers (MiCUps), efsevin and kaempferol, significantly reduced episodes of stress-induced ventricular tachycardia in RyR2 R4496C/WT mice in vivo and abolished diastolic, arrhythmogenic Ca 2+ events in human iPSC-derived cardiomyocytes.

Heat stress redistributes blood flow in arteries of the brain during dynamic exercise.

PubMed

Sato, Kohei; Oue, Anna; Yoneya, Marina; Sadamoto, Tomoko; Ogoh, Shigehiko

2016-04-01

We hypothesized that heat stress would decrease anterior and posterior cerebral blood flow (CBF) during exercise, and the reduction in anterior CBF would be partly associated with large increase in extracranial blood flow (BF). Nine subjects performed 40 min of semirecumbent cycling at 60% of the peak oxygen uptake in hot (35°C; Heat) and thermoneutral environments (25°C; Control). We evaluated BF and conductance (COND) in the external carotid artery (ECA), internal carotid artery (ICA), and vertebral artery (VA) using ultrasonography. During the Heat condition, ICA and VA BF were significantly increased 10 min after the start of exercise (P < 0.05) and thereafter gradually decreased. ICA COND was significantly decreased (P < 0.05), whereas VA COND remained unchanged throughout Heat. Compared with the Control, either BF or COND of ICA and VA at the end of Heat tended to be lower, but not significantly. In contrast, ECA BF and COND at the end of Heat were both higher than levels in the Control condition (P < 0.01). During Heat, a reduction in ICA BF appears to be associated with a decline in end-tidal CO2 tension (r = 0.84), whereas VA BF appears to be affected by a change in cardiac output (r = 0.87). In addition, a change in ECA BF during Heat was negatively correlated with a change in ICA BF (r = -0.75). Heat stress resulted in modification of the vascular response of head and brain arteries to exercise, which resulted in an alteration in the distribution of cardiac output. Moreover, a hyperthermia-induced increase in extracranial BF might compromise anterior CBF during exercise with heat stress. Copyright © 2016 the American Physiological Society.

Altitude matters: differences in cardiovascular and respiratory responses to hypoxia in bar-headed geese reared at high and low altitudes.

PubMed

Lague, Sabine L; Chua, Beverly; Farrell, Anthony P; Wang, Yuxiang; Milsom, William K

2016-07-01

Bar-headed geese (Anser indicus) fly at high altitudes during their migration across the Himalayas and Tibetan plateau. However, we know relatively little about whether rearing at high altitude (i.e. phenotypic plasticity) facilitates this impressive feat because most of what is known about their physiology comes from studies performed at sea level. To provide this information, a comprehensive analysis of metabolic, cardiovascular and ventilatory responses to progressive decreases in the equivalent fractional composition of inspired oxygen (FiO2 : 0.21, 0.12, 0.09, 0.07 and 0.05) was made on bar-headed geese reared at either high altitude (3200 m) or low altitude (0 m) and on barnacle geese (Branta leucopsis), a low-altitude migrating species, reared at low altitude (0 m). Bar-headed geese reared at high altitude exhibited lower metabolic rates and a modestly increased hypoxic ventilatory response compared with low-altitude-reared bar-headed geese. Although the in vivo oxygen equilibrium curves and blood-oxygen carrying capacity did not differ between the two bar-headed goose study groups, the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher FiO2  threshold in bar-headed geese raised at high altitude. Thus, bar-headed geese reared at high altitude exhibited a reduced oxygen demand at rest and a modest but significant increase in oxygen uptake and delivery during progressive hypoxia compared with bar-headed geese reared at low altitude. © 2016. Published by The Company of Biologists Ltd.

Improvements in exercise performance with high-intensity interval training coincide with an increase in skeletal muscle mitochondrial content and function.

PubMed

Jacobs, Robert Acton; Flück, Daniela; Bonne, Thomas Christian; Bürgi, Simon; Christensen, Peter Møller; Toigo, Marco; Lundby, Carsten

2013-09-01

Six sessions of high-intensity interval training (HIT) are sufficient to improve exercise capacity. The mechanisms explaining such improvements are unclear. Accordingly, the aim of this study was to perform a comprehensive evaluation of physiologically relevant adaptations occurring after six sessions of HIT to determine the mechanisms explaining improvements in exercise performance. Sixteen untrained (43 ± 6 ml·kg(-1)·min(-1)) subjects completed six sessions of repeated (8-12) 60 s intervals of high-intensity cycling (100% peak power output elicited during incremental maximal exercise test) intermixed with 75 s of recovery cycling at a low intensity (30 W) over a 2-wk period. Potential training-induced alterations in skeletal muscle respiratory capacity, mitochondrial content, skeletal muscle oxygenation, cardiac capacity, blood volumes, and peripheral fatigue resistance were all assessed prior to and again following training. Maximal measures of oxygen uptake (Vo2peak; ∼8%; P = 0.026) and cycling time to complete a set amount of work (∼5%; P = 0.008) improved. Skeletal muscle respiratory capacities increased, most likely as a result of an expansion of skeletal muscle mitochondria (∼20%, P = 0.026), as assessed by cytochrome c oxidase activity. Skeletal muscle deoxygenation also increased while maximal cardiac output, total hemoglobin, plasma volume, total blood volume, and relative measures of peripheral fatigue resistance were all unaltered with training. These results suggest that increases in mitochondrial content following six HIT sessions may facilitate improvements in respiratory capacity and oxygen extraction, and ultimately are responsible for the improvements in maximal whole body exercise capacity and endurance performance in previously untrained individuals.

Smokeless tobacco, sport and the heart.

PubMed

Chagué, Frédéric; Guenancia, Charles; Gudjoncik, Aurélie; Moreau, Daniel; Cottin, Yves; Zeller, Marianne

2015-01-01

Smokeless tobacco (snuff) is a finely ground or shredded tobacco that is sniffed through the nose or placed between the cheek and gum. Chewing tobacco is used by putting a wad of tobacco inside the cheek. Smokeless tobacco is widely used by young athletes to enhance performance because nicotine improves some aspects of physiology. However, smokeless tobacco has harmful health effects, including cardiovascular disorders, linked to nicotine physiological effects, mainly through catecholamine release. Nicotine decreases heart rate variability and the ventricular fibrillation threshold, and promotes the occurrence of various arrhythmias; it also impairs endothelial-dependent vasodilation and could therefore promote premature atherogenesis. At rest, heart rate, blood pressure, inotropism, cardiac output and myocardial oxygen consumption are increased by nicotine, leading to an imbalance between myocardial oxygen demand and supply. The same occurs at submaximal levels of exercise. These increases are accompanied by a rise in systemic resistances. At maximal exercise, heart rate, cardiac output and maximal oxygen uptake (V˙O2max) are unaffected by nicotine. Because endothelial dysfunction is promoted by nicotine, paradoxical coronary vasoconstriction may occur during exercise and recovery. Nicotine induces a decrease in muscular strength and impairs anaerobic performance. However, nicotine is used in sports as it diminishes anxiety, enhances concentration and agility, improves aerobic performance and favours weight control. Importantly, smokeless tobacco, similar to cigarette smoking, leads to nicotine dependence through dopaminergic pathways. Smokeless tobacco has harmful cardiovascular effects and is addictive: it fulfils all the criteria for inclusion in the World Anti-Doping Agency prohibited list as a doping product. Smokeless tobacco use in sporting activities must be discouraged. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Chronic AMPK activity dysregulation produces myocardial insulin resistance in the human Arg302Gln-PRKAG2 glycogen storage disease mouse model

PubMed Central

2013-01-01

Background The cardiac PRKAG2 mutation in the γ2-subunit of adenosine monophosphate activated kinase (AMPK) is characterized by excessive glycogen deposition, hypertrophy, frequent arrhythmias, and progressive conduction system disease. We investigated whether myocardial glucose uptake (MGU) was augmented following insulin stimulation in a mouse model of the PRKAG2 cardiac syndrome. Methods Myocardial and skeletal muscle glucose uptake was assessed with 2-[18F]fluoro-2-deoxyglucose positron emission tomography imaging in n = 3 transgenic wildtype (TGwt) vs n = 7 PRKAG2 mutant (TGmut) mice at baseline and 1 week later, 30 min following acute insulin. Systolic function, cardiac glycogen stores, phospho-AMPK α, and insulin-receptor expression levels were analyzed to corroborate to the in vivo findings. Results TGmut Patlak Ki was reduced 56% at baseline compared to TGwt (0.3 ± 0.2 vs 0.7 ± 0.1, t test p = 0.01). MGU was augmented 71% in TGwt mice following acute insulin from baseline (0.7 ± 0.1 to 1.2 ± 0.2, t test p < 0.05). No change was observed in TGmut mice. As expected for this cardiac specific transgene, skeletal muscle was unaffected at baseline with a 33% to 38% increase (standard uptake values) for both genotypes following insulin stimulation. TGmut mice had a 47% reduction in systolic function with a fourfold increase in cardiac glycogen stores correlated with a 29% reduction in phospho-AMPK α levels. There was no difference in cardiac insulin receptor expression between mouse genotypes. Conclusions These results demonstrate a correlation between insulin resistance and AMPK activity and provide the basis for the use of this animal model for assessing metabolic therapy in the treatment of affected PRKAG2 patients. PMID:23829931

Sensitivity of technetium-99m-pyrophosphate scintigraphy in diagnosing cardiac amyloidosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falk, R.H.; Lee, V.W.; Rubinow, A.

1983-03-01

To determine the value of technetium-99m-pyrophosphate myocardial scintigraphy in the diagnosis of amyloid heart disease this procedure was prospectively performed in 20 consecutive patients with biopsy-proven primary amyloidosis. Eleven patients had echocardiographic abnormalities compatible with amyloid cardiomyopathy, 9 of whom had congestive heart failure. Diffuse myocardial pyrophosphate uptake was of equal or greater intensity than that of the ribs in 9 of the 11 patients with echocardiograms suggestive of amyloidosis, but in only 2 of the 9 with normal echocardiograms, despite abnormal electrocardiograms (p less than 0.01). Increased wall thickness measured by M-mode echocardiography correlated with myocardial pyrophosphate uptake (rmore » . 0.68, p less than 0.01). None of 10 control patients with nonamyloid, nonischemic heart disease had a strongly positive myocardial pyrophosphate uptake. Thus, myocardial technetium-99m-pyrophosphate scanning is a sensitive and specific test for the diagnosis of cardiac amyloidosis in patients with congestive heart failure of obscure origin. It does not appear to be of value for the early detection of cardiac involvement in patients with known primary amyloidosis without echocardiographic abnormalities.« less

Do interindividual differences in cardiac output during submaximal exercise explain differences in exercising muscle oxygenation and ratings of perceived exertion?

PubMed

Bentley, Robert F; Jones, Joshua H; Hirai, Daniel M; Zelt, Joel T; Giles, Matthew D; Raleigh, James P; Quadrilatero, Joe; Gurd, Brendon J; Neder, J Alberto; Tschakovsky, Michael E

2018-01-01

Considerable interindividual differences in the Q˙-V˙O2 relationship during exercise have been documented but implications for submaximal exercise tolerance have not been considered. We tested the hypothesis that these interindividual differences were associated with differences in exercising muscle deoxygenation and ratings of perceived exertion (RPE) across a range of submaximal exercise intensities. A total of 31 (21 ± 3 years) healthy recreationally active males performed an incremental exercise test to exhaustion 24 h following a resting muscle biopsy. Cardiac output (Q˙ L/min; inert gas rebreathe), oxygen uptake (V˙O2 L/min; breath-by-breath pulmonary gas exchange), quadriceps saturation (near infrared spectroscopy) and exercise tolerance (6-20; Borg Scale RPE) were measured. The Q˙-V˙O2 relationship from 40 to 160 W was used to partition individuals post hoc into higher (n = 10; 6.3 ± 0.4) versus lower (n = 10; 3.7 ± 0.4, P < 0.001) responders. The Q˙-V˙O2 difference between responder types was not explained by arterial oxygen content differences (P = 0.5) or peripheral skeletal muscle characteristics (P from 0.1 to 0.8) but was strongly associated with stroke volume (P < 0.05). Despite considerable Q˙-V˙O2 difference between groups, no difference in quadriceps deoxygenation was observed during exercise (all P > 0.4). Lower cardiac responders had greater leg (P = 0.027) and whole body (P = 0.03) RPE only at 185 W, but this represented a higher %peak V˙O2 in lower cardiac responders (87 ± 15% vs. 66 ± 12%, P = 0.005). Substantially lower Q˙-V˙O2 in the lower responder group did not result in altered RPE or exercising muscle deoxygenation. This suggests substantial recruitment of blood flow redistribution in the lower responder group as part of protecting matching of exercising muscle oxygen delivery to demand. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Acetazolamide Therapy for Metabolic Alkalosis in Pediatric Intensive Care Patients.

PubMed

López, Carolina; Alcaraz, Andrés José; Toledo, Blanca; Cortejoso, Lucía; Gil-Ruiz, Maite Augusta

2016-12-01

Patients in PICUs frequently present hypochloremic metabolic alkalosis secondary to loop diuretic treatment, especially those undergoing cardiac surgery. This study evaluates the effectiveness of acetazolamide therapy for metabolic alkalosis in PICU patients. Retrospective, observational study. A tertiary care children's hospital PICU. Children receiving at least a 2-day course of enteral acetazolamide. None. Demographic variables, diuretic treatment and doses of acetazolamide, urine output, serum electrolytes, urea and creatinine, acid-base excess, pH, and use of mechanical ventilation during treatment were collected. Patients were studied according to their pathology (postoperative cardiac surgery, decompensated heart failure, or respiratory disease). A total of 78 episodes in 58 patients were identified: 48 were carried out in cardiac postoperative patients, 22 in decompensated heart failure, and eight in respiratory patients. All patients received loop diuretics. A decrease in pH and PCO2 in the first 72 hours, a decrease in serum HCO3 (mean, 4.65 ± 4.83; p < 0.001), and an increase in anion gap values were observed. Urine output increased in cardiac postoperative patients (4.5 ± 2.2 vs 5.1 ± 2.0; p = 0.020), whereas diuretic treatment was reduced in cardiac patients. There was no significant difference in serum electrolytes, blood urea, creatinine, nor chloride after the administration of acetazolamide from baseline. Acetazolamide treatment was well tolerated in all patients. Acetazolamide decreases serum HCO3 and PCO2 in PICU cardiac patients with metabolic alkalosis secondary to diuretic therapy. Cardiac postoperative patients present a significant increase in urine output after acetazolamide treatment.

Age-dependent effects of milrinone and levosimendan on ventricular function and haemodynamics in newborn and mature pigs.

PubMed

Hyldebrandt, Janus A; Larsen, Signe H; Schmidt, Michael R; Hjortdal, Vibeke E; Ravn, Hanne B

2011-10-01

Inodilators are used in the treatment of low cardiac output, mainly after cardiac surgery. At present, there is little knowledge of the effect of inodilators in the newborn heart. Immediately after birth and in the neonatal period, the metabolism and physiology of the heart undergo major changes. We hypothesised that effects of the inodilators milrinone and levosimendan on myocardial contractility and haemodynamics under normal physiological conditions were age dependent. Animal studies were conducted on 48 pigs using a closed-chest biventricular conductance catheter method. Pigs in two age groups, that is, 5-6 days and 5-6 weeks, were assigned to milrinone, levosimendan, or a control group. We observed that both milrinone - 19.2% with a p value of 0.05 - and levosimendan - 25.7% with a p value of 0.03 compared with the control group increased cardiac output, as well as myocardial contractility with a maximum pressure development over time: milrinone 28.2%, p = 0.01 and levosimendan 19.4%, p = 0.05. Milrinone improved diastolic performance (p < 0.05) in the left ventricle in the 5-6-week-old animals. In the newborn animals, neither of the inodilators increased ventricular contractility or cardiac output; however, we observed a significant decrease in the mean arterial pressure: milrinone 34.6%, p < 0.01 and levosimendan 30.1%, p = 0.02. Both inodilators demonstrated age-dependent haemodynamic effects, and it is noteworthy that neither milrinone nor levosimendan was able to increase cardiac output in the newborn heart.

Single allele Lmbrd1 knockout results in cardiac hypertrophy.

PubMed

Tseng, Linda Tzu-Ling; Lin, Chieh-Liang; Pan, Kuei-Hsiang; Tzen, Kai-Yuan; Su, Ming-Jai; Tsai, Chia-Ti; Li, Yi-Han; Li, Pai-Chi; Chiang, Fu-Tien; Chang, Shin C; Chang, Ming-Fu

2018-06-01

LMBD1 protein, a type IV-B plasma membrane protein possessing nine putative trans-membrane domains, was previously demonstrated at cellular level to play a critical part in the signaling cascade of insulin receptor through its involvement in regulating clathrin-mediated endocytosis. However, at physiological level, the significance of LMBD1 protein in cardiac development remains unclear. To understand the role of Lmbrd1 gene involved in the cardiac function, heterozygous knockout mice were used as an animal model system. The pathological outcomes were analyzed by micro-positron emission tomography, ECG acquisition, cardiac ultrasound, and immunohistochemistry. By studying the heterozygous knockout of Lmbrd1 (Lmbrd1 +/- ), we discovered that lack of Lmbrd1 not only resulted in the increase of cardiac-glucose uptake, pathological consequences were also observed. Here, we have distinguished that Lmbrd1 +/- is sufficient in causing cardiac diseases through a pathway independent of the recessive vitamin B 12 cblF cobalamin transport defect. Lmbrd1 +/- mice exhibited an increase in myocardial glucose uptake and insulin receptor signaling that is insensitive to the administration of additional insulin. Pathological symptoms such as cardiac hypertrophy, ventricular tissue fibrosis, along with the increase of heart rate and cardiac muscle contractility were observed. As Lmbrd1 +/- mice aged, the decrease in ejection fraction and fraction shortening showed signs of ventricular function deterioration. The results suggested that Lmbrd1 gene not only plays a significant role in mediating the energy homeostasis in cardiac tissue, it may also be a key factor in the regulation of cardiac function in mice. Copyright © 2017. Published by Elsevier B.V.

Whole plant based treatment of hypercholesterolemia with Crataegus laevigata in a zebrafish model

PubMed Central

2012-01-01

Background Consumers are increasingly turning to plant-based complementary and alternative medicines to treat hypercholesterolemia. Many of these treatments are untested and their efficacy is unknown. This multitude of potential remedies necessitates a model system amenable to testing large numbers of organisms that maintains similarity to humans in both mode of drug administration and overall physiology. Here we develop the larval zebrafish (4–30 days post fertilization) as a vertebrate model of dietary plant-based treatment of hypercholesterolemia and test the effects of Crataegus laevigata in this model. Methods Larval zebrafish were fed high cholesterol diets infused with fluorescent sterols and phytomedicines. Plants were ground with mortar and pestle into a fine powder before addition to food. Fluorescent sterols were utilized to optically quantify relative difference in intravascular cholesterol levels between groups of fish. We utilized the Zeiss 7-Live Duo high-speed confocal platform in order to both quantify intravascular sterol fluorescence and to capture video of the heart beat for determination of cardiac output. Results In this investigation we developed and utilized a larval zebrafish model to investigate dietary plant-based intervention of the pathophysiology of hypercholesterolemia. We found BODIPY-cholesterol effectively labels diet-introduced intravascular cholesterol levels (P < 0.05, Student’s t-test). We also established that zebrafish cardiac output declines as cholesterol dose increases (difference between 0.1% and 8% (w/w) high cholesterol diet-treated cardiac output significant at P < 0.05, 1-way ANOVA). Using this model, we found hawthorn leaves and flowers significantly reduce intravascular cholesterol levels (P < 0.05, 1-way ANOVA) and interact with cholesterol to impact cardiac output in hypercholesterolemic fish (2-way ANOVA, P < 0.05 for interaction effect). Conclusions The results of this study demonstrate that the larval zebrafish has the potential to become a powerful model to test plant based dietary intervention of hypercholesterolemia. Using this model we have shown that hawthorn leaves and flowers have the potential to affect cardiac output as well as intravascular cholesterol levels. Further, our observation that hawthorn leaves and flowers interact with cholesterol to impact cardiac output indicates that the physiological effects of hawthorn may depend on diet. PMID:22824306

Uncertainty and variability in computational and mathematical models of cardiac physiology.

PubMed

Mirams, Gary R; Pathmanathan, Pras; Gray, Richard A; Challenor, Peter; Clayton, Richard H

2016-12-01

Mathematical and computational models of cardiac physiology have been an integral component of cardiac electrophysiology since its inception, and are collectively known as the Cardiac Physiome. We identify and classify the numerous sources of variability and uncertainty in model formulation, parameters and other inputs that arise from both natural variation in experimental data and lack of knowledge. The impact of uncertainty on the outputs of Cardiac Physiome models is not well understood, and this limits their utility as clinical tools. We argue that incorporating variability and uncertainty should be a high priority for the future of the Cardiac Physiome. We suggest investigating the adoption of approaches developed in other areas of science and engineering while recognising unique challenges for the Cardiac Physiome; it is likely that novel methods will be necessary that require engagement with the mathematics and statistics community. The Cardiac Physiome effort is one of the most mature and successful applications of mathematical and computational modelling for describing and advancing the understanding of physiology. After five decades of development, physiological cardiac models are poised to realise the promise of translational research via clinical applications such as drug development and patient-specific approaches as well as ablation, cardiac resynchronisation and contractility modulation therapies. For models to be included as a vital component of the decision process in safety-critical applications, rigorous assessment of model credibility will be required. This White Paper describes one aspect of this process by identifying and classifying sources of variability and uncertainty in models as well as their implications for the application and development of cardiac models. We stress the need to understand and quantify the sources of variability and uncertainty in model inputs, and the impact of model structure and complexity and their consequences for predictive model outputs. We propose that the future of the Cardiac Physiome should include a probabilistic approach to quantify the relationship of variability and uncertainty of model inputs and outputs. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

A new approach to non-invasive oxygenated mixed venous PCO(sub)2

NASA Technical Reports Server (NTRS)

Fisher, Joseph A.; Ansel, Clifford A.

1986-01-01

A clinically practical technique was developed to calculate mixed venous CO2 partial pressure for the calculation of cardiac output by the Fick technique. The Fick principle states that the cardiac output is equal to the CO2 production divided by the arterio-venous CO2 content difference of the pulmonary vessels. A review of the principles involved in the various techniques used to estimate venous CO2 partial pressure is presented.

Improved aortic enhancement in CT angiography using slope-based triggering with table speed optimization: a pilot study.

PubMed

Bashir, Mustafa R; Weber, Paul W; Husarik, Daniela B; Howle, Laurens E; Nelson, Rendon C

2012-08-01

To assess whether a scan triggering technique based on the slope of the time-attenuation curve combined with table speed optimization may improve arterial enhancement in aortic CT angiography compared to conventional threshold-based triggering techniques. Measurements of arterial enhancement were performed in a physiologic flow phantom over a range of simulated cardiac outputs (2.2-8.1 L/min) using contrast media boluses of 80 and 150 mL injected at 4 mL/s. These measurements were used to construct computer models of aortic attenuation in CT angiography, using cardiac output, aortic diameter, and CT table speed as input parameters. In-plane enhancement was calculated for normal and aneurysmal aortic diameters. Calculated arterial enhancement was poor (<150 HU) along most of the scan length using the threshold-based triggering technique for low cardiac outputs and the aneurysmal aorta model. Implementation of the slope-based triggering technique with table speed optimization improved enhancement in all scenarios and yielded good- (>200 HU; 13/16 scenarios) to excellent-quality (>300 HU; 3/16 scenarios) enhancement in all cases. Slope-based triggering with table speed optimization may improve the technical quality of aortic CT angiography over conventional threshold-based techniques, and may reduce technical failures related to low cardiac output and slow flow through an aneurysmal aorta.

Cardiovascular effects of anti-G suit inflation at 1 and 2 G.

PubMed

Montmerle, Stéphanie; Linnarsson, Dag

2005-06-01

We sought to determine to which pressure a full-coverage anti-G suit needs to be inflated in order to obtain the same stroke volume during a brief exposure to twice the normal gravity (2 G) as that at 1 G without anti-G suit inflation. Nine sitting subjects were studied at normal (1 G) and during 20 s of exposure to 2 G. They wore anti-G suits, which were inflated at both G-levels to the following target pressures: 0, 70, 140 and 210 mmHg. Stroke volume was computed from cardiac output, which was measured by rebreathing. Heart rate and mean arterial pressure at heart level were recorded. Inflation to 70 mmHg compensated for the decrease in stroke volume and cardiac output caused by hypergravity. Mean arterial pressure at heart level was comparable at 1 G and at 2 G and increased gradually and similarly with inflation (P<0.001) at both gravity levels. Thus, anti-G suits act by increasing both preload and afterload but the two effects counteract each other in terms of cardiac output, so that cardiac output at 2 G is maintained at its 1 G level. This effect is reached already at 70 mmHg of inflation. Greater inflation pressure further increases mean arterial pressure at heart level and compensates for the increased difference in hydrostatic pressure between heart and head in moderate hypergravity.

Life Satisfaction and Hemodynamic Reactivity to Mental Stress.

PubMed

Schwerdtfeger, Andreas; Gaisbachgrabner, Kerstin; Traunmüller, Claudia

2017-06-01

Satisfaction with life has been considered a health-protective variable, which could impact cardiovascular morbidity and mortality. However, few studies have examined the physiological pathways involved in the potentially salutary effect of life satisfaction. It was hypothesized that life satisfaction should be associated with a cardiovascular response profile that signals challenge (i.e., higher cardiac output, lower peripheral resistance), rather than threat during a mental stress task. A sample of 75 healthy, medication-free men without clinical signs of psychological disorders who worked full-time and occupied highly demanding positions participated in this study. They performed two mental stress tasks (n-back) with varying degrees of difficulty. The tasks were embedded between a baseline and a recovery period. Cardiovascular and hemodynamic variables (heart rate, blood pressure, cardiac output, total peripheral resistance) were recorded by means of impedance cardiography. Individuals who were more satisfied with their life displayed higher cardiac output and lower peripheral resistance levels during the stress tasks, indicating a challenge rather than a threat profile. Findings were robust when controlled for physical activity, smoking, age, and depressive symptoms. Life satisfaction could be positively correlated with beneficial hemodynamic stress reactivity, indicating that individuals with higher levels of life satisfaction can more adaptively cope with stress. Increased cardiac output and decreased peripheral resistance during stress may constitute one route through which life satisfaction can benefit health.

The effects of endothelin-1 on the cardiorespiratory physiology of the freshwater trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias).

PubMed

Perry, S F; Montpetit, C J; McKendry, J; Desforges, P R; Gilmour, K M; Wood, C M; Olson, K R

2001-11-01

The aim of the present study was to evaluate the effects of endothelin-l-elicited cardiovascular events on respiratory gas transfer in the freshwater rainbow trout (Oncorhynchus mykiss) and the marine dogfish (Squalus acanthias). In both species, endothelin-1 (666 pmol kg(-1)) caused a rapid (within 4 min) reduction (ca. 30-50 mmHg) in arterial blood partial pressure of O2. The effects of endothelin-1 on arterial blood partial pressure of CO2 were not synchronised with the changes in O2 partial pressure and the responses were markedly different in trout and dogfish. In trout, arterial CO2 partial pressure was increased transiently by approximately 1.0 mmHg but the onset of the response was delayed and occurred 12 min after endothelin-1 injection. In contrast, CO2 partial pressure remained more-or-less constant in dogfish after injection of endothelin-1 and was increased only slightly (approximately 0.1 mmHg) after 60 min. Pre-treatment of trout with bovine carbonic anhydrase (5 mg ml(-1)) eliminated the increase in CO2 partial pressure that was normally observed after endothelin-1 injection. In both species, endothelin-1 injection caused a decrease in arterial blood pH that mirrored the changes in CO2 partial pressure. Endothelin-1 injection was associated with transient (trout) or persistent (dogfish) hyperventilation as indicated by pronounced increases in breathing frequency and amplitude. In trout, arterial blood pressure remained constant or was decreased slightly and was accompanied by a transient increase in systemic resistance, and a temporary reduction in cardiac output. The decrease in cardiac output was caused solely by a reduction in cardiac frequency; cardiac stroke volume was unaffected. In dogfish, arterial blood pressure was lowered by approximately 10 mmHg at 6-10 min after endothelin-1 injection but then was rapidly restored to pre-injection levels. The decrease in arterial blood pressure reflected an increase in branchial vascular resistance (as determined using in situ perfused gill preparations) that was accompanied by simultaneous decreases in systemic resistance and cardiac output. Cardiac frequency and stroke volume were reduced by endothelin-1 injection and thus both variables contributed to the changes in cardiac output. We conclude that the net consequences of endothelin-1 on arterial blood gases result from the opposing effects of reduced gill functional surface area (caused by vasoconstriction) and an increase in blood residence time within the gill (caused by decreased cardiac output.

Initial Experience with IV Ketamine Infusion for Treatment of Post Sternotomy Pain in a Patient with a Total Artificial Heart.

PubMed

Maher, Dermot P; Loyferman, Rusty; Yumul, Roya; Louy, Charles

2015-01-01

The implantation of total artificial hearts (TAH) via midline sternotomy for the treatment of severe biventricular cardiac dysfunction is associated with complex postoperative pain management. Ketamaine increases blood pressure by raising sympathetic outflow and cardiac output; however, ketamine is a direct vasodilator on isolated arterial tissues. In the setting of a TAH with a mechanically fixed cardiac output, a ketamine infusion for postoperative pain control has the potential to decrease blood pressure due to direct arterial vasodilation. We present the initial experience with a ketamine infusion in a patient with a TAH with minimal observed decreases in blood pressure and significantly improved postoperative pain.

Pulse Wave Transit Time Measurements of Cardiac Output in Septic Shock Patients: A Comparison of the Estimated Continuous Cardiac Output System with Transthoracic Echocardiography.

PubMed

Feissel, Marc; Aho, Ludwig Serge; Georgiev, Stefan; Tapponnier, Romain; Badie, Julio; Bruyère, Rémi; Quenot, Jean-Pierre

2015-01-01

We determined reliability of cardiac output (CO) measured by pulse wave transit time cardiac output system (esCCO system; COesCCO) vs transthoracic echocardiography (COTTE) in mechanically ventilated patients in the early phase of septic shock. A secondary objective was to assess ability of esCCO to detect change in CO after fluid infusion. Mechanically ventilated patients admitted to the ICU, aged >18 years, in sinus rhythm, in the early phase of septic shock were prospectively included. We performed fluid infusion of 500 ml of crystalloid solution over 20 minutes and recorded CO by EsCCO and TTE immediately before (T0) and 5 minutes after (T1) fluid administration. Patients were divided into 2 groups (responders and non-responders) according to a threshold of 15% increase in COTTE in response to volume expansion. In total, 25 patients were included, average 64±15 years, 15 (60%) were men. Average SAPSII and SOFA scores were 55±21.3 and 13±2, respectively. ICU mortality was 36%. Mean cardiac output at T0 was 5.8±1.35 L/min by esCCO and 5.27±1.17 L/min by COTTE. At T1, respective values were 6.63 ± 1.57 L/min for esCCO and 6.10±1.29 L/min for COTTE. Overall, 12 patients were classified as responders, 13 as non-responders by the reference method. A threshold of 11% increase in COesCCO was found to discriminate responders from non-responders with a sensitivity of 83% (95% CI, 0.52-0.98) and a specificity of 77% (95% CI, 0.46-0.95). We show strong correlation esCCO and echocardiography for measuring CO, and change in CO after fluid infusion in ICU patients.

Role of the Frank-Starling mechanism in maintaining cardiac output during increasing levels of treadmill exercise in beta-blocked normal men.

PubMed

Bevilacqua, M; Savonitto, S; Bosisio, E; Chebat, E; Bertora, P L; Sardina, M; Norbiato, G

1989-04-01

To determine the effects of beta blockade on hemodynamics during increasing levels of treadmill exercise, 10 healthy volunteers were studied after 1 week of placebo, and then after 1 week of treatment with oral propranolol, 80 mg twice daily, or dilevalol, 400 mg once daily. The study was randomized and double-blind, with a crossover sequence. Hemodynamics were measured by CO2 rebreathing at rest and at 25, 50, 75 and 100% of VO2 max. After placebo, cardiac output increased from 5.8 +/- 2.1 (rest), to 19.4 +/- 6.4 liters/min (100% VO2 max), mainly due to an increase in heart rate from 84 +/- 6 to 169 +/- 15 beats/min. Stroke volume increased from 70 +/- 27 (rest), to 137 +/- 65 ml (25% VO2 max), and then leveled off to 116 +/- 41 at 100% VO2 max. After both beta blockers, exercise cardiac output was maintained at 100% VO2 max: 20.1 +/- 9.3 liters/min with propranolol and 19.1 +/- 8.6 with dilevalol. However, a significant reduction versus placebo values was observed for cardiac output at 25% VO2 max, from 13.7 +/- 5.9 during placebo, to 9.4 +/- 2.5 during propranolol, and to 9.6 +/- 2.3 during dilevalol (both p less than 0.01 vs placebo). Maintenance of cardiac output with both beta blockers at higher levels of exercise came from an increased stroke volume (p less than 0.05 vs placebo), while heart rate (in beats/min) was greatly reduced (propranolol 61.6 +/- 9.4 rest, 90.1 +/- 10.7 at 100% VO2 max; dilevalol 70.8 +/- 6.4 rest, 99.2 +/- 11.8 at 100% VO2 max, p less than 0.01 vs placebo for each).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic response to exercise and head-up tilt of patients implanted with a rotary blood pump: a computational modeling study.

PubMed

Lim, Einly; Salamonsen, Robert Francis; Mansouri, Mahdi; Gaddum, Nicholas; Mason, David Glen; Timms, Daniel L; Stevens, Michael Charles; Fraser, John; Akmeliawati, Rini; Lovell, Nigel Hamilton

2015-02-01

The present study investigates the response of implantable rotary blood pump (IRBP)-assisted patients to exercise and head-up tilt (HUT), as well as the effect of alterations in the model parameter values on this response, using validated numerical models. Furthermore, we comparatively evaluate the performance of a number of previously proposed physiologically responsive controllers, including constant speed, constant flow pulsatility index (PI), constant average pressure difference between the aorta and the left atrium, constant average differential pump pressure, constant ratio between mean pump flow and pump flow pulsatility (ratioP I or linear Starling-like control), as well as constant left atrial pressure ( P l a ¯ ) control, with regard to their ability to increase cardiac output during exercise while maintaining circulatory stability upon HUT. Although native cardiac output increases automatically during exercise, increasing pump speed was able to further improve total cardiac output and reduce elevated filling pressures. At the same time, reduced venous return associated with upright posture was not shown to induce left ventricular (LV) suction. Although P l a ¯ control outperformed other control modes in its ability to increase cardiac output during exercise, it caused a fall in the mean arterial pressure upon HUT, which may cause postural hypotension or patient discomfort. To the contrary, maintaining constant average pressure difference between the aorta and the left atrium demonstrated superior performance in both exercise and HUT scenarios. Due to their strong dependence on the pump operating point, PI and ratioPI control performed poorly during exercise and HUT. Our simulation results also highlighted the importance of the baroreflex mechanism in determining the response of the IRBP-assisted patients to exercise and postural changes, where desensitized reflex response attenuated the percentage increase in cardiac output during exercise and substantially reduced the arterial pressure upon HUT. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Prototype development of an electrical impedance based simultaneous respiratory and cardiac monitoring system for gated radiotherapy.

PubMed

Kohli, Kirpal; Liu, Jeff; Schellenberg, Devin; Karvat, Anand; Parameswaran, Ash; Grewal, Parvind; Thomas, Steven

2014-10-14

In radiotherapy, temporary translocations of the internal organs and tumor induced by respiratory and cardiac activities can undesirably lead to significantly lower radiation dose on the targeted tumor but more harmful radiation on surrounding healthy tissues. Respiratory and cardiac gated radiotherapy offers a potential solution for the treatment of tumors located in the upper thorax. The present study focuses on the design and development of simultaneous acquisition of respiratory and cardiac signal using electrical impedance technology for use in dual gated radiotherapy. An electronic circuitry was developed for monitoring the bio-impedance change due to respiratory and cardiac motions and extracting the cardiogenic ECG signal. The system was analyzed in terms of reliability of signal acquisition, time delay, and functionality in a high energy radiation environment. The resulting signal of the system developed was also compared with the output of the commercially available Real-time Position Management™ (RPM) system in both time and frequency domains. The results demonstrate that the bioimpedance-based method can potentially provide reliable tracking of respiratory and cardiac motion in humans, alternative to currently available methods. When compared with the RPM system, the impedance-based system developed in the present study shows similar output pattern but different sensitivities in monitoring different respiratory rates. The tracking of cardiac motion was more susceptible to interference from other sources than respiratory motion but also provided synchronous output compared with the ECG signal extracted. The proposed hardware-based implementation was observed to have a worst-case time delay of approximately 33 ms for respiratory monitoring and 45 ms for cardiac monitoring. No significant effect on the functionality of the system was observed when it was tested in a radiation environment with the electrode lead wires directly exposed to high-energy X-Rays. The developed system capable of rendering quality signals for tracking both respiratory and cardiac motions can potentially provide a solution for simultaneous dual-gated radiotherapy.

A comparison of dobutamine and levosimendan on hepatic blood flow in patients with a low cardiac output state after cardiac surgery: a randomised controlled study.

PubMed

Alvarez, J; Baluja, A; Selas, S; Otero, P; Rial, M; Veiras, S; Caruezo, V; Taboada, M; Rodriguez, I; Castroagudin, J; Tome, S; Rodriguez, A; Rodriguez, J

2013-11-01

Liver dysfunction due to a low cardiac output state after cardiac surgery is associated with a poor prognosis, but whether one inotrope is superior to another in improving hepatic perfusion remains uncertain. This study compared the systemic and hepatic haemodynamic effects of levosimendan to dobutamine in patients with a low cardiac output state (cardiac index < 2.2 l/min/m2) after on-pump cardiac surgery. A total of 25 patients were randomised to receive either an intravenous bolus of levosimendan (12 µg/kg) over 15 minutes, followed by an infusion of 0.2 µg/kg/min for 24 hours, or an infusion of dobutamine 7.5 µg/kg/min for 24 hours and completed the study. The systemic and hepatic haemodynamics at 24 and 48 hours were all better after levosimendan than dobutamine (dobutamine group: cardiac index (l/min/m2)=2.51 [standard deviation ±0.29], 2.40±0.23; portal vein flow (ml/min): 614.0±124.7, 585.9±144.8; pulsatility index: 2.02±0,28, 2.98±0.27 versus the levosimendan group: cardiac index: 3.02± 0.27, 2.98± 0.30; portal vein flow: 723.0± 143.5, 702.9±117.8; pulsatility index: 1.71±0.26, 1.73±0.27). The improvement in portal vein blood flow at 48 hours was significantly better after levosimendan than dobutamine (41% vs. 11% increment from baseline, P<0.05). In addition, there was a significant reduction in hepatic artery resistance after levosimendan but not dobutamine (resistance index reduction 6.5% vs. 0%, P<0.05). In summary, levosimendan can be considered as a selective liver vasodilator and can improve hepatic blood flow through both the hepatic artery and portal venous system, whereas dobutamine can only improve the portal venous blood flow without vasodilating the hepatic artery.

A nursing diagnosis approach to the patient awaiting cardiac transplantation.

PubMed

Cardin, S; Clark, S

1985-09-01

The most common reason to perform cardiac transplantation is dilated cardiomyopathy. Alterations in cardiac output secondary to decreased contractility and increased preload and afterload will, over time, lead to progressive deterioration of the patient with this type of end-stage cardiac disease. Heart transplantation is now an accepted therapy for these patients. This article focused on the patient in the period awaiting cardiac transplantation. Five pertinent nursing diagnoses were identified and discussed. A case study approach was utilized to highlight patient problems and nursing interventions.

Cardiac fatty acid uptake and metabolism in the rat model of polycystic ovary syndrome.

PubMed

Tepavčević, Snežana; Milutinović, Danijela Vojnović; Macut, Djuro; Stojiljković, Mojca; Nikolić, Marina; Božić-Antić, Ivana; Ćulafić, Tijana; Bjekić-Macut, Jelica; Matić, Gordana; Korićanac, Goran

2015-09-01

Polycystic ovary syndrome (PCOS) is associated with an altered plasma lipid profile and increased risk for cardiovascular diseases. We hypothesized that molecular mechanisms underlying cardiac pathology in PCOS involve changes in expression and subcellular localization of several key proteins involved in cardiac lipid transport and metabolism, such as fatty acid transporter CD36, lipin 1, peroxisome proliferator-activated receptor α (PPARα), peroxisome proliferator-activated receptor γ coactivator-1 (PGC1), and carnitine palmitoyltransferase 1 (CPT1). We used the animal model of PCOS obtained by treating female rats with dihydrotestosterone (DHT). Protein levels of CD36, lipin 1, PPARα, PGC1, and antioxidative enzymes were assessed by Western blot in different cardiac cell compartments. Cardiac triglycerides (TG) and lipid peroxidation were also measured. The content of CD36 was decreased in both the cardiac plasma membranes and intracellular pool. On the other hand, total content of cardiac lipin 1 in DHT-treated rats was elevated, in contrast to decreased microsomal lipin 1 content. An increase in nuclear content of lipin 1 was observed together with elevation of nuclear PPARα and PGC1, and an increase in CPT1 expression. However, lipid peroxidation was reduced in the heart, without alterations in antioxidative enzymes expression and cardiac TG content. The results indicate that treatment of female rats with DHT is accompanied by a decrease of fatty acid uptake and a reduction of lipid peroxidation in the heart. The observed elevation of lipin 1, PPARα, PGC1, and CPT1 expression suggests that cardiac fatty acid metabolism is shifted toward mitochondrial beta oxidation.

Defibrillator synchronization tester.

PubMed

Demirbilek, Fatma N; Krajnak, Mike; Stolarczyk, George

2009-01-01

A defibrillator sync output signal connector provides an ECG synchronization signal that can be used by some defibrillators for the purpose of performing synchronized cardioversion [1]. This process is used to stop an abnormally fast heart rate or cardiac arrhythmia by the delivery of a therapeutic dose of electric current to the heart during the R-wave of the cardiac cycle. Timing the shock to the R-wave prevents the delivery of the shock during the vulnerable period of the cardiac cycle, which could induce ventricular fibrillation [2]. GE patient monitors include a selectable analog output feature, which provides an analog ECG or arterial blood pressure signal. The blood pressure signal can be used to synchronize balloon pumps to provide cardiac assist to post-MI patients with poor injection fraction. Proper operation requires the defibrillator sync and analog output function to be checked. Checkouts are typically done during planned maintenance and after major part replacements such as patient monitor's main CPU board. Checking out defibrillator sync signals could be done using a GE defibrillator sync tester. The defibrillator sync tester provides a loop back path for the defibrillator sync signals to be displayed on the patient monitor screen and eliminates the need for an external oscilloscope.

Stroke volume obtained from the brachial artery using transbrachial electrical bioimpedance velocimetry.

PubMed

Henry, Isaac C; Bernstein, Donald P; Banet, Matt J

2012-01-01

Stroke volume (SV) is the quantity of blood ejected by the cardiac ventricles per each contraction. When SV is multiplied by heart rate, cardiac output is the result. Cardiac output (CO), in conjunction with hemoglobin concentration and arterial oxygen saturation are the cornerstones of oxygen transport. Measurement of CO is important, especially in sick humans suffering from decompensated heart disease and systemic diseases affecting the contractility or loading conditions of the heart. Although reasonably accurate invasive cardiac output methods are available, their use is restricted to those individuals hospitalized in the intensive care units. Thus, a robust noninvasive alternative is considered desirable. Impedance cardiography (ICG) is one such method, but in patients with severe heart disease and/or excess extravascular lung water, the method is inaccurate. This paper concerns the introduction of a new method, transbrachial electrical bioimpedance velocimetry (TBEV). The technique involves passage of a constant magnitude, high frequency, and low amperage ac from the upper arm to the antecubital fossa. In all other respects, the operational aspects of TBEV are consistent with ICG. There is good evidence suggesting that the TBEV waveform and its derivatives are generated by blood resistivity changes only.

Right atrial pressure: determinant or result of change in venous return?

PubMed

Bendjelid, Karim

2005-11-01

According to the concept of Guyton, cardiac output is largely controlled by venous return, which is determined by the difference between mean systemic venous pressure and right atrial pressure. In the analysis of the venous return curve, other authors have suggested that right atrial pressure is the dependent variable and venous return is the independent variable (right atrial pressure decreased because cardiac output increased). The present report analyzes this historical debate, which has already lasted > 50 years.

Rapid multislice T1 mapping of mouse myocardium: Application to quantification of manganese uptake in α-Dystrobrevin knockout mice.

PubMed

Jiang, Kai; Li, Wen; Li, Wei; Jiao, Sen; Castel, Laurie; Van Wagoner, David R; Yu, Xin

2015-11-01

The aim of this study was to develop a rapid, multislice cardiac T1 mapping method in mice and to apply the method to quantify manganese (Mn(2+)) uptake in a mouse model with altered Ca(2+) channel activity. An electrocardiography-triggered multislice saturation-recovery Look-Locker method was developed and validated both in vitro and in vivo. A two-dose study was performed to investigate the kinetics of T1 shortening, Mn(2+) relaxivity in myocardium, and the impact of Mn(2+) on cardiac function. The sensitivity of Mn(2+)-enhanced MRI in detecting subtle changes in altered Ca(2+) channel activity was evaluated in a mouse model with α-dystrobrevin knockout. Validation studies showed strong agreement between the current method and an established method. High Mn(2+) dose led to significantly accelerated T1 shortening. Heart rate decreased during Mn(2+) infusion, while ejection ratio increased slightly at the end of imaging protocol. No statistical difference in cardiac function was detected between the two dose groups. Mice with α-dystrobrevin knockout showed enhanced Mn(2+) uptake in vivo. In vitro patch-clamp study showed increased Ca(2+) channel activity. The saturation recovery method provides rapid T1 mapping in mouse hearts, which allowed sensitive detection of subtle changes in Mn(2+) uptake in α-dystrobrevin knockout mice. © 2014 Wiley Periodicals, Inc.

Effects of 12 days exposure to simulated microgravity on central circulatory hemodynamics in the rhesus monkey

NASA Astrophysics Data System (ADS)

Convertino, V. A.; Koenig, S. C.; Krotov, V. P.; Fanton, J. W.; Korolkov, V. I.; Trambovetsky, E. V.; Ewert, D. L.; Truzhennikov, A.; Latham, R. D.

Central circulatory hemodynamic responses were measured before and during the initial 9 days of a 12-day 10 ° head-down tilt (HDT) in 4 flight-sized juvenile rhesus monkeys who were surgically instrumented with a variety of intrathoracic catheters and blood flow sensors to assess the effects of simulated microgravity on central circulatory hemodynamics. Each subject underwent measurements of aortic and left ventricular pressures, and aortic flow before and during HDT as well as during a passive head-up postural test before and after HDT. Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure were measured, and dP/dt and left ventricular elastance was calculated from hemodynamic measurements. The postural test consisted of 5 min of supine baseline control followed by 5 minutes of 90 ° upright tilt (HUT). Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure showed no consistent alterations during HDT. Left ventricular elastance was reduced in all animals throughout HDT, indicating that cardiac compliance was increased. HDT did not consistently alter left ventricular +dP/dt, indicating no change in cardiac contractility. Heart rate during the post-HDT HUT postural test was elevated compared to pre-HDT while post-HDT cardiac output was decreased by 52% as a result of a 54% reduction in stroke volume throughout HUT. Results from this study using an instrumented rhesus monkey suggest that exposure to microgravity may increase ventricular compliance without alterating cardiac contractility. Our project supported the notion that an invasively-instrumented animal model should be viable for use in spaceflight cardiovascular experiments to assess potential changes in myocardial function and cardiac compliance.

Effects of 12 days exposure to simulated microgravity on central circulatory hemodynamics in the rhesus monkey

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Koenig, S. C.; Krotov, V. P.; Fanton, J. W.; Korolkov, V. I.; Trambovetsky, E. V.; Ewert, D. L.; Truzhennikov, A.; Latham, R. D.

1998-01-01

Central circulatory hemodynamic responses were measured before and during the initial 9 days of a 12-day 10 degrees head-down tilt (HDT) in 4 flight-sized juvenile rhesus monkeys who were surgically instrumented with a variety of intrathoracic catheters and blood flow sensors to assess the effects of simulated microgravity on central circulatory hemodynamics. Each subject underwent measurements of aortic and left ventricular pressures, and aortic flow before and during HDT as well as during a passive head-up postural test before and after HDT. Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure were measured, and dP/dt and left ventricular elastance was calculated from hemodynamic measurements. The postural test consisted of 5 min of supine baseline control followed by 5 minutes of 90 degrees upright tilt (HUT). Heart rate, stroke volume, cardiac output, and left ventricular end-diastolic pressure showed no consistent alterations during HDT. Left ventricular elastance was reduced in all animals throughout HDT, indicating that cardiac compliance was increased. HDT did not consistently alter left ventricular +dP/dt, indicating no change in cardiac contractility. Heart rate during the post-HDT HUT postural test was elevated compared to pre-HDT while post-HDT cardiac output was decreased by 52% as a result of a 54% reduction in stroke volume throughout HUT. Results from this study using an instrumented rhesus monkey suggest that exposure to microgravity may increase ventricular compliance without alternating cardiac contractility. Our project supported the notion that an invasively-instrumented animal model should be viable for use in spaceflight cardiovascular experiments to assess potential changes in myocardial function and cardiac compliance.

Electrical velocimetry for non-invasive monitoring of the closure of the ductus arteriosus in preterm infants.

PubMed

Rodríguez Sánchez de la Blanca, Ana; Sánchez Luna, M; González Pacheco, N; Arriaga Redondo, M; Navarro Patiño, N

2018-02-01

Closure of a patent ductus arteriosus (PDA) in preterm infants modifies cardiac output and induces adaptive changes in the hemodynamic situation. The present study aims to analyze those changes, through a non-invasive cardiac output monitor based on blood electrical velocimetry, in preterm babies. A prospective observational study of preterm infants with a gestational age of less than 28 weeks, and a hemodynamic significant PDA, requires intravenous ibuprofen or surgical closure. All patients were monitored with electrical velocimetry before treatment and through the following 72 h. Two groups were defined, ibuprofen and surgical closure. Variations of cardiac output were analyzed from the basal situation and at 1, 8, 24, 48, and 72 h on each group. During a 12-month period, 18 patients were studied. The median gestational age in the ibuprofen group (12/18) was 26 +5  weeks (25 +5 -27 +3 ) with a median birth weight of 875 (670-1010) g. The cardiac output index (CI) value was 0.29 l/kg/min (0.24-0.34). Among the patients with confirmed ductus closure (50%), a significant CI decrease was shown (0.24 vs 0.29 l/kg/min; P 0.03) after 72 h (three ibuprofen doses). A statistically significant decrease in systolic volume (SVI) was found: 1.62 vs 1.88 ml/kg, P 0.03 with a decrease in contractility (ICON), 85 vs 140, P 0.02. The gestational age in the surgical group (6/18) was 25 +2  weeks (24-26 +3 ) with a median weight of 745 (660-820) g. All patients in this group showed a decrease in the immediate postoperative CI (1 h after surgery) 0.24 vs 0.30 l/kg/min, P 0.05, and a significant decrease in contractility (ICON 77 vs 147, P 0.03). In addition, a no statistically significant decrease in SVI (1.54 vs 1.83 ml/kg, P 0.06), as well as an increase in systemic vascular resistance (10,615 vs 8797 dyn/cm 2 , P 0.08), were detected. This deterioration was transient without significant differences in the remaining periods of time evaluated. The surgical closure of the PDA in preterm infants causes a transient deterioration of cardiac function linked to a documented decrease in the left ventricular output. The hemodynamic changes detected after pharmacological PDA closure are similar but those patients present a better clinical tolerance to changes in the cardiac output. What is Known: • Surgical ductus closure generates acute hemodynamic changes in cardiac output and left ventricular function. What is New: • The hemodynamic changes detected after pharmacological ductus closure are similar to those found in the surgical closure. Electrical velocimetry can detect those changes.

Interaction between left ventricular twist mechanics and arterial haemodynamics during localised, non-metabolic hyperaemia with and without blood flow restriction.

PubMed

van Mil, Anke C C M; Pearson, James; Drane, Aimee L; Cockcroft, John R; McDonnell, Barry J; Stöhr, Eric J

2016-04-01

What is the central question of this study? Left ventricular (LV) twist is reduced when afterload is increased, but the meaning of this specific heart muscle response and its impact on cardiac output are not well understood. What is the main finding and its importance? This study shows that LV twist responds even when arterial haemodynamics are altered only locally, and without apparent change in metabolic (i.e. heat-induced) demand. The concurrent decline in cardiac output and LV twist during partial arterial occlusion despite the increased peripheral demand caused by heat stress suggests that LV twist may be involved in the protective sensing of heart muscle stress that can override the provision of the required cardiac output. Whether left ventricular (LV) twist and untwisting rate (LV twist mechanics) respond to localised, peripheral, non-metabolic changes in arterial haemodynamics within an individual's normal afterload range is presently unknown. Furthermore, previous studies indicate that LV twist mechanics may override the provision of cardiac output, but this hypothesis has not been examined purposefully. Therefore, we acutely altered local peripheral arterial haemodynamics in 11 healthy humans (women/men n = 3/8; age 26 ± 5 years) by bilateral arm heating (BAH). Ultrasonography was used to examine arterial haemodynamics, LV twist mechanics and the twist-to-shortening ratio (TSR). To determine the arterial function-dependent contribution of LV twist mechanics to cardiac output, partial blood flow restriction to the arms was applied during BAH (BAHBFR ). Bilateral arm heating increased arm skin temperatures [change (Δ) +6.4 ± 0.9°C, P < 0.0001] but not core temperature (Δ -0.0 ± 0.1°C, P > 0.05), concomitant to increases in brachial artery blood flow (Δ 212 ± 77 ml, P < 0.0001), cardiac output (Δ 495 ± 487 l min(-1) , P < 0.05), LV twist (Δ 3.0 ± 3.5 deg, P < 0.05) and TSR (Δ 3.3 ± 1.3, P < 0.05) but maintained carotid artery blood flow (Δ 18 ± 147 ml, P > 0.05). Subsequently, BAHBFR reduced all parameters to preheating levels, except for TSR and heart rate, which remained at BAH levels. In conclusion, LV twist mechanics responded to local peripheral arterial haemodynamics within the normal afterload range, in part independent of TSR and heart rate. The findings suggest that LV twist mechanics may be more closely associated with intrinsic sensing of excessive pressure stress rather than being associated with the delivery of adequate cardiac output. © 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.

Beta blocker infusion decreases the magnitude of core hypothermia after anesthesia induction.

PubMed

Inoue, S; Abe, R; Kawaguchi, M; Kobayashi, H; Furuya, H

2010-12-01

Beta-1-receptor blockade reduces heart rate, cardiac output, and arterial pressure while increasing peripheral vascular resistance. It is possible that beta blockers not only inhibit the core-to-peripheral re-distribution of body heat and cutaneous heat loss due to vasodilation after anesthesia induction but also reduce the convective transfer of heat from the core to peripheral tissues by decreasing cardiac output. The authors investigated whether the co-administration of esmolol or landiolol, ultra-short-acting beta blockers, attenuates the magnitude of initial re-distribution hypothermia after anesthesia induction and tracheal intubation. Immediately prior to the induction of anesthesia, patients were randomly assigned to receive 0.2 mg kg-1 of landiolol (landiolol group; N=30), 1 mg kg-1 of esmolol (esmolol group; N=30), or 0.1 mL kg-1 of saline (control group; N=30). Heart rate, blood pressure, cardiac output, and tympanic, forearm, and digit temperatures were recorded. Forearm minus fingertip skin-surface temperature gradients (temperature gradient) were calculated. Tympanic membrane temperatures 15 to 60 min after the induction of anesthesia were significantly higher in the esmolol group than in the control group although the temperature gradient was similar among the three groups. Both esmolol and landiolol inhibited the increase in HR and MAP after the induction of anesthesia and tracheal intubation. The cardiac index in the esmolol group was significantly lower than in the control group. The degree of hemodynamic attenuation after induction by esmolol was larger than that of landiolol. The co-administration of esmolol, but not landiolol, attenuated the magnitude of initial re-distribution hypothermia after anesthesia induction and tracheal intubation. Esmolol likely prevented initial hypothermia because it attenuated the convective transfer of heat from the core to peripheral tissues by decreasing cardiac output.

The Effect of Milrinone on Splanchnic and Cerebral Perfusion in Infants With Congenital Heart Disease Prior to Surgery: An Observational Study.

PubMed

Bianchi, Maria Otilia; Cheung, Po-Yin; Phillipos, Ernest; Aranha-Netto, Abimael; Joynt, Chloe

2015-08-01

Despite the advancement in the postoperative care of neonates with congenital heart disease (CHD), there is little information on preoperative management of systemic and regional hemodynamics, which may be related to outcomes. We aimed to determine the preoperative effect of milrinone, a phosphodiesterase III inhibitor, on cardiac output and splanchnic and cerebral perfusion in neonates with CHD. Neonates with CHD requiring cardiac surgery were enrolled in a prospective, single-blinded study once a clinical decision of starting milrinone (0.75 μg/kg per minute intravenously) using institutional criteria was made. Demographic and clinical variables and outcomes were recorded. Combined cardiac output and measures of splanchnic (superior mesenteric and celiac arteries) and cerebral (anterior and middle cerebral arteries) perfusion were determined by Doppler studies at 0, 6, 24, and 48 h after milrinone infusion. Investigators were unaware of intervention time points and patients in analyzing blood flow measurements. Seventeen term (39.2 ± 1.3 weeks) neonates were included with hypoplastic left-sided heart syndrome (78.5%) as the most common diagnosis. Combined cardiac output increased by 28% within 48 h (613 ± 154 vs. 479 ± 147 mL/kg per minute at baseline, P < 0.05). Superior mesenteric artery mean velocity increased at 6 h and throughout 48 h of milrinone infusion (P < 0.05). Peak and mean velocities at cerebral arteries increased with milrinone infusion (P < 0.05~0.08), and the corresponding changes at celiac artery were modest. There were no significant changes in splanchnic and cerebral resistive and pulsatility indices during milrinone infusion. Milrinone increases cardiac output with concurrent effects on splanchnic and cerebral blood flows during the short-term preoperative use in neonates with CHD.

Epinephrine and the metabolic syndrome.

PubMed

Ziegler, Michael G; Elayan, Hamzeh; Milic, Milos; Sun, Ping; Gharaibeh, Munir

2012-02-01

Epinephrine is the prototypical stress hormone. Its stimulation of all α and β adrenergic receptors elicits short-term systolic hypertension, hyperglycemia, and other aspects of the metabolic syndrome. Acute epinephrine infusion increases cardiac output and induces insulin resistance, but removal of the adrenal medulla has no consistent effect on blood pressure. Epinephrine is the most effective endogenous agonist at the β2 receptor. Transgenic mice that cannot make epinephrine and mice that lack the β2 receptor become hypertensive during exercise, presumably owing to the absence of β2-mediated vasodilatation. Epinephrine-deficient mice also have cardiac remodeling and poor cardiac responses to stress, but do not develop resting hypertension. Mice that cannot make epinephrine have a normal metabolism on a regular 14% fat diet but become hyperglycemic and insulin resistant when they eat a high fat diet. Vigorous exercise prevents diabetes in young mice and humans that overeat. However, exercise is a less effective treatment in older type 2 human diabetics and had no effect on glucose or insulin responses in older, diabetic mice. Sensitivity of the β2 receptor falls sharply with advancing age, and adrenal epinephrine release also decreases. However, treatment of older diabetic mice with a β2 adrenergic agonist improved insulin sensitivity, indicating that β2 subsensitivity can be overcome pharmacologically. Recent studies show that over the long term, epinephrine prevents hypertension during stress and improves glucose tolerance. The hyperglycemic influence of epinephrine is short-lived. Chronic administration of epinephrine and other β2 agonists improves cellular glucose uptake and metabolism. Overall, epinephrine counteracts the metabolic syndrome.

Left Ventricular Assist Device as a Bridge to Recovery for Patients With Advanced Heart Failure.

PubMed

Jakovljevic, Djordje G; Yacoub, Magdi H; Schueler, Stephan; MacGowan, Guy A; Velicki, Lazar; Seferovic, Petar M; Hothi, Sandeep; Tzeng, Bing-Hsiean; Brodie, David A; Birks, Emma; Tan, Lip-Bun

2017-04-18

Left ventricular assist devices (LVADs) have been used as an effective therapeutic option in patients with advanced heart failure, either as a bridge to transplantation, as destination therapy, or in some patients, as a bridge to recovery. This study evaluated whether patients undergoing an LVAD bridge-to-recovery protocol can achieve cardiac and physical functional capacities equivalent to those of healthy controls. Fifty-eight male patients-18 implanted with a continuous-flow LVAD, 16 patients with LVAD explanted (recovered patients), and 24 heart transplant candidates (HTx)-and 97 healthy controls performed a maximal graded cardiopulmonary exercise test with continuous measurements of respiratory gas exchange and noninvasive (rebreathing) hemodynamic data. Cardiac function was represented by peak exercise cardiac power output (mean arterial blood pressure × cardiac output) and functional capacity by peak exercise O 2 consumption. All patients demonstrated a significant exertional effort as demonstrated with the mean peak exercise respiratory exchange ratio >1.10. Peak exercise cardiac power output was significantly higher in healthy controls and explanted LVAD patients compared with other patients (healthy 5.35 ± 0.95 W; explanted 3.45 ± 0.72 W; LVAD implanted 2.37 ± 0.68 W; and HTx 1.31 ± 0.31 W; p < 0.05), as was peak O 2 consumption (healthy 36.4 ± 10.3 ml/kg/min; explanted 29.8 ± 5.9 ml/kg/min; implanted 20.5 ± 4.3 ml/kg/min; and HTx 12.0 ± 2.2 ml/kg/min; p < 0.05). In the LVAD explanted group, 38% of the patients achieved peak cardiac power output and 69% achieved peak O 2 consumption within the ranges of healthy controls. The authors have shown that a substantial number of patients who recovered sufficiently to allow explantation of their LVAD can even achieve cardiac and physical functional capacities nearly equivalent to those of healthy controls. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Measurement of bronchial blood flow in the sheep by video dilution technique.

PubMed Central

Link, D P; Parsons, G H; Lantz, B M; Gunther, R A; Green, J F; Cross, C E

1985-01-01

Bronchial blood flow was determined in five adult anaesthetised sheep by the video dilution technique. This is a new fluoroscopic technique for measuring blood flow that requires only arterial catheterisation. Catheters were placed into the broncho-oesophageal artery and ascending aorta from the femoral arteries for contrast injections and subsequent videotape recording. The technique yields bronchial blood flow as a percentage of cardiac output. The average bronchial artery blood flow was 0.6% (SD 0.20%) of cardiac output. In one sheep histamine (90 micrograms) injected directly into the bronchial artery increased bronchial blood flow by a factor of 6 and histamine (90 micrograms) plus methacholine (4.5 micrograms) augmented flow by a factor of 7.5 while leaving cardiac output unchanged. This study confirms the high degree of reactivity of the bronchial circulation and demonstrates the feasibility of using the video dilution technique to investigate the determinants of total bronchial artery blood flow in a stable animal model avoiding thoracotomy. Images PMID:3883564

Restoration of hemodynamics in apnea struggle phase in association with involuntary breathing movements.

PubMed

Palada, Ivan; Bakovic, Darija; Valic, Zoran; Obad, Ante; Ivancev, Vladimir; Eterovic, Davor; Shoemaker, J Kevin; Dujic, Zeljko

2008-04-30

Involuntary breathing movements (IBM) that occur in the struggle phase of maximal apneas produce waves of negative intrathoracic pressure. This could augment the venous return, increasing thereby the cardiac output and gas exchange, and release the fresh blood from venous pools of spleen and liver. To test these hypotheses we used photoplethysmography and ultrasound for assessment of hemodynamics and spleen size before, during and after maximal dry apneas at large lung volume in 7 trained divers. During the easy-going phase cardiac output was reduced about 40%, due to reduction in stroke volume and in presence of reduced inferior vena cava venous return, while the spleen contracted for about 60 ml. Towards the end of the struggle phase, in presence of intense IBM, the spleen volume further decreased for about 70 ml, while cardiac output and caval flow almost renormalized. In conclusion, IBM coincide with splenic volume reduction and restoration of hemodynamics, likely facilitating the use of the last oxygen reserves before apnea cessation.

The use of cardiac output monitoring to guide the administration of intravenous fluid during hyperthermic intraperitoneal chemotherapy.

PubMed

Thanigaimani, K; Mohamed, F; Cecil, T; Moran, B J; Bell, J

2013-12-01

The optimal strategy for intravenous (IV) fluid management during administration of hyperthermic intraperitoneal chemotherapy (HIPEC) is unclear. In this prospective study we describe the use of a LiDCOrapid™ (LiDCO, Cambridge, UK) cardiac output monitor to guide IV fluid management during cytoreductive surgery (CRS) with HIPEC. The aim of this study was to determine whether cardiac output monitoring will allow close maintenance of physiological parameters during the HIPEC phase. Twenty-five patients who underwent CRS combined with HIPEC were included in the study. Intra-operative IV fluid boluses were titrated using parameters measured by the LiDCOrapid™ monitor. Stroke volume variation was maintained below 10% with fluid boluses and mean arterial pressure was maintained within 20% of the baseline figure with vasopressors. There was no significant change in heart rate and cardiac output. The systemic vascular resistance dropped from an average of 966 dyn.s/cm-5 to 797 dyn s/cm(5) at 60 min during the HIPEC phase (P = 0.62) despite an increase in the dose of phenylepherine. The average total volume of fluid given was 748 ml in the first 30 min and 630 ml in the second 30 min with an average urine output of 307 and 445 ml, respectively. The change in lactate levels was not statistically or clinically significant. LiDCOrapid™ is an effective noninvasive tool for guiding fluid management in this population. It allows the anaesthesiologist to maintain tight control of essential physiological parameters during a phase of the procedure in which there is a risk of renal injury. Colorectal Disease © 2013 The Association of Coloproctology of Great Britain and Ireland.

Physiological rules for the heart, lungs and other pressure-based organs

PubMed Central

Camilleri, Liberato; Manché, Alexander; Gatt, Ruben; Gauci, Marilyn; Camilleri-Podesta, Marie-Therese; Grima, Joseph N.; Chetcuti, Stanley

2017-01-01

Background The adherence of the heart to physical laws, such as Laplace’s Law, may act as a measure of the organ’s relative efficiency. Allometric relationships were investigated to assess the heart’s efficiency concerning end-diastolic and end-systolic volumes, cardiac pressurization energy, cardiac output and mass. Methods Data to generate allometric relationships was obtained using a literature search, identifying heart and lung data across different mammalian and bird species. Statistical analysis was carried out using ordinary least squares (OLS) estimation. Results Near isometric relationships exist between body mass and seven parameters indicating no “efficiency of size” with scaling of the heart, and size-matching of the heart to the lungs and whole body. Even though there was equal efficiency in pressurization energy generation, cardiac output was maximally efficient in small mammals <10 kg and birds; the human heart reached only 71% efficiency. This loss in cardiac efficiency with increasing body mass can be explained by the aortic cross-section that scales following the three-quarter allometry law, compared to end-systolic and end-diastolic volumes that scale isometrically. The heart is therefore throttled by a relatively small aorta at large body size. Conclusions Mammalian and avian hearts operate at similar efficiencies, demonstrating a high degree of symmorphosis, however cardiac output efficiency decreases in larger animals due to a relatively negative aortic cross-section allometry. This work has a myriad of potential applications including explaining cardiac dysfunction in athletes, patient-prosthesis mismatch in aortic valve replacement and why heavy exercise is associated with a worse prognosis than mild or moderate exercise. PMID:29268387

Impact of High-Intensity-NIV on the heart in stable COPD: a randomised cross-over pilot study.

PubMed

Duiverman, Marieke Leontine; Maagh, Petra; Magnet, Friederike Sophie; Schmoor, Claudia; Arellano-Maric, Maria Paola; Meissner, Axel; Storre, Jan Hendrik; Wijkstra, Peter Jan; Windisch, Wolfram; Callegari, Jens

2017-05-02

Although high-intensity non-invasive ventilation has been shown to improve outcomes in stable COPD, it may adversely affect cardiac performance. Therefore, the aims of the present pilot study were to compare cardiac and pulmonary effects of 6 weeks of low-intensity non-invasive ventilation and 6 weeks of high-intensity non-invasive ventilation in stable COPD patients. In a randomised crossover pilot feasibility study, the change in cardiac output after 6 weeks of each NIV mode compared to baseline was assessed with echocardiography in 14 severe stable COPD patients. Furthermore, CO during NIV, gas exchange, lung function, and health-related quality of life were investigated. Three patients dropped out: two deteriorated on low-intensity non-invasive ventilation, and one presented with decompensated heart failure while on high-intensity non-invasive ventilation. Eleven patients were included in the analysis. In general, cardiac output and NTproBNP did not change, although individual effects were noticed, depending on the pressures applied and/or the co-existence of heart failure. High-intensity non-invasive ventilation tended to be more effective in improving gas exchange, but both modes improved lung function and the health-related quality of life. Long-term non-invasive ventilation with adequate pressure to improve gas exchange and health-related quality of life did not have an overall adverse effect on cardiac performance. Nevertheless, in patients with pre-existing heart failure, the application of very high inspiratory pressures might reduce cardiac output. The trial was registered in the Deutsches Register Klinischer Studien (DRKS-ID: DRKS00007977 ).

ACE insertion/deletion polymorphism and submaximal exercise hemodynamics in postmenopausal women.

PubMed

Hagberg, James M; McCole, Steve D; Brown, Michael D; Ferrell, Robert E; Wilund, Kenneth R; Huberty, Andrea; Douglass, Larry W; Moore, Geoffrey E

2002-03-01

We sought to determine whether the angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism is associated with submaximal exercise cardiovascular hemodynamics. Postmenopausal healthy women (20 sedentary, 20 physically active, 22 endurance athletes) had cardiac output (acetylene rebreathing) measured during 40, 60, and 80% VO(2 max) exercise. The interaction of ACE genotype and habitual physical activity (PA) level was significantly associated with submaximal exercise systolic blood pressure, with only sedentary women exhibiting differences among genotypes. No significant effects of ACE genotype or its interaction with PA levels was observed for submaximal exercise diastolic blood pressure. ACE genotype was significantly associated with submaximal exercise heart rate (HR) with ACE II having approximately 10 beats/min higher HR than ACE ID/DD genotype women. ACE genotype did not interact significantly with habitual PA level to associate with submaximal exercise HR. ACE genotype was not independently, but was interactively with habitual PA levels, associated with differences in submaximal exercise cardiac output and stroke volume. For cardiac output, ACE II genotype women athletes had ~25% greater cardiac output than ACE DD genotype women athletes, whereas for stroke volume genotype-dependent differences were observed in both the physically active and athletic women. ACE genotype was not significantly associated, either independently or interactively with habitual PA levels, with submaximal exercise total peripheral resistance or arteriovenous O(2) difference. Thus the common ACE locus polymorphic variation is associated with many submaximal exercise cardiovascular hemodynamic responses.

Detrimental effect of hypothermia during acute normovolaemic haemodilution in anaesthetized cats

NASA Astrophysics Data System (ADS)

Talwar, A.; Fahim, Mohammad

Haemodynamic responses to hypothermia were studied at normal haematocrit and following the induction of acute normovolaemic haemodilution. Experiments were performed on 20 cats anaesthetized with a mixture of chloralose and urethane in two groups. In one group (n=10) the effects of hypothermia on various haemodynamic variables were studied at normal haematocrit (41.0+/-1.7%) and in the second group of cats (n=10) the effects of hypothermia on various haemodynamic variables were studied after the induction of acute normovolaemic haemodilution (14.0+/-1.0%). The haemodynamic variables left ventricular pressure, left ventricular contractility, arterial blood pressure, heart rate and right atrial pressure were recorded on a polygraph. Cardiac output was measured using a cardiac output computer. In both groups hypothermia was induced by surface cooling with the help of ice. Cardiovascular variables were recorded at each 1° C fall in body temperature. Hypothermia produced a significant (P<0.05) drop in heart rate, cardiac output, arterial blood pressure and left ventricular contractility in both groups. However, the percentage decrease in these variables in response to hypothermia was significantly (P<0.05) higher in cats with low haematocrit than in those with normal haematocrit. The severity of hypothermia - induced cardiovascular effects is evident from the drastic decrease in heart rate, cardiac output, arterial blood pressure and myocardial contractility in cats with low haematocrit, indicating a higher risk of circulatory failure under anaemic conditions at low temperatures.

Effects of CGS 21680, a selective A2A adenosine receptor agonist, on cardiac output and vascular resistance in acute heart failure in the anaesthetized rat

PubMed Central

Nekooeian, Ali A; Tabrizchi, Reza

1998-01-01

The effects of CGS 21680, a selective A2A adenosine receptor agonist, on cardiac output, blood pressure, mean circulatory filling pressure (Pmcf), arterial and venous resistances, heart rate and left ventricular end-diastolic pressure were assessed in rats with acute heart failure by means of coronary artery occlusion.Animals (n=6 in each group) were divided into five groups: group I, sham-operated vehicle-treated (0.9% saline; 0.018 mL min−1); groups II-V, subject to coronary artery occlusion and treated with vehicle (0.9% saline; 0.018 ml min−1) and CGS 21680 (0.1, 0.3 and 1.0 μg kg−1 min−1), respectively. Haemodynamic measurements were taken one hour after completion of surgery, ninety minutes after coronary artery occlusion (except in group I), and fifteen minutes after infusion of saline or CGS 21680.Baseline haemodynamic measurements before occlusion were found not to differ significantly between the different groups of animals. However, after occlusion, cardiac output, rate of rise in left ventricular pressure (+dP/dt) and blood pressure were significantly reduced when compared to corresponding values in sham-operated animals. In addition, occlusion of the coronary artery resulted in a significant elevation in venous resistance, Pmcf and left ventricular end-diastolic pressure as compared to corresponding values in sham-operated animals.Infusion with CGS 21680 at the highest dose significantly reduced blood pressure, arterial resistance and left ventricular end-diastolic pressure when compared to occluded vehicle-treated animals (group II). Administration of CGS 21680 at the highest dose also significantly increased cardiac output (28%) and heart rate (10%) in comparison to occluded vehicle-treated animals. In addition, the highest dose of CGS 21680 significantly reduced Pmcf (9%) and venous resistance (62%) in comparison to occluded vehicle-treated animals. Administration of CGS 21680 did not significantly affect +dP/dt when compared to occluded vehicle-treated animals.The results from the present investigation indicate that occlusion of the coronary artery in rats results in a state of heart failure characterized by reduced arterial pressure and cardiac output, and increased venous resistance, Pmcf and left ventricular end-diastolic pressure. Administration of CGS 21680 to animals with acute heart failure resulted in increased cardiac output which was due to reduced venous resistance, as well as increased heart rate. PMID:9605574

Effects of CGS 21680, a selective A2A adenosine receptor agonist, on cardiac output and vascular resistance in acute heart failure in the anaesthetized rat.

PubMed

Nekooeian, A A; Tabrizchi, R

1998-04-01

1. The effects of CGS 21680, a selective A2A adenosine receptor agonist, on cardiac output, blood pressure, mean circulatory filling pressure (Pmcf), arterial and venous resistances, heart rate and left ventricular end-diastolic pressure were assessed in rats with acute heart failure by means of coronary artery occlusion. 2. Animals (n=6 in each group) were divided into five groups: group I, sham-operated vehicle-treated (0.9% saline; 0.018 mL min(-1)); groups II-V, subject to coronary artery occlusion and treated with vehicle (0.9% saline; 0.018 ml min(-1)) and CGS 21680 (0.1, 0.3 and 1.0 microg kg(-1) min(-1)), respectively. Haemodynamic measurements were taken one hour after completion of surgery, ninety minutes after coronary artery occlusion (except in group I), and fifteen minutes after infusion of saline or CGS 21680. 3. Baseline haemodynamic measurements before occlusion were found not to differ significantly between the different groups of animals. However, after occlusion, cardiac output, rate of rise in left ventricular pressure (+ dP/dt) and blood pressure were significantly reduced when compared to corresponding values in sham-operated animals. In addition, occlusion of the coronary artery resulted in a significant elevation in venous resistance, Pmcf and left ventricular end-diastolic pressure as compared to corresponding values in sham-operated animals. 4. Infusion with CGS 21680 at the highest dose significantly reduced blood pressure, arterial resistance and left ventricular end-diastolic pressure when compared to occluded vehicle-treated animals (group II). Administration of CGS 21680 at the highest dose also significantly increased cardiac output (28%) and heart rate (10%) in comparison to occluded vehicle-treated animals. In addition, the highest dose of CGS 21680 significantly reduced Pmcf (9%) and venous resistance (62%) in comparison to occluded vehicle-treated animals. Administration of CGS 21680 did not significantly affect +dP/dt when compared to occluded vehicle-treated animals. 5. The results from the present investigation indicate that occlusion of the coronary artery in rats results in a state of heart failure characterized by reduced arterial pressure and cardiac output, and increased venous resistance, Pmcf and left ventricular end-diastolic pressure. Administration of CGS 21680 to animals with acute heart failure resulted in increased cardiac output which was due to reduced venous resistance, as well as increased heart rate.

Cardiac Iodine-123-Meta-Iodo-Benzylguanidine Uptake in Carotid Sinus Hypersensitivity.

PubMed

Tan, Maw Pin; Murray, Alan; Hawkins, Terry; Chadwick, Thomas J; Kerr, Simon R J; Parry, Steve W

2015-01-01

Carotid sinus syndrome is the association of carotid sinus hypersensitivity with syncope, unexplained falls and drop attacks in generally older people. We evaluated cardiac sympathetic innervation in this disorder in individuals with carotid sinus syndrome, asymptomatic carotid sinus hypersensitivity and controls without carotid sinus hypersensitivity. Consecutive patients diagnosed with carotid sinus syndrome at a specialist falls and syncope unit were recruited. Asymptomatic carotid sinus hypersensitivity and non-carotid sinus hypersensitivity control participants recruited from a community-dwelling cohort. Cardiac sympathetic innervation was determined using Iodine-123-metaiodobenzylguanidine (123-I-MIBG) scanning. Heart to mediastinal uptake ratio (H:M) were determined for early and late uptake on planar scintigraphy at 20 minutes and 3 hours following intravenous injection of 123-I-MIBG. Forty-two subjects: carotid sinus syndrome (n = 21), asymptomatic carotid sinus hypersensitivity (n = 12) and no carotid sinus hypersensitivity (n = 9) were included. Compared to the non- carotid sinus hypersensitivity control group, the carotid sinus syndrome group had significantly higher early H:M (estimated mean difference, B = 0.40; 95% confidence interval, CI = 0.13 to 0.67, p = 0.005) and late H:M (B = 0.32; 95%CI = 0.03 to 0.62, p = 0.032). There was, however, no significant difference in early H:M (p = 0.326) or late H:M (p = 0.351) between the asymptomatic carotid sinus hypersensitivity group and non- carotid sinus hypersensitivity controls. Cardiac sympathetic neuronal activity is increased relative to age-matched controls in individuals with carotid sinus syndrome but not those with asymptomatic carotid sinus hypersensitivity. Blood pressure and heart rate measurements alone may therefore represent an over simplification in the assessment for carotid sinus syndrome and the relative increase in cardiac sympathetic innervation provides additional clues to understanding the mechanisms behind the symptomatic presentation of carotid sinus hypersensitivity.

Translocation of myocardial GLUT-4 and increased glucose uptake through activation of AMPK by AICAR.

PubMed

Russell, R R; Bergeron, R; Shulman, G I; Young, L H

1999-08-01

Insulin increases glucose uptake through the translocation of GLUT-4 via a pathway mediated by phosphatidylinositol 3-kinase (PI3K). In contrast, myocardial glucose uptake during ischemia and hypoxia is stimulated by the translocation of GLUT-4 to the surface of cardiac myocytes through a PI3K-independent pathway that has not been characterized. AMP-activated protein kinase (AMPK) activity is also increased by myocardial ischemia, and we examined whether AMPK stimulates glucose uptake and GLUT-4 translocation. In isolated rat ventricular papillary muscles, 5-aminoimidazole-4-carboxyamide-1-beta-D-ribofuranoside (AICAR), an activator of AMPK, as well as cyanide-induced chemical hypoxia and insulin, increased 2-[(3)H]deoxyglucose uptake two- to threefold. Wortmannin, a PI3K inhibitor, did not affect either the AICAR- or the cyanide-stimulated increase in deoxyglucose uptake but eliminated the insulin-stimulated increase in deoxyglucose uptake. Immunofluorescence studies demonstrated translocation of GLUT-4 to the myocyte sarcolemma in response to stimulation with AICAR, cyanide, or insulin. Preincubation of papillary muscles with the kinase inhibitor iodotubercidin or adenine 9-beta-D-arabinofuranoside (araA), a precursor of araATP (a competitive inhibitor of AMPK), decreased AICAR- and cyanide-stimulated glucose uptake but did not affect basal or insulin-stimulated glucose uptake. In vivo infusion of AICAR caused myocardial AMPK activation and GLUT-4 translocation in the rat. We conclude that AMPK activation increases cardiac muscle glucose uptake through translocation of GLUT-4 via a pathway that is independent of PI3K. These findings suggest that AMPK activation may be important in ischemia-induced translocation of GLUT-4 in the heart.

Comprehensive cardiac rehabilitation improves outcome for patients with implantable cardioverter defibrillator. Findings from the COPE-ICD randomised clinical trial.

PubMed

Berg, Selina Kikkenborg; Pedersen, Preben U; Zwisler, Ann-Dorthe; Winkel, Per; Gluud, Christian; Pedersen, Birthe D; Svendsen, Jesper H

2015-02-01

The aim of this randomised clinical trial was to assess a comprehensive cardiac rehabilitation intervention including exercise training and psycho-education vs 'treatment as usual' in patients treated with an implantable cardioverter defibrillator (ICD). In this study 196 patients with first time ICD implantation (mean age 57.2 (standard deviation (SD)=13.2); 79% men) were randomised (1:1) to comprehensive cardiac rehabilitation vs 'treatment as usual'. Altogether 144 participants completed the 12 month follow-up. The intervention consisted of twelve weeks of exercise training and one year of psycho-educational follow-up focusing on modifiable factors associated with poor outcomes. Two primary outcomes, general health score (Short Form-36 (SF-36)) and peak oxygen uptake (VO₂), were used. Post-hoc analyses included SF-36 and ICD therapy history. Comprehensive cardiac rehabilitation significantly increased VO2 uptake after exercise training to 23.0 (95% confidence interval (CI) 20.9-22.7) vs 20.8 (95% CI 18.9-22.7) ml/min/kg in the control group (p=0.004 (multiplicity p=0.015)). Comprehensive cardiac rehabilitation significantly increased general health; at three months (mean 62.8 (95% CI 58.1-67.5) vs 64.4 (95% CI: 59.6-69.2)) points; at six months (mean 66.7 (95% CI 61.5-72.0) vs 61.9 (95% CI 56.1-67.7) points); and 12 months (mean 63.5 (95% CI 57.7-69.3) vs 62.1 (95% CI 56.2-68.0)) points (p <0.05). Explorative analyses showed a significant difference between groups in favour of the intervention group. No significant difference was seen in ICD therapy history. Comprehensive cardiac rehabilitation combining exercise training and a psycho-educational intervention improves VO₂-uptake and general health. Furthermore, mental health seems improved. No significant difference was found in the number of ICD shocks or anti-tachycardia pacing therapy. © The European Society of Cardiology 2014.

Alterations in left ventricular volumes induced by Valsalva manoeuvre

NASA Technical Reports Server (NTRS)

Brooker, J. Z.; Alderman, E. L.; Harrison, D. C.

1974-01-01

Five patients were studied with left ventriculography during different phases of the Valsalva manoeuvre. Small doses of contrast medium allowed adequate repetitive visualization of the left ventricle for volume calculation. During strain phase, the volume of the left ventricle decreased by nearly 50 per cent in each case, and stroke volume and cardiac output also dropped strikingly. Release of straining was attended by a sharp rebound of left ventricular volume to control levels, with a transient surge of increased cardiac output 42 per cent above that of the resting state.

Coordinated changes in hepatic amino acid metabolism and endocrine signals support hepatic glucose production during fetal hypoglycemia

PubMed Central

Houin, Satya S.; Rozance, Paul J.; Brown, Laura D.; Hay, William W.; Wilkening, Randall B.

2014-01-01

Reduced fetal glucose supply, induced experimentally or as a result of placental insufficiency, produces an early activation of fetal glucose production. The mechanisms and substrates used to fuel this increased glucose production rate remain unknown. We hypothesized that in response to hypoglycemia, induced experimentally with maternal insulin infusion, the fetal liver would increase uptake of lactate and amino acids (AA), which would combine with hormonal signals to support hepatic glucose production. To test this hypothesis, metabolic studies were done in six late gestation fetal sheep to measure hepatic glucose and substrate flux before (basal) and after [days (d)1 and 4] the start of hypoglycemia. Maternal and fetal glucose concentrations decreased by 50% on d1 and d4 (P < 0.05). The liver transitioned from net glucose uptake (basal, 5.1 ± 1.5 μmol/min) to output by d4 (2.8 ± 1.4 μmol/min; P < 0.05 vs. basal). The [U-13C]glucose tracer molar percent excess ratio across the liver decreased over the same period (basal: 0.98 ± 0.01, vs. d4: 0.89 ± 0.01, P < 0.05). Total hepatic AA uptake, but not lactate or pyruvate uptake, increased by threefold on d1 (P < 0.05) and remained elevated throughout the study. This AA uptake was driven largely by decreased glutamate output and increased glycine uptake. Fetal plasma concentrations of insulin were 50% lower, while cortisol and glucagon concentrations increased 56 and 86% during hypoglycemia (P < 0.05 for basal vs. d4). Thus increased hepatic AA uptake, rather than pyruvate or lactate uptake, and decreased fetal plasma insulin and increased cortisol and glucagon concentrations occur simultaneously with increased fetal hepatic glucose output in response to fetal hypoglycemia. PMID:25516551

Congestive renal failure: the pathophysiology and treatment of renal venous hypertension.

PubMed

Ross, Edward A

2012-12-01

Longstanding experimental evidence supports the role of renal venous hypertension in causing kidney dysfunction and "congestive renal failure." A focus has been heart failure, in which the cardiorenal syndrome may partly be due to high venous pressure, rather than traditional mechanisms involving low cardiac output. Analogous diseases are intra-abdominal hypertension and renal vein thrombosis. Proposed pathophysiologic mechanisms include reduced transglomerular pressure, elevated renal interstitial pressure, myogenic and neural reflexes, baroreceptor stimulation, activation of sympathetic nervous and renin angiotensin aldosterone systems, and enhanced proinflammatory pathways. Most clinical trials have addressed the underlying condition rather than venous hypertension per se. Interpreting the effects of therapeutic interventions on renal venous congestion are therefore problematic because of such confounders as changes in left ventricular function, cardiac output, and blood pressure. Nevertheless, there is preliminary evidence from small studies of intense medical therapy or extracorporeal ultrafiltration for heart failure that there can be changes to central venous pressure that correlate inversely with renal function, independently from the cardiac index. Larger more rigorous trials are needed to definitively establish under what circumstances conventional pharmacologic or ultrafiltration goals might best be directed toward central venous pressures rather than left ventricular or cardiac output parameters. Copyright © 2012 Elsevier Inc. All rights reserved.

Effects of obstructive sleep apnea and obesity on exercise function in children.

PubMed

Evans, Carla A; Selvadurai, Hiran; Baur, Louise A; Waters, Karen A

2014-06-01

Evaluate the relative contributions of weight status and obstructive sleep apnea (OSA) to cardiopulmonary exercise responses in children. Prospective, cross-sectional study. Participants underwent anthropometric measurements, overnight polysomnography, spirometry, cardiopulmonary exercise function testing on a cycle ergometer, and cardiac doppler imaging. OSA was defined as ≥ 1 obstructive apnea or hypopnea per hour of sleep (OAHI). The effect of OSA on exercise function was evaluated after the parameters were corrected for body mass index (BMI) z-scores. Similarly, the effect of obesity on exercise function was examined when the variables were adjusted for OAHI. Tertiary pediatric hospital. Healthy weight and obese children, aged 7-12 y. N/A. Seventy-one children were studied. In comparison with weight-matched children without OSA, children with OSA had a lower cardiac output, stroke volume index, heart rate, and oxygen consumption (VO2 peak) at peak exercise capacity. After adjusting for BMI z-score, children with OSA had 1.5 L/min (95% confidence interval -2.3 to -0.6 L/min; P = 0.001) lower cardiac output at peak exercise capacity, but minute ventilation and ventilatory responses to exercise were not affected. Obesity was only associated with physical deconditioning. Cardiac dysfunction was associated with the frequency of respiratory-related arousals, the severity of hypoxia, and heart rate during sleep. Children with OSA are exercise limited due to a reduced cardiac output and VO2 peak at peak exercise capacity, independent of their weight status. Comorbid OSA can further decrease exercise performance in obese children.

Improved hepatic arterial fraction estimation using cardiac output correction of arterial input functions for liver DCE MRI

NASA Astrophysics Data System (ADS)

Chouhan, Manil D.; Bainbridge, Alan; Atkinson, David; Punwani, Shonit; Mookerjee, Rajeshwar P.; Lythgoe, Mark F.; Taylor, Stuart A.

2017-02-01

Liver dynamic contrast enhanced (DCE) MRI pharmacokinetic modelling could be useful in the assessment of diffuse liver disease and focal liver lesions, but is compromised by errors in arterial input function (AIF) sampling. In this study, we apply cardiac output correction to arterial input functions (AIFs) for liver DCE MRI and investigate the effect on dual-input single compartment hepatic perfusion parameter estimation and reproducibility. Thirteen healthy volunteers (28.7  ±  1.94 years, seven males) underwent liver DCE MRI and cardiac output measurement using aortic root phase contrast MRI (PCMRI), with reproducibility (n  =  9) measured at 7 d. Cardiac output AIF correction was undertaken by constraining the first pass AIF enhancement curve using the indicator-dilution principle. Hepatic perfusion parameters with and without cardiac output AIF correction were compared and 7 d reproducibility assessed. Differences between cardiac output corrected and uncorrected liver DCE MRI portal venous (PV) perfusion (p  =  0.066), total liver blood flow (TLBF) (p  =  0.101), hepatic arterial (HA) fraction (p  =  0.895), mean transit time (MTT) (p  =  0.646), distribution volume (DV) (p  =  0.890) were not significantly different. Seven day corrected HA fraction reproducibility was improved (mean difference 0.3%, Bland-Altman 95% limits-of-agreement (BA95%LoA)  ±27.9%, coefficient of variation (CoV) 61.4% versus 9.3%, ±35.5%, 81.7% respectively without correction). Seven day uncorrected PV perfusion was also improved (mean difference 9.3 ml min-1/100 g, BA95%LoA  ±506.1 ml min-1/100 g, CoV 64.1% versus 0.9 ml min-1/100 g, ±562.8 ml min-1/100 g, 65.1% respectively with correction) as was uncorrected TLBF (mean difference 43.8 ml min-1/100 g, BA95%LoA  ±586.7 ml min-1/ 100 g, CoV 58.3% versus 13.3 ml min-1/100 g, ±661.5 ml min-1/100 g, 60.9% respectively with correction). Reproducibility of uncorrected MTT was similar (uncorrected mean difference 2.4 s, BA95%LoA  ±26.7 s, CoV 60.8% uncorrected versus 3.7 s, ±27.8 s, 62.0% respectively with correction), as was and DV (uncorrected mean difference 14.1%, BA95%LoA  ±48.2%, CoV 24.7% versus 10.3%, ±46.0%, 23.9% respectively with correction). Cardiac output AIF correction does not significantly affect the estimation of hepatic perfusion parameters but demonstrates improvements in normal volunteer 7 d HA fraction reproducibility, but deterioration in PV perfusion and TLBF reproducibility. Improved HA fraction reproducibility maybe important as arterialisation of liver perfusion is increased in chronic liver disease and within malignant liver lesions.

Early Cardiac Involvement Affects Left Ventricular Longitudinal Function in Females Carrying α-Galactosidase A Mutation: Role of Hybrid Positron Emission Tomography and Magnetic Resonance Imaging and Speckle-Tracking Echocardiography.

PubMed

Spinelli, Letizia; Imbriaco, Massimo; Nappi, Carmela; Nicolai, Emanuele; Giugliano, Giuseppe; Ponsiglione, Andrea; Diomiaiuti, Tommaso Claudio; Riccio, Eleonora; Duro, Giovanni; Pisani, Antonio; Trimarco, Bruno; Cuocolo, Alberto

2018-04-01

Hybrid 18 F-fluorodeoxyglucose (FDG) positron emission tomography and magnetic resonance imaging may differentiate mature fibrosis or scar from fibrosis associated to active inflammation in patients with Anderson-Fabry disease, even in nonhypertrophic stage. This study was designed to compare the results of positron emission tomography and magnetic resonance cardiac imaging with those of speckle-tracking echocardiography in heterozygous Anderson-Fabry disease females. Twenty-four heterozygous females carrying α-galactosidase A mutation and without left ventricular hypertrophy underwent cardiac positron emission tomography and magnetic resonance using 18 F-FDG for glucose uptake and 2-dimensional strain echocardiography. 18 F-FDG myocardial uptake was quantified by measuring the coefficient of variation (COV) of the standardized uptake value using a 17-segment model. Focal 18 F-FDG uptake with COV >0.17 was detected in 13 patients, including 2 patients with late gadolinium enhancement at magnetic resonance. COV was 0.30±0.14 in patients with focal 18 F-FDG uptake and 0.12±0.03 in those without ( P <0.001). Strain echocardiography revealed worse global longitudinal systolic strain in patients with COV >0.17 compared with those with COV ≤0.17 (-18.5±2.7% versus -22.2±1.8%; P =0.024). For predicting COV >0.17, a global longitudinal strain >-19.8% had 77% sensitivity and 91% specificity and a value >2 dysfunctional segments 92% sensitivity and 100% specificity. In females carrying α-galactosidase A mutation, focal 18 F-FDG uptake represents an early sign of disease-related myocardial damage and is associated with impaired left ventricular longitudinal function. These findings support the hypothesis that inflammation plays an important role in glycosphingolipids storage disorders. © 2018 American Heart Association, Inc.

Exercise physiology with a left ventricular assist device: Analysis of heart-pump interaction with a computational simulator.

PubMed

Fresiello, Libera; Rademakers, Frank; Claus, Piet; Ferrari, Gianfranco; Di Molfetta, Arianna; Meyns, Bart

2017-01-01

Patients with a Ventricular Assist Device (VAD) are hemodynamically stable but show an impaired exercise capacity. Aim of this work is to identify and to describe the limiting factors of exercise physiology with a VAD. We searched for data concerning exercise in heart failure condition and after VAD implantation from the literature. Data were analyzed by using a cardiorespiratory simulator that worked as a collector of inputs coming from different papers. As a preliminary step the simulator was used to reproduce the evolution of hemodynamics from rest to peak exercise (ergometer cycling) in heart failure condition. Results evidence an increase of cardiac output of +2.8 l/min and a heart rate increase to 67% of the expected value. Then, we simulated the effect of a continuous-flow VAD at both rest and exercise. Total cardiac output increases of +3.0 l/min (+0.9 l/min due to the VAD and +2.1 l/min to the native ventricle). Since the left ventricle works in a non-linear portion of the diastolic stiffness line, we observed a consistent increase of pulmonary capillary wedge pressure (from 14 to 20 mmHg) for a relatively small increase of end-diastolic volume (from 182 to 189 cm3). We finally increased VAD speed during exercise to the maximum possible value and we observed a reduction of wedge pressure (-4.5 mmHg), a slight improvement of cardiac output (8.0 l/min) and a complete unloading of the native ventricle. The VAD can assure a proper hemodynamics at rest, but provides an insufficient unloading of the left ventricle and does not prevent wedge pressure from rising during exercise. Neither the VAD provides major benefits during exercise in terms of total cardiac output, which increases to a similar extend to an unassisted heart failure condition. VAD speed modulation can contribute to better unload the ventricle but the maximal flow reachable with the current devices is below the cardiac output observed in a healthy heart.

AKAP-scaffolding proteins and regulation of cardiac physiology

PubMed Central

Mauban, JRH; O'Donnell, M; Warrier, S; Manni, S; Bond, M

2009-01-01

A kinase anchoring proteins (AKAPs) compose a growing list of diverse but functionally related proteins defined by their ability to bind to the regulatory subunit of protein kinase A. AKAPs perform an integral role in the spatiotemporal modulation of a multitude of cellular signaling pathways. This review highlights the extensive role of AKAPs in cardiac excitation/contraction coupling and cardiac physiology. The literature shows that particular AKAPs are involved in cardiac Ca2+ influx, release, re-uptake, and myocyte repolarization. Studies have also suggested roles for AKAPs in cardiac remodeling. Transgenic studies show functional effects of AKAPs, not only in the cardiovascular system, but in other organ systems as well. PMID:19364910

[Cardiac failure in endocrine diseases].

PubMed

Hashizume, K

1993-05-01

Several endocrine diseases show the symptoms of cardiac failure. Among them, patients with acromegaly show a specific cardiomyopathy which results in a severe left-sided cardiac failure. Hypoparathyroidism also induces cardiac failure, which is resulted from hypocalcemia and low levels of serum parathyroid hormone. In the cases of hypothyroidism, the patients with myxedemal coma show a severe cardiac failure, which is characterized by disturbance of central nervous system, renal function, and cardiac function. In the patients with thyroid crisis (storm), the cardiac failure comes from the great reduction of cardiac output with dehydration. The reduction of circulation volume, observed in the patients with pheochromocytoma easily induces cardiac failure (shock) just after the removal of adrenal tumor. In patients with malignant carcinoid syndrome, right-sided ventricular failure which may be occurred through the actions of biogenic amines is observed.

Efficacy of a new intraaortic propeller pump vs the intraaortic balloon pump: an animal study.

PubMed

Dekker, André; Reesink, Koen; van der Veen, Erik; Van Ommen, Vincent; Geskes, Gijs; Soemers, Cecile; Maessen, Jos

2003-06-01

To compare the efficacy of a new intraaortic propeller pump (PP) to provide hemodynamic support to the intraaortic balloon pump (IABP) in an acute mitral regurgitation (MR) animal model. A new intraaortic PP (Reitan catheter pump; Jomed; Helsingborg, Sweden) recently has been introduced. The pump's aim is a reduction in afterload via a deployable propeller that is placed in the high descending aorta and can be set at rotational speeds of

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model.

PubMed

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Chronic resuscitation after trauma-hemorrhage and acute fluid replacement improves hepatocellular function and cardiac output.

PubMed

Remmers, D E; Wang, P; Cioffi, W G; Bland, K I; Chaudry, I H

1998-01-01

To determine whether prolonged (chronic) resuscitation has any beneficial effects on cardiac output and hepatocellular function after trauma-hemorrhage and acute fluid replacement. Acute fluid resuscitation after trauma-hemorrhage restores but does not maintain the depressed hepatocellular function and cardiac output. Male Sprague-Dawley rats underwent a 5-cm laparotomy (i.e., trauma was induced) and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of maximal bleed-out volume was returned in the form of Ringer's lactate (RL). The animals were acutely resuscitated with RL using 4 times the volume of maximum bleed-out over 60 minutes, followed by chronic resuscitation of 0, 5, or 10 mL/kg/hr RL for 20 hours. Hepatocellular function was determined by an in vivo indocyanine green clearance technique. Hepatic microvascular blood flow was assessed by laser Doppler flowmetry. Plasma levels of interleukin-6 (IL-6) were determined by bioassay. Chronic resuscitation with 5 mL/kg/hr RL, but not with 0 or 10 mL/kg/hr RL, restored cardiac output, hepatocellular function, and hepatic microvascular blood flow at 20 hours after hemorrhage. The regimen above also reduced plasma IL-6 levels. Because chronic resuscitation with 5 mL/kg/hr RL after trauma-hemorrhage and acute fluid replacement restored hepatocellular function and hepatic microvascular blood flow and decreased plasma levels of IL-6, we propose that chronic fluid resuscitation in addition to acute fluid replacement should be routinely used in experimental studies of trauma-hemorrhage.

Exercise Responses after Inactivity

NASA Technical Reports Server (NTRS)

Convertino, Victor A.

1986-01-01

The exercise response after bed rest inactivity is a reduction in the physical work capacity and is manifested by significant decreases in oxygen uptake. The magnitude of decrease in maximal oxygen intake V(dot)O2max is related to the duration of confinement and the pre-bed-rest level of aerobic fitness; these relationships are relatively independent of age and gender. The reduced exercise performance and V(dot)O2max following bed rest are associated with various physiological adaptations including reductions in blood volume, submaximal and maximal stroke volume, maximal cardiac output, sceletal muscle tone and strength, and aerobic enzyme capacities, as well as increases in venous compliance and submaximal and maximal heart rate. This reduction in physiological capacity can be partially restored by specific countermeasures that provide regular muscular activity or orhtostatic stress or both during the bed rest exposure. The understanding of these physiological and physical responses to exercise following bed rest inactivity has important implications for the solution to safety and health problems that arise in clinical medicine, aerospace medicine, sedentary living, and aging.

Skylab experiment M-171 'Metabolic Activity' - Results of the first manned mission

NASA Technical Reports Server (NTRS)

Michel, E. L.; Rummel, J. A.; Sawin, C. F.

1975-01-01

The experiment was performed to ascertain whether man's ability to perform mechanical work would be altered as a result of exposure to the weightless environment. Skylab II crewmen were exercised on a bicycle ergometer at loads approximating 25%, 50%, and 75% of their maximum oxygen uptake while their physiological responses were monitored. The results of these tests indicate that the crewmen had no significant decrement in their response to exercise during their exposure to zero gravity. Immediately postflight, however, all crewmen demonstrated an inability to perform the programmed exercise with the same metabolic effectiveness as they did both preflight and inflight. The most significant changes were elevated heart rates for the same work load and oxygen consumption (decreased oxygen pulse), decreased stroke volume, and decreased cardiac output at the same oxygen consumption level. It is apparent that the changes occurred inflight, but did not manifest themselves until the crewmen attempted to readapt to the 1-G environment.

Effects of increasing left ventricular filling pressure in patients with acute myocardial infarction

PubMed Central

Russell, Richard O.; Rackley, Charles E.; Pombo, Jaoquin; Hunt, David; Potanin, Constantine; Dodge, Harold T.

1970-01-01

Left ventricular performance in 19 patients with acute myocardial infarction has been evaluated by measuring left ventricular response in terms of cardiac output, stroke volume, work, and power to progressive elevation of filling pressure accomplished by progressive expansion of blood volume with rapid infusion of low molecular weight dextran. Such infusion can elevate the cardiac output, stroke volume, work, and power and thus delineate the function of the left ventricle by Frank-Starling function curves. Left ventricular filling pressure in the range of 20-24 mm Hg was associated with the peak of the curves and when the filling pressure exceeded this range, the curves became flattened or decreased. An increase in cardiac output could be maintained for 4 or more hr. Patients with a flattened function curve had a high mortality in the ensuing 8 wk. The function curve showed improvement in myocardial function during the early convalescence. When left ventricular filling pressure is monitored directly or as pulmonary artery end-diastolic pressure, low molecular weight dextran provides a method for assessment of left ventricular function. Images PMID:5431663

Mean circulatory filling pressure: its meaning and measurement.

PubMed

Rothe, C F

1993-02-01

The volume-pressure relationship of the vasculature of the body as a whole, its vascular capacitance, requires a measurement of the mean circulatory filling pressure (Pmcf). A change in vascular capacitance induced by reflexes, hormones, or drugs has physiological consequences similar to a rapid change in blood volume and thus strongly influences cardiac output. The Pmcf is defined as the mean vascular pressure that exists after a stop in cardiac output and redistribution of blood, so that all pressures are the same throughout the system. The Pmcf is thus related to the fullness of the circulatory system. A change in Pmcf provides a uniquely useful index of a change in overall venous smooth muscle tone if the blood volume is not concomitantly changed. The Pmcf also provides an estimate of the distending pressure in the small veins and venules, which contain most of the blood in the body and comprise most of the vascular compliance. Thus the Pmcf, which is normally independent of the magnitude of the cardiac output, provides an estimate of the upstream pressure that determines the rate of flow returning to the heart.

The precision of a special purpose analog computer in clinical cardiac output determination.

PubMed Central

Sullivan, F J; Mroz, E A; Miller, R E

1975-01-01

Three hundred dye-dilution curves taken during our first year of clinical experience with the Waters CO-4 cardiac output computer were analyzed to estimate the errors involved in its use. Provided that calibration is accurate and 5.0 mg of dye are injected for each curve, then the percentage standard deviation of measurement using this computer is about 8.7%. Included in this are the errors inherent in the computer, errors due to baseline drift, errors in the injection of dye and acutal variation of cardiac output over a series of successive determinations. The size of this error is comparable to that involved in manual calculation. The mean value of five successive curves will be within 10% of the real value in 99 cases out of 100. Advances in methodology and equipment are discussed which make calibration simpler and more accurate, and which should also improve the quality of computer determination. A list of suggestions is given to minimize the errors involved in the clinical use of this equipment. Images Fig. 4. PMID:1089394

Dose-dependent heart rate reducing effect of nizatidine, a histamine H2-receptor antagonist.

PubMed Central

Hinrichsen, H; Halabi, A; Fuhrmann, G; Kirch, W

1993-01-01

1. Twelve healthy subjects were treated in a randomised placebo-controlled crossover study with placebo, 150 mg, 300 mg, and 600 mg nizatidine, 100 mg pirenzepine, and 300 mg nizatidine plus 100 mg pirenzepine for 1 week each. 2. On the seventh treatment day, heart rate, blood pressure, systolic time intervals, impedance cardiographic and Doppler ultrasound variables were measured. 3. Stroke volume and blood pressure were not altered by nizatidine and/or pirenzepine. By contrast, heart rate and cardiac output significantly (P < 0.05) decreased in a dose-dependent manner 1.5 and 3 h after administration of 300 and 600 mg nizatidine. Treatment with 150 mg nizatidine led to similar though non-significant trends. 4. While a slightly insignificant rise in heart rate was detected with pirenzepine alone, heart rate and cardiac output remained unchanged upon combined nizatidine and pirenzepine treatment as compared with placebo and baseline values. 5. In conclusion, nizatidine reduced heart rate and cardiac output in a dose-dependent manner, whereas this negative chronotropic effect was counteracted by concurrent administration of the anti-cholinergic drug pirenzepine. PMID:8099802

[The role of the adreno-cholinergic interaction in the pulmonary hemodynamics changes following myocardial ischemia].

PubMed

Evlakhov, V I; Poiasov, I Z

2014-06-01

In acute experiments in anesthetized rabbits the pulmonary hemodynamics changes were studied following 60 s myocardial ischemia in the region of the descendent left coronary artery in control state and after the blockade of M- or N-cholinoreceptors and acetylcholine infusion. Following myocardial ischemia in control animals the pulmonary artery pressure and flow decreased, the pulmonary vascular resistance was not changed. Following myocardial ischemia after the blockade of M-cholinoreceptors by atropine the changes of pulmonary hemodynamics were the same as in control animals, the cardiac output decreased twice as more as in control animals. Following myocardial ischemia after the blockade of N-cholinoreceptors by hexamethonium the pulmonary hemodynamics changes were the same as in the control rabbits. Following myocardial ischemia after the acetylcholine infusion the pulmonary artery flow decreased more than the cardiac output, the pulmonary vascular resistance was diminished. The disbalance of the cardiac output and pulmonary artery flow changes has revealed the significance of the adreno-cholinergic interaction in the changes of the pulmonary vessels capacitance and resistive functions following myocardial ischemia.

Circulatory failure during severe hyperthermia in dog.

PubMed

Miki, K; Morimoto, T; Nose, H; Itoh, T; Yamada, S

1983-01-01

The effect of acute hyperthermia on circulatory function was studied in 6 mongrel dogs. At a core temperature of about 40 degrees C, central venous pressure and stroke volume were maintained at almost normal level. Cardiac output significantly increased (26 ml/(kg . min)) while systemic vascular resistance significantly decreased (1.2 mmHg . sec/ml). In addition, significant decrease in vascular compliance by 40% was observed. When body temperature was raised further (severe hyperthermia), an abrupt fall of arterial pressure was observed at the rectal temperature of about 41-42 degrees C. Concomitant decreases in central venous pressure (3 mmHg), stroke volume (2.1 ml/beat) and cardiac output (29 ml/(kg . min)) were observed while heart rate increased (48 beats/min). These results suggest that the decrease in cardiac output during severe hyperthermia is due to the fall of central venous pressure, and the fall was attributed to the increase in unstressed vascular volume of systemic circulation due to the heat-induced cutaneous vasodilation. The observed decrease in systemic vascular compliance is considered to have a significant role in the maintenance of central venous pressure under hyperthermia.

Maternal hemodynamics early in labor: a possible link with obstetric risk?

PubMed

Valensise, H; Tiralongo, G M; Pisani, I; Farsetti, D; Lo Presti, D; Gagliardi, G; Basile, M R; Novelli, G P; Vasapollo, B

2018-04-01

To determine if hemodynamic assessment in 'low-risk' pregnant women at term with an appropriate-for-gestational age (AGA) fetus can improve the identification of patients who will suffer maternal or fetal/neonatal complications during labor. This was a prospective observational study of 77 women with low-risk term pregnancy and AGA fetus, in the early stages of labor. Hemodynamic indices were obtained using the UltraSonic Cardiac Output Monitor (USCOM ® ) system. Patients were followed until the end of labor to identify fetal/neonatal and maternal outcomes, and those which developed complications of labor were compared with those delivering without complications. Eleven (14.3%) patients had a complication during labor: in seven there was fetal distress and in four there were maternal complications (postpartum hemorrhage and/or uterine atony). Patients who developed complications during labor had lower cardiac output (5.6 ± 1.0 vs 6.7 ± 1.3 L/min, P = 0.01) and cardiac index (3.1 ± 0.6 vs 3.5 ± 0.7 L/min/m 2 , P = 0.04), and higher total vascular resistance (1195.3 ± 205.3 vs 1017.8 ± 225.6 dynes × s/cm 5 , P = 0.017) early in labor, compared with those who did not develop complications. Receiver-operating characteristics curve analysis to determine cut-offs showed cardiac output ≤ 5.8 L/min (sensitivity, 81.8%; specificity, 69.7%), cardiac index ≤ 2.9 L/min/m 2 (sensitivity, 63.6%; specificity, 76.9%) and total vascular resistance > 1069 dynes × s/cm 5 (sensitivity, 81.8%; specificity, 63.6%) to best predict maternal or fetal/neonatal complications. The study of maternal cardiovascular adaptation at the end of pregnancy could help to identify low-risk patients who may develop complications during labor. In particular, low cardiac output and high total vascular resistance are apparently associated with higher risk of fetal distress or maternal complications. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Cardiac structure and function in the obese: a cardiovascular magnetic resonance imaging study.

PubMed

Danias, Peter G; Tritos, Nicholas A; Stuber, Matthias; Kissinger, Kraig V; Salton, Carol J; Manning, Warren J

2003-07-01

Obesity is a major health problem in the Western world. Among obese subjects cardiac pathology is common, but conventional noninvasive imaging modalities are often suboptimal for detailed evaluation of cardiac structure and function. We investigated whether cardiovascular magnetic resonance imaging (CMR) can better characterize possible cardiac abnormalities associated with obesity, in the absence of other confounding comorbidities. In this prospective cross-sectional study, CMR was used to quantify left and right ventricular volumes, ejection fraction, mass, cardiac output, and apical left ventricular rotation in 25 clinically healthy obese men and 25 age-matched lean controls. Obese subjects had higher left ventricular mass (203 +/- 38 g vs. 163 +/- 22 g, p < 0.001), end-diastolic volume (176 +/- 29 mL vs. 156 +/- 25 mL, p < 0.05), and cardiac output (8.2 +/- 1.2 L/min vs. 6.4 +/- 1.3 L/min, p < 0.001). The obese also had increased right ventricular mass (105 +/- 25 g vs. 87 +/- 18 g, p < 0.005) and end-diastolic volume (179 +/- 36 mL vs. 155 +/- 28 mL, p < 0.05). When indexed for height, differences in left and right ventricular mass, and left ventricular end-diastolic volume remained significant. Apical left ventricular rotation and rotational velocity patterns were also different between obese and lean subjects. Obesity is independently associated with remodeling of the heart. Cardiovascular magnetic resonance imaging identifies subtle cardiac abnormalities and may be the preferred imaging technique to evaluate cardiac structure and function in the obese.

Attenuation of Exaggerated Exercise Blood Pressure Response in African-American Women by Regular Aerobic Physical Activity

PubMed Central

Bond, Vernon; Millis, Richard M.; Adams, R. George; Oke, Luc M.; Enweze, Larry; Blakely, Raymond; Banks, Marshall; Thompson, Terry; Obisesan, Thomas; Sween, Jennifer C.

2011-01-01

Introduction A hyperreactive blood pressure response to exercise is a predictor of developing hypertension. The present study determined the influence of physical activity on an exaggerated exercise blood pressure response (EEBPR) in normotensive African-American women. Methods We screened 36 women 18–26 years of age for EEBPR defined as a ≥50 mm Hg difference in systolic blood pressure at rest and during exercise at 50% peak oxygen uptake (VO2peak). Seven subjects demonstrated an EEBPR and participated in the study. Study participants trained for eight weeks on a bicycle ergometer at a work intensity of 70% VO2peak. Blood pressure, heart rate, cardiac output (CO), stroke volume (SV), and total peripheral vascular resistance (TPR) were determined at baseline and during submaximal exercise at power outputs of 30 W and 50% VO2peak. Subjects served as their own controls, and data were evaluated by using a paired t test at P<.05. Results Effectiveness of the intervention was shown by a significantly greater VO2peak associated with significant decrements in systolic and mean arterial pressures at power outputs of 30 W and 50% VO2peak. A significant decrement in heart rate was observed during exercise at 30 W. Significant increments in CO and SV and decrement in TPR were found during exercise at 50% VO2peak. Conclusion The reduction in TPR associated with regular aerobic physical activity may attenuate the EEBPR and decrease the risk for hypertension in normotensive, young-adult, African-American women. PMID:16315376

Comparison of dexmedetomidine versus propofol on hemodynamics in surgical critically ill patients.

PubMed

Chang, Ya-Fei; Chao, Anne; Shih, Po-Yuan; Hsu, Yen-Chun; Lee, Chen-Tse; Tien, Yu-Wen; Yeh, Yu-Chang; Chen, Lee-Wei

2018-08-01

Sedation with dexmedetomidine and propofol may cause hypotension or bradycardia. This study aimed to compare the effects of dexmedetomidine and propofol on hemodynamics and clinical outcomes in surgical intensive care unit (ICU) patients after major abdominal surgery. Enrolled patients were randomly allocated to the dexmedetomidine or propofol group. Cardiac index was measured using a continuous noninvasive cardiac output monitor on the basis of chest bioreactance. Heart rate, blood pressure, opioid requirement, urine output, delirium incidence, ICU length of stay, and total hospital length of stay were compared between the two groups. The incidences of bradycardia, hypotension, and severe low cardiac index were compared. We enrolled 60 patients. Heart rate and mean arterial pressure were significantly lower in the dexmedetomidine group than in the propofol group. Cardiac index did not differ significantly between the two groups (dexmedetomidine group 3.1 L/min/m 2 , [95% confidence interval {95% CI} 2.8-3.3] versus propofol group 3.2 L/min/m 2 [95% CI 2.9-3.5], P = 0.578). The incidences of bradycardia, hypotension, and severe low cardiac index did not differ significantly between the two groups. Cardiac index did not differ significantly between the dexmedetomidine and propofol groups in surgical ICU patients after major abdominal surgery. Copyright © 2018 Elsevier Inc. All rights reserved.

Prioritizing blood flow: cardiovascular performance in response to the competing demands of locomotion and digestion for the Burmese python, Python molurus.

PubMed

Secor, Stephen M; White, Scott E

2010-01-01

Individually, the metabolic demands of digestion or movement can be fully supported by elevations in cardiovascular performance, but when occurring simultaneously, vascular perfusion may have to be prioritized to either the gut or skeletal muscles. Burmese pythons (Python molurus) experience similar increases in metabolic rate during the digestion of a meal as they do while crawling, hence each would have an equal demand for vascular supply when these two actions are combined. To determine, for the Burmese python, whether blood flow is prioritized when snakes are digesting and moving, we examined changes in cardiac performance and blood flow in response to digestion, movement, and the combination of digestion and movement. We used perivascular blood flow probes to measure blood flow through the left carotid artery, dorsal aorta, superior mesenteric artery and hepatic portal vein, and to calculate cardiac output, heart rate and stroke volume. Fasted pythons while crawling experienced a 2.7- and 3.3-fold increase, respectively, in heart rate and cardiac output, and a 66% decrease in superior mesenteric flow. During the digestion of a rodent meal equaling in mass to 24.7% of the snake's body mass, heart rate and cardiac output increased by 3.3- and 4.4-fold, respectively. Digestion also resulted in respective 11.6- and 14.1-fold increases in superior mesenteric and hepatic portal flow. When crawling while digesting, cardiac output and dorsal aorta flow increased by only 21% and 9%, respectively, a modest increase compared with that when they start to crawl on an empty stomach. Crawling did triggered a significant reduction in blood flow to the digesting gut, decreasing superior mesenteric and hepatic portal flow by 81% and 47%, respectively. When faced with the dual demands of digestion and crawling, Burmese pythons prioritize blood flow, apparently diverting visceral supply to the axial muscles.

Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity.

PubMed

Oppenheimer, Beno W; Berger, Kenneth I; Ali, Saleem; Segal, Leopoldo N; Donnino, Robert; Katz, Stuart; Parikh, Manish; Goldring, Roberta M

2016-01-01

Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways. We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response. 54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC. Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity. Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the structure of the alveolar capillary membrane may be considered often unrecognized causes of airway dysfunction in obesity.

Cardiovascular Ultrasound of Neonatal Long Evans Rats Exposed Prenatally to Trichloroacetic Acid: Effects on Heart Rate, Ejection Fraction, and Cardiac Output

EPA Science Inventory

This abstract describes the use of a relatively new technology, cardiovascular ultrasound (echocardiography) for evaluating developmental toxicity affecting heart development. The abstract describes the effects of two known cardiac teratogens, trichloroacetic acid and dimethadio...

Cardiovascular and haematological responses of Atlantic cod (Gadus morhua) to acute temperature increase.

PubMed

Gollock, M J; Currie, S; Petersen, L H; Gamperl, A K

2006-08-01

For fish to survive large acute temperature increases (i.e. >10.0 degrees C) that may bring them close to their critical thermal maximum (CTM), oxygen uptake at the gills and distribution by the cardiovascular system must increase to match tissue oxygen demand. To examine the effects of an acute temperature increase ( approximately 1.7 degrees C h(-1) to CTM) on the cardiorespiratory physiology of Atlantic cod, we (1) carried out respirometry on 10.0 degrees C acclimated fish, while simultaneously measuring in vivo cardiac parameters using Transonic probes, and (2) constructed in vitro oxygen binding curves on whole blood from 7.0 degrees C acclimated cod at a range of temperatures. Both cardiac output (Q) and heart rate (fh) increased until near the fish's CTM (22.2+/-0.2 degrees C), and then declined rapidly. Q(10) values for Q and fh were 2.48 and 2.12, respectively, and increases in both parameters were tightly correlated with O(2) consumption. The haemoglobin (Hb)-oxygen binding curve at 24.0 degrees C showed pronounced downward and rightward shifts compared to 20.0 degrees C and 7.0 degrees C, indicating that both binding capacity and affinity decreased. Further, Hb levels were lower at 24.0 degrees C than at 20.0 degrees C and 7.0 degrees C. This was likely to be due to cell swelling, as electrophoresis of Hb samples did not suggest protein denaturation, and at 24.0 degrees C Hb samples showed peak absorbance at the expected wavelength (540 nm). Our results show that cardiac function is unlikely to limit metabolic rate in Atlantic cod from Newfoundland until close to their CTM, and we suggest that decreased blood oxygen binding capacity may contribute to the plateau in oxygen consumption.

Increase in cardiac myosin heavy-chain (MyHC) alpha protein isoform in hibernating ground squirrels, with echocardiographic visualization of ventricular wall hypertrophy and prolonged contraction

PubMed Central

Nelson, O. Lynne; Rourke, Bryan C.

2013-01-01

SUMMARY Deep hibernators such as golden-mantled ground squirrels (Callospermophilus lateralis) have multiple challenges to cardiac function during low temperature torpor and subsequent arousals. As heart rates fall from over 300 beats min−1 to less than 10, chamber dilation and reduced cardiac output could lead to congestive myopathy. We performed echocardiography on a cohort of individuals prior to and after several months of hibernation. The left ventricular chamber exhibited eccentric and concentric hypertrophy during hibernation and thus calculated ventricular mass was ~30% greater. Ventricular ejection fraction was mildly reduced during hibernation but stroke volumes were greater due to the eccentric hypertrophy and dramatically increased diastolic filling volumes. Globally, the systolic phase in hibernation was ~9.5 times longer, and the diastolic phase was 28× longer. Left atrial ejection generally was not observed during hibernation. Atrial ejection returned weakly during early arousal. Strain echocardiography assessed the velocity and total movement distance of contraction and relaxation for regional ventricular segments in active and early arousal states. Myocardial systolic strain during early arousal was significantly greater than the active state, indicating greater total contractile movement. This mirrored the increased ventricular ejection fraction noted with early arousal. However, strain rates were slower during early arousal than during the active period, particularly systolic strain, which was 33% of active, compared with the rate of diastolic strain, which was 67% of active. As heart rate rose during the arousal period, myocardial velocities and strain rates also increased; this was matched closely by cardiac output. Curiously, though heart rates were only 26% of active heart rates during early arousal, the cardiac output was nearly 40% of the active state, suggesting an efficient pumping system. We further analyzed proportions of cardiac myosin heavy-chain (MyHC) isoforms in a separate cohort of squirrels over 5 months, including time points before hibernation, during hibernation and just prior to emergence. Hibernating individuals were maintained in both a 4°C cold room and a 20°C warm room. Measured by SDS-PAGE, relative percentages of cardiac MyHC alpha were increased during hibernation, at both hibernacula temperatures. A potential increase in contractile speed, and power, from more abundant MyHC alpha may aid force generation at low temperature and at low heart rates. Unlike many models of cardiomyopathies where the alpha isoform is replaced by the beta isoform in order to reduce oxygen consumption, ground squirrels demonstrate a potential cardioprotective mechanism to maintain cardiac output during torpor. PMID:24072796

Cardiac Uptake of Minocycline and Mechanisms for In Vivo Cardioprotection

PubMed Central

Romero-Perez, Diego; Fricovsky, Eduardo; Yamasaki, Katrina Go; Griffin, Michael; Barraza-Hidalgo, Maraliz; Dillmann, Wolfgang; Villarreal, Francisco

2008-01-01

Objectives The ability of minocycline to be transported into cardiac cells, concentrate in normal and ischemic myocardium and act as in vivo cardioprotector was examined. We also determined minocycline's capacity to act as a reducer of myocardial oxidative stress and matrix metalloproteinase (MMP) activity. Background The identification of compounds with the potential to reduce myocardial ischemic injury is of great interest. Tetracyclines (TTCs) are antibiotics with pleiotropic cytoprotective properties that accumulate in normal and diseased tissues. Minocycline is highly lipophilic and has shown promise as a possible cardioprotector. However, minocycline's potential as an in vivo cardioprotector as well as the means by which this action is attained are not well understood. Methods Rats were subjected to 45 min of ischemia and 48 h of reperfusion. Animals were treated 48 h before and 48 h after thoracotomy with either vehicle or 50 mg/kg/day minocycline. Tissue samples were used for biochemical assays and cultured cardiac cells for minocycline uptake experiments. Results Minocycline significantly reduced infarct size (∼33%), tissue MMP-9 activity and oxidative stress. Minocycline was concentrated ∼24-fold in normal (0.5 mM) and ∼50-fold in ischemic regions (1.1 mM) vs. blood. Neonatal rat cardiac fibroblasts, myocytes and adult fibroblasts demonstrate a time- and temperature-dependent uptake of minocycline to levels that approximate those of normal myocardium. Conclusions Given the high intracellular levels observed and results from the assessment of in vitro antioxidant and MMP inhibitor capacities, it is likely that minocycline acts to limit myocardial ischemic injury via mass action effects. PMID:18848143

Dynamic changes in genes related to glucose uptake and utilization during pig skeletal and cardiac muscle development.

PubMed

Guo, Yanqin; Jin, Long; Wang, Fengjiao; He, Mengnan; Liu, Rui; Li, Mingzhou; Shuai, Surong

2014-01-01

Skeletal and cardiac muscle have important roles in glucose uptake and utilization. However, changes in expression of protein coding genes and miRNAs that participate in glucose metabolism during development are not fully understood. In this study, we investigated the expression of genes related to glucose metabolism during muscle development. We found an age-dependent increase in gene expression in cardiac muscle, with enrichment in heart development- and energy-related metabolic processes. A subset of genes that were up-regulated until 30 or 180 days postnatally, and then down-regulated in psoas major muscle was significantly enriched in mitochondrial oxidative-related processes, while genes that up-regulated in longissimus doris muscle was significantly enriched in glycolysis-related processes. Meanwhile, expression of energy-related microRNAs decreased with increasing age. In addition, we investigated the correlation between microRNAs and mRNAs in three muscle types across different stages of development and found many potential microRNA-mRNA pairs involved in regulating glucose metabolism.

Cardiac Sarcoidosis Concomitant with Large-vessel Aortitis Detected by 18F-fluorodeoxyglucose Positron Emission Tomography.

PubMed

Higuchi, Yoshihiro; Kimoto, Yasutaka; Tanoue, Rika; Tokunou, Tomotake; Tomonari, Kenichiro; Maeda, Toyoki; Horiuchi, Takahiko

2018-06-01

We herein report a case of concurrent cardiac sarcoidosis and large-vessel aortitis detected by 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) and followed up during immunosuppressive therapy. After high-dose prednisolone administration (1 mg/kg), serial FDG-PET showed that almost all of the abnormal FDG uptake in the heart and extracardiac region, including the abdominal to bilateral iliac arteries, had been disappeared. During the tapering of prednisolone, additive methotrexate therapy was needed to treat the recurrence of cardiac sarcoidosis. FDG-PET is a useful tool for detecting cardiac sarcoidosis concomitant with large-vessel aortitis and monitoring the effectiveness of immunosuppressive therapy.

Power loss and right ventricular efficiency in patients after tetralogy of Fallot repair with pulmonary insufficiency: clinical implications.

PubMed

Fogel, Mark A; Sundareswaran, Kartik S; de Zelicourt, Diane; Dasi, Lakshmi P; Pawlowski, Tom; Rome, Jack; Yoganathan, Ajit P

2012-06-01

To quantify right ventricular output power and efficiency and correlate these to ventricular function in patients with repaired tetralogy of Fallot. This might aid in determining the optimal timing for pulmonary valve replacement. We reviewed the cardiac catheterization and magnetic resonance imaging data of 13 patients with tetralogy of Fallot (age, 22 ± 17 years). Using pressure and flow measurements in the main pulmonary artery, cardiac output and regurgitation fraction, right ventricular (RV) power output, loss, and efficiency were calculated. The RV function was evaluated using cardiac magnetic resonance imaging. The RV systolic power was 1.08 ± 0.62 W, with 20.3% ± 8.6% power loss owing to 41% ± 14% pulmonary regurgitation (efficiency, 79.7% ± 8.6%; 0.84 ± 0.73 W), resulting in a net cardiac output of 4.24 ± 1.82 L/min. Power loss correlated significantly with the indexed RV end-diastolic and end-systolic volume (R = 0.78, P = .002 and R = 0.69, P = .009, respectively). The normalized RV power output had a significant negative correlation with RV end-diastolic and end-systolic volumes (both R = -0.87, P = .002 and R = -0.68, P = .023, respectively). A rapid decrease occurred in the RV power capacity with an increasing RV volume, with the curve flattening out at an indexed RV end-diastolic and end-systolic volume threshold of 139 mL/m(2) and 75 mL/m(2), respectively. Significant power loss is present in patients with repaired tetralogy of Fallot and pulmonary regurgitation. A rapid decrease in efficiency occurs with increasing RV volume, suggesting that pulmonary valve replacement should be done before the critical value of 139 mL/m(2) and 75 mL/m(2) for the RV end-diastolic and end-systolic volume, respectively, to preserve RV function. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Comparing Methods for Cardiac Output: Intraoperatively Doppler-Derived Cardiac Output Measured With 3-Dimensional Echocardiography Is Not Interchangeable With Cardiac Output by Pulmonary Catheter Thermodilution.

PubMed

Graeser, Karin; Zemtsovski, Mikhail; Kofoed, Klaus F; Winther-Jensen, Matilde; Nilsson, Jens C; Kjaergaard, Jesper; Møller-Sørensen, Hasse

2018-01-09

Estimation of cardiac output (CO) is essential in the treatment of circulatory unstable patients. CO measured by pulmonary artery catheter thermodilution is considered the gold standard but carries a small risk of severe complications. Stroke volume and CO can be measured by transesophageal echocardiography (TEE), which is widely used during cardiac surgery. We hypothesized that Doppler-derived CO by 3-dimensional (3D) TEE would agree well with CO measured with pulmonary artery catheter thermodilution as a reference method based on accurate measurements of the cross-sectional area of the left ventricular outflow tract. The primary aim was a systematic comparison of CO with Doppler-derived 3D TEE and CO by thermodilution in a broad population of patients undergoing cardiac surgery. A subanalysis was performed comparing cross-sectional area by TEE with cardiac computed tomography (CT) angiography. Sixty-two patients, scheduled for elective heart surgery, were included; 1 was subsequently excluded for logistic reasons. Inclusion criteria were coronary artery bypass surgery (N = 42) and aortic valve replacement (N = 19). Exclusion criteria were chronic atrial fibrillation, left ventricular ejection fraction below 0.40 and intracardiac shunts. Nineteen randomly selected patients had a cardiac CT the day before surgery. All images were stored for blinded post hoc analyses, and Bland-Altman plots were used to assess agreement between measurement methods, defined as the bias (mean difference between methods), limits of agreement (equal to bias ± 2 standard deviations of the bias), and percentage error (limits of agreement divided by the mean of the 2 methods). Precision was determined for the individual methods (equal to 2 standard deviations of the bias between replicate measurements) to determine the acceptable limits of agreement. We found a good precision for Doppler-derived CO measured by 3D TEE, but although the bias for Doppler-derived CO by 3D compared to thermodilution was only 0.3 L/min (confidence interval, 0.04-0.58), there were wide limits of agreement (-1.8 to 2.5 L/min) with a percentage error of 55%. Measurements of cross-sectional area by 3D TEE had low bias of -0.27 cm (confidence interval, -0.45 to -0.08) and a percentage error of 18% compared to cardiac CT angiography. Despite low bias, the wide limits of agreement of Doppler-derived CO by 3D TEE compared to CO by thermodilution will limit clinical application and can therefore not be considered interchangeable with CO obtained by thermodilution. The lack of agreement is not explained by lack of agreement of the 3D technique.

The cardiovascular work of competitive dinghy sailing.

PubMed

Felici, F; Rodio, A; Madaffari, A; Ercolani, L; Marchetti, M

1999-12-01

Hiking is the special manoeuvre, which the dinghy sailor uses to counterbalance the capsizing effect of the wind on the boat. In the present research the work required of the heart by this exercise was studied in the laboratory using a boat simulator. Seven Laser male sailors selected from those in the first places in the junior national rank participated in this study. Their endurance, at different levels of isometric hiking efforts, was measured. Energy expenditure due to hiking was estimated from measurements of oxygen consumption, carbon dioxide elimination and blood lactate concentration. The cardiac load was evaluated by measuring blood pressure using the conventional method and heart rate measured by electrocardiography. Cardiac output was measured using the CO2 re-breathing method. Left ventricular work was then calculated as cardiac output multiplied by mean arterial pressure. The most relevant result was that, while whole body cost of hiking was relatively low (about 1 IO2 min-1), the power of the heart was very significant: cardiac output almost doubled with respect to that at rest and arterial mean pressure rose from 12.5 kPa (rest) to 18.5 kPa (hiking). Thus, left ventricular power rose from 1.2 Watt to 3.2 Watt, which is a typical cardiovascular response to muscular isometric contraction. These results assume relevance when a person's eligibility for sailing sports is evaluated.

Accurate, noninvasive continuous monitoring of cardiac output by whole-body electrical bioimpedance.

PubMed

Cotter, Gad; Moshkovitz, Yaron; Kaluski, Edo; Cohen, Amram J; Miller, Hilton; Goor, Daniel; Vered, Zvi

2004-04-01

Cardiac output (CO) is measured but sparingly due to limitations in its measurement technique (ie, right-heart catheterization). Yet, in recent years it has been suggested that CO may be of value in the diagnosis, risk stratification, and treatment titration of cardiac patients, especially those with congestive heart failure (CHF). We examine the use of a new noninvasive, continuous whole-body bioimpedance system (NICaS; NI Medical; Hod-Hasharon, Israel) for measuring CO. The aim of the present study was to test the validity of this noninvasive cardiac output system/monitor (NICO) in a cohort of cardiac patients. Prospective, double-blind comparison of the NICO and thermodilution CO determinations. We enrolled 122 patients in three different groups: during cardiac catheterization (n = 40); before, during, and after coronary bypass surgery (n = 51); and while being treated for acute congestive heart failure (CHF) exacerbation (n = 31). MEASUREMENTS AND INTERVENTION: In all patients, CO measurements were obtained by two independent blinded operators. CO was measured by both techniques three times, and an average was determined for each time point. CO was measured at one time point in patients undergoing coronary catheterization; before, during, and after bypass surgery in patients undergoing coronary bypass surgery; and before and during vasodilator treatment in patients treated for acute heart failure. Overall, 418 paired CO measurements were obtained. The overall correlation between the NICO cardiac index (CI) and the thermodilution CI was r = 0.886, with a small bias (0.0009 +/- 0.684 L) [mean +/- 2 SD], and this finding was consistent within each group of patients. Thermodilution readings were 15% higher than NICO when CI was < 1.5 L/min/m(2), and 5% lower than NICO when CI was > 3 L/min/m(2). The NICO has also accurately detected CI changes during coronary bypass operation and vasodilator administration for acute CHF. The results of the present study indicate that whole-body bioimpedance CO measurements obtained by the NICO are accurate in rapid, noninvasive measurement and the follow-up of CO in a wide range of cardiac clinical situations.

Linear and non-linear contributions to oxygen transport and utilization during moderate random exercise in humans.

PubMed

Beltrame, T; Hughson, R L

2017-05-01

What is the central question of this study? The pulmonary oxygen uptake (pV̇O2) data used to study the muscle aerobic system dynamics during moderate-exercise transitions is classically described as a mono-exponential function controlled by a complex interaction of the oxygen delivery-utilization balance. This elevated complexity complicates the acquisition of relevant information regarding aerobic system dynamics based on pV̇O2 data during a varying exercise stimulus. What is the main finding and its importance? The elevated complexity of pV̇O2 dynamics is a consequence of a multiple-order interaction between muscle oxygen uptake and circulatory distortion. Our findings challenge the use of a first-order function to study the influences of the oxygen delivery-utilization balance over the pV̇O2 dynamics. The assumption of aerobic system linearity implies that the pulmonary oxygen uptake (pV̇O2) dynamics during exercise transitions present a first-order characteristic. The main objective of this study was to test the linearity of the oxygen delivery-utilization balance during random moderate exercise. The cardiac output (Q̇) and deoxygenated haemoglobin concentration ([HHb]) were measured to infer the central and local O 2 availability, respectively. Thirteen healthy men performed two consecutive pseudorandom binary sequence cycling exercises followed by an incremental protocol. The system input and the outputs pV̇O2, [HHb] and Q̇ were submitted to frequency-domain analysis. The linearity of the variables was tested by computing the ability of the response at a specific frequency to predict the response at another frequency. The predictability levels were assessed by the coefficient of determination. In a first-order system, a participant who presents faster dynamics at a specific frequency should also present faster dynamics at any other frequency. All experimentally obtained variables (pV̇O2, [HHb] and Q̇) presented a certainly degree of non-linearity. The local O 2 availability, evaluated by the ratio pV̇O2/[HHb], presented the most irregular behaviour. The overall [HHb] kinetics were faster than pV̇O2 and Q̇ kinetics. In conclusion, the oxygen delivery-utilization balance behaved as a non-linear phenomenon. Therefore, the elevated complexity of the pulmonary oxygen uptake dynamics is governed by a complex multiple-order interaction between the oxygen delivery and utilization systems. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Antioxidant-Mediated Effects in a Gerbil Model of Iron Overload

PubMed Central

Otto-Duessel, Maya; Aguilar, Michelle; Moats, Rex; Wood, John C.

2010-01-01

Introduction Iron cardiomyopathy is a lethal complication of transfusion therapy in thalassemia major. Nutritional supplements decreasing cardiac iron uptake or toxicity would have clinical significance. Murine studies suggest taurine may prevent oxidative damage and inhibit Ca2+-channel-mediated iron transport. We hypothesized that taurine supplementation would decrease cardiac iron-overloaded toxicity by decreasing cardiac iron. Vitamin E and selenium served as antioxidant control. Methods Animals were divided into control, iron, taurine, and vitamin E/selenium groups. Following sacrifice, iron and selenium measurements, histology, and biochemical analyses were performed. Results No significant differences were found in heart and liver iron content between treatment groups, except for higher hepatic dry-weight iron concentrations in taurine-treated animals (p < 0.03). Serum iron increased with iron loading (751 ± 66 vs. 251 ± 54 μg/dl, p < 0.001) and with taurine (903 ± 136 μg/dl, p = 0.03). Conclusion Consistent with oxidative stress, iron overload increased cardiac malondialdehyde levels, decreased heart glutathione peroxidase (GPx) activity, and increased serum aspartate aminotransferase. Taurine ameliorated these changes, but only significantly for liver GPx activity. Selenium and vitamin E supplementation did not improve oxidative markers and worsened cardiac GPx activity. These results suggest that taurine acts primarily as an antioxidant rather than inhibiting iron uptake. Future studies should illuminate the complexity of these results. PMID:17940334

Effects of Sinoaortic Denervation on Hemodynamic Parameters During Natural Sleep in Rats

PubMed Central

Silveira, Neide P.; Moreira, Edson D.; Drager, Luciano F.; Silva, Gustavo J. J.; Krieger, Eduardo M.

2008-01-01

Study Objectives: To analyze the role of arterial baroreflex on hemodynamic changes during synchronized and desynchronized sleep phases of natural sleep in rats. Design: Experimental study. Setting: Laboratory. Participants: Seventeen male Wistar rats. Interventions: No intervention (control, n = 8) or sinoaortic denervation (SAD, n = 9). Measurements and Results: Sleep phases were monitored by electrocorticogram, and blood pressure was measured directly by a catheter in the carotid artery. Cardiac output, as well as total and regional vascular resistances, were determined by measuring the subdiaphragmatic aorta and iliac artery flows with Doppler flow probes, respectively. In contrast to the control group, the SAD group had a strong reduction in blood pressure (−19.9% ± 2.6% vs −0.7% ± 2.1%) during desynchronized sleep, and cardiac output showed an exacerbated reduction (−10.4% ± 3.5% vs 1.1% ± 1.7%). In SAD rats, total vascular resistance decreased during desynchronized sleep (−10.1% ± 3.5% vs −1.0% ± 1.7%), and the increase in regional vascular resistance observed in the control group was abolished (27.5% ± 8.3% vs −0.8% ± 9.4%). Conclusions: SAD caused profound changes in blood pressure, cardiac output, and total vascular resistance, with a significant increase in muscle vascular resistance during synchronized sleep. Our results suggest that baroreflex plays an important role in maintaining the normal balance of cardiac output and total vascular resistance during sleep. Citation: Silveira NP; Moreira ED; Drager LF; Silva GJJ; Krieger EM. Effects of sinoaortic denervation on hemodynamic parameters during natural sleep in rats. SLEEP 2008;31(3):328-333. PMID:18363308

Methylene Blue to Treat Protamine-induced Anaphylaxis Reactions. An Experimental Study in Pigs.

PubMed

Albuquerque, Agnes Afrodite S; Margarido, Edson A; Menardi, Antonio Carlos; Scorzoni, Adilson; Celotto, Andrea Carla; Rodrigues, Alfredo J; Vicente, Walter Vilella A; Evora, Paulo Roberto B

2016-01-01

To examine if methylene blue (MB) can counteract or prevent protamine (P) cardiovascular effects. The protocol included five heparinized pig groups: Group Sham -without any drug; Group MB - MB 3 mg/kg infusion; Group P - protamine; Group P/MB - MB after protamine; Group MB/P - MB before protamine. Nitric oxide levels were obtained by the nitric oxide/ozone chemiluminescence method, performed using the Nitric Oxide Analizer 280i (Sievers, Boulder, CO, USA). Malondialdehyde plasma levels were estimated using the thiobarbiturate technique. 1) Groups Sham and MB presented unchanged parameters; 2) Group P - a) Intravenous protamine infusion caused mean arterial pressure decrease and recovery trend after 25-30 minutes, b) Cardiac output decreased and remained stable until the end of protamine injection, and c) Sustained systemic vascular resistance increased until the end of protamine injection; 3) Methylene blue infusion after protamine (Group P/MB) - a) Marked mean arterial pressure decreased after protamine, but recovery after methylene blue injection, b) Cardiac output decreased after protamine infusion, recovering after methylene blue infusion, and c) Sustained systemic vascular resistance increased after protamine infusion and methylene blue injections; 4) Methylene blue infusion before protamine (Group MB/P) - a) Mean arterial pressure decrease was less severe with rapid recovery, b) After methylene blue, there was a progressive cardiac output increase up to protamine injection, when cardiac output decreased, and c) Sustained systemic vascular resistance decreased after protamine, followed by immediate Sustained systemic vascular resistance increase; 5) Plasma nitrite/nitrate and malondialdehyde values did not differ among the experimental groups. Reviewing these experimental results and our clinical experience, we suggest methylene blue safely prevents and treats hemodynamic protamine complications, from the endothelium function point of view.

Significant correlation of comprehensive Aristotle score with total cardiac output during the early postoperative period after the Norwood procedure.

PubMed

Li, Jia; Zhang, Gencheng; Holtby, Helen; Cai, Sally; Walsh, Mark; Caldarone, Christopher A; Van Arsdell, Glen S

2008-07-01

The comprehensive Aristotle score has been proposed as an individualized measure of the complexity of a given surgical procedure and has been reported to significantly correlate with postoperative morbidity and mortality after the Norwood procedure. An important factor leading to postoperative morbidity and mortality is low cardiac output. We studied the correlation between the comprehensive Aristotle score and cardiac output (CO) in infants after the Norwood procedure. Respiratory mass spectrometry was used to continuously measure systemic oxygen consumption (VO(2)) in 22 infants for 72 hours postoperatively. Arterial, superior vena caval and pulmonary venous blood gases were measured at 2 to 4 hour intervals to calculate CO. The comprehensive Aristotle score was collected. Hospital mortality was 4.5%. The comprehensive Aristotle score ranged from 14.5 to 23.5 and negatively correlated with CO (P = 0.027). Among the patient-adjusted factors, myocardial dysfunction (n = 10), mechanical ventilation to treat cardiorespiratory failure (n = 9) and atrioventricular valve regurgitation (n = 4) (P = 0.01) negatively correlated with CO (P = 0.06 to 0.07). Aortic atresia (n = 9) was associated with a lower CO (P = 0.01) for the first 24 hours which linearly increased overtime (P = 0.0001). No correlation was found between CO and other factors (P > 0.3 for all). Comprehensive Aristotle score significantly negatively correlates with CO after the Norwood procedure. A preoperative estimation of the comprehensive Aristotle score, particularly in association with myocardial dysfunction, mechanical ventilation to treat cardiorespiratory failure, atrioventricular valve regurgitation and aortic atresia may help to anticipate a high postoperative morbidity with low cardiac output syndrome.

Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

PubMed Central

Park, Marcelo; Mendes, Pedro Vitale; Costa, Eduardo Leite Vieira; Barbosa, Edzangela Vasconcelos Santos; Hirota, Adriana Sayuri; Azevedo, Luciano Cesar Pontes

2016-01-01

Objective The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin. PMID:27096671

The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output.

PubMed

Smerup, Morten; Damkjær, Mads; Brøndum, Emil; Baandrup, Ulrik T; Kristiansen, Steen Buus; Nygaard, Hans; Funder, Jonas; Aalkjær, Christian; Sauer, Cathrine; Buchanan, Rasmus; Bertelsen, Mads Frost; Østergaard, Kristine; Grøndahl, Carsten; Candy, Geoffrey; Hasenkam, J Michael; Secher, Niels H; Bie, Peter; Wang, Tobias

2016-02-01

Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300 mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38 kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min(-1), respectively. End-diastolic and end-systolic volumes were 521±61 ml and 228±42 ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59 ml kg(-1). Left ventricular circumferential wall stress was 7.83±1.76 kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output. © 2016. Published by The Company of Biologists Ltd.

Analysis of factors that influence rates of carbon monoxide uptake, distribution, and washout from blood and extravascular tissues using a multicompartment model.

PubMed

Bruce, Margaret C; Bruce, Eugene N

2006-04-01

To better understand factors that influence carbon monoxide (CO) washout rates, we utilized a multicompartment mathematical model to predict rates of CO uptake, distribution in vascular and extravascular (muscle vs. other soft tissue) compartments, and washout over a range of exposure and washout conditions with varied subject-specific parameters. We fitted this model to experimental data from 15 human subjects, for whom subject-specific parameters were known, multiple washout carboxyhemoglobin (COHb) levels were available, and CO exposure conditions were identical, to investigate the contributions of exposure conditions and individual variability to CO washout from blood. We found that CO washout from venous blood was biphasic and that postexposure times at which COHb samples were obtained significantly influenced the calculated CO half times (P < 0.0001). The first, more rapid, phase of CO washout from the blood reflected the loss of CO to the expired air and to a slow uptake by the muscle compartment, whereas the second, slower washout phase was attributable to CO flow from the muscle compartment back to the blood and removal from blood via the expired air. When the model was used to predict the effects of varying exposure conditions for these subjects, the CO exposure duration, concentration, peak COHb levels, and subject-specific parameters each influenced washout half times. Blood volume divided by ventilation correlated better with half-time predictions than did cardiac output, muscle mass, or ventilation, but it explained only approximately 50% of half-time variability. Thus exposure conditions, COHb sampling times, and individual parameters should be considered when estimating CO washout rates for poisoning victims.

Mg(2+) differentially regulates two modes of mitochondrial Ca(2+) uptake in isolated cardiac mitochondria: implications for mitochondrial Ca(2+) sequestration.

PubMed

Blomeyer, Christoph A; Bazil, Jason N; Stowe, David F; Dash, Ranjan K; Camara, Amadou K S

2016-06-01

The manner in which mitochondria take up and store Ca(2+) remains highly debated. Recent experimental and computational evidence has suggested the presence of at least two modes of Ca(2+) uptake and a complex Ca(2+) sequestration mechanism in mitochondria. But how Mg(2+) regulates these different modes of Ca(2+) uptake as well as mitochondrial Ca(2+) sequestration is not known. In this study, we investigated two different ways by which mitochondria take up and sequester Ca(2+) by using two different protocols. Isolated guinea pig cardiac mitochondria were exposed to varying concentrations of CaCl2 in the presence or absence of MgCl2. In the first protocol, A, CaCl2 was added to the respiration buffer containing isolated mitochondria, whereas in the second protocol, B, mitochondria were added to the respiration buffer with CaCl2 already present. Protocol A resulted first in a fast transitory uptake followed by a slow gradual uptake. In contrast, protocol B only revealed a slow and gradual Ca(2+) uptake, which was approximately 40 % of the slow uptake rate observed in protocol A. These two types of Ca(2+) uptake modes were differentially modulated by extra-matrix Mg(2+). That is, Mg(2+) markedly inhibited the slow mode of Ca(2+) uptake in both protocols in a concentration-dependent manner, but not the fast mode of uptake exhibited in protocol A. Mg(2+) also inhibited Na(+)-dependent Ca(2+) extrusion. The general Ca(2+) binding properties of the mitochondrial Ca(2+) sequestration system were reaffirmed and shown to be independent of the mode of Ca(2+) uptake, i.e. through the fast or slow mode of uptake. In addition, extra-matrix Mg(2+) hindered Ca(2+) sequestration. Our results indicate that mitochondria exhibit different modes of Ca(2+) uptake depending on the nature of exposure to extra-matrix Ca(2+), which are differentially sensitive to Mg(2+). The implications of these findings in cardiomyocytes are discussed.

The Effects of Mental Fatigue on Physical Performance: A Systematic Review.

PubMed

Van Cutsem, Jeroen; Marcora, Samuele; De Pauw, Kevin; Bailey, Stephen; Meeusen, Romain; Roelands, Bart

2017-08-01

Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. It has recently been suggested that mental fatigue can affect physical performance. Our objective was to evaluate the literature on impairment of physical performance due to mental fatigue and to create an overview of the potential factors underlying this effect. Two electronic databases, PubMed and Web of Science (until 28 April 2016), were searched for studies designed to test whether mental fatigue influenced performance of a physical task or influenced physiological and/or perceptual responses during the physical task. Studies using short (<30 min) self-regulatory depletion tasks were excluded from the review. A total of 11 articles were included, of which six were of strong and five of moderate quality. The general finding was a decline in endurance performance (decreased time to exhaustion and self-selected power output/velocity or increased completion time) associated with a higher than normal perceived exertion. Physiological variables traditionally associated with endurance performance (heart rate, blood lactate, oxygen uptake, cardiac output, maximal aerobic capacity) were unaffected by mental fatigue. Maximal strength, power, and anaerobic work were not affected by mental fatigue. The duration and intensity of the physical task appear to be important factors in the decrease in physical performance due to mental fatigue. The most important factor responsible for the negative impact of mental fatigue on endurance performance is a higher perceived exertion.

Cardiac Iodine-123-Meta-Iodo-Benzylguanidine Uptake in Carotid Sinus Hypersensitivity

PubMed Central

Tan, Maw Pin; Murray, Alan; Hawkins, Terry; Chadwick, Thomas J.; Kerr, Simon R. J.; Parry, Steve W.

2015-01-01

Background Carotid sinus syndrome is the association of carotid sinus hypersensitivity with syncope, unexplained falls and drop attacks in generally older people. We evaluated cardiac sympathetic innervation in this disorder in individuals with carotid sinus syndrome, asymptomatic carotid sinus hypersensitivity and controls without carotid sinus hypersensitivity. Methods Consecutive patients diagnosed with carotid sinus syndrome at a specialist falls and syncope unit were recruited. Asymptomatic carotid sinus hypersensitivity and non-carotid sinus hypersensitivity control participants recruited from a community-dwelling cohort. Cardiac sympathetic innervation was determined using Iodine-123-metaiodobenzylguanidine (123-I-MIBG) scanning. Heart to mediastinal uptake ratio (H:M) were determined for early and late uptake on planar scintigraphy at 20 minutes and 3 hours following intravenous injection of 123-I-MIBG. Results Forty-two subjects: carotid sinus syndrome (n = 21), asymptomatic carotid sinus hypersensitivity (n = 12) and no carotid sinus hypersensitivity (n = 9) were included. Compared to the non- carotid sinus hypersensitivity control group, the carotid sinus syndrome group had significantly higher early H:M (estimated mean difference, B = 0.40; 95% confidence interval, CI = 0.13 to 0.67, p = 0.005) and late H:M (B = 0.32; 95%CI = 0.03 to 0.62, p = 0.032). There was, however, no significant difference in early H:M (p = 0.326) or late H:M (p = 0.351) between the asymptomatic carotid sinus hypersensitivity group and non- carotid sinus hypersensitivity controls. Conclusions Cardiac sympathetic neuronal activity is increased relative to age-matched controls in individuals with carotid sinus syndrome but not those with asymptomatic carotid sinus hypersensitivity. Blood pressure and heart rate measurements alone may therefore represent an over simplification in the assessment for carotid sinus syndrome and the relative increase in cardiac sympathetic innervation provides additional clues to understanding the mechanisms behind the symptomatic presentation of carotid sinus hypersensitivity. PMID:26057525

Left ventricular vascular and metabolic adaptations to high-intensity interval and moderate intensity continuous training: a randomized trial in healthy middle-aged men.

PubMed

Eskelinen, Jari-Joonas; Heinonen, Ilkka; Löyttyniemi, Eliisa; Hakala, Juuso; Heiskanen, Marja A; Motiani, Kumail K; Virtanen, Kirsi; Pärkkä, Jussi P; Knuuti, Juhani; Hannukainen, Jarna C; Kalliokoski, Kari K

2016-12-01

High-intensity interval training (HIIT) has become popular, time-sparing alternative to moderate intensity continuous training (MICT), although the cardiac vascular and metabolic effects of HIIT are incompletely known. We compared the effects of 2-week interventions with HIIT and MICT on myocardial perfusion and free fatty acid and glucose uptake. Insulin-stimulated myocardial glucose uptake was decreased by training without any significantly different response between the groups, whereas free fatty acid uptake remained unchanged. Adenosine-stimulated myocardial perfusion responded differently to the training modes (change in mean HIIT: -19%; MICT: +9%; P = 0.03 for interaction) and was correlated with myocardial glucose uptake for the entire dataset and especially after HIIT training. HIIT and MICT induce similar metabolic and functional changes in the heart, although myocardial vascular hyperaemic reactivity is impaired after HIIT, and this should be considered when prescribing very intense HIIT for previously untrained subjects. High-intensity interval training (HIIT) is a time-efficient way of obtaining the health benefits of exercise, although the cardiac effects of this training mode are incompletely known. We compared the effects of short-term HIIT and moderate intensity continuous training (MICT) interventions on myocardial perfusion and metabolism and cardiac function in healthy, sedentary, middle-aged men. Twenty-eight healthy, middle-aged men were randomized to either HIIT or MICT groups (n = 14 in both) and underwent six cycle ergometer training sessions within 2 weeks (HIIT session: 4-6 × 30 s all-out cycling/4 min recovery, MICT session 40-60 min at 60% V̇O2 peak ). Cardiac magnetic resonance imaging (CMRI) was performed to measure cardiac structure and function and positron emission tomography was used to measure myocardial perfusion at baseline and during adenosine stimulation, insulin-stimulated glucose uptake (MGU) and fasting free fatty acid uptake (MFFAU). End-diastolic and end-systolic volumes increased and ejection fraction slightly decreased with both training modes, although no other changes in CMRI were observed. MFFAU and basal myocardial perfusion remained unchanged. MGU was decreased by training (HIIT from 46.5 to 35.9; MICT from 47.4 to 44.4 mmol 100 g -1  min -1 , P = 0.007 for time, P = 0.11 for group × time). Adenosine-stimulated myocardial perfusion responded differently to the training modes (change in mean HIIT: -19%; MICT: +9%; P = 0.03 for group × time interaction). HIIT and MICT induce similar metabolic and functional changes in the heart, although myocardial vascular hyperaemic reactivity is impaired after HIIT. This should be taken into account when prescribing very intense HIIT for previously untrained subjects. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Left ventricular vascular and metabolic adaptations to high‐intensity interval and moderate intensity continuous training: a randomized trial in healthy middle‐aged men

PubMed Central

Eskelinen, Jari‐Joonas; Heinonen, Ilkka; Löyttyniemi, Eliisa; Hakala, Juuso; Heiskanen, Marja A.; Motiani, Kumail K.; Virtanen, Kirsi; Pärkkä, Jussi P.; Knuuti, Juhani; Hannukainen, Jarna C.

2016-01-01

Key points High‐intensity interval training (HIIT) has become popular, time‐sparing alternative to moderate intensity continuous training (MICT), although the cardiac vascular and metabolic effects of HIIT are incompletely known.We compared the effects of 2‐week interventions with HIIT and MICT on myocardial perfusion and free fatty acid and glucose uptake.Insulin‐stimulated myocardial glucose uptake was decreased by training without any significantly different response between the groups, whereas free fatty acid uptake remained unchanged.Adenosine‐stimulated myocardial perfusion responded differently to the training modes (change in mean HIIT: –19%; MICT: +9%; P = 0.03 for interaction) and was correlated with myocardial glucose uptake for the entire dataset and especially after HIIT training.HIIT and MICT induce similar metabolic and functional changes in the heart, although myocardial vascular hyperaemic reactivity is impaired after HIIT, and this should be considered when prescribing very intense HIIT for previously untrained subjects. Abstract High‐intensity interval training (HIIT) is a time‐efficient way of obtaining the health benefits of exercise, although the cardiac effects of this training mode are incompletely known. We compared the effects of short‐term HIIT and moderate intensity continuous training (MICT) interventions on myocardial perfusion and metabolism and cardiac function in healthy, sedentary, middle‐aged men. Twenty‐eight healthy, middle‐aged men were randomized to either HIIT or MICT groups (n = 14 in both) and underwent six cycle ergometer training sessions within 2 weeks (HIIT session: 4–6 × 30 s all‐out cycling/4 min recovery, MICT session 40–60 min at 60% V˙O2 peak ). Cardiac magnetic resonance imaging (CMRI) was performed to measure cardiac structure and function and positron emission tomography was used to measure myocardial perfusion at baseline and during adenosine stimulation, insulin‐stimulated glucose uptake (MGU) and fasting free fatty acid uptake (MFFAU). End‐diastolic and end‐systolic volumes increased and ejection fraction slightly decreased with both training modes, although no other changes in CMRI were observed. MFFAU and basal myocardial perfusion remained unchanged. MGU was decreased by training (HIIT from 46.5 to 35.9; MICT from 47.4 to 44.4 mmol 100 g–1 min–1, P = 0.007 for time, P = 0.11 for group × time). Adenosine‐stimulated myocardial perfusion responded differently to the training modes (change in mean HIIT: –19%; MICT: +9%; P = 0.03 for group × time interaction). HIIT and MICT induce similar metabolic and functional changes in the heart, although myocardial vascular hyperaemic reactivity is impaired after HIIT. This should be taken into account when prescribing very intense HIIT for previously untrained subjects. PMID:27500951

Roles of PDE1 in Pathological Cardiac Remodeling and Dysfunction.

PubMed

Chen, Si; Knight, Walter E; Yan, Chen

2018-04-23

Pathological cardiac hypertrophy and dysfunction is a response to various stress stimuli and can result in reduced cardiac output and heart failure. Cyclic nucleotide signaling regulates several cardiac functions including contractility, remodeling, and fibrosis. Cyclic nucleotide phosphodiesterases (PDEs), by catalyzing the hydrolysis of cyclic nucleotides, are critical in the homeostasis of intracellular cyclic nucleotide signaling and hold great therapeutic potential as drug targets. Recent studies have revealed that the inhibition of the PDE family member PDE1 plays a protective role in pathological cardiac remodeling and dysfunction by the modulation of distinct cyclic nucleotide signaling pathways. This review summarizes recent key findings regarding the roles of PDE1 in the cardiac system that can lead to a better understanding of its therapeutic potential.

The correlation between the first heart sound and cardiac output as measured by using digital esophageal stethoscope under anaesthesia.

PubMed

Duck Shin, Young; Hoon Yim, Kyoung; Hi Park, Sang; Wook Jeon, Yong; Ho Bae, Jin; Soo Lee, Tae; Hwan Kim, Myoung; Jin Choi, Young

2014-03-01

The use of an esophageal stethoscope is a basic heart sounds monitoring procedure performed in patients under general anesthesia. As the size of the first heart sound can express the left ventricle function, its correlation with cardiac output should be investigated. The aim of this study was to investigate the effects of cardiac output (CO) on the first heart sound (S1) amplitude. Methods : Six male beagles were chosen. The S1 was obtained with the newly developed esophageal stethoscope system. CO was measured using NICOM, a non-invasive CO measuring device. Ephedrine and beta blockers were administered to the subjects to compare changes in figures, and the change from using an inhalation anesthetic was also compared. The S1 amplitude displayed positive correlation with the change rate of CO (r = 0.935, p < 0.001). The heart rate measured using the esophageal stethoscope and ECG showed considerably close figures through the Bland-Altman plot and showed a high positive correlation (r = 0.988, p < 0,001). In beagles, the amplitude of S1 had a significant correlation with changes in CO in a variety of situations.

Cardiac output and performance during a marathon race in middle-aged recreational runners.

PubMed

Billat, Véronique L; Petot, Hélène; Landrain, Morgan; Meilland, Renaud; Koralsztein, Jean Pierre; Mille-Hamard, Laurence

2012-01-01

Despite the increasing popularity of marathon running, there are no data on the responses of stroke volume (SV) and cardiac output (CO) to exercise in this context. We sought to establish whether marathon performance is associated with the ability to sustain high fractional use of maximal SV and CO (i.e, cardiac endurance) and/or CO, per meter (i.e., cardiac cost). We measured the SV, heart rate (HR), CO, and running speed of 14 recreational runners in an incremental, maximal laboratory test and then during a real marathon race (mean performance: 3 hr 30 min ± 45 min). Our data revealed that HR, SV and CO were all in a high but submaximal steady state during the marathon (87.0 ± 1.6%, 77.2 ± 2.6%, and 68.7 ± 2.8% of maximal values, respectively). Marathon performance was inversely correlated with an upward drift in the CO/speed ratio (mL of CO × m(-1)) (r = -0.65, P < 0.01) and positively correlated with the runner's ability to complete the race at a high percentage of the speed at maximal SV (r = 0.83, P < 0.0002). Our results showed that marathon performance is inversely correlated with cardiac cost and positively correlated with cardiac endurance. The CO response could be a benchmark for race performance in recreational marathon runners.

Functional significance of cardiac reinnervation in heart transplant recipients.

PubMed

Schwaiblmair, M; von Scheidt, W; Uberfuhr, P; Ziegler, S; Schwaiger, M; Reichart, B; Vogelmeier, C

1999-09-01

There is accumulating evidence of structural sympathetic reinnervation after human cardiac transplantation. However, the functional significance of reinnervation in terms of exercise capacity has not been established as yet; we therefore investigated the influence of reinnervation on cardiopulmonary exercise testing. After orthotopic heart transplantation 35 patients (mean age, 49.1 +/- 8.4 years) underwent positron emission tomography with scintigraphically measured uptake of C11-hydroxyephedrine (HED), lung function testing, and cardiopulmonary exercise testing. Two groups were defined based on scintigraphic findings, indicating a denervated group (n = 15) with a HED uptake of 5.45%/min and a reinnervated group (n = 20) with a HED uptake of 10.59%/min. The two study groups did not show significant differences with regard to anthropometric data, number of rejection episodes, preoperative hemodynamics, and postoperative lung function data. The reinnervated group had a significant longer time interval from transplantation (1625 +/- 1069 versus 800 +/- 1316 days, p < .05). In transplant recipients with reinnervation, heart rate at maximum exercise (137 +/- 15 versus 120 +/- 20 beats/min, p = .012), peak oxygen uptake (21.0 +/- 4 versus 16.1 +/- 5 mL/min/kg, p = .006), peak oxygen pulse (12.4 +/- 2.9 versus 10.2 +/- 2.7 mL/min/beat, p = .031), and anaerobic threshold (11.2 +/- 1.8 versus 9.5 +/- 2.1 mL/min, p = .046) were significantly increased in comparison to denervated transplant recipients. Additionally, a decreased functional dead space ventilation (0.24 +/- 0.05 versus 0.30 +/- 0.05, p = .004) was observed in the reinnervated group. Our study results support the hypothesis that partial sympathetic reinnervation after cardiac transplantation is of functional significance. Sympathetic reinnervation enables an increased peak oxygen uptake. This is most probably due to partial restoration of the chronotropic and inotropic competence of the heart as well as an improved oxygen delivery to the exercising muscles and a reduced ventilation-perfusion mismatching.

Improvement in cardiac function and free fatty acid metabolism in a case of dilated cardiomyopathy with CD36 deficiency.

PubMed

Hirooka, K; Yasumura, Y; Ishida, Y; Komamura, K; Hanatani, A; Nakatani, S; Yamagishi, M; Miyatake, K

2000-09-01

A 27-year-old man diagnosed as having dilated cardiomyopathy (DCM) without myocardial accumulation of 123I-beta-methyl-iodophenylpentadecanoic acid, and he was found to have type I CD36 deficiency. This abnormality of cardiac free fatty acid metabolism was also confirmed by other methods: 18F-fluoro-2-deoxyglucose positron emission tomography, measurements of myocardial respiratory quotient and cardiac fatty acid uptake. Although the type I CD36 deficiency was reconfirmed after 3 months, the abnormal free fatty acid metabolism improved after carvedilol therapy and was accompanied by improved cardiac function. Apart from a cause-and-effect relationship, carvedilol can improve cardiac function and increase free fatty acid metabolism in patients with both DCM and CD36 deficiency.

Effects of Obstructive Sleep Apnea and Obesity on Exercise Function in Children

PubMed Central

Evans, Carla A.; Selvadurai, Hiran; Baur, Louise A.; Waters, Karen A.

2014-01-01

Study Objectives: Evaluate the relative contributions of weight status and obstructive sleep apnea (OSA) to cardiopulmonary exercise responses in children. Design: Prospective, cross-sectional study. Participants underwent anthropometric measurements, overnight polysomnography, spirometry, cardiopulmonary exercise function testing on a cycle ergometer, and cardiac doppler imaging. OSA was defined as ≥ 1 obstructive apnea or hypopnea per hour of sleep (OAHI). The effect of OSA on exercise function was evaluated after the parameters were corrected for body mass index (BMI) z-scores. Similarly, the effect of obesity on exercise function was examined when the variables were adjusted for OAHI. Setting: Tertiary pediatric hospital. Participants: Healthy weight and obese children, aged 7–12 y. Interventions: N/A. Measurements and Results: Seventy-one children were studied. In comparison with weight-matched children without OSA, children with OSA had a lower cardiac output, stroke volume index, heart rate, and oxygen consumption (VO2 peak) at peak exercise capacity. After adjusting for BMI z-score, children with OSA had 1.5 L/min (95% confidence interval -2.3 to -0.6 L/min; P = 0.001) lower cardiac output at peak exercise capacity, but minute ventilation and ventilatory responses to exercise were not affected. Obesity was only associated with physical deconditioning. Cardiac dysfunction was associated with the frequency of respiratory-related arousals, the severity of hypoxia, and heart rate during sleep. Conclusions: Children with OSA are exercise limited due to a reduced cardiac output and VO2 peak at peak exercise capacity, independent of their weight status. Comorbid OSA can further decrease exercise performance in obese children. Citation: Evans CA, Selvadurai H, Baur LA, Waters KA. Effects of obstructive sleep apnea and obesity on exercise function in children. SLEEP 2014;37(6):1103-1110. PMID:24882905

Cluster Differentiating 36 (CD36) Deficiency Attenuates Obesity-Associated Oxidative Stress in the Heart.

PubMed

Gharib, Mohamed; Tao, Huan; Fungwe, Thomas V; Hajri, Tahar

2016-01-01

Obesity is often associated with a state of oxidative stress and increased lipid deposition in the heart. More importantly, obesity increases lipid influx into the heart and induces excessive production of reactive oxygen species (ROS) leading to cell toxicity and metabolic dysfunction. Cluster differentiating 36 (CD36) protein is highly expressed in the heart and regulates lipid utilization but its role in obesity-associated oxidative stress is still not clear. The aim of this study was to determine the impact of CD36 deficiency on cardiac steatosis, oxidative stress and lipotoxicity associated with obesity. Studies were conducted in control (Lean), obese leptin-deficient (Lepob/ob) and leptin-CD36 double null (Lepob/obCD36-/-) mice. Compared to lean mice, cardiac steatosis, and fatty acid (FA) uptake and oxidation were increased in Lepob/ob mice, while glucose uptake and oxidation was reduced. Moreover, insulin resistance, oxidative stress markers and NADPH oxidase-dependent ROS production were markedly enhanced. This was associated with the induction of NADPH oxidase expression, and increased membrane-associated p47phox, p67phox and protein kinase C. Silencing CD36 in Lepob/ob mice prevented cardiac steatosis, increased insulin sensitivity and glucose utilization, but reduced FA uptake and oxidation. Moreover, CD36 deficiency reduced NADPH oxidase activity and decreased NADPH oxidase-dependent ROS production. In isolated cardiomyocytes, CD36 deficiency reduced palmitate-induced ROS production and normalized NADPH oxidase activity. CD36 deficiency prevented obesity-associated cardiac steatosis and insulin resistance, and reduced NADPH oxidase-dependent ROS production. The study demonstrates that CD36 regulates NADPH oxidase activity and mediates FA-induced oxidative stress.

Sudden cardiac arrest as a rare presentation of myxedema coma: case report.

PubMed

Salhan, Divya; Sapkota, Deepak; Verma, Prakash; Kandel, Saroj; Abdulfattah, Omar; Lixon, Antony; Zwenge, Deribe; Schmidt, Frances

2017-01-01

Myxedema coma is a decompensated hypothyroidism which occurs due to long-standing, undiagnosed, or untreated hypothyroidism. Untreated hypothyroidism is known to affect almost all organs including the heart. It is associated with a decrease in cardiac output, stroke volume due to decreased myocardial contractility, and an increase in systemic vascular resistance. It can cause cardiac arrhythmias and the most commonly seen conduction abnormalities are sinus bradycardia, heart block, ventricular tachycardia, and torsade de pointes. The authors report a case of an elderly man who presented with sudden cardiac arrest and myxedema coma and who was successfully revived.

The accuracy of PiCCO® in measuring cardiac output in patients under therapeutic hypothermia: Comparison with transthoracic echocardiography.

PubMed

Souto Moura, T; Aguiar Rosa, S; Germano, N; Cavaco, R; Sequeira, T; Alves, M; Papoila, A L; Bento, L

2018-03-01

Invasive cardiac monitoring using thermodilution methods such as PiCCO® is widely used in critically ill patients and provides a wide range of hemodynamic variables, including cardiac output (CO). However, in post-cardiac arrest patients subjected to therapeutic hypothermia, the low body temperature possibly could interfere with the technique. Transthoracic Doppler echocardiography (ECHO) has long proved its accuracy in estimating CO, and is not influenced by temperature changes. To assess the accuracy of PiCCO® in measuring CO in patients under therapeutic hypothermia, compared with ECHO. Thirty paired COECHO/COPiCCO measurements were analyzed in 15 patients subjected to hypothermia after cardiac arrest. Eighteen paired measurements were obtained at under 36°C and 12 at ≥36°C. A value of 0.5l/min was considered the maximum accepted difference between the COECHO and COPiCCO values. Under conditions of normothermia (≥36°C), the mean difference between COECHO and COPiCCO was 0.030 l/min, with limits of agreement (-0.22, 0.28) - all of the measurements differing by less than 0.5 l/min. In situations of hypothermia (<36°C), the mean difference in CO measurements was -0.426 l/min, with limits of agreement (-1.60, 0.75), and only 44% (8/18) of the paired measurements fell within the interval (-0.5, 0.5). The calculated temperature cut-off point maximizing specificity was 35.95°C: above this temperature, specificity was 100%, with a false-positive rate of 0%. The results clearly show clinically relevant discordance between COECHO and COPiCCO at temperatures of <36°C, demonstrating the inaccuracy of PiCCO® for cardiac output measurements in hypothermic patients. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

The Role of PDH Inhibition in the Development of Hypertrophy in the Hyperthyroid Rat Heart: A Combined MRI and Hyperpolarized MRS Study

PubMed Central

Atherton, Helen J.; Dodd, Michael S.; Heather, Lisa C.; Schroeder, Marie A.; Griffin, Julian L.; Radda, George K.; Clarke, Kieran; Tyler, Damian J.

2015-01-01

Background Hyperthyroidism increases heart rate, contractility and cardiac output, as well as metabolic rate. It is also accompanied by alterations in the regulation of cardiac substrate utilisation. Specifically, hyperthyroidism increases the ex vivo activity of pyruvate dehydrogenase kinase (PDK), thereby inhibiting glucose oxidation via pyruvate dehydrogenase (PDH). Cardiac hypertrophy is another effect of hyperthyroidism, with an increase in the abundance of mitochondria. Although the hypertrophy is initially beneficial, it can eventually lead to heart failure. The aim of this study was to use hyperpolarized magnetic resonance spectroscopy (MRS) to investigate the rate and regulation of in vivo pyruvate dehydrogenase (PDH) flux in the hyperthyroid heart, and to establish whether modulation of flux through PDH would alter cardiac hypertrophy. Methods & Results Hyperthyroidism was induced in 18 male Wistar rats with 7 daily intraperitoneal injections of freshly prepared triiodothyronine (T3; 0.2 mg/kg/day). In vivo PDH flux, assessed using hyperpolarized MRS, was reduced by 59% in hyperthyroid animals (0.0022 ± 0.0002 s−1 vs 0.0055 ± 0.0005 s−1, P = 0.0003) and this reduction was completely reversed by both acute and chronic delivery of the PDK inhibitor, dichloroacetic acid (DCA). Hyperpolarized [2-13C]pyruvate was also used to evaluate Krebs cycle metabolism and demonstrated a unique marker of anaplerosis, the level of which was significantly increased in the hyperthyroid heart. Cine MRI showed that chronic DCA treatment significantly reduced the hypertrophy observed in hyperthyroid animals (100 ± 20 mg vs 200 ± 30 mg; P = 0.04) despite no change to the increase observed in cardiac output. Conclusions This work has demonstrated that inhibition of glucose oxidation in the hyperthyroid heart in vivo is PDK mediated. Relieving this inhibition can increase the metabolic flexibility of the hyperthyroid heart and reduce the level of hypertrophy that develops whilst maintaining the increased cardiac output required to meet the higher systemic metabolic demand. PMID:21606392

Cardiac output by pulse contour analysis does not match the increase measured by rebreathing during human spaceflight.

PubMed

Hughson, Richard L; Peterson, Sean D; Yee, Nicholas J; Greaves, Danielle K

2017-11-01

Pulse contour analysis of the noninvasive finger arterial pressure waveform provides a convenient means to estimate cardiac output (Q̇). The method has been compared with standard methods under a range of conditions but never before during spaceflight. We compared pulse contour analysis with the Modelflow algorithm to estimates of Q̇ obtained by rebreathing during preflight baseline testing and during the final month of long-duration spaceflight in nine healthy male astronauts. By Modelflow analysis, stroke volume was greater in supine baseline than seated baseline or inflight. Heart rate was reduced in supine baseline so that there were no differences in Q̇ by Modelflow estimate between the supine (7.02 ± 1.31 l/min, means ± SD), seated (6.60 ± 1.95 l/min), or inflight (5.91 ± 1.15 l/min) conditions. In contrast, rebreathing estimates of Q̇ increased from seated baseline (4.76 ± 0.67 l/min) to inflight (7.00 ± 1.39 l/min, significant interaction effect of method and spaceflight, P < 0.001). Pulse contour analysis utilizes a three-element Windkessel model that incorporates parameters dependent on aortic pressure-area relationships that are assumed to represent the entire circulation. We propose that a large increase in vascular compliance in the splanchnic circulation invalidates the model under conditions of spaceflight. Future spaceflight research measuring cardiac function needs to consider this important limitation for assessing absolute values of Q̇ and stroke volume. NEW & NOTEWORTHY Noninvasive assessment of cardiac function during human spaceflight is an important tool to monitor astronaut health. This study demonstrated that pulse contour analysis of finger arterial blood pressure to estimate cardiac output failed to track the 46% increase measured by a rebreathing method. These results strongly suggest that alternative methods not dependent on pulse contour analysis are required to track cardiac function in spaceflight. Copyright © 2017 the American Physiological Society.

Toward a new cold and warm nondepolarizing, normokalemic arrest paradigm for orthotopic heart transplantation.

PubMed

Rudd, Donna M; Dobson, Geoffrey P

2009-01-01

Currently, the safe human heart preservation time is limited to around 4 to 5 hours of cold ischemic storage. Longer arrest times can lead to donor heart damage, early graft dysfunction, and chronic rejection. The aim of this study was to examine a new nondepolarizing, normokalemic preservation solution with adenosine and lidocaine for as long as 6 hours of arrest at cold and warmer storage temperatures. Isolated perfused rat hearts (n = 87) were switched from working to Langendorff (nonworking) mode and arrested at 37 degrees C with 200-micromol/L adenosine and 500-micromol/L lidocaine in Krebs-Henseleit buffer (10-mmol/L glucose, pH 7.7, 37 degrees C) or with Celsior (Sangstat Medical Corp, Fremont, CA). Hearts were removed and placed in static storage at 4 degrees C for 2 and 6 hours or remained on the apparatus and were intermittently flushed at 37 degrees C every 20 minutes for 2 minutes at 68 mm Hg (average arrest temperature 28 degrees -30 degrees C) for 2 and 6 hours. We further investigated the effect of the warmer adenosine-lidocaine solution supplemented with 1- or 5-mmol/L pyruvate. Adenosine-lidocaine solution arrested hearts in 16 +/- 2 seconds (n = 32), whereas Celsior did so in 39 +/- 4 seconds (n = 23). After 2 hours of cold static storage, there were no functional differences between the adenosine-lidocaine and Celsior groups, with approximately 70% return of cardiac output. In contrast, after 6 hours of 4 degrees C storage, adenosine-lidocaine hearts had significantly higher functional recoveries (68% +/- 5% cardiac output) than Celsior hearts (47% +/- 14% cardiac output) during 60 minutes of reperfusion. In addition, Celsior hearts took 5 minutes longer to reanimate and showed early reperfusion arrhythmias. At warmer temperatures after 2 hours of arrest, adenosine-lidocaine and Celsior hearts were not significantly different, despite a 43% higher cardiac output in adenosine-lidocaine hearts (80% +/- 3% vs 56% +/- 12%). After 6 hours, adenosine-lidocaine hearts had recovered 55% +/- 3% of prearrest cardiac output, which increased significantly to 75% +/- 4% with addition of 1-mmol/L pyruvate. Adenosine-lidocaine with 1-mmol/L pyruvate hearts spontaneously recovered 106% heart rate, 93% to 105% developed pressures, 70% aortic flow, and 81% coronary flow. Coronary vascular resistance increased 1.7- to 1.9-fold during the 6-hour arrest. In contrast, Celsior hearts did not have return of aortic or coronary flow after 6 hours in these warmer conditions. A new nondepolarizing, normokalemic adenosine-lidocaine arrest solution in Krebs-Henseleit buffer with 10-mmol/L glucose was versatile at both 4 degrees C and 28 degrees C to 30 degrees C relative to Celsior, and the addition of 1-mmol/L pyruvate significantly improved cardiac output at warmer arrest temperatures. This new arrest paradigm may be useful in the harvest, storage, and implantation of donor hearts.

Hemodynamic response to fluid removal during hemodialysis: categorization of causes of intradialytic hypotension.

PubMed

Levin, Nathan W; de Abreu, Marcia H F G; Borges, Lucas E; Tavares Filho, Helcio A; Sarwar, Rabia; Gupta, Surendra; Hafeez, Tahir; Lev, Shaul; Williams, Caroline

2018-04-14

Intradialytic hypotension is a clinically significant problem, however, the hemodynamics that underlie ultrafiltration and consequent hypotensive episodes has not been studied comprehensively. Intradialytic cardiac output, cardiac power and peripheral resistance changes from pretreatment measurements were evaluated using a novel regional impedance cardiographic device (NICaS, NI Medical, Peta Tikva, Israel) in 263 hemodialysis sessions in 54 patients in dialysis units in the USA and Brazil with the goal of determining the various hemodynamic trends as blood pressure decreases. Hypotensive episodes occurred in 99 (13.5%) of 736 intra- and postdialytic evaluations. The hemodynamic profiles of the episodes were categorized: (i) The cardiac power index significantly decreased in 35% of episodes by 36%, from 0.66 [95% confidence interval (CI) 0.60-0.72] to 0.43 (95% CI 0.37-0.48) [w/m2] with a small reduction in the total peripheral resistance index. (ii) The total peripheral resistance index significantly decreased in 37.4% of episodes by 33%, from 3342 (95% CI 2824-3859) to 2251 (95% CI 1900-2602) [dyn × s/cm5 × m2] with a small reduction in the cardiac power index. (iii) Both the cardiac power index and total peripheral resistance index significantly decreased in 27.3% of episodes, the cardiac power index by 25% from 0.63 (95% CI 0.57-0.70) to 0.48 (95% CI 0.42-0.53) [w/m2] and the total peripheral resistance index by 23% from 2964 (95% CI 2428-3501) to 2266 (95% CI 1891-2642). The hemodynamic profiles clearly define specific hemodynamic mechanisms of cardiac power reduction and/or vasodilatation as underlying intradialytic hypotensive episodes. A reduction in cardiac power (reduction of both blood pressure and cardiac output) could be the result of preload reduction due to a high ultrafiltration rate with not enough refilling or low target weight. A reduction in peripheral resistance (reduction in blood pressure and increase in cardiac output) could be the result of relative vasodilatation as arteries do not contract to compensate for volume reduction due to autonomous dysfunction. As both phenomena are independent, they may appear at the same time. Based on these results, a reduction of ultrafiltration rate and an increase in target weight to improve preload or immediate therapeutic actions to increase peripheral resistance are rational measures that could be taken to maintain blood pressure and prevent hypotensive ischemic complications in dialysis patients.

High-Intensity Interval Training Increases Cardiac Output and V˙O2max.

PubMed

Astorino, Todd A; Edmunds, Ross M; Clark, Amy; King, Leesa; Gallant, Rachael A; Namm, Samantha; Fischer, Anthony; Wood, Kimi M

2017-02-01

Increases in maximal oxygen uptake (V˙O2max) frequently occur with high-intensity interval training (HIIT), yet the specific adaptation explaining this result remains elusive. This study examined changes in V˙O2max and cardiac output (CO) in response to periodized HIIT. Thirty-nine active men and women (mean age and V˙O2max = 22.9 ± 5.4 yr and 39.6 ± 5.6 mL·kg·min) performed HIIT and 32 men and women (age and V˙O2max = 25.7 ± 4.5 yr and 40.7 ± 5.2 mL·kg·min) were nonexercising controls (CON). The first 10 sessions of HIIT required eight to ten 60 s bouts of cycling at 90%-110% percent peak power output interspersed with 75 s recovery, followed by randomization to one of three regimes (sprint interval training (SIT), high-volume interval training (HIITHI), or periodized interval training (PER) for the subsequent 10 sessions. Before, midway, and at the end of training, progressive cycling to exhaustion was completed during which V˙O2max and maximal CO were estimated. Compared with CON, significant (P < 0.001) increases in V˙O2max in HIIT + SIT (39.8 ± 7.3 mL·kg·min to 43.6 ± 6.1 mL·kg·min), HIIT + HIITHI (41.1 ± 4.9 mL·kg·min to 44.6 ± 7.0 mL·kg·min), and HIIT + PER (39.5 ± 5.6 mL·kg·min to 44.1 ± 5.4 mL·kg·min) occurred which were mediated by significant increases in maximal CO (20.0 ± 3.1 L·min to 21.7 ± 3.2 L·min, P = 0.04). Maximal stroke volume was increased with HIIT (P = 0.04), although there was no change in maximal HR (P = 0.88) or arteriovenous O2 difference (P = 0.36). These CO data are accurate and represent the mean changes from pre- to post-HIIT across all three training groups. Increases in V˙O2max exhibited in response to different HIIT regimes are due to improvements in oxygen delivery.

Comparison of Minimally and More Invasive Methods of Determining Mixed Venous Oxygen Saturation.

PubMed

Smit, Marli; Levin, Andrew I; Coetzee, Johan F

2016-04-01

To investigate the accuracy of a minimally invasive, 2-step, lookup method for determining mixed venous oxygen saturation compared with conventional techniques. Single-center, prospective, nonrandomized, pilot study. Tertiary care hospital, university setting. Thirteen elective cardiac and vascular surgery patients. All participants received intra-arterial and pulmonary artery catheters. Minimally invasive oxygen consumption and cardiac output were measured using a metabolic module and lithium-calibrated arterial waveform analysis (LiDCO; LiDCO, London), respectively. For the minimally invasive method, Step 1 involved these minimally invasive measurements, and arterial oxygen content was entered into the Fick equation to calculate mixed venous oxygen content. Step 2 used an oxyhemoglobin curve spreadsheet to look up mixed venous oxygen saturation from the calculated mixed venous oxygen content. The conventional "invasive" technique used pulmonary artery intermittent thermodilution cardiac output, direct sampling of mixed venous and arterial blood, and the "reverse-Fick" method of calculating oxygen consumption. LiDCO overestimated thermodilution cardiac output by 26%. Pulmonary artery catheter-derived oxygen consumption underestimated metabolic module measurements by 27%. Mixed venous oxygen saturation differed between techniques; the calculated values underestimated the direct measurements by between 12% to 26.3%, this difference being statistically significant. The magnitude of the differences between the minimally invasive and invasive techniques was too great for the former to act as a surrogate of the latter and could adversely affect clinical decision making. Copyright © 2016 Elsevier Inc. All rights reserved.

Changes in calcium uptake rate by rat cardiac mitochondria during postnatal development.

PubMed

Bassani, R A; Fagian, M M; Bassani, J W; Vercesi, A E

1998-10-01

Ca2+ uptake, transmembrane electrical potential (Deltapsim) and oxygen consumption were measured in isolated ventricular mitochondria of rats from 3 days to 5 months of age. Estimated values of ruthenium red-sensitive, succinate-supported maximal rate of Ca2+ uptake (Vmax, expressed as nmol Ca2+/min/mg protein) were higher in neonates and gradually fell during postnatal development (from 435+/-24 at 3-6 days, to 156+/-10 in adults,P<0.001), whereas K0.5 values (approximately 10 microM were not significantly affected by age. Under similar conditions, mitochondria from adults (5 months old) and neonates (4-6 days old) showed comparable state 4 (succinate and alpha-ketoglutarate as substrates) and state 3ADP (alpha-ketoglutarate-supported) respiration rates, as well as Deltapsim values (approximately-150 mV). Respiration-independent Deltapsim and Ca2+ uptake, supported by valinomycin-induced K+ efflux were also investigated at these ages. A transient Deltapsim (approximately -30 mV) was evoked by valinomycin in both neonatal and adult mitochondria. Respiration-independent Ca2+ uptake was also transient, but its initial rate was significantly higher in neonates than in adults (49. 4+/-10.0v 28.0+/-5.7 mmol Ca2+/min/mg protein,P<0.01). These results indicate that Ca2+ uptake capacity of rat cardiac mitochondria is remarkably high just after birth and declines over the first weeks of postnatal life, without change in apparent affinity of the transporter. Increased mitochondrial Ca2+ uptake rate in neonates appears to be related to the uniporter itself, rather than to modification of the driving force of the transport. Copyright 1998 Academic Press

Fluid balance, glomerular filtration rate, and urine output in dogs anesthetized for an orthopedic surgical procedure.

PubMed

Boscan, Pedro; Pypendop, Bruno H; Siao, Kristine T; Francey, Thierry; Dowers, Kristy; Cowgill, Larry; Ilkiw, Jan E

2010-05-01

To determine fluid retention, glomerular filtration rate, and urine output in dogs anesthetized for a surgical orthopedic procedure. 23 dogs treated with a tibial plateau leveling osteotomy. 12 dogs were used as a control group. Cardiac output was measured in 5 dogs, and 6 dogs received carprofen for at least 14 days. Dogs received oxymorphone, atropine, propofol, and isoflurane for anesthesia (duration, 4 hours). Urine and blood samples were obtained for analysis every 30 minutes. Lactated Ringer's solution was administered at 10 mL/kg/h. Urine output was measured and glomerular filtration rate was estimated. Fluid retention was measured by use of body weight, fluid balance, and bioimpedance spectroscopy. No difference was found among control, cardiac output, or carprofen groups, so data were combined. Median urine output and glomerular filtration rate were 0.46 mL/kg/h and 1.84 mL/kg/min. Dogs retained a large amount of fluids during anesthesia, as indicated by increased body weight, positive fluid balance, increased total body water volume, and increased extracellular fluid volume. The PCV, total protein concentration, and esophageal temperature decreased in a linear manner. Dogs anesthetized for a tibial plateau leveling osteotomy retained a large amount of fluids, had low urinary output, and had decreased PCV, total protein concentration, and esophageal temperature. Evaluation of urine output alone in anesthetized dogs may not be an adequate indicator of fluid balance.

Oral theophylline in chronic heart failure

PubMed Central

Al-Damluji, S.; Johnston, A.; Spurrell, R. A. J.; Nathan, A. W.; Banim, S. O.; Camm, A. J.

1982-01-01

Theophylline choline 600 mg was given as a single oral dose to nine patients in chronic left ventricular failure due to myocardial dysfunction. Cardiac output, left ventricular filling pressure (LVFP) and right atrial pressure (RAP) were measured with a pulmonary artery thermodilution catheter for the following 3 hr. Continuous recordings of cardiac rhythm were made throughout the study. Mean cardiac index increased from 1·75 (±0·14 s.e. mean) to 2·04 (±0·11) 1/min/m2 (P<0·02), mean LVFP fell from 27 (±2·4) to 22 (±1·5) mmHg (P<0·01), mean RAP fell from 5 (±1·3) to 3 (±2·0) mmHg (P<0·05) and mean systemic arterial pressure rose from 80 (±3) to 86 (±3·5) mmHg (P<0·05). There were no significant changes in heart rate or systemic vascular resistance; thus the increase in cardiac output was probably due to a positive inotropic effect. Side effects were seen in two patients, both of whom proved to have toxic plasma theophylline concentrations. This study demonstrated a beneficial acute haemodynamic effect of oral theophylline in chronic cardiac failure. PMID:7111101

In Vivo Self-Powered Wireless Cardiac Monitoring via Implantable Triboelectric Nanogenerator.

PubMed

Zheng, Qiang; Zhang, Hao; Shi, Bojing; Xue, Xiang; Liu, Zhuo; Jin, Yiming; Ma, Ye; Zou, Yang; Wang, Xinxin; An, Zhao; Tang, Wei; Zhang, Wei; Yang, Fan; Liu, Yang; Lang, Xilong; Xu, Zhiyun; Li, Zhou; Wang, Zhong Lin

2016-07-26

Harvesting biomechanical energy in vivo is an important route in obtaining sustainable electric energy for powering implantable medical devices. Here, we demonstrate an innovative implantable triboelectric nanogenerator (iTENG) for in vivo biomechanical energy harvesting. Driven by the heartbeat of adult swine, the output voltage and the corresponding current were improved by factors of 3.5 and 25, respectively, compared with the reported in vivo output performance of biomechanical energy conversion devices. In addition, the in vivo evaluation of the iTENG was demonstrated for over 72 h of implantation, during which the iTENG generated electricity continuously in the active animal. Due to its excellent in vivo performance, a self-powered wireless transmission system was fabricated for real-time wireless cardiac monitoring. Given its outstanding in vivo output and stability, iTENG can be applied not only to power implantable medical devices but also possibly to fabricate a self-powered, wireless healthcare monitoring system.

Videodensitometric Methods for Cardiac Output Measurements

NASA Astrophysics Data System (ADS)

Mischi, Massimo; Kalker, Ton; Korsten, Erik

2003-12-01

Cardiac output is often measured by indicator dilution techniques, usually based on dye or cold saline injections. Developments of more stable ultrasound contrast agents (UCA) are leading to new noninvasive indicator dilution methods. However, several problems concerning the interpretation of dilution curves as detected by ultrasound transducers have arisen. This paper presents a method for blood flow measurements based on UCA dilution. Dilution curves are determined by real-time densitometric analysis of the video output of an ultrasound scanner and are automatically fitted by the Local Density Random Walk model. A new fitting algorithm based on multiple linear regression is developed. Calibration, that is, the relation between videodensity and UCA concentration, is modelled by in vitro experimentation. The flow measurement system is validated by in vitro perfusion of SonoVue contrast agent. The results show an accurate dilution curve fit and flow estimation with determination coefficient larger than 0.95 and 0.99, respectively.

Pharmacological interference with 123I-metaiodobenzylguanidine: a limitation to developing cardiac innervation imaging in clinical practice?

PubMed

Stefanelli, A; Treglia, G; Bruno, I; Rufini, V; Giordano, A

2013-05-01

(123)I-metaiodo-benzylguanidine (MIBG) scintigraphy is considered a valid imaging test to evaluate the cardiac sympathetic nervous system. However, scientific literature showed that some drugs are able to or are expected to interfere with MIBG uptake. Thirty years after introduction of the method and over 15 years since the appearance of the first document on pharmacological interference with MIBG, an update on this issue has become necessary. The aims of this review paper are: (1) to identify the pharmacological basis of interference of a variety of substances with MIBG uptake; and (2) to update the list of drugs that definitely interfere with MIBG on the grounds of evidence in the literature. A MEDLINE search was conducted. Scientific studies, case report and review articles were collected. Papers published demonstrating drugs interfering with MIBG uptake were evaluated. Drugs may interact with MIBG uptake by 5 mechanism: (1) type-1 uptake inhibition; (2) inhibition of active transport to vesicles; (3) competition in transport to vesicles; (4) depletion of neurosecretory vesicle content; (5) calcium-mediated mechanism. We find that drugs like cocaine, antidepressants, some antipsychotic, tramadol, labetalol, sympatho-mimetics, reserpine and some calcium antagonists (as diltiazem, verapamil and nifedipine) do interfere with MIBG uptake. On the other hand, we find that controversial data are available on scientific literature regarding digoxin and amiodarone. A compiled statement of MIBG interfering medicines is now recommended to help nuclear medicine physicians in clinical practice to avoid potential pitfalls and improve the efficacy of (123)I-MIBG scintigraphy as a diagnostic tool.

Validation of an ultrasound dilution technology for cardiac output measurement and shunt detection in infants and children.

PubMed

Lindberg, Lars; Johansson, Sune; Perez-de-Sa, Valeria

2014-02-01

To validate cardiac output measurements by ultrasound dilution technology (COstatus monitor) against those obtained by a transit-time ultrasound technology with a perivascular flow probe and to investigate ultrasound dilution ability to estimate pulmonary to systemic blood flow ratio in children. Prospective observational clinical trial. Pediatric cardiac operating theater in a university hospital. In 21 children (6.1 ± 2.6 kg, mean ± SD) undergoing heart surgery, cardiac output was simultaneously recorded by ultrasound dilution (extracorporeal arteriovenous loop connected to existing arterial and central venous catheters) and a transit-time ultrasound probe applied to the ascending aorta, and when possible, the main pulmonary artery. The pulmonary to systemic blood flow ratio estimated from ultrasound dilution curve analysis was compared with that estimated from transit-time ultrasound technology. Bland-Altman analysis of the whole cohort (90 pairs, before and after surgery) showed a bias between transit-time ultrasound (1.01 ± 0.47 L/min) and ultrasound dilution technology (1.03 ± 0.51 L/min) of -0.02 L/min, limits of agreement -0.3 to 0.3 L/min, and percentage error of 31%. In children with no residual shunts, the bias was -0.04 L/min, limits of agreement -0.28 to 0.2 L/min, and percentage error 19%. The pooled co efficient of variation was for the whole cohort 3.5% (transit-time ultrasound) and 6.3% (ultrasound dilution), and in children without shunt, it was 2.9% (transit-time ultrasound) and 4% (ultrasound dilution), respectively. Ultrasound dilution identified the presence of shunts (pulmonary to systemic blood flow ≠ 1) with a sensitivity of 100% and a specificity of 92%. Mean pulmonary to systemic blood flow ratio by transit-time ultrasound was 2.6 ± 1.0 and by ultrasound dilution 2.2 ± 0.7 (not significant). The COstatus monitor is a reliable technique to measure cardiac output in children with high sensitivity and specificity for detecting the presence of shunts.

Effect of Different Formulations of Magnesium Chloride Used As Anesthetic Agents on the Performance of the Isolated Heart of Octopus vulgaris.

PubMed

Pugliese, Chiara; Mazza, Rosa; Andrews, Paul L R; Cerra, Maria C; Fiorito, Graziano; Gattuso, Alfonsina

2016-01-01

Magnesium chloride (MgCl 2 ) is commonly used as a general anesthetic in cephalopods, but its physiological effects including those at cardiac level are not well-characterized. We used an in vitro isolated perfused systemic heart preparation from the common octopus, Octopus vulgaris , to investigate: (a) if in vivo exposure to MgCl 2 formulations had an effect on cardiac function in vitro and, if so, could this impact recovery and (b) direct effects of MgCl 2 formulations on cardiac function. In vitro hearts removed from animals exposed in vivo to 3.5% MgCl 2 in sea water (20 min) or to a mixture of MgCl 2 + ethanol (1.12/1%; 20 min) showed cardiac function (heart rate, stroke volume, cardiac output) comparable to hearts removed from animals killed under hypothermia. However, 3.5% MgCl 2 (1:1, sea water: distilled water, 20 min) produced a significant impairment of the Frank-Starling response as did 45 min exposure to the MgCl 2 + ethanol mixture. Perfusion of the isolated heart with MgCl 2 ± ethanol formulations produced a concentration-related bradycardia (and arrest), a decreased stroke volume and cardiac output indicating a direct effect on the heart. The cardiac effects of MgCl 2 are discussed in relation to the involvement of magnesium, sodium, chloride, and calcium ions, exposure time and osmolality of the formulations and the implications for the use of various formulations of MgCl 2 as anesthetics in octopus. Overall, provided that the in vivo exposure to 3.5% MgCl 2 in sea water or to a mixture of MgCl 2 + ethanol is limited to ~20 min, residual effects on cardiac function are unlikely to impact post-anesthetic recovery.

Translational neurocardiology: preclinical models and cardioneural integrative aspects

PubMed Central

Andresen, M. C.; Armour, J. A.; Billman, G. E.; Chen, P.‐S.; Foreman, R. D.; Herring, N.; O'Leary, D. S.; Sabbah, H. N.; Schultz, H. D.; Sunagawa, K.; Zucker, I. H.

2016-01-01

Abstract Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various ‘levels’ become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics. PMID:27098459

Connective tissue growth factor induces cardiac hypertrophy through Akt signaling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayata, Nozomi; Fujio, Yasushi; Yamamoto, Yasuhiro

2008-05-30

In the process of cardiac remodeling, connective tissue growth factor (CTGF/CCN2) is secreted from cardiac myocytes. Though CTGF is well known to promote fibroblast proliferation, its pathophysiological effects in cardiac myocytes remain to be elucidated. In this study, we examined the biological effects of CTGF in rat neonatal cardiomyocytes. Cardiac myocytes stimulated with full length CTGF and its C-terminal region peptide showed the increase in cell surface area. Similar to hypertrophic ligands for G-protein coupled receptors, such as endothelin-1, CTGF activated amino acid uptake; however, CTGF-induced hypertrophy is not associated with the increased expression of skeletal actin or BNP, analyzedmore » by Northern-blotting. CTGF treatment activated ERK1/2, p38 MAPK, JNK and Akt. The inhibition of Akt by transducing dominant-negative Akt abrogated CTGF-mediated increase in cell size, while the inhibition of MAP kinases did not affect the cardiac hypertrophy. These findings indicate that CTGF is a novel hypertrophic factor in cardiac myocytes.« less

Evidence for increased cardiac compliance during exposure to simulated microgravity

NASA Technical Reports Server (NTRS)

Koenig, S. C.; Convertino, V. A.; Fanton, J. W.; Reister, C. A.; Gaffney, F. A.; Ludwig, D. A.; Krotov, V. P.; Trambovetsky, E. V.; Latham, R. D.

1998-01-01

We measured hemodynamic responses during 4 days of head-down tilt (HDT) and during graded lower body negative pressure (LBNP) in invasively instrumented rhesus monkeys to test the hypotheses that exposure to simulated microgravity increases cardiac compliance and that decreased stroke volume, cardiac output, and orthostatic tolerance are associated with reduced left ventricular peak dP/dt. Six monkeys underwent two 4-day (96 h) experimental conditions separated by 9 days of ambulatory activities in a crossover counterbalance design: 1) continuous exposure to 10 degrees HDT and 2) approximately 12-14 h per day of 80 degrees head-up tilt and 10-12 h supine (control condition). Each animal underwent measurements of central venous pressure (CVP), left ventricular and aortic pressures, stroke volume, esophageal pressure (EsP), plasma volume, alpha1- and beta1-adrenergic responsiveness, and tolerance to LBNP. HDT induced a hypovolemic and hypoadrenergic state with reduced LBNP tolerance compared with the control condition. Decreased LBNP tolerance with HDT was associated with reduced stroke volume, cardiac output, and peak dP/dt. Compared with the control condition, a 34% reduction in CVP (P = 0.010) and no change in left ventricular end-diastolic area during HDT was associated with increased ventricular compliance (P = 0.0053). Increased cardiac compliance could not be explained by reduced intrathoracic pressure since EsP was unaltered by HDT. Our data provide the first direct evidence that increased cardiac compliance was associated with headward fluid shifts similar to those induced by exposure to spaceflight and that reduced orthostatic tolerance was associated with lower cardiac contractility.

The importance of biomass net uptake for a trace metal budget in a forest stand in north-eastern France.

PubMed

Gandois, L; Nicolas, M; VanderHeijden, G; Probst, A

2010-11-01

The trace metal (TM: Cd, Cu, Ni, Pb and Zn) budget (stocks and annual fluxes) was evaluated in a forest stand (silver fir, Abies alba Miller) in north-eastern France. Trace metal concentrations were measured in different tree compartments in order to assess TM partitioning and dynamics in the trees. Inputs included bulk deposition, estimated dry deposition and weathering. Outputs were leaching and biomass exportation. Atmospheric deposition was the main input flux. The estimated dry deposition accounted for about 40% of the total trace metal deposition. The relative importance of leaching (estimated by a lumped parameter water balance model, BILJOU) and net biomass uptake (harvesting) for ecosystem exportation depended on the element. Trace metal distribution between tree compartments (stem wood and bark, branches and needles) indicated that Pb was mainly stored in the stem, whereas Zn and Ni, and to a lesser extent Cd and Cu, were translocated to aerial parts of the trees and cycled in the ecosystem. For Zn and Ni, leaching was the main output flux (>95% of the total output) and the plot budget (input-output) was negative, whereas for Pb the biomass net exportation represented 60% of the outputs and the budget was balanced. Cadmium and Cu had intermediate behaviours, with 18% and 30% of the total output relative to biomass exportation, respectively, and the budgets were negative. The net uptake by biomass was particularly important for Pb budgets, less so for Cd and Cu and not very important for Zn and Ni in such forest stands. Copyright © 2010 Elsevier B.V. All rights reserved.

Prognostic value of cardiac power output to left ventricular mass in patients with left ventricular dysfunction and dobutamine stress echo negative by wall motion criteria.

PubMed

Cortigiani, Lauro; Sorbo, Simone; Miccoli, Mario; Scali, Maria Chiara; Simioniuc, Anca; Morrone, Doralisa; Bovenzi, Francesco; Marzilli, Mario; Dini, Frank Lloyd

2017-02-01

Cardiac power output to left ventricular mass (power/mass) is an index of myocardial efficiency reflecting the rate at which cardiac work is delivered with respect to the potential energy stored in the left ventricular mass. In the present study, we sought to investigate the capability of power/mass assessed at peak of dobutamine stress echocardiography to predict mortality in patients with ischaemic cardiomyopathy and no inducible ischaemia. One-hundred eleven patients (95 males; age 68 ± 10 years) with 35 ± 7% mean left ventricular ejection fraction and a dobutamine stress echocardiography (up to 40 µg/kg/min) negative by wall motion criteria formed the study population. Power/mass at peak stress was obtained as the product of a constant (K = 2.22 × 10 -1 ) with cardiac output and the mean arterial pressure divided by left ventricular mass to convert the units to W/100 g. Patients were followed up for a median of 29 months (inter-quartile range 16-72 months). All-cause mortality was the only accepted clinical end point. Mean peak-stress power/mass was 0.70 ± 0.31 W/100 g. During follow-up, 29 deaths (26%) were registered. With a receiver operating characteristic analysis, a peak-stress power/mass ≤0.50 W/100 g [area under curve 0.72 (95% CI 0.63; 0.80), sensitivity 59%, specificity 80%] was the best value for predicting mortality. Univariate prognostic indicators were age, male sex, peak-stress ejection fraction, peak-stress stroke volume, peak-stress cardiac output, peak-stress cardiac power output ≤1.48 W, and peak-stress power/mass ≤0.50 W/100 g. At multivariate analysis, age (HR 1.08, 95% CI 1.04; 1.14; P = 0.004) and peak-stress power/mass ≤0.50 W/100 g (HR 4.05, 95% CI 1.36; 12.00; P = 0.01) provided independent prognostic information. Three-year mortality was 14% in patients with peak-stress power/mass >0.50 W/100 g and 47% in those with peak-stress power/mass ≤0.50 W/100 g (log-rank 20.4; P < 0.0001). Power/mass assessed at peak of dobutamine stress echocardiography allows effective prognostication in patients with ischaemic cardiomyopathy and test result negative by wall motion criteria. In particular, a peak-stress power/mass ≤50 W/100 g is a strong and multivariable predictor of mortality. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Mammary blood flow regulation in the nursing rabbit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, M.; Creasy, R.K.

Cardiac output and mammary blood flow distribution prior to and after suckling were studied in 10 nursing rabbits by means of radionuclide-labeled microspheres. Suckling was followed by a 5.8% rise in cardiac output and a 20.4% rise in mammary blood flow. Determinations of intraglandular blood flow distribution have shown that there was a 43% increase in blood flow to the glands suckled from as compared to a 22.7% rise to the contralateral untouched glands and a 4.9% rise in the remainder of untouched glands. The conclusion is that a local mechanism may be involved in the regulation of mammary bloodmore » flow in the nursing rabbit.« less

Monitoring pulmonary function with superimposed pulmonary gas exchange curves from standard analyzers.

PubMed

Zar, Harvey A; Noe, Frances E; Szalados, James E; Goodrich, Michael D; Busby, Michael G

2002-01-01

A repetitive graphic display of the single breath pulmonary function can indicate changes in cardiac and pulmonary physiology brought on by clinical events. Parallel advances in computer technology and monitoring make real-time, single breath pulmonary function clinically practicable. We describe a system built from a commercially available airway gas monitor and off the shelf computer and data-acquisition hardware. Analog data for gas flow rate, O2, and CO2 concentrations are introduced into a computer through an analog-to-digital conversion board. Oxygen uptake (VO2) and carbon dioxide output (VCO2) are calculated for each breath. Inspired minus expired concentrations for O2 and CO2 are displayed simultaneously with the expired gas flow rate curve for each breath. Dead-space and alveolar ventilation are calculated for each breath and readily appreciated from the display. Graphs illustrating the function of the system are presented for the following clinical scenarios; upper airway obstruction, bronchospasm, bronchopleural fistula, pulmonary perfusion changes and inadequate oxygen delivery. This paper describes a real-time, single breath pulmonary monitoring system that displays three parameters graphed against time: expired flow rate, oxygen uptake and carbon dioxide production. This system allows for early and rapid recognition of treatable conditions that may lead to adverse events without any additional patient measurements or invasive procedures. Monitoring systems similar to the one described in this paper may lead to a higher level of patient safety without any additional patient risk.

Cardiac Output and Performance during a Marathon Race in Middle-Aged Recreational Runners

PubMed Central

Billat, Véronique L.; Petot, Hélène; Landrain, Morgan; Meilland, Renaud; Koralsztein, Jean Pierre; Mille-Hamard, Laurence

2012-01-01

Purpose. Despite the increasing popularity of marathon running, there are no data on the responses of stroke volume (SV) and cardiac output (CO) to exercise in this context. We sought to establish whether marathon performance is associated with the ability to sustain high fractional use of maximal SV and CO (i.e, cardiac endurance) and/or CO, per meter (i.e., cardiac cost). Methods. We measured the SV, heart rate (HR), CO, and running speed of 14 recreational runners in an incremental, maximal laboratory test and then during a real marathon race (mean performance: 3 hr 30 min ± 45 min). Results. Our data revealed that HR, SV and CO were all in a high but submaximal steady state during the marathon (87.0 ± 1.6%, 77.2 ± 2.6%, and 68.7 ± 2.8% of maximal values, respectively). Marathon performance was inversely correlated with an upward drift in the CO/speed ratio (mL of CO × m−1) (r = −0.65, P < 0.01) and positively correlated with the runner's ability to complete the race at a high percentage of the speed at maximal SV (r = 0.83, P < 0.0002). Conclusion. Our results showed that marathon performance is inversely correlated with cardiac cost and positively correlated with cardiac endurance. The CO response could be a benchmark for race performance in recreational marathon runners. PMID:22645458

Chronic fatigue syndrome: illness severity, sedentary lifestyle, blood volume and evidence of diminished cardiac function.

PubMed

Hurwitz, Barry E; Coryell, Virginia T; Parker, Meela; Martin, Pedro; Laperriere, Arthur; Klimas, Nancy G; Sfakianakis, George N; Bilsker, Martin S

2009-10-19

The study examined whether deficits in cardiac output and blood volume in a CFS (chronic fatigue syndrome) cohort were present and linked to illness severity and sedentary lifestyle. Follow-up analyses assessed whether differences in cardiac output levels between CFS and control groups were corrected by controlling for cardiac contractility and TBV (total blood volume). The 146 participants were subdivided into two CFS groups based on symptom severity data, severe (n=30) and non-severe (n=26), and two healthy non-CFS control groups based on physical activity, sedentary (n=58) and non-sedentary (n=32). Controls were matched to CFS participants using age, gender, ethnicity and body mass. Echocardiographic measures indicated that the severe CFS participants had 10.2% lower cardiac volume (i.e. stroke index and end-diastolic volume) and 25.1% lower contractility (velocity of circumferential shortening corrected by heart rate) than the control groups. Dual tag blood volume assessments indicated that the CFS groups had lower TBV, PV (plasma volume) and RBCV (red blood cell volume) than control groups. Of the CFS subjects with a TBV deficit (i.e. > or = 8% below ideal levels), the mean+/-S.D. percentage deficit in TBV, PV and RBCV were -15.4+/-4.0, -13.2+/-5.0 and -19.1+/-6.3% respectively. Lower cardiac volume levels in CFS were substantially corrected by controlling for prevailing TBV deficits, but were not affected by controlling for cardiac contractility levels. Analyses indicated that the TBV deficit explained 91-94% of the group differences in cardiac volume indices. Group differences in cardiac structure were offsetting and, hence, no differences emerged for left ventricular mass index. Therefore the findings indicate that lower cardiac volume levels, displayed primarily by subjects with severe CFS, were not linked to diminished cardiac contractility levels, but were probably a consequence of a co-morbid hypovolaemic condition. Further study is needed to address the extent to which the cardiac and blood volume alterations in CFS have physiological and clinical significance.

Design of a specialized computer for on-line monitoring of cardiac stroke volume

NASA Technical Reports Server (NTRS)

Webb, J. A., Jr.; Gebben, V. D.

1972-01-01

The design of a specialized analog computer for on-line determination of cardiac stroke volume by means of a modified version of the pressure pulse contour method is presented. The design consists of an analog circuit for computation and a timing circuit for detecting necessary events on the pressure waveform. Readouts of arterial pressures, systolic duration, heart rate, percent change in stroke volume, and percent change in cardiac output are provided for monitoring cardiac patients. Laboratory results showed that computational accuracy was within 3 percent, while animal experiments verified the operational capability of the computer. Patient safety considerations are also discussed.

Ga-67 citrate myocardial uptake in a patient with AIDS, toxoplasmosis, and myocarditis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Memel, D.S.; DeRogatis, A.J.; William, D.C.

1991-05-01

A 38-year-old man with AIDS presented with fever of unknown origin, splenomegaly, anemia, and thrombocytopenia. Admission laboratory data revealed a positive toxoplasmosis titer in the blood. The initial chest x-ray showed small bilateral pleural effusions, a normal cardiac silhouette, no infiltrates, and no interstitial edema. Ga-67 imaging revealed markedly abnormal uptake in the myocardium. A diagnosis of toxoplasmosis myocarditis was made based on laboratory and imaging data. The patient was treated for toxoplasmosis. No myocardial uptake of tracer was demonstrated on a follow-up Ga-67 scan, performed after completion of treatment for toxoplasmosis.

The role of hemoglobin oxygen affinity in oxygen transport at high altitude.

PubMed

Winslow, Robert M

2007-09-30

Hemoglobin is involved in the regulation of O(2) transport in two ways: a long-term adjustment in red cell mass is mediated by erythropoietin (EPO), a response to renal oxgyenation. Short-term, rapid-response adjustments are mediated by ventilation, cardiac output, hemoglobin oxygen affinity (P50), barriers to O(2) diffusion, and the control of local microvascular tissue perfusion. The distribution of O(2) between dissolved (PO2) and hemoglobin-bound (saturation) is the familiar oxygen equilibrium curve, whose position is noted as P50. Human hemoglobin is not genetically adapted for function at high altitude. However, more specialized species native to high altitudes (guinea pig and bar-headed goose, for example) seem to have a lower P50 than their sea level counterparts, an adaptation that presumably promotes O(2) uptake from a hypoxic environment. Humans, native to very high altitude either in the Andes or Himalayan mountains, also can increase O(2) affinity, not because of a fundamental difference in hemoglobin structure or function, but because of extreme hyperventilation and alkalosis.

Increases in intramuscular pressure raise arterial blood pressure during dynamic exercise

NASA Technical Reports Server (NTRS)

Gallagher, K. M.; Fadel, P. J.; Smith, S. A.; Norton, K. H.; Querry, R. G.; Olivencia-Yurvati, A.; Raven, P. B.

2001-01-01

This investigation was designed to determine the role of intramuscular pressure-sensitive mechanoreceptors and chemically sensitive metaboreceptors in affecting the blood pressure response to dynamic exercise in humans. Sixteen subjects performed incremental (20 W/min) cycle exercise to fatigue under four conditions: control, exercise with thigh cuff occlusion of 90 Torr (Cuff occlusion), exercise with lower body positive pressure (LBPP) of 45 Torr, and a combination of thigh cuff occlusion and LBPP (combination). Indexes of central command (heart rate, oxygen uptake, ratings of perceived exertion, and electromyographic activity), cardiac output, stroke volume, and total peripheral resistance were not significantly different between the four conditions. Mechanical stimulation during LBPP and combination conditions resulted in significant elevations in intramuscular pressure and mean arterial pressure from control at rest and throughout the incremental exercise protocol (P < 0.05). Conversely, there existed no significant changes in mean arterial pressure when the metaboreflex was stimulated by cuff occlusion. These findings suggest that under normal conditions the mechanoreflex is tonically active and is the primary mediator of exercise pressor reflex-induced alterations in arterial blood pressure during submaximal dynamic exercise in humans.

Anaemia only causes a small reduction in the upper critical temperature of sea bass: is oxygen delivery the limiting factor for tolerance of acute warming in fishes?

PubMed

Wang, Tobias; Lefevre, Sjannie; Iversen, Nina K; Findorf, Inge; Buchanan, Rasmus; McKenzie, David J

2014-12-15

To address how the capacity for oxygen transport influences tolerance of acute warming in fishes, we investigated whether a reduction in haematocrit, by means of intra-peritoneal injection of the haemolytic agent phenylhydrazine, lowered the upper critical temperature of sea bass. A reduction in haematocrit from 42±2% to 20±3% (mean ± s.e.m.) caused a significant but minor reduction in upper critical temperature, from 35.8±0.1 to 35.1±0.2°C, with no correlation between individual values for haematocrit and upper thermal limit. Anaemia did not influence the rise in oxygen uptake between 25 and 33°C, because the anaemic fish were able to compensate for reduced blood oxygen carrying capacity with a significant increase in cardiac output. Therefore, in sea bass the upper critical temperature, at which they lost equilibrium, was not determined by an inability of the cardio-respiratory system to meet the thermal acceleration of metabolic demands. © 2014. Published by The Company of Biologists Ltd.

Late response to whole-lung irradiation alone and with whole-body hyperthermia in dogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gillette, S.M.; Gillette, E.L.; Dawson, C.A.

1997-02-01

The late effects of whole-lung irradiation with and without whole-body hyperthermia were studied in beagle dogs. The reference doses ranged from 18 to 49.5 Gy given in 1.5-Gy fractions over 6 weeks. Whole-body hyperthermia was given in three 2-h treatments to a deep rectal temperature of 42.0{degrees}C. Radiation was given simultaneously with hyperthermia on those days. Physiological and histopathological responses were evaluated. Physiological changes included decreases in cardiac output, systemic blood pressure, dynamic compliance and serotonin uptake. Early changes included an increase in extravascular water and total protein in the lavage. These changes were considered mild, were compensated for andmore » occurred only in dogs receiving doses of 40.5 Gy or greater given in 1.5-Gy fractions over 6 weeks. Histopathological change were typical of irradiated lung and included pleural fibrosis, interstitial fibrosis, fibrotic foci, and peribronchial and perivascular fibrosis. There was no enhancement of late injury to lung by hyperthermia seen in this study. 17 refs., 3 figs., 2 tabs.« less

[Clinical exercise testing and the Fick equation: strategic thinking for optimizing diagnosis].

PubMed

Perrault, H; Richard, R

2012-04-01

This article examines the expected exercise-induced changes in the components of the oxygen transport system as described by the Fick equation with a view to enable a critical analysis of a standard incremental exercise test to identify normal and abnormal patterns of responses and generate hypotheses as to potential physiological and/or pathophysiological causes. The text reviews basic physiological principals and provides useful reminders of standard equations that serve to integrate circulatory, respiratory and skeletal muscle functions. More specifically, the article provides a conceptual and quantitative framework linking the exercise-induced increase in whole body oxygen uptake to central circulatory and peripheral circulatory factors with the view to establish the normalcy of response. Thus, the article reviews the exercise response to cardiac output determinants and provides qualitative and quantitative perspective bases for making assumptions on the peripheral circulatory factors and oxygen use. Finally, the article demonstrates the usefulness of exercise testing as an effective integrative physiological approach to develop clinical reasoning or verify pathophysiological outcomes. Copyright © 2012 SPLF. Published by Elsevier Masson SAS. All rights reserved.

The Association Between Urine Output, Creatinine Elevation, and Death.

PubMed

Engoren, Milo; Maile, Michael D; Heung, Michael; Jewell, Elizabeth S; Vahabzadeh, Christie; Haft, Jonathan W; Kheterpal, Sachin

2017-04-01

Acute kidney injury can be defined by a fall in urine output, and urine output criteria may be more sensitive in identifying acute kidney injury than traditional serum creatinine criteria. However, as pointed out in the Kidney Disease Improving Global Outcome guidelines, the association of urine output with subsequent creatinine elevations and death is poorly characterized. The purpose of this study was to determine what degrees of reduced urine output are associated with subsequent creatinine elevation and death. This was a retrospective cohort study of adult patients (age ≥18 years) cared for in a cardiovascular intensive care unit after undergoing cardiac operations in a tertiary care university medical center. All adult patients who underwent cardiac operations and were not receiving dialysis preoperatively were studied. The development of acute kidney injury was defined as an increase in creatinine of more than 0.3 mg/dL or by more than 50% above baseline by postoperative day 3. Acute kidney injury developed in 1,061 of 4,195 patients (25%). Urine output had moderate discrimination in predicting subsequent acute kidney injury (C statistic = .637 ± .054). Lower urine output and longer duration of low urine output were associated with greater odds of developing acute kidney injury and death. We found that there is similar accuracy in using urine output corrected for actual, ideal, or adjusted weight to discriminate future acute kidney injury by creatinine elevation and recommend using actual weight for its simplicity. We also found that low urine output is associated with subsequent acute kidney injury and that the association is greater for lower urine output and for low urine output of longer durations. Low urine output (<0.2 mL · kg -1 · h -1 ), even in the absence of acute kidney injury by creatinine elevation, is independently associated with mortality. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

The dose effect of ephedrine on the onset time of vecuronium.

PubMed

Kim, Kyo S; Cheong, Mi A; Jeon, Jeong W; Lee, Jeong H; Shim, Jae C

2003-04-01

A small dose of ephedrine decreases the onset time of rocuronium and cisatracurium; however, ephedrine might be associated with adverse hemodynamic effects. The appropriate dose of ephedrine has not been determined. We, therefore, studied 120 patients anesthetized with fentanyl 2 microg/kg and propofol 2-2.5 mg/kg who were randomly divided to receive either ephedrine (30, 70, or 110 microg/kg) or saline. During propofol anesthesia, the neuromuscular block was monitored by mechanomyography by using submaximal current of train-of-four stimulation every 10 s. To determine cardiac output, a transcutaneous Doppler probe was placed externally at the suprasternal notch. Tracheal intubation was performed by a blinded investigator at 2 min after vecuronium. Neuromuscular block, intubating conditions, and hemodynamic effects were measured during the induction of anesthesia. Both ephedrine 70 and 110 microg/kg improved intubating conditions at 2 min after vecuronium; however, 110 microg/kg was associated with adverse hemodynamic effects. We conclude that ephedrine 70 microg/kg given before the induction of anesthesia improved intubating conditions at 2 min after vecuronium, probably by increased cardiac output without significant adverse hemodynamic effects. Ephedrine 70 microg/kg given before the induction of anesthesia improved tracheal intubating conditions at 2 min after vecuronium by increased cardiac output without significant adverse hemodynamic effects.

[Effect of a serotonin S2 receptor antagonist on portal hypertension due to cirrhosis. Preliminary results of a heart and liver hemodynamic study].

PubMed

Deflandre, J; Pirotte, J; Etienne, M; Carlier, J

1988-01-01

In 10 cirrhotic patients, with two balloon catheters introduced in the right internal jugular vein, the following parameters were measured before and after injection of ketanserine (0.1 mg/kg): cardiac output using the thermo-dilution method, free supra-hepatic pressure, wedged supra-hepatic pressure at rest and during cough, right atrial pressure, pulmonary capillary and arterial pressures. After 30 minutes, the following modifications were recorded: the cardiac output goes from 8.0 +/- 2.4 l/min to 8.7 +/- 2.5 l/min (p less than 0.05); the mean arterial pressure goes from 107.0 +/- 18.8 mmHg to 94.7 +/- 25.9 mmHg (p less than 0.02); the wedged supra-hepatic pressure, during coughing goes from 85.2 +/- 36.1 mmHg to 64.6 +/- 23.1 mmHg (p less than 0.005). As in non-cirrhotic patients, ketanserine causes a drop in the mean arterial pressure and a transient elevation of the cardiac output. Ketanserine is able to lower portal pressure of cirrhotic patients at rest as well as during coughing. These results seem to indicate that the activation of serotonin S2 receptors may play a role in determining the portal hypertension in cirrhotic patients.

The effects of hypoxemia on myocardial blood flow during exercise.

PubMed

Paridon, S M; Bricker, J T; Dreyer, W J; Reardon, M; Smith, E O; Porter, C B; Michael, L; Fisher, D J

1989-03-01

We evaluated the adequacy of regional and transmural blood flow during exercise and rapid pacing after 1 wk of hypoxemia. Seven mature mongrel dogs were made hypoxemic (mean O2 saturation = 72.4%) by anastomosis of left pulmonary artery to left atrial appendage. Catheters were placed in the left atrium, right atrium, pulmonary artery, and aorta. Atrial and ventricular pacing wires were placed. An aortic flow probe was placed to measure cardiac output. Ten nonshunted dogs, similarly instrumented, served as controls. Recovery time was approximately 1 wk. Cardiac output, mean aortic pressure, and oxygen saturation were measured at rest, with ventricular pacing, atrial pacing, and with treadmill exercise. Ventricular and atrial pace and exercise were at a heart rate of 200. Right ventricular free wall, left ventricular free wall, and septal blood flow were measured with radionuclide-labeled microspheres. Cardiac output, left atrial blood pressure, and aortic blood pressure were similar between the two groups of dogs in all testing states. Myocardial blood flow was significantly higher in the right and left ventricular free wall in the hypoxemic animals during resting and exercise testing states. Myocardial oxygen delivery was similar between the two groups of animals. Pacing resulted in an increase in myocardial blood flow in the control animals but not the hypoxemic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects on increasing cardiac output with adrenaline or isoprenaline on arterial haemoglobin oxygen saturation and shunt during one-lung ventilation.

PubMed

Russell, W J; James, M F

2000-12-01

Theoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial haemoglobin oxygen saturation (SaO2) should improve as the venous oxygen extraction per ml of blood decreases. To test this hypothesis, eight pigs were subjected to one-lung ventilation and adrenaline and isoprenaline infusions used to increase the cardiac output. The mixed venous oxygen, shunt fraction and oxygen consumption were measured. With both adrenaline and isoprenaline, although there was a small rise in mixed venous oxygen content, there was a fall in SaO2. With adrenaline, the mean shunt rose from 48% to 65%, the mean oxygen consumption rose from 126 ml/min to 134 ml/min and the mean SaO2 fell from 86.9% to 82.5%. With isoprenaline, the mean shunt rose from 45% to 59%, the mean oxygen consumption rose from 121 ml/min to 137 ml/min and the mean SaO2 fell from 89.5% to 84.7%. It is concluded that potential improvement in SaO2, which might occur from a catecholamine-induced increase in mixed venous oxygen content during one-lung ventilation, is more than offset by increased shunting and oxygen consumption which reduce SaO2.

Penetrating mine injury to the heart with a pericardial tamponade.

PubMed

Maye, J; Marshall, N E

1996-02-01

Cardiac tamponade is a life-threatening emergency. Immediate recognition and surgical intervention is essential to preserve myocardial function and maintain cardiac output. The following is a case report of a penetrating mine injury to the heart with a resulting pericardial tamponade. The positive outcome and the facilities in which the resuscitation and surgical repair occurred make this a unique case report.

The parasitic copepod Lernaeocera branchialis negatively affects cardiorespiratory function in Gadus morhua.

PubMed

Behrens, J W; Seth, H; Axelsson, M; Buchmann, K

2014-05-01

The parasitic copepod Lernaeocera branchialis had a negative effect on cardiorespiratory function in Atlantic cod Gadus morhua such that it caused pronounced cardiac dysfunction with irregular rhythm and reduced stroke amplitude compared with uninfected fish. In addition, parasite infection depressed the postprandial cardiac output and oxygen consumption. © 2014 The Fisheries Society of the British Isles.

Closed-chest cardiopulmonary bypass and cardioplegia: basis for less invasive cardiac surgery.

PubMed

Peters, W S; Siegel, L C; Stevens, J H; St Goar, F G; Pompili, M F; Burdon, T A

1997-06-01

We developed a method of closed-chest cardiopulmonary bypass to arrest and protect the heart with cardioplegic solution. This method was used in 54 dogs and the results were retrospectively analyzed. Bypass cannulas were placed in the right femoral vessels. A balloon occlusion catheter was passed via the left femoral artery and positioned in the ascending aorta. A pulmonary artery vent was placed via the jugular vein. In 17 of the dogs retrograde cardioplegia was provided with a percutaneous coronary sinus catheter. Cardiopulmonary bypass time was 111 +/- 27 minutes (mean +/- standard deviation) and cardiac arrest time was 66 +/- 21 minutes. Preoperative cardiac outputs were 2.9 +/- 0.70 L/min and postoperative outputs were 2.9 +/- 0.65 L/min (p = not significant). Twenty-one-French and 23F femoral arterial cannulas that allowed coaxial placement of the ascending aortic balloon catheter were tested in 3 male calves. Line pressures were higher, but not clinically limiting, with the balloon catheter placed coaxially. Adequate cardiopulmonary bypass and cardioplegia can be achieved in the dog without opening the chest, facilitating less invasive cardiac operations. A human clinical trial is in progress.

[The Contribution of Vascular Capacity and Blood Volume to Maintain Stable Blood Circulation during General Anesthesia].

PubMed

Shigemi, Kenji

2016-05-01

To maintain proper cardiac preload is one of the most effective procedures for the systemic circulation remaining stable. In particular, the balance between vascular capacity and total blood volume must be maintained within appropriate range by the administration of fluids, blood and/or vasoactive drugs with mean circulatory filling pressure (Pmcf), central venous pressure (CVP) or stroke volume variation (SVV). End-diastolic left ventricular volume (Ved) is theoretically the best index of cardiac preload; however, without transesophageal echocardbalanceiogram we cannot directly monitor Ved during anesthesia. The infused fluid volume remaining in intravascular space, the vascular capacity controlled by autonomic nervous system and/or vasoactive agents, and the unstressed blood volume properly mobilized to excess blood volume are the crucial factors to maintain cardiac output The knowledge of vascular physiology contribute the decision making to manipulate such factors to control blood circulation during general anesthesia. For example, CVP is usually maintained in the narrow range and seems to be stable; however, it must be changed just after the circulatory disturbances, such as acute bleeding, blood transfusion, and fluid infusion, and followed by gradual returning to initial value, because of the solid mechanism to preserve cardiac output

CardioNet: a human metabolic network suited for the study of cardiomyocyte metabolism.

PubMed

Karlstädt, Anja; Fliegner, Daniela; Kararigas, Georgios; Ruderisch, Hugo Sanchez; Regitz-Zagrosek, Vera; Holzhütter, Hermann-Georg

2012-08-29

Availability of oxygen and nutrients in the coronary circulation is a crucial determinant of cardiac performance. Nutrient composition of coronary blood may significantly vary in specific physiological and pathological conditions, for example, administration of special diets, long-term starvation, physical exercise or diabetes. Quantitative analysis of cardiac metabolism from a systems biology perspective may help to a better understanding of the relationship between nutrient supply and efficiency of metabolic processes required for an adequate cardiac output. Here we present CardioNet, the first large-scale reconstruction of the metabolic network of the human cardiomyocyte comprising 1793 metabolic reactions, including 560 transport processes in six compartments. We use flux-balance analysis to demonstrate the capability of the network to accomplish a set of 368 metabolic functions required for maintaining the structural and functional integrity of the cell. Taking the maintenance of ATP, biosynthesis of ceramide, cardiolipin and further important phospholipids as examples, we analyse how a changed supply of glucose, lactate, fatty acids and ketone bodies may influence the efficiency of these essential processes. CardioNet is a functionally validated metabolic network of the human cardiomyocyte that enables theorectical studies of cellular metabolic processes crucial for the accomplishment of an adequate cardiac output.

Traction force microscopy of engineered cardiac tissues.

PubMed

Pasqualini, Francesco Silvio; Agarwal, Ashutosh; O'Connor, Blakely Bussie; Liu, Qihan; Sheehy, Sean P; Parker, Kevin Kit

2018-01-01

Cardiac tissue development and pathology have been shown to depend sensitively on microenvironmental mechanical factors, such as extracellular matrix stiffness, in both in vivo and in vitro systems. We present a novel quantitative approach to assess cardiac structure and function by extending the classical traction force microscopy technique to tissue-level preparations. Using this system, we investigated the relationship between contractile proficiency and metabolism in neonate rat ventricular myocytes (NRVM) cultured on gels with stiffness mimicking soft immature (1 kPa), normal healthy (13 kPa), and stiff diseased (90 kPa) cardiac microenvironments. We found that tissues engineered on the softest gels generated the least amount of stress and had the smallest work output. Conversely, cardiomyocytes in tissues engineered on healthy- and disease-mimicking gels generated significantly higher stresses, with the maximal contractile work measured in NRVM engineered on gels of normal stiffness. Interestingly, although tissues on soft gels exhibited poor stress generation and work production, their basal metabolic respiration rate was significantly more elevated than in other groups, suggesting a highly ineffective coupling between energy production and contractile work output. Our novel platform can thus be utilized to quantitatively assess the mechanotransduction pathways that initiate tissue-level structural and functional remodeling in response to substrate stiffness.

Extracardiac 18F-florbetapir imaging in patients with systemic amyloidosis: more than hearts and minds.

PubMed

Wagner, T; Page, J; Burniston, M; Skillen, A; Ross, J C; Manwani, R; McCool, D; Hawkins, P N; Wechalekar, Ashutosh D

2018-07-01

18 F-Florbetapir has been reported to show cardiac uptake in patients with systemic light-chain amyloidosis (AL). This study systematically assessed uptake of 18 F-florbetapir in patients with proven systemic amyloidosis at sites outside the heart. Seventeen patients with proven cardiac amyloidosis underwent 18 F-florbetapir PET/CT imaging, 15 with AL and 2 with transthyretin amyloidosis (ATTR). Three patients had repeat scans. All patients had protocolized assessment at the UK National Amyloidosis Centre including imaging with 123 I-serum amyloid P component (SAP). 18 F-Florbetapir images were assessed for areas of increased tracer accumulation and time-uptake curves in terms of standardized uptake values (SUV mean ) were produced. All 17 patients showed 18 F-florbetapir uptake at one or more extracardiac sites. Uptake was seen in the spleen in 6 patients (35%; 6 of 9, 67%, with splenic involvement on 123 I-SAP scintigraphy), in the fat in 11 (65%), in the tongue in 8 (47%), in the parotids in 8 (47%), in the masticatory muscles in 7 (41%), in the lungs in 3 (18%), and in the kidney in 2 (12%) on the late half-body images. The 18 F-florbetapir spleen retention index (SRI) was calculated. SRI >0.045 had 100% sensitivity/sensitivity (in relation to 123 I-SAP splenic uptake, the current standard) in detecting splenic amyloid on dynamic imaging and a sensitivity of 66.7% and a specificity of 100% on the late half-body images. Intense lung uptake was seen in three patients, one of whom had lung interstitial infiltration suggestive of amyloid deposition on previous high-resolution CT. Repeat imaging showed a stable appearance in all three patients suggesting no early impact of treatment response. 18 F-Florbetapir PET/CT is a promising tool for the detection of extracardiac sites of amyloid deposition. The combination of uptake in the heart and uptake in the spleen on 18 F-florbetapir PET/CT, a hallmark of AL, suggests that this tracer holds promise as a screening tool for AL.

A randomized study of the effects of exercise training on patients with atrial fibrillation.

PubMed

Osbak, Philip Samuel; Mourier, Malene; Kjaer, Andreas; Henriksen, Jens Henrik; Kofoed, Klaus Fuglsang; Jensen, Gorm Boje

2011-12-01

Exercise training is beneficial in ischemic and congestive heart disease. However, the effect on atrial fibrillation (AF) is unknown. Forty-nine patients with permanent AF (age [mean ± SD], 70.2 ± 7.8 years; male-to-female ratio, 0.75; body mass index [mean ± SD], 29.7 ± 4.3 kg/m(2)) were randomized to 12-week aerobic exercise training or a control group. Exercise capacity, 6-minute walk test (6MWT), cardiac output, quality of life, and natriuretic peptides were measured. Cardiac output was measured at rest and during ergometer testing, and atrial natriuretic peptide and N-terminal pro-B-type natriuretic peptide were measured before and after the training period. Quality of life was evaluated using the Short-Form 36 and Minnesota Living With Heart Failure (MLHF-Q) questionnaires. Improved exercise capacity and 6MWT were observed in the active patients (P < .001), and at study end, there was a significant difference between the active patients and the controls (P = .002). Resting pulse decreased in the active patients (94.8 ± 22.4 to 86.3 ± 22.5 beats/min, P = .049) but remained unchanged in the controls. Cardiac output was unchanged from baseline to end-of-study period. The MLHF-Q score improved in the active group (21.1 ± 18.0 vs 15.4 ± 17.5, P = .03). Active patients showed progress in 3 of the 8 Short-Form 36 subscales: physical functioning (P = .02), general health perceptions (P = .001), and vitality (P = .02). Natriuretic peptides were unchanged. Twelve weeks of exercise training increased exercise capacity and 6MWT and decreased resting pulse rate significantly in patients with AF. Overall quality of life increased significantly as measured by the cardiology-related MLHF-Q. Cardiac output and natriuretic peptides were unchanged in both groups. Copyright © 2011 Mosby, Inc. All rights reserved.

Continuous positive airway pressure (CPAP) decreases pulmonary shunt in anaesthetized horses.

PubMed

Mosing, Martina; MacFarlane, Paul; Bardell, David; Lüthi, Laura; Cripps, Peter J; Bettschart-Wolfensberger, Regula

2016-11-01

To evaluate the effects of continuous positive airway pressure (CPAP) on intrapulmonary shunt, cardiac output and oxygen delivery in horses subjected to a 6 hour period of general anaesthesia. Randomized, experimental, crossover study. Ten healthy adult horses. Following medetomidine, diazepam and ketamine administration, orotracheal intubation was performed and horses positioned in dorsal recumbency. Anaesthesia was maintained with isoflurane carried in an oxygen and air mix (FiO 2 0.5) combined with a medetomidine infusion. Horses were anaesthetized twice and either CPAP (8 cmH 2 O) or physiologic airway pressure (NO CPAP) was applied to the lungs for 6 hours; the order of treatments was randomly assigned. Following induction of anaesthesia, cardiovascular and respiratory variables (including arterial blood gas analysis) were recorded every 30 minutes, cardiac output was measured every 60 minutes using the lithium dilution technique and oxygen delivery calculated. If PaCO 2 exceeded 100 mmHg (13.3 kPa), controlled ventilation was initiated and horses excluded from further data collection. Groups were compared using a general linear model. Data from eight horses were analysed. PaO 2 was 15-56 mmHg (2.00-7.45 kPa) higher (p < 0.001) and shunt fraction 6-14% lower (p < 0.001) in the CPAP group. No differences were seen for cardiac output and oxygen delivery. The lack of difference in oxygen delivery was attributed to lower haemoglobin levels in the CPAP group than in the NO CPAP group. CPAP of 8 cmH 2 O can be used in dorsally recumbent horses to decrease pulmonary shunt fraction without causing a decrease in cardiac output during longterm anaesthesia. © 2016 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Translational neurocardiology: preclinical models and cardioneural integrative aspects.

PubMed

Ardell, J L; Andresen, M C; Armour, J A; Billman, G E; Chen, P-S; Foreman, R D; Herring, N; O'Leary, D S; Sabbah, H N; Schultz, H D; Sunagawa, K; Zucker, I H

2016-07-15

Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various 'levels' become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Significant decreases in blood propofol concentrations during adrenalectomy for phaeochromocytoma.

PubMed

Watanabe, Tatsunori; Hiraoka, Haruhiko; Araki, Takuya; Nagano, Daisuke; Aomori, Tohru; Nakamura, Tomonori; Yamamoto, Koujirou; Baba, Hiroshi

2017-10-01

The kinetics of propofol are influenced by cardiac output. The aim of this study was to examine changes in blood propofol concentrations during phaeochromocytoma surgery using target-controlled infusion (TCI) anaesthesia with propofol. This is a prospective observational study. Ten patients with phaeochromocytoma who underwent unilateral adrenalectomy were included. Cardiac output was measured using an arterial pressure-based cardiac output analysis method. The target blood propofol concentrations were adjusted to maintain an approximate bispectral index (BIS) value of 40 before initiating surgery. The settings remained constant during surgery. Blood samples for propofol concentrations were collected from the radial artery at seven time points: two before tumour manipulation (T1, 2), two during tumour manipulation (T3, 4), and three after tumour vein ligation (T4-7). BIS values, the arterial pressure cardiac index (APCI) and haemodynamic parameters were measured at the same time points as the blood samples. The prop-ratio was calculated by dividing blood propofol concentrations by target concentrations of TCI. APCI increased during tumour manipulation and after tumour vein ligation. The prop-ratio was reduced significantly by approximately 40% and showed a significant negative correlation with APCI. BIS values increased significantly and showed a significant negative correlation with the prop-ratio. The increased APCI during tumour manipulation and after tumour vein ligation was associated with markedly reduced blood propofol concentrations. These results reveal that significant decreases in the anaesthetic effect may be observed in patients undergoing phaeochromocytoma surgery even if TCI anaesthesia is used with propofol. © 2017 The British Pharmacological Society.

Non-Dimensional Formulation of Ventricular Work-Load Severity Under Concomitant Heart Valve Disease

NASA Astrophysics Data System (ADS)

Dong, Melody; Simon-Walker, Rachael; Dasi, Lakshmi

2012-11-01

Current guidelines on assessing the severity of heart valve disease rely on dimensional disease specific measures and are thus unable to capture severity under a concomitant heart valve disease scenario. Experiments were conducted to measure ventricular work-load in an in-house in-vitro left heart simulator. In-house tri-leaflet heart valves were built and parameterized to model concomitant heart valve disease. Measured ventricular power varied non-linearly with cardiac output and mean aortic pressure. Significant data collapse could be achieved by the non-dimensionalization of ventricular power with cardiac output, fluid density, and a length scale. The dimensionless power, Circulation Energy Dissipation Index (CEDI), indicates that concomitant conditions require a significant increase in the amount of work needed to sustain cardiac function. It predicts severity without the need to quantify individual disease severities. This indicates the need for new fluid-dynamics similitude based clinical guidelines to assist patients with multiple heart valve diseases. Funded by the American Heart Association.

Successful treatment of inverted Takotsubo cardiomyopathy after severe traumatic brain injury with milrinone after dobutamine failure.

PubMed

Mrozek, Ségolène; Srairi, Mohamed; Marhar, Fouad; Delmas, Clément; Gaussiat, François; Abaziou, Timothée; Larcher, Claire; Atthar, Vincent; Menut, Rémi; Fourcade, Olivier; Geeraerts, Thomas

2016-01-01

Takotsubo cardiomyopathy can occur at the early phase of severe acute brain injuries. In the case of cardiac output decrease or shock, the optimal treatment is still a matter of debate. Due to massive stress hormone release, the infusion of catecholamines may have limited effects and may even aggravate cardiac failure. Other inotropic agents may be an option. Levosimendan has been shown to have potential beneficial effects in this setting, although milrinone has not been studied. We report a case of a young female presenting with inverted Takotsubo cardiomyopathy syndrome after severe traumatic brain injury. Due to hemodynamic instability and increasing levels of infused norepinephrine, dobutamine infusion was begun but rapidly stopped due to tachyarrhythmia. Milrinone infusion stabilized the patient's hemodynamic status and improved cardiac output without deleterious effects. Milrinone could be a good alternative when inotropes are required in Takotsubo cardiomyopathy and when dobutamine infusion is associated with tachyarrhythmia. Copyright © 2016 Elsevier Inc. All rights reserved.

Length dependence of force generation exhibit similarities between rat cardiac myocytes and skeletal muscle fibres.

PubMed

Hanft, Laurin M; McDonald, Kerry S

2010-08-01

According to the Frank-Starling relationship, increased ventricular volume increases cardiac output, which helps match cardiac output to peripheral circulatory demand. The cellular basis for this relationship is in large part the myofilament length-tension relationship. Length-tension relationships in maximally calcium activated preparations are relatively shallow and similar between cardiac myocytes and skeletal muscle fibres. During twitch activations length-tension relationships become steeper in both cardiac and skeletal muscle; however, it remains unclear whether length dependence of tension differs between striated muscle cell types during submaximal activations. The purpose of this study was to compare sarcomere length-tension relationships and the sarcomere length dependence of force development between rat skinned left ventricular cardiac myocytes and fast-twitch and slow-twitch skeletal muscle fibres. Muscle cell preparations were calcium activated to yield 50% maximal force, after which isometric force and rate constants (k(tr)) of force development were measured over a range of sarcomere lengths. Myofilament length-tension relationships were considerably steeper in fast-twitch fibres compared to slow-twitch fibres. Interestingly, cardiac myocyte preparations exhibited two populations of length-tension relationships, one steeper than fast-twitch fibres and the other similar to slow-twitch fibres. Moreover, myocytes with shallow length-tension relationships were converted to steeper length-tension relationships by protein kinase A (PKA)-induced myofilament phosphorylation. Sarcomere length-k(tr) relationships were distinct between all three cell types and exhibited patterns markedly different from Ca(2+) activation-dependent k(tr) relationships. Overall, these findings indicate cardiac myocytes exhibit varied length-tension relationships and sarcomere length appears a dominant modulator of force development rates. Importantly, cardiac myocyte length-tension relationships appear able to switch between slow-twitch-like and fast-twitch-like by PKA-mediated myofibrillar phosphorylation, which implicates a novel means for controlling Frank-Starling relationships.

Equine Cardiovascular Therapeutics.

PubMed

Sleeper, Meg M

2017-04-01

Heart disease can be defined as any abnormality of the heart whether it is a cardiac dysrhythmia or structural heart disease, either congenital or acquired. Heart failure occurs when a cardiac abnormality results in the inability of the heart to pump enough blood to meet the body's needs. Heart disease can be present without leading to heart failure. Heart failure, however, is a consequence of heart disease. There are 4 main areas where the clinician can intervene to improve cardiac output with heart failure: preload, afterload, myocardial contractility, and heart rate. Copyright © 2016 Elsevier Inc. All rights reserved.

Assessment of hemodynamic load components affecting optimization of cardiac resynchronization therapy by lumped parameter mode.

PubMed

Xu, Ke; Butlin, Mark; Avolio, Alberto P

2012-01-01

Timing of biventricular pacing devices employed in cardiac resynchronization therapy (CRT) is a critical determinant of efficacy of the procedure. Optimization is done by maximizing function in terms of arterial pressure (BP) or cardiac output (CO). However, BP and CO are also determined by the hemodynamic load of the pulmonary and systemic vasculature. This study aims to use a lumped parameter circulatory model to assess the influence of the arterial load on the atrio-ventricular (AV) and inter-ventricular (VV) delay for optimal CRT performance.

[Remote results of plastic operations on the tricuspid valve in patients with cardiac insufficiency at terminal stage].

PubMed

Habriielian, A V; Smorzhevs'kyĭ, V I; Onishchenko, V F; Beleĭovych, V V; Topchu, Ie I; Domans'kyĭ, T M; Myroniuk, O I

2011-07-01

Comparative analysis of the results of plastic operations performance on a tricuspid valve (TV) in patients, suffering cardiac insufficiency in terminal stage, was conducted. In late postoperative period the indices of intracardial hemodynamics (cardiac output fraction, regurgitation on TV) and clinical features (severity of symptoms, quality of life) after plastic operations, using a support ring, have differed significantly from those after performance of a sutured plasty. The valve function during five years was secured in 91.1% of patients.

Is the 6-minute walk test a reliable substitute for peak oxygen uptake in patients with dilated cardiomyopathy?

PubMed

Zugck, C; Krüger, C; Dürr, S; Gerber, S H; Haunstetter, A; Hornig, K; Kübler, W; Haass, M

2000-04-01

The 6-min walk test may serve as a more simple clinical tool to assess functional capacity in congestive heart failure than determination of peak oxygen uptake by cardiopulmonary exercise testing. The purpose of the study was to prospectively examine whether the distance ambulated during a 6-min walk test (i) correlates with peak oxygen uptake, (ii) allows peak oxygen uptake to be predicted, and (iii) provides prognostic information similar to peak oxygen uptake in patients with dilated cardiomyopathy and left ventricular ejection fraction < or = 35%. In 113 patients (age: 54+/-12 years, NYHA: 2.2+/-0.8) with dilated cardiomyopathy (left ventricular ejection fraction 19+/-7%) a 6-min walk test and cardiopulmonary exercise testing were performed. The 6-min walk test and peak oxygen uptake were closely correlated at the initial visit (r=0.68, n=113), as well as after 263+/-114 (r=0.71, n=28) and 381+/-170 days (r=0.74, n=14). During serial exercise testing the 6-min walk test allowed peak oxygen uptake to be reliably predicted (r=0.76 between calculated and real peak oxygen uptake). After 528+/-234 days, 42 patients were hospitalized due to worsening heart failure and/or died from cardiovascular causes. Compared to clinically stable patients, these 42 patients walked a shorter distance (423+/-104 vs 501+/-95 m, P<0.001) and had a lower peak oxygen uptake (12.7+/-4.0 vs 17.4 + 5.6 ml x min(-1) x kg(-1), P<0.001). By univariate analysis the 6-min walk test outperformed other prognostic parameters such as left ventricular ejection fraction, cardiac index and plasma norepinephrine concentration and conferred a prognostic power similar to peak oxygen uptake. This predictive value could be further improved in a multivariate model, by combining the 6-min walk test with independent variables, such as left ventricular ejection fraction or cardiac index. The 6-min walk test correlated with peak oxygen uptake when tested serially over the course of the disease. Although both tests define two distinct domains of functional capacity, the 6-min walk test provides prognostic information very similar to peak oxygen uptake in congestive heart failure patients with dilated cardiomyopathy.

Myocardial Dysfunction and Shock after Cardiac Arrest

PubMed Central

Jentzer, Jacob C.; Chonde, Meshe D.; Dezfulian, Cameron

2015-01-01

Postarrest myocardial dysfunction includes the development of low cardiac output or ventricular systolic or diastolic dysfunction after cardiac arrest. Impaired left ventricular systolic function is reported in nearly two-thirds of patients resuscitated after cardiac arrest. Hypotension and shock requiring vasopressor support are similarly common after cardiac arrest. Whereas shock requiring vasopressor support is consistently associated with an adverse outcome after cardiac arrest, the association between myocardial dysfunction and outcomes is less clear. Myocardial dysfunction and shock after cardiac arrest develop as the result of preexisting cardiac pathology with multiple superimposed insults from resuscitation. The pathophysiology involves cardiovascular ischemia/reperfusion injury and cardiovascular toxicity from excessive levels of inflammatory cytokine activation and catecholamines, among other contributing factors. Similar mechanisms occur in myocardial dysfunction after cardiopulmonary bypass, in sepsis, and in stress-induced cardiomyopathy. Hemodynamic stabilization after resuscitation from cardiac arrest involves restoration of preload, vasopressors to support arterial pressure, and inotropic support if needed to reverse the effects of myocardial dysfunction and improve systemic perfusion. Further research is needed to define the role of postarrest myocardial dysfunction on cardiac arrest outcomes and identify therapeutic strategies. PMID:26421284

Myocardial Dysfunction and Shock after Cardiac Arrest.

PubMed

Jentzer, Jacob C; Chonde, Meshe D; Dezfulian, Cameron

2015-01-01

Postarrest myocardial dysfunction includes the development of low cardiac output or ventricular systolic or diastolic dysfunction after cardiac arrest. Impaired left ventricular systolic function is reported in nearly two-thirds of patients resuscitated after cardiac arrest. Hypotension and shock requiring vasopressor support are similarly common after cardiac arrest. Whereas shock requiring vasopressor support is consistently associated with an adverse outcome after cardiac arrest, the association between myocardial dysfunction and outcomes is less clear. Myocardial dysfunction and shock after cardiac arrest develop as the result of preexisting cardiac pathology with multiple superimposed insults from resuscitation. The pathophysiology involves cardiovascular ischemia/reperfusion injury and cardiovascular toxicity from excessive levels of inflammatory cytokine activation and catecholamines, among other contributing factors. Similar mechanisms occur in myocardial dysfunction after cardiopulmonary bypass, in sepsis, and in stress-induced cardiomyopathy. Hemodynamic stabilization after resuscitation from cardiac arrest involves restoration of preload, vasopressors to support arterial pressure, and inotropic support if needed to reverse the effects of myocardial dysfunction and improve systemic perfusion. Further research is needed to define the role of postarrest myocardial dysfunction on cardiac arrest outcomes and identify therapeutic strategies.

Influence of cardiac and respiratory motion on tomographic reconstructions of the heart: implications for quantitative nuclear cardiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ter-Pogossian, M.M.; Bergmann, S.R.; Sobel, B.E.

1982-12-01

The potential influence of physiological, periodic motions of the heart due to the cardiac cycle, the respiratory cycle, or both on quantitative image reconstruction by positron emission tomography (PET) has been largely neglected. To define their quantitative impact, cardiac PET was performed in 6 dogs after injection of /sup 11/C-palmitate under disparate conditions including: normal cardiac and respiration cycles and cardiac arrest with and without respiration. Although in vitro assay of myocardial samples demonstrated that palmitate uptake was homogeneous (coefficient of variation . 10.1%), analysis of the reconstructed images demonstrated significant heterogeneity of apparent cardiac distribution of radioactivity due tomore » both intrinsic cardiac and respiratory motion. Image degradation due to respiratory motion was demonstrated in a healthy human volunteer as well, in whom cardiac tomography was performed with Super PETT I during breath-holding and during normal breathing. The results indicate that quantitatively significant degradation of reconstructions of true tracer distribution occurs in cardiac PET due to both intrinsic cardiac and respiratory induced motion of the heart. They suggest that avoidance of or minimization of these influences can be accomplished by gating with respect to both the cardiac cycle and respiration or by employing brief scan times during breath-holding.« less

Mesenchymal stem cell transplantation for the infarcted heart: a role in minimizing abnormalities in cardiac-specific energy metabolism

PubMed Central

Johnsen, Virginia L.; Ma, Lianli; James, Freyja D.; Young, Pampee P.; Wasserman, David H.; Rottman, Jeffrey N.; Hittel, Dustin S.; Shearer, Jane

2012-01-01

Intense interest has been focused on cell-based therapy for the infarcted heart given that stem cells have exhibited the ability to reduce infarct size and mitigate cardiac dysfunction. Despite this, it is unknown whether mesenchymal stem cell (MSC) therapy can prevent metabolic remodeling following a myocardial infarction (MI). This study examines the ability of MSCs to rescue the infarcted heart from perturbed substrate uptake in vivo. C57BL/6 mice underwent chronic ligation of the left anterior descending coronary artery to induce a MI. Echocardiography was performed on conscious mice at baseline as well as 7 and 23 days post-MI. Twenty-eight days following the ligation procedure, hyperinsulinemic euglycemic clamps assessed in vivo insulin sensitivity. Isotopic tracer administration evaluated whole body, peripheral tissue, and cardiac-specific glucose and fatty acid utilization. To gain insight into the mechanisms by which MSCs modulate metabolism, mitochondrial function was assessed by high-resolution respirometry using permeabilized cardiac fibers. Data show that MSC transplantation preserves insulin-stimulated fatty acid uptake in the peri-infarct region (4.25 ± 0.64 vs. 2.57 ± 0.34 vs. 3.89 ± 0.54 μmol·100 g−1·min−1, SHAM vs. MI + PBS vs. MI + MSC; P < 0.05) and prevents increases in glucose uptake in the remote left ventricle (3.11 ± 0.43 vs. 3.81 ± 0.79 vs. 6.36 ± 1.08 μmol·100 g−1·min−1, SHAM vs. MI + PBS vs. MI + MSC; P < 0.05). This was associated with an enhanced efficiency of mitochondrial oxidative phosphorylation with a respiratory control ratio of 3.36 ± 0.18 in MSC-treated cardiac fibers vs. 2.57 ± 0.14 in the infarct-only fibers (P < 0.05). In conclusion, MSC therapy exhibits the potential to rescue the heart from metabolic aberrations following a MI. Restoration of metabolic flexibility is important given the metabolic demands of the heart and the role of energetics in the progression to heart failure. PMID:21971524

Effects of testosterone and nandrolone on cardiac function: a randomized, placebo-controlled study.

PubMed

Chung, T; Kelleher, S; Liu, P Y; Conway, A J; Kritharides, L; Handelsman, D J

2007-02-01

Androgens have striking effects on skeletal muscle, but the effects on human cardiac muscle function are not well defined, neither has the role of metabolic activation (aromatization, 5alpha reduction) of testosterone on cardiac muscle been directly studied. To assess the effects of testosterone and nandrolone, a non-amplifiable and non-aromatizable pure androgen, on cardiac muscle function in healthy young men. Double-blind, randomized, placebo-controlled, three-arm parallel group clinical trial. Ambulatory care research centre. Healthy young men randomized into three groups of 10 men. Weekly intramuscular injections of testosterone (200 mg mixed esters), nandrolone (200 mg nandrolone decanoate) or matching (2 ml arachis oil vehicle) placebo for 4 weeks. Comprehensive measures of cardiac muscle function involving transthoracic cardiac echocardiography measuring myocardial tissue velocity, peak systolic strain and strain rates, and bioimpedance measurement of cardiac output and systematic vascular resistance. Left ventricular (LV) function (LV ejection fraction, LV modified TEI index), right ventricular (RV) function (ejection area, tricuspid annular systolic planar motion, RV modified TEI index) as well as cardiac afterload (mean arterial pressure, systemic vascular resistance) and overall cardiac contractility (stroke volume, cardiac output) were within age- and gender-specific reference ranges and were not significantly (P < 0.05) altered by either androgen or placebo over 4 weeks of treatment. Minor changes remaining within normal range were observed solely within the testosterone group for: increased LV end-systolic diameter (30 +/- 7 vs. 33 +/- 5 mm, P = 0.04) and RV end-systolic area (12.8 +/- 1.3 vs. 14.6 +/- 3.3 cm(2), P = 0.04), reduced LV diastolic septal velocity (Em, 9.5 +/- 2.6 vs. 8.7 +/- 2.0 cm/s, P = 0.006), increased LV filling pressure (E/Em ratio, 7.1 +/- 1.6 vs. 8.3 +/- 1.8, P = 0.02) and shortened PR interval on the electrocardiogram (167 +/- 13 vs. 154 +/- 12, P = 0.03). Four weeks of treatment with testosterone or nandrolone had no beneficial or adverse effects compared with placebo on cardiac function in healthy young men.

Plant-derived cardiac glycosides: Role in heart ailments and cancer management.

PubMed

Patel, Seema

2016-12-01

Cardiac glycosides, the cardiotonic steroids such as digitalis have been in use as heart ailment remedy since ages. They manipulate the renin-angiotensin axis to improve cardiac output. However; their safety and efficacy have come under scrutiny in recent times, as poisoning and accidental mortalities have been observed. In order to better understand and exploit them as cardiac ionotropes, studies are being pursued using different cardiac glycosides such as digitoxin, digoxin, ouabain, oleandrin etc. Several cardiac glycosides as peruvoside have shown promise in cancer control, especially ovary cancer and leukemia. Functional variability of these glycosides has revealed that not all cardiac glycosides are alike. Apart from their specific affinity to sodium-potassium ATPase, their therapeutic dosage and behavior in poly-morbidity conditions needs to be considered. This review presents a concise account of the key findings in recent years with adequate elaboration of the mechanisms. This compilation is expected to contribute towards management of cardiac, cancer, even viral ailments. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Identification of a cardiac specific protein transduction domain by in vivo biopanning using a M13 phage peptide display library in mice.

PubMed

Zahid, Maliha; Phillips, Brett E; Albers, Sean M; Giannoukakis, Nick; Watkins, Simon C; Robbins, Paul D

2010-08-17

A peptide able to transduce cardiac tissue specifically, delivering cargoes to the heart, would be of significant therapeutic potential for delivery of small molecules, proteins and nucleic acids. In order to identify peptide(s) able to transduce heart tissue, biopanning was performed in cell culture and in vivo with a M13 phage peptide display library. A cardiomyoblast cell line, H9C2, was incubated with a M13 phage 12 amino acid peptide display library. Internalized phage was recovered, amplified and then subjected to a total of three rounds of in vivo biopanning where infectious phage was isolated from cardiac tissue following intravenous injection. After the third round, 60% of sequenced plaques carried the peptide sequence APWHLSSQYSRT, termed cardiac targeting peptide (CTP). We demonstrate that CTP was able to transduce cardiomyocytes functionally in culture in a concentration and cell-type dependent manner. Mice injected with CTP showed significant transduction of heart tissue with minimal uptake by lung and kidney capillaries, and no uptake in liver, skeletal muscle, spleen or brain. The level of heart transduction by CTP also was greater than with a cationic transduction domain. Biopanning using a peptide phage display library identified a peptide able to transduce heart tissue in vivo efficiently and specifically. CTP could be used to deliver therapeutic peptides, proteins and nucleic acid specifically to the heart.

Low cardiac output syndrome in the postoperative period of cardiac surgery. Profile, differences in clinical course and prognosis. The ESBAGA study.

PubMed

Pérez Vela, J L; Jiménez Rivera, J J; Alcalá Llorente, M Á; González de Marcos, B; Torrado, H; García Laborda, C; Fernández Zamora, M D; González Fernández, F J; Martín Benítez, J C

2018-04-01

An analysis is made of the clinical profile, evolution and differences in morbidity and mortality of low cardiac output syndrome (LCOS) in the postoperative period of cardiac surgery, according to the 3 diagnostic subgroups defined by the SEMICYUC Consensus 2012. A multicenter, prospective cohort study was carried out. ICUs of Spanish hospitals with cardiac surgery. A consecutive sample of 2,070 cardiac surgery patients was included, with the analysis of 137 patients with LCOS. No intervention was carried out. The mean patient age was 68.3±9.3 years (65.2% males), with a EuroSCORE II of 9.99±13. NYHA functional class III-IV (52.9%), left ventricular ejection fraction<35% (33.6%), AMI (31.9%), severe PHT (21.7%), critical preoperative condition (18.8%), prior cardiac surgery (18.1%), PTCA/stent placement (16.7%). According to subgroups, 46 patients fulfilled hemodynamic criteria of LCOS (group A), 50 clinical criteria (group B), and the rest (n=41) presented cardiogenic shock (group C). Significant differences were observed over the evolutive course between the subgroups in terms of time subjected to mechanical ventilation (114.4, 135.4 and 180.3min in groups A, B and C, respectively; P<.001), renal replacement requirements (11.4, 14.6 and 36.6%; P=.007), multiorgan failure (16.7, 13 and 47.5%), and mortality (13.6, 12.5 and 35.9%; P=.01). The mean maximum lactate concentration was higher in cardiogenic shock patients (P=.002). The clinical evolution of these patients leads to high morbidity and mortality. We found differences between the subgroups in terms of the postoperative clinical course and mortality. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Augmented baroreflex heart rate gain after moderate-intensity, dynamic exercise

NASA Technical Reports Server (NTRS)

Halliwill, J. R.; Taylor, J. A.; Hartwig, T. D.; Eckberg, D. L.

1996-01-01

The occurrence of a sustained vasodilation and hypotension after acute, dynamic exercise suggests that exercise may alter arterial baroreflex mechanisms. Therefore, we assessed systemic hemodynamics, baroreflex regulation of heart rate, and cardiac vagal tone after 60 min of cycling at 60% peak oxygen consumption in 12 healthy, untrained men and women (ages 21-28 yr). We derived sigmoidal carotid-cardiac baroreflex relations by measurement of R-R interval changes induced by ramped, stepwise, R-wave-triggered changes in external neck pressure from 40 to -65 mmHg. We estimated tonic cardiac vagal control with power spectral analysis of R-R interval variability in the respiratory frequency band (0.2-0.3 Hz) during frequency- and tidal volume-controlled breathing. Both mean arterial pressure and total peripheral resistance were reduced postexercise [pressure: from 86 +/- 2 (mean +/- SE) to 81 +/- 2 mmHg; resistance: from 23 +/- 2 to 16 +/- 1 units; both P < 0.05]. Cardiac output was increased postexercise (from 3.9 +/- 0.3 to 5.5 +/- 0.5 l/min, P < 0.05). Both slope and range of the carotid-cardiac baroreflex relation were increased postexercise (slope: from 4.7 +/- 0.7 to 6.1 +/- 0.9 ms/mmHg; range: from 186 +/- 23 to 238 +/- 30 ms, P < 0.05). Respiratory R-R interval variability (cardiac vagal tone) was not changed at any time after exercise, whereas heart rate and plasma norepinephrine levels were elevated. Thus moderate-intensity, dynamic exercise increases heart rate and cardiac output, reduces peripheral vascular resistance, and augments baroreflex responsiveness. Our data suggest that augmented baroreflex heart rate gain restrains rather than contributes to postexercise hypotension, which appears to be mediated predominately by vasodilation.

Right Ventricular Volumes and Systolic Function by Cardiac Magnetic Resonance and the Impact of Sex, Age, and Obesity in a Longitudinally Followed Cohort Free of Pulmonary and Cardiovascular Disease: The Framingham Heart Study.

PubMed

Foppa, Murilo; Arora, Garima; Gona, Philimon; Ashrafi, Arman; Salton, Carol J; Yeon, Susan B; Blease, Susan J; Levy, Daniel; O'Donnell, Christopher J; Manning, Warren J; Chuang, Michael L

2016-03-01

Cardiac magnetic resonance is uniquely well suited for noninvasive imaging of the right ventricle. We sought to define normal cardiac magnetic resonance reference values and to identify the main determinants of right ventricular (RV) volumes and systolic function using a modern imaging sequence in a community-dwelling, longitudinally followed cohort free of clinical cardiovascular and pulmonary disease. The Framingham Heart Study Offspring cohort has been followed since 1971. We scanned 1794 Offspring cohort members using steady-state free precession cardiac magnetic resonance and identified a reference group of 1336 adults (64±9 years, 576 men) free of prevalent cardiovascular and pulmonary disease. RV trabeculations and papillary muscles were considered cavity volume. Men had greater RV volumes and cardiac output before and after indexation to body size (all P<0.001). Women had higher RV ejection fraction than men (68±6% versus 64±7%; P<0.0001). RV volumes and cardiac output decreased with advancing age. There was an increase in raw and height-indexed RV measurements with increasing body mass index, but this trend was weakly inverted after indexation of RV volumes to body surface area. Sex, age, height, body mass index, and heart rate account for most of the variability in RV volumes and function in this community-dwelling population. We report sex-specific normative values for RV measurements among principally middle-aged and older adults. RV ejection fraction is greater in women. RV volumes increase with body size, are greater in men, and are smaller in older people. Body surface area seems to be appropriate for indexation of cardiac magnetic resonance-derived RV volumes. © 2016 American Heart Association, Inc.

Effect of Levosimendan on Low Cardiac Output Syndrome in Patients With Low Ejection Fraction Undergoing Coronary Artery Bypass Grafting With Cardiopulmonary Bypass

PubMed Central

Caruba, Thibaut; Grosjean, Sandrine; Amour, Julien; Ouattara, Alexandre; Villacorta, Judith; Miguet, Bertrand; Guinet, Patrick; Lévy, François; Squara, Pierre; Aït Hamou, Nora; Carillon, Aude; Boyer, Julie; Boughenou, Marie-Fazia; Rosier, Sebastien; Robin, Emmanuel; Radutoiu, Mihail; Durand, Michel; Guidon, Catherine; Desebbe, Olivier; Charles-Nelson, Anaïs; Menasché, Philippe; Rozec, Bertrand; Girard, Claude; Fellahi, Jean-Luc; Pirracchio, Romain; Chatellier, Gilles

2017-01-01

Importance Low cardiac output syndrome after cardiac surgery is associated with high morbidity and mortality in patients with impaired left ventricular function. Objective To assess the ability of preoperative levosimendan to prevent postoperative low cardiac output syndrome. Design, Setting, and Participants Randomized, double-blind, placebo-controlled trial conducted in 13 French cardiac surgical centers. Patients with a left ventricular ejection fraction less than or equal to 40% and scheduled for isolated or combined coronary artery bypass grafting with cardiopulmonary bypass were enrolled from June 2013 until May 2015 and followed during 6 months (last follow-up, November 30, 2015). Interventions Patients were assigned to a 24-hour infusion of levosimendan 0.1 µg/kg/min (n = 167) or placebo (n = 168) initiated after anesthetic induction. Main Outcomes and Measures Composite end point reflecting low cardiac output syndrome with need for a catecholamine infusion 48 hours after study drug initiation, need for a left ventricular mechanical assist device or failure to wean from it at 96 hours after study drug initiation when the device was inserted preoperatively, or need for renal replacement therapy at any time postoperatively. It was hypothesized that levosimendan would reduce the incidence of this composite end point by 15% in comparison with placebo. Results Among 336 randomized patients (mean age, 68 years; 16% women), 333 completed the trial. The primary end point occurred in 87 patients (52%) in the levosimendan group and 101 patients (61%) in the placebo group (absolute risk difference taking into account center effect, −7% [95% CI, −17% to 3%]; P = .15). Predefined subgroup analyses found no interaction with ejection fraction less than 30%, type of surgery, and preoperative use of β-blockers, intra-aortic balloon pump, or catecholamines. The prevalence of hypotension (57% vs 48%), atrial fibrillation (50% vs 40%), and other adverse events did not significantly differ between levosimendan and placebo. Conclusions and Relevance Among patients with low ejection fraction who were undergoing coronary artery bypass grafting with cardiopulmonary bypass, levosimendan compared with placebo did not result in a significant difference in the composite end point of prolonged catecholamine infusion, use of left ventricular mechanical assist device, or renal replacement therapy. These findings do not support the use of levosimendan for this indication. Trial Registration EudraCT Number: 2012-000232-25; clinicaltrials.gov Identifier: NCT02184819 PMID:28787507

A wearable device for continuous monitoring of heart mechanical function based on impedance cardiography.

PubMed

Panfili, G; Piccini, L; Maggi, L; Parini, S; Andreoni, G

2006-01-01

In this study we explored the possibility to realize a low power device for Cardiac Output continuous monitoring based on impedance cardiography technique. We assessed the possibility to develop a system able to record data allow an intra-subjective analysis based on the daily variations of this measure. The device was able to acquire and to send signals using a wireless Bluetooth transmission. The electronic circuit was designed in order to minimize power consumption, dimension and weight. The reported results were interesting for what concerns the power consumption and then noise level. In this way was obtained a wearable device that will permit to define specific clinical protocols based on continuous monitoring of the Cardiac Output signal.

Peak oxygen uptake in a sprint interval testing protocol vs. maximal oxygen uptake in an incremental testing protocol and their relationship with cross-country mountain biking performance.

PubMed

Hebisz, Rafał; Hebisz, Paulina; Zatoń, Marek; Michalik, Kamil

2017-04-01

In the literature, the exercise capacity of cyclists is typically assessed using incremental and endurance exercise tests. The aim of the present study was to confirm whether peak oxygen uptake (V̇O 2peak ) attained in a sprint interval testing protocol correlates with cycling performance, and whether it corresponds to maximal oxygen uptake (V̇O 2max ) determined by an incremental testing protocol. A sample of 28 trained mountain bike cyclists executed 3 performance tests: (i) incremental testing protocol (ITP) in which the participant cycled to volitional exhaustion, (ii) sprint interval testing protocol (SITP) composed of four 30 s maximal intensity cycling bouts interspersed with 90 s recovery periods, (iii) competition in a simulated mountain biking race. Oxygen uptake, pulmonary ventilation, work, and power output were measured during the ITP and SITP with postexercise blood lactate and hydrogen ion concentrations collected. Race times were recorded. No significant inter-individual differences were observed in regards to any of the ITP-associated variables. However, 9 individuals presented significantly increased oxygen uptake, pulmonary ventilation, and work output in the SITP compared with the remaining cyclists. In addition, in this group of 9 cyclists, oxygen uptake in SITP was significantly higher than in ITP. After the simulated race, this group of 9 cyclists achieved significantly better competition times (99.5 ± 5.2 min) than the other cyclists (110.5 ± 6.7 min). We conclude that mountain bike cyclists who demonstrate higher peak oxygen uptake in a sprint interval testing protocol than maximal oxygen uptake attained in an incremental testing protocol demonstrate superior competitive performance.

Role of pyruvate dehydrogenase inhibition in the development of hypertrophy in the hyperthyroid rat heart: a combined magnetic resonance imaging and hyperpolarized magnetic resonance spectroscopy study.

PubMed

Atherton, Helen J; Dodd, Michael S; Heather, Lisa C; Schroeder, Marie A; Griffin, Julian L; Radda, George K; Clarke, Kieran; Tyler, Damian J

2011-06-07

Hyperthyroidism increases heart rate, contractility, cardiac output, and metabolic rate. It is also accompanied by alterations in the regulation of cardiac substrate use. Specifically, hyperthyroidism increases the ex vivo activity of pyruvate dehydrogenase kinase, thereby inhibiting glucose oxidation via pyruvate dehydrogenase. Cardiac hypertrophy is another effect of hyperthyroidism, with an increase in the abundance of mitochondria. Although the hypertrophy is initially beneficial, it can eventually lead to heart failure. The aim of this study was to use hyperpolarized magnetic resonance spectroscopy to investigate the rate and regulation of in vivo pyruvate dehydrogenase flux in the hyperthyroid heart and to establish whether modulation of flux through pyruvate dehydrogenase would alter cardiac hypertrophy. Hyperthyroidism was induced in 18 male Wistar rats with 7 daily intraperitoneal injections of freshly prepared triiodothyronine (0.2 mg x kg(-1) x d(-1)). In vivo pyruvate dehydrogenase flux, assessed with hyperpolarized magnetic resonance spectroscopy, was reduced by 59% in hyperthyroid animals (0.0022 ± 0.0002 versus 0.0055 ± 0.0005 second(-1); P=0.0003), and this reduction was completely reversed by both short- and long-term delivery of dichloroacetic acid, a pyruvate dehydrogenase kinase inhibitor. Hyperpolarized [2-(13)C]pyruvate was also used to evaluate Krebs cycle metabolism and demonstrated a unique marker of anaplerosis, the level of which was significantly increased in the hyperthyroid heart. Cine magnetic resonance imaging showed that long-term dichloroacetic acid treatment significantly reduced the hypertrophy observed in hyperthyroid animals (100 ± 20 versus 200 ± 30 mg; P=0.04) despite no change in the increase observed in cardiac output. This work has demonstrated that inhibition of glucose oxidation in the hyperthyroid heart in vivo is mediated by pyruvate dehydrogenase kinase. Relieving this inhibition can increase the metabolic flexibility of the hyperthyroid heart and reduce the level of hypertrophy that develops while maintaining the increased cardiac output required to meet the higher systemic metabolic demand.

Design and testing of an MRI-compatible cycle ergometer for non-invasive cardiac assessments during exercise

PubMed Central

2012-01-01

Background Magnetic resonance imaging (MRI) is an important tool for cardiac research, and it is frequently used for resting cardiac assessments. However, research into non-pharmacological stress cardiac evaluation is limited. Methods We aimed to design a portable and relatively inexpensive MRI cycle ergometer capable of continuously measuring pedalling workload while patients exercise to maintain target heart rates. Results We constructed and tested an MRI-compatible cycle ergometer for a 1.5 T MRI scanner. Resting and sub-maximal exercise images (at 110 beats per minute) were successfully obtained in 8 healthy adults. Conclusions The MRI-compatible cycle ergometer constructed by our research group enabled cardiac assessments at fixed heart rates, while continuously recording power output by directly measuring pedal force and crank rotation. PMID:22423637

Triple-site pacing for cardiac resynchronization in permanent atrial fibrillation - Acute phase results from a prospective observational study.

PubMed

Marques, Pedro; Nobre Menezes, Miguel; Lima da Silva, Gustavo; Bernardes, Ana; Magalhães, Andreia; Cortez-Dias, Nuno; Carpinteiro, Luís; de Sousa, João; Pinto, Fausto J

2016-06-01

Multi-site pacing is emerging as a new method for improving response to cardiac resynchronization therapy (CRT), but has been little studied, especially in patients with atrial fibrillation. We aimed to assess the effects of triple-site (Tri-V) vs. biventricular (Bi-V) pacing on hemodynamics and QRS duration. This was a prospective observational study of patients with permanent atrial fibrillation and ejection fraction <40% undergoing CRT implantation (n=40). One right ventricular (RV) lead was implanted in the apex and another in the right ventricular outflow tract (RVOT) septal wall. A left ventricular (LV) lead was implanted in a conventional venous epicardial position. Cardiac output (using the FloTrac™ Vigileo™ system), mean QRS and ejection fraction were calculated. Mean cardiac output was 4.81±0.97 l/min with Tri-V, 4.68±0.94 l/min with RVOT septal and LV pacing, and 4.68±0.94 l/min with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV). Mean pre-implantation QRS was 170±25 ms, 123±18 ms with Tri-V, 141±25 ms with RVOT septal pacing and LV pacing and 145±19 with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV and pre-implantation). Mean ejection fraction was significantly higher with Tri-V (30±11%) vs. Bi-V pacing (28±12% with RVOT septal and LV pacing and 28±11 with RV apical and LV pacing) and pre-implantation (25±8%). Tri-V pacing produced higher cardiac output and shorter QRS duration than Bi-V pacing. This may have a significant impact on the future of CRT. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Indexation of cardiac output to biometric parameters in critically ill patients: A systematic analysis of a transpulmonary thermodilution-derived database.

PubMed

Saugel, Bernd; Mair, Sebastian; Götz, Simon Q; Tschirdewahn, Julia; Frank, Johanna; Höllthaler, Josef; Schmid, Roland M; Huber, Wolfgang

2015-10-01

Cardiac output (CO) (liters per minute) is usually normalized (ie, indexed) to the patient's body surface area (BSA) resulting in the hemodynamic variable cardiac index (CI) (liters per minute per square meter). We aimed (1) to evaluate the impact of different body weight-based CO indexations on the resulting CI values and (2) to identify biometric parameters independently associated with CO in critically ill patients. The study is an analysis of a database containing transpulmonary thermodilution-derived hemodynamic variables of 234 medical intensive care unit patients. Cardiac index indexed to actual BSA was statistically significantly lower compared with CI indexed to predicted BSA in the totality of patients and in the subgroups of patients with body mass index greater than or equal to 25 kg/m(2) but less than 30 kg/m(2) and body mass index greater than or equal to 30 kg/m(2) (with a statistically significant difference in the proportion of low and high CI measurements). Multivariate analysis of the first CO measurement of each patient demonstrated that CO was independently associated with age (P < .001), height (P = .001), and actual body weight (BWact) (P = .030). Multivariate analysis of the mean of the patients' CO measurements confirmed age (P < .001), height (P = .001), and BWact (P < .001) as biometric factors independently associated with CO. Age was identified as the most important factor with each year of age decreasing CO by 66 mL/min (95% confidence interval, 47-86 mL/min). The indexation of CO to BSA is highly dependent on the body weight estimation formula used to calculate BSA. Cardiac output is independently associated with the biometric factors age, height, and BWact. These factors might be considered for indexation of CO. Copyright © 2015 Elsevier Inc. All rights reserved.

Prophylactic levosimendan for the prevention of low cardiac output syndrome and mortality in paediatric patients undergoing surgery for congenital heart disease.

PubMed

Hummel, Johanna; Rücker, Gerta; Stiller, Brigitte

2017-08-02

Low cardiac output syndrome remains a serious complication, and accounts for substantial morbidity and mortality in the postoperative course of paediatric patients undergoing surgery for congenital heart disease. Standard prophylactic and therapeutic strategies for low cardiac output syndrome are based mainly on catecholamines, which are effective drugs, but have considerable side effects. Levosimendan, a calcium sensitiser, enhances the myocardial function by generating more energy-efficient myocardial contractility than achieved via adrenergic stimulation with catecholamines. Thus potentially, levosimendan is a beneficial alternative to standard medication for the prevention of low cardiac output syndrome in paediatric patients after open heart surgery. To review the efficacy and safety of the postoperative prophylactic use of levosimendan for the prevention of low cardiac output syndrome and mortality in paediatric patients undergoing surgery for congenital heart disease. We identified trials via systematic searches of CENTRAL, MEDLINE, Embase, and Web of Science, as well as clinical trial registries, in June 2016. Reference lists from primary studies and review articles were checked for additional references. We only included randomised controlled trials (RCT) in our analysis that compared prophylactic levosimendan with standard medication or placebo, in infants and children up to 18 years of age, who were undergoing surgery for congenital heart disease. Two review authors independently extracted data and assessed risk of bias according to a pre-defined protocol. We obtained additional information from all but one of the study authors of the included studies. We used the five GRADE considerations (study limitations, consistency of effect, imprecision, indirectness, and publication bias) to assess the quality of evidence from the studies that contributed data to the meta-analyses for the prespecified outcomes. We created a 'Summary of findings' table to summarise the results and the quality of evidence for each outcome. We included five randomised controlled trials with a total of 212 participants in the analyses. All included participants were under five years of age. Using GRADE, we assessed there was low-quality evidence for all analysed outcomes. We assessed high risk of performance and detection bias for two studies due to their unblinded setting. Levosimendan showed no clear effect on risk of mortality (risk ratio (RR) 0.47, 95% confidence interval (CI) 0.12 to 1.82; participants = 123; studies = 3) and no clear effect on low cardiac output syndrome (RR 0.64, 95% CI 0.39 to 1.04; participants = 83; studies = 2) compared to standard treatments. Data on time-to-death were not available from any of the included studies.There was no conclusive evidence on the effect of levosimendan on the secondary outcomes. The length of intensive care unit stays (mean difference (MD) 0.33 days, 95% CI -1.16 to 1.82; participants = 188; studies = 4), length of hospital stays (MD 0.26 days, 95% CI -3.50 to 4.03; participants = 75; studies = 2), duration of mechanical ventilation (MD -0.04 days, 95% CI -0.08 to 0.00; participants = 208; studies = 5), and the risk of mechanical circulatory support or cardiac transplantation (RR 1.49, 95% CI 0.19 to 11.37; participants = 60; studies = 2) did not clearly differ between the groups. Published data about adverse effects of levosimendan were limited. A meta-analysis of hypotension, one of the most feared side effects of levosimendan, was not feasible because of the heterogeneous expression of blood pressure values. The current level of evidence is insufficient to judge whether prophylactic levosimendan prevents low cardiac output syndrome and mortality in paediatric patients undergoing surgery for congenital heart disease. So far, no significant differences have been detected between levosimendan and standard inotrope treatments in this setting.The authors evaluated the quality of evidence as low, using the GRADE approach. Reasons for downgrading were serious risk of bias (performance and detection bias due to unblinded setting of two RCTs), serious risk of inconsistency, and serious to very serious risk of imprecision (small number of included patients, low event rates).

Effects of Obesity on Cardiovascular Hemodynamics, Cardiac Morphology, and Ventricular Function.

PubMed

Alpert, Martin A; Omran, Jad; Bostick, Brian P

2016-12-01

Obesity produces a variety of hemodynamic alterations that may cause changes in cardiac morphology which predispose to left and right ventricular dysfunction. Various neurohormonal and metabolic alterations commonly associated with obesity may contribute to these abnormalities of cardiac structure and function. These changes in cardiovascular hemodynamics, cardiac morphology, and ventricular function may, in severely obese patients, predispose to heart failure, even in the absence of other forms of heart disease (obesity cardiomyopathy). In normotensive obese patients, cardiac involvement is commonly characterized by elevated cardiac output, low peripheral vascular resistance, and increased left ventricular (LV) end-diastolic pressure. Sleep-disordered breathing may lead to pulmonary arterial hypertension and, in association with left heart failure, may contribute to elevation of right heart pressures. These alterations, in association with various neurohormonal and metabolic abnormalities, may produce LV hypertrophy; impaired LV diastolic function; and less commonly, LV systolic dysfunction. Many of these alterations are reversible with substantial voluntary weight loss.

Coi-wiz: An interactive computer wizard for analyzing cardiac optical signals.

PubMed

Yuan, Xiaojing; Uyanik, Ilyas; Situ, Ning; Xi, Yutao; Cheng, Jie

2009-01-01

A number of revolutionary techniques have been developed for cardiac electrophysiology research to better study the various arrhythmia mechanisms that can enhance ablating strategies for cardiac arrhythmias. Once the three-dimensional high resolution cardiac optical imaging data is acquired, it is time consuming to manually go through them and try to identify the patterns associated with various arrhythmia symptoms. In this paper, we present an interactive computer wizard that helps cardiac electrophysiology researchers to visualize and analyze the high resolution cardiac optical imaging data. The wizard provides a file interface that accommodates different file formats. A series of analysis algorithms output waveforms, activation and action potential maps after spatial and temporal filtering, velocity field and heterogeneity measure. The interactive GUI allows the researcher to identify the region of interest in both the spatial and temporal domain, thus enabling them to study different heart chamber at their choice.

Cardiac Endothelial Cell Transcriptome.

PubMed

Lother, Achim; Bergemann, Stella; Deng, Lisa; Moser, Martin; Bode, Christoph; Hein, Lutz

2018-03-01

Endothelial cells (ECs) are a highly specialized cell type with marked diversity between different organs or vascular beds. Cardiac ECs are an important player in cardiac physiology and pathophysiology but are not sufficiently characterized yet. Thus, the aim of the present study was to analyze the cardiac EC transcriptome. We applied fluorescence-assisted cell sorting to isolate pure ECs from adult mouse hearts. RNAseq revealed 1288 genes predominantly expressed in cardiac ECs versus heart tissue including several transcription factors. We found an overrepresentation of corresponding transcription factor binding motifs within the promotor region of EC-enriched genes, suggesting that they control the EC transcriptome. Cardiac ECs exhibit a distinct gene expression profile when compared with renal, cerebral, or pulmonary ECs. For example, we found the Meox2 / Tcf15, Fabp4 , and Cd36 signaling cascade higher expressed in cardiac ECs which is a key regulator of fatty acid uptake and involved in the development of atherosclerosis. The results from this study provide a comprehensive resource of gene expression and transcriptional control in cardiac ECs. The cardiac EC transcriptome exhibits distinct differences in gene expression compared with other cardiac cell types and ECs from other organs. We identified new candidate genes that have not been investigated in ECs yet as promising targets for future evaluation. © 2018 American Heart Association, Inc.

Potential diagnostic value of 131I-MIBG myocardial scintigraphy in discrimination between Alzheimer disease and dementia with Lewy bodies.

PubMed

Abbasi, Mehrshad; Ghalandari, Nafise; Farzanefar, Saeed; Aghamollaii, Vajiheh; Ahmadi, Mona; Ganji, Morsaleh; Afarideh, Mohsen; Loloee, Sogol; Naseri, Maryam; Tafakhori, Abbas

2017-12-01

Clinical difficulty to discriminate between the Alzheimer disease (AD) and dementia with Lewy bodies (DLB) has led researchers to focus on highly sensitive functional imaging modalities. The aim of the present study was to assess 131 I-MIBG cardiac imaging to distinguish between AD and DLB. Seventeen patients who were known cases of dementia underwent 131 I-MIBG myocardial scintigraphy to differentiate AD from DLB. Planar and 131 I-MIBG SPECT were obtained 2h after the injection of 1mCi 131 I-MIBG on a dual head gamma camera. The visual assessment of the heart uptake compared with lungs and the quantification based on the heart to mediastinal ratio (HMR) were done. The cardiac receiver operating characteristic (ROC) curve was designed for the optimal HMR cut-off values to predict the diagnoses of the patients. The diagnoses were clinically confirmed during the follow up of 14±8.2 months. Out of 17 patients (13 males; 76.5%), 10 patients had AD (7 males; 70%) and 7 patients had DLB (6 males; 85%). The pooled HMR was 1.74±0.33 in the study population; with 1.95±0.22 in the AD group and 1.43±0.20 in the DLB group to demonstrate significantly different HMR scores between patients with AD and DLB (p value=0.001). The visual interpretation was positive in 10 patients (accuracy of 88.2%). The shortest distance on the ROC curve to the optimal value corresponding to HMR=1.57 identified 10 patients with a high HMR (positive cardiac uptake) and 7 patients with a low HMR (negative cardiac uptake), the accuracy calculated at 88.2%. 131 I-MIBG myocardial scintigraphy is a potential alternative diagnostic modality for discrimination between AD and DLB when 123 I is not available. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxygen Uptake Efficiency Slope and Breathing Reserve, Not Anaerobic Threshold, Discriminate Between Patients With Cardiovascular Disease Over Chronic Obstructive Pulmonary Disease.

PubMed

Barron, Anthony; Francis, Darrel P; Mayet, Jamil; Ewert, Ralf; Obst, Anne; Mason, Mark; Elkin, Sarah; Hughes, Alun D; Wensel, Roland

2016-04-01

The study sought to compare the relative discrimination of various cardiopulmonary exercise testing (CPX) variables between cardiac and respiratory disease. CPX testing is used in many cardiorespiratory diseases. However, discrimination of cardiac and respiratory dysfunction can be problematic. Anaerobic threshold (AT) and oxygen-uptake to work-rate relationship (VO2/WR slope) have been proposed as diagnostic of cardiac dysfunction, but multiple variables have not been compared. A total of 73 patients with chronic obstructive pulmonary disease (COPD) (n = 25), heart failure with reduced ejection fraction (HFrEF) (n = 40), or combined COPD and HFrEF (n = 8) were recruited and underwent CPX testing on a bicycle ergometer. Following a familiarization test, each patient underwent a personalized second test aiming for maximal exercise after ∼10 min. Measurements from this test were used to calculate area under the receiver-operator characteristic curve (AUC). Peak VO2 was similar between the 2 principal groups (COPD 17.1 ± 4.6 ml/min/kg; HFrEF 16.4 ± 3.6 ml/min/kg). Breathing reserve (AUC: 0.91) and percent predicted oxygen uptake efficiency slope (OUES) (AUC: 0.87) had the greatest ability to discriminate between COPD and HFrEF. VO2/WR slope performed significantly worse (AUC: 0.68). VO2 at the AT did not discriminate (AUC for AT as percent predicted peak VO2: 0.56). OUES and breathing reserve remained strong discriminators when compared with an external cohort of healthy matched controls, and were comparable to B-type natriuretic peptide. Breathing reserve and OUES discriminate heart failure from COPD. Despite it being considered an important determinant of cardiac dysfunction, the AT could not discriminate these typical clinical populations while the VO2/WR slope showed poor to moderate discriminant ability. (Identifying an Ideal Cardiopulmonary Exercise Test Parameter [PVA]; NCT01162083). Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Oxygen Uptake Efficiency Slope and Breathing Reserve, Not Anaerobic Threshold, Discriminate Between Patients With Cardiovascular Disease Over Chronic Obstructive Pulmonary Disease

PubMed Central

Barron, Anthony; Francis, Darrel P.; Mayet, Jamil; Ewert, Ralf; Obst, Anne; Mason, Mark; Elkin, Sarah; Hughes, Alun D.; Wensel, Roland

2016-01-01

Objectives The study sought to compare the relative discrimination of various cardiopulmonary exercise testing (CPX) variables between cardiac and respiratory disease. Background CPX testing is used in many cardiorespiratory diseases. However, discrimination of cardiac and respiratory dysfunction can be problematic. Anaerobic threshold (AT) and oxygen-uptake to work-rate relationship (VO2/WR slope) have been proposed as diagnostic of cardiac dysfunction, but multiple variables have not been compared. Methods A total of 73 patients with chronic obstructive pulmonary disease (COPD) (n = 25), heart failure with reduced ejection fraction (HFrEF) (n = 40), or combined COPD and HFrEF (n = 8) were recruited and underwent CPX testing on a bicycle ergometer. Following a familiarization test, each patient underwent a personalized second test aiming for maximal exercise after ∼10 min. Measurements from this test were used to calculate area under the receiver-operator characteristic curve (AUC). Results Peak VO2 was similar between the 2 principal groups (COPD 17.1 ± 4.6 ml/min/kg; HFrEF 16.4 ± 3.6 ml/min/kg). Breathing reserve (AUC: 0.91) and percent predicted oxygen uptake efficiency slope (OUES) (AUC: 0.87) had the greatest ability to discriminate between COPD and HFrEF. VO2/WR slope performed significantly worse (AUC: 0.68). VO2 at the AT did not discriminate (AUC for AT as percent predicted peak VO2: 0.56). OUES and breathing reserve remained strong discriminators when compared with an external cohort of healthy matched controls, and were comparable to B-type natriuretic peptide. Conclusions Breathing reserve and OUES discriminate heart failure from COPD. Despite it being considered an important determinant of cardiac dysfunction, the AT could not discriminate these typical clinical populations while the VO2/WR slope showed poor to moderate discriminant ability. (Identifying an Ideal Cardiopulmonary Exercise Test Parameter [PVA]; NCT01162083) PMID:26874378

Immunogold labeling study of the distribution of GLUT-1 and GLUT-4 in cardiac tissue following stimulation by insulin or ischemia.

PubMed

Davey, Katherine A B; Garlick, Pamela B; Warley, Alice; Southworth, Richard

2007-04-01

Whereas glucose transporter 1 (GLUT-1) is thought to be responsible for basal glucose uptake in cardiac myocytes, little is known about its relative distribution between the different plasma membranes and cell types in the heart. GLUT-4 translocates to the myocyte surface to increase glucose uptake in response to a number of stimuli. The mechanisms underlying ischemia- and insulin-mediated GLUT-4 translocation are known to be different, raising the possibility that the intracellular destinations of GLUT-4 following these stimuli also differ. Using immunogold labeling, we describe the cellular localization of these two transporters and investigate whether insulin and ischemia induce differential translocation of GLUT-4 to different cardiac membranes. Immunogold labeling of GLUT-1 and GLUT-4 was performed on left ventricular sections from isolated hearts following 30 min of either insulin, ischemia, or control perfusion. In control tissue, GLUT-1 was predominantly (76%) localized in the capillary endothelial cells, with only 24% of total cardiac GLUT-1 present in myocytes. GLUT-4 was found predominantly in myocytes, distributed between sarcolemmal and T tubule membranes (1.84 +/- 0.49 and 1.54 +/- 0.33 golds/microm, respectively) and intracellular vesicles (127 +/- 18 golds/microm(2)). Insulin increased T tubule membrane GLUT-4 content (2.8 +/- 0.4 golds/microm, P < 0.05) but had less effect on sarcolemmal GLUT-4 (1.72 +/- 0.53 golds/microm). Ischemia induced greater GLUT-4 translocation to both membrane types (4.25 +/- 0.84 and 4.01 +/- 0.27 golds/microm, respectively P < 0.05). The localization of GLUT-1 suggests a significant role in transporting glucose across the capillary wall before myocyte uptake via GLUT-1 and GLUT-4. We demonstrate independent spatial translocation of GLUT-4 under insulin or ischemic stimulation and propose independent roles for T-tubular and sarcolemmal GLUT-4.

Low STAT3 expression sensitizes to toxic effects of β-adrenergic receptor stimulation in peripartum cardiomyopathy

PubMed Central

Stapel, Britta; Kohlhaas, Michael; Ricke-Hoch, Melanie; Haghikia, Arash; Erschow, Sergej; Knuuti, Juhani; Silvola, Johanna M. U.; Roivainen, Anne; Saraste, Antti; Nickel, Alexander G.; Saar, Jasmin A.; Sieve, Irina; Pietzsch, Stefan; Müller, Mirco; Bogeski, Ivan; Kappl, Reinhard; Jauhiainen, Matti; Thackeray, James T.; Scherr, Michaela; Bengel, Frank M.; Hagl, Christian; Tudorache, Igor; Bauersachs, Johann; Maack, Christoph; Hilfiker-Kleiner, Denise

2017-01-01

Abstract Aims The benefit of the β1-adrenergic receptor (β1-AR) agonist dobutamine for treatment of acute heart failure in peripartum cardiomyopathy (PPCM) is controversial. Cardiac STAT3 expression is reduced in PPCM patients. Mice carrying a cardiomyocyte-restricted deletion of STAT3 (CKO) develop PPCM. We hypothesized that STAT3-dependent signalling networks may influence the response to β-AR agonist treatment in PPCM patients and analysed this hypothesis in CKO mice. Methods and results Follow-up analyses in 27 patients with severe PPCM (left ventricular ejection fraction ≤25%) revealed that 19 of 20 patients not obtaining dobutamine improved cardiac function. All seven patients obtaining dobutamine received heart transplantation (n = 4) or left ventricular assist devices (n = 3). They displayed diminished myocardial triglyceride, pyruvate, and lactate content compared with non-failing controls. The β-AR agonist isoproterenol (Iso) induced heart failure with high mortality in postpartum female, in non-pregnant female and in male CKO, but not in wild-type mice. Iso induced heart failure and high mortality in CKO mice by impairing fatty acid and glucose uptake, thereby generating a metabolic deficit. The latter was governed by disturbed STAT3-dependent signalling networks, microRNA-199a-5p, microRNA-7a-5p, insulin/glucose transporter-4, and neuregulin/ErbB signalling. The resulting cardiac energy depletion and oxidative stress promoted dysfunction and cardiomyocyte loss inducing irreversible heart failure, which could be attenuated by the β1-AR blocker metoprolol or glucose-uptake-promoting drugs perhexiline and etomoxir. Conclusions Iso impairs glucose uptake, induces energy depletion, oxidative stress, dysfunction, and death in STAT3-deficient cardiomyocytes mainly via β1-AR stimulation. These cellular alterations may underlie the dobutamine-induced irreversible heart failure progression in PPCM patients who frequently display reduced cardiac STAT3 expression. PMID:28201733

Measurement of renal blood flow by phase-contrast magnetic resonance imaging during septic acute kidney injury: a pilot investigation.

PubMed

Prowle, John R; Molan, Maurice P; Hornsey, Emma; Bellomo, Rinaldo

2012-06-01

In septic patients, decreased renal perfusion is considered to play a major role in the pathogenesis of acute kidney injury. However, the accurate measurement of renal blood flow in such patients is problematic and invasive. We sought to overcome such obstacles by measuring renal blood flow in septic patients with acute kidney injury using cine phase-contrast magnetic resonance imaging. Pilot observational study. University-affiliated general adult intensive care unit. Ten adult patients with established septic acute kidney injury and 11 normal volunteers. Cine phase-contrast magnetic resonance imaging measurement of renal blood flow and cardiac output. The median age of the study patients was 62.5 yrs and eight were male. At the time of magnetic resonance imaging, eight patients were mechanically ventilated, nine were on continuous hemofiltration, and five required vasopressors. Cine phase-contrast magnetic resonance imaging examinations were carried out without complication. Median renal blood flow was 482 mL/min (range 335-1137) in septic acute kidney injury and 1260 mL/min (range 791-1750) in healthy controls (p = .003). Renal blood flow indexed to body surface area was 244 mL/min/m2 (range 165-662) in septic acute kidney injury and 525 mL/min/m2 (range 438-869) in controls (p = .004). In patients with septic acute kidney injury, median cardiac index was 3.5 L/min/m2 (range 1.6-8.7), and median renal fraction of cardiac output was only 7.1% (range 4.4-10.8). There was no rank correlation between renal blood flow index and creatinine clearance in patients with septic acute kidney injury (r = .26, p = .45). Cine phase-contrast magnetic resonance imaging can be used to noninvasively and safely assess renal perfusion during critical illness in man. Near-simultaneous accurate measurement of cardiac output enables organ blood flow to be assessed in the context of the global circulation. Renal blood flow seems consistently reduced as a fraction of cardiac output in established septic acute kidney injury. Cine phase-contrast magnetic resonance imaging may be a valuable tool to further investigate renal blood flow and the effects of therapies on renal blood flow in critical illness.

Effects of lung protective mechanical ventilation associated with permissive respiratory acidosis on regional extra-pulmonary blood flow in experimental ARDS.

PubMed

Hering, Rudolf; Kreyer, Stefan; Putensen, Christian

2017-10-27

Lung protective mechanical ventilation with limited peak inspiratory pressure has been shown to affect cardiac output in patients with ARDS. However, little is known about the impact of lung protective mechanical ventilation on regional perfusion, especially when associated with moderate permissive respiratory acidosis. We hypothesized that lung protective mechanical ventilation with limited peak inspiratory pressure and moderate respiratory acidosis results in an increased cardiac output but unequal distribution of blood flow to the different organs of pigs with oleic-acid induced ARDS. Twelve pigs were enrolled, 3 died during instrumentation and induction of lung injury. Thus, 9 animals received pressure controlled mechanical ventilation with a PEEP of 5 cmH 2 O and limited peak inspiratory pressure (17 ± 4 cmH 2 O) versus increased peak inspiratory pressure (23 ± 6 cmH 2 O) in a crossover-randomized design and were analyzed. The sequence of limited versus increased peak inspiratory pressure was randomized using sealed envelopes. Systemic and regional hemodynamics were determined by double indicator dilution technique and colored microspheres, respectively. The paired student t-test and the Wilcoxon test were used to compare normally and not normally distributed data, respectively. Mechanical ventilation with limited inspiratory pressure resulted in moderate hypercapnia and respiratory acidosis (PaCO 2 71 ± 12 vs. 46 ± 9 mmHg, and pH 7.27 ± 0.05 vs. 7.38 ± 0.04, p < 0.001, respectively), increased cardiac output (140 ± 32 vs. 110 ± 22 ml/min/kg, p<0.05) and regional blood flow in the myocardium, brain and spinal cord, adrenal and thyroid glands, the mucosal layers of the esophagus and jejunum, the muscularis layers of the esophagus and duodenum, and the gall and urinary bladders. Perfusion of kidneys, pancreas, spleen, hepatic arterial bed, and the mucosal and muscularis blood flow to the other evaluated intestinal regions remained unchanged. In this porcine model of ARDS mechanical ventilation with limited peak inspiratory pressure resulting in moderate respiratory acidosis was associated with an increase in cardiac output. However, the better systemic blood flow was not uniformly directed to the different organs. This observation may be of clinical interest in patients, e.g. with cardiac, renal and cerebral pathologies.

Creatine uptake in mouse hearts with genetically altered creatine levels

PubMed Central

Hove, Michiel ten; Makinen, Kimmo; Sebag-Montefiore, Liam; Hunyor, Imre; Fischer, Alexandra; Wallis, Julie; Isbrandt, Dirk; Lygate, Craig; Neubauer, Stefan

2008-01-01

Creatine plays an important role in energy metabolism in the heart. Cardiomyocytes accumulate creatine via a specific creatine transporter (CrT), the capacity of which is reduced in the failing heart, resulting in lower myocardial creatine concentration. Therefore, to gain insight into how the CrT is regulated, we studied two mouse models of severely altered myocardial creatine levels. Cardiac creatine uptake levels were measured in isolated hearts from creatine-free guanidinoacetate-N-methyl transferase knock out (GAMT−/−) mice and from mice overexpressing the myocardial CrT (CrT-OE) using 14C-radiolabeled creatine. CrT mRNA levels were measured using real time RT-PCR and creatine levels with HPLC. Hearts from GAMT−/− mice showed a 7-fold increase in Vmax of creatine uptake and a 1.4-fold increase in CrT mRNA levels. The increase in Cr uptake and in CrT mRNA levels, however, was almost completely prevented when mice were fed a creatine supplemented diet, indicating that creatine uptake is subject to negative feedback regulation. Cardiac creatine uptake levels in CrT-OE mice were increased on average 2.7-fold, showing a considerable variation, in line with a similar variation in creatine content. Total CrT mRNA levels correlated well with myocardial creatine content (r = 0.67; p < 0.0001) but endogenous CrT mRNA levels did not correlate at all with myocardial creatine content (r = 0.01; p = 0.96). This study shows that creatine uptake can be massively upregulated in the heart, by almost an order of magnitude and that this upregulation is subject to feedback inhibition. In addition, our results strongly suggest that CrT activity is predominantly regulated by mechanisms other than alterations in gene expression. PMID:18602925

Sustained βAR Stimulation Mediates Cardiac Insulin Resistance in a PKA-Dependent Manner

PubMed Central

Denkaew, Tananat; Phosri, Sarawuth; Pinthong, Darawan; Parichatikanond, Warisara; Shimauchi, Tsukasa; Nishida, Motohiro

2016-01-01

Insulin resistance is a condition in which cells are defective in response to the actions of insulin in tissue glucose uptake. Overstimulation of β-adrenergic receptors (βARs) leads to the development of heart failure and is associated with the pathogenesis of insulin resistance in the heart. However, the mechanisms by which sustained βAR stimulation affects insulin resistance in the heart are incompletely understood. In this study, we demonstrate that sustained βAR stimulation resulted in the inhibition of insulin-induced glucose uptake, and a reduction of insulin induced glucose transporter (GLUT)4 expression that were mediated by the β2AR subtype in cardiomyocytes and heart tissue. Overstimulation of β2AR inhibited the insulin-induced translocation of GLUT4 to the plasma membrane of cardiomyocytes. Additionally, βAR mediated cardiac insulin resistance by reducing glucose uptake and GLUT4 expression via the cAMP-dependent and protein kinase A-dependent pathways. Treatment with β-blockers, including propranolol and metoprolol antagonized isoproterenol-mediated insulin resistance in the heart. The data in this present study confirm a critical role for protein kinase A in βAR-mediated insulin resistance. PMID:26652903

Lvad pump speed increase is associated with increased peak exercise cardiac output and vo2, postponed anaerobic threshold and improved ventilatory efficiency.

PubMed

Vignati, Carlo; Apostolo, Anna; Cattadori, Gaia; Farina, Stefania; Del Torto, Alberico; Scuri, Silvia; Gerosa, Gino; Bottio, Tomaso; Tarzia, Vincenzo; Bejko, Jonida; Sisillo, Erminio; Nicoli, Flavia; Sciomer, Susanna; Alamanni, Francesco; Paolillo, Stefania; Agostoni, Piergiuseppe

2017-03-01

Peak exercise cardiac output (CO) increase is associated with an increase of peak oxygen uptake (VO 2 ), provided that arteriovenous O 2 difference [Δ(Ca-Cv)O 2 ] does not decrease. At anaerobic threshold, VO 2 , is related to CO. We tested the hypothesis that, in heart failure (HF) patients with left ventricular assistance device (LVAD), an acute increase of CO obtained through changes in LVAD pump speed is associated with peak exercise and anaerobic threshold VO 2 increase. Fifteen of 20 patients bearing LVAD (Jarvik 2000) enrolled in the study successfully performed peak exercise evaluation. All patients had severe HF as shown by clinical evaluation, laboratory tests, echocardiography, spirometry with alveolar-capillary diffusion, and maximal cardiopulmonary exercise testing (CPET). CPETs with non-invasive CO measurements at rest and peak exercise were done on 2days at LVAD pump speed set randomly at 2 and 4. Increasing LVAD pump speed from 2 to 4 increased CO from 3.4±0.9 to 3.8±1.0L/min (ΔCO 0.4±0.6L/min, p=0.04) and from 5.3±1.3 to 5.9±1.4L/min (ΔCO 0.6±0.7L/min, p<0.01) at rest and peak exercise, respectively. Similarly, VO 2 increased from 788±169 to 841±152mL/min (ΔVO 2 52±76mL/min, p=0.01) and from 568±116 to 619±124mL/min (ΔVO 2 69±96mL/min, p=0.02) at peak exercise and at anaerobic threshold, respectively. Δ(Ca-Cv)O 2 did not change significantly, while ventilatory efficiency improved (VE/VCO 2 slope from 39.9±5.4 to 34.9±8.3, ΔVE/VCO 2 -5.0±6.4, p<0.01). In HF, an increase in CO with a higher LVAD pump speed is associated with increased peak VO 2 , postponed anaerobic threshold, and improved ventilatory efficiency. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Decreased cardiac SERCA2 expression, SR Ca uptake, and contractile function in hypothyroidism are attenuated in SERCA2 overexpressing transgenic rats.

PubMed

Vetter, Roland; Rehfeld, Uwe; Reissfelder, Christoph; Fechner, Henry; Seppet, Enn; Kreutz, Reinhold

2011-03-01

The sarco/endoplasmic reticulum (SR) Ca(2+)-ATPase SERCA2a has a key role in controlling cardiac contraction and relaxation. In hypothyroidism, decreased expression of the thyroid hormone (TH)-responsive SERCA2 gene contributes to slowed SR Ca(2+) reuptake and relaxation. We investigated whether cardiac expression of a TH-insensitive SERCA2a cDNA minigene can rescue SR Ca(2+) handling and contractile function in female SERCA2a-transgenic rats (TG) with experimental hypothyroidism. Wild-type rats (WT) and TG were rendered hypothyroid by 6-N-propyl-2-thiouracil treatment for 6 wk; control rats received no treatment. In vivo measured left ventricular (LV) hemodynamic parameters were compared with SERCA2a expression and function in LV tissue. Hypothyroidism decreased LV peak systolic pressure, dP/dt(max), and dP/dt(min) in both WT and TG. However, loss of function was less in TG. Thus slowed relaxation in hypothyroidism was found to be 1.5-fold faster in TG compared with WT (P < 0.05). In parallel, a 1.4-fold higher V(max) value of homogenate SR Ca(2+) uptake was observed in hypothyroid TG (P < 0.05 vs. hypothyroid WT), and the hypothyroidism-caused decline of LV SERCA2a mRNA expression in TG by -24% was markedly less than the decrease of -49% in WT (P < 0.05). A linear relationship was observed between the SERCA2a/PLB mRNA ratio values and the V(max) values of SR Ca(2+) uptake when the respective data of all experimental groups were plotted together (r = 0.90). The data show that expression of the TH-insensitive SERCA2a minigene compensates for loss of expressional activity of the TH-responsive native SERCA2a gene in the female hypothyroid rat heart. However, SR Ca(2+) uptake and in vivo heart function were only partially rescued.

Active metabolite of GLP-1 mediates myocardial glucose uptake and improves left ventricular performance in conscious dogs with dilated cardiomyopathy.

PubMed

Nikolaidis, Lazaros A; Elahi, Dariush; Shen, You-Tang; Shannon, Richard P

2005-12-01

We have shown previously that the glucagon-like peptide-1 (GLP-1)-(7-36) amide increases myocardial glucose uptake and improves left ventricular (LV) and systemic hemodynamics in both conscious dogs with pacing-induced dilated cardiomyopathy (DCM) and humans with LV systolic dysfunction after acute myocardial infarction. However, GLP-1-(7-36) is rapidly degraded in the plasma to GLP-1-(9-36) by dipeptidyl peptidase IV (DPP IV), raising the issue of which peptide is the active moiety. By way of methodology, we compared the efficacy of a 48-h continuous intravenous infusion of GLP-1-(7-36) (1.5 pmol.kg(-1).min(-1)) to GLP-1-(9-36) (1.5 pmol.kg(-1).min(-1)) in 28 conscious, chronically instrumented dogs with pacing-induced DCM by measuring LV function and transmyocardial substrate uptake under basal and insulin-stimulated conditions using hyperinsulinemic-euglycemic clamps. As a result, dogs with DCM demonstrated myocardial insulin resistance under basal and insulin-stimulated conditions. Both GLP-1-(7-36) and GLP-1-(9-36) significantly reduced (P < 0.01) LV end-diastolic pressure [GLP-1-(7-36), 28 +/- 1 to 15 +/- 2 mmHg; GLP-1-(9-36), 29 +/- 2 to 16 +/- 1 mmHg] and significantly increased (P < 0.01) the first derivative of LV pressure [GLP-1-(7-36), 1,315 +/- 81 to 2,195 +/- 102 mmHg/s; GLP-1-(9-36), 1,336 +/- 77 to 2,208 +/- 68 mmHg] and cardiac output [GLP-1-(7-36), 1.5 +/- 0.1 to 1.9 +/- 0.1 l/min; GLP-1-(9-36), 2.0 +/- 0.1 to 2.4 +/- 0.05 l/min], whereas an equivolume infusion of saline had no effect. Both peptides increased myocardial glucose uptake but without a significant increase in plasma insulin. During the GLP-1-(9-36) infusion, negligible active (NH2-terminal) peptide was measured in the plasma. In conclusion, in DCM, GLP-1-(9-36) mimics the effects of GLP-1-(7-36) in stimulating myocardial glucose uptake and improving LV and systemic hemodynamics through insulinomimetic as opposed to insulinotropic effects. These data suggest that GLP-1-(9-36) amide is an active peptide.

Cardiac function, myocardial mechano-energetic efficiency, and ventricular-arterial coupling in normal pregnancy.

PubMed

Iacobaeus, Charlotte; Andolf, Ellika; Thorsell, Malin; Bremme, Katarina; Östlund, Eva; Kahan, Thomas

2018-04-01

To assess cardiac function, myocardial mechanoenergetic efficiency (MEE), and ventricular-arterial coupling (VAC) longitudinally during normal pregnancy, and to study if there was an association between cardiac structure and function, and fetal growth. Cardiac structure and function, MEE, and ventricular-arterial coupling was assessed longitudinally in 52 healthy nulliparous women at 14, 24, and 34 weeks' gestation and 9-month postpartum. Left atrial diameter increased during pregnancy (30.41 ± 3.59 mm in the nonpregnant state and 31.02 ± 3.91, 34.06 ± 3.58, and 33.9 ± 2.97 mm in the first, second, and third trimesters, P < 0.001). Left ventricular mass increased 117.12 ± 45.0 g in the nonpregnant state and 116.5 ± 33.0, 126.9 ± 34.5, 128.4 ± 36 g in the first, second, and third trimesters (P < 0.001). Cardiac output increased from 3.4 ± 1.2 l/min to 4.3 ± 0.7 l/min in the second and third trimesters (P < 0.001). Diastolic function decreased as both E/A and e'/a' decreased during pregnancy (P < 0.05 and P < 0.001, respectively). MEE and VAC were retained during pregnancy. Heart rate was associated with birth weight centile in the first (r = 0.41, P = 0.002) and second (r = 0.46, P = 0.002) trimester. The increase in cardiac output during normal pregnancy is obtained by an increase in heart rate, followed by structural cardiac changes. The impaired systolic function is accomplished by a deteriorated diastolic function. Despite these rapid changes, the myocardium manages to work efficient with a preserved MEE. Cardiac and arterial adaption to pregnancy seems to appear parallel as evidenced by a preserved VAC.

Post-hypothermic cardiac left ventricular systolic dysfunction after rewarming in an intact pig model

PubMed Central

2010-01-01

Introduction We developed a minimally invasive, closed chest pig model with the main aim to describe hemodynamic function during surface cooling, steady state severe hypothermia (one hour at 25°C) and surface rewarming. Methods Twelve anesthetized juvenile pigs were acutely catheterized for measurement of left ventricular (LV) pressure-volume loops (conductance catheter), cardiac output (Swan-Ganz), and for vena cava inferior occlusion. Eight animals were surface cooled to 25°C, while four animals were kept as normothermic time-matched controls. Results During progressive cooling and steady state severe hypothermia (25°C) cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), maximal deceleration of pressure in the cardiac cycle (dP/dtmin), indexes of LV contractility (preload recruitable stroke work, PRSW, and maximal acceleration of pressure in the cardiac cycle, dP/dtmax) and LV end diastolic and systolic volumes (EDV and ESV) were significantly reduced. Systemic vascular resistance (SVR), isovolumetric relaxation time (Tau), and oxygen content in arterial and mixed venous blood increased significantly. LV end diastolic pressure (EDP) remained constant. After rewarming all the above mentioned hemodynamic variables that were depressed during 25°C remained reduced, except for CO that returned to pre-hypothermic values due to an increase in heart rate. Likewise, SVR and EDP were significantly reduced after rewarming, while Tau, EDV, ESV and blood oxygen content normalized. Serum levels of cardiac troponin T (TnT) and tumor necrosis factor-alpha (TNF-α) were significantly increased. Conclusions Progressive cooling to 25°C followed by rewarming resulted in a reduced systolic, but not diastolic left ventricular function. The post-hypothermic increase in heart rate and the reduced systemic vascular resistance are interpreted as adaptive measures by the organism to compensate for a hypothermia-induced mild left ventricular cardiac failure. A post-hypothermic increase in TnT indicates that hypothermia/rewarming may cause degradation of cardiac tissue. There were no signs of inadequate global oxygenation throughout the experiments. PMID:21092272

Alternating versus synchronous ventilation of left and right lungs in piglets.

PubMed

Versprille, A; Hrachovina, V; Jansen, J R

1995-12-01

We tested whether alternating ventilation (AV) of each lung (i.e. with a phase difference of half a ventilatory cycle) would decrease central venous pressure and so increase cardiac output when compared with simultaneous ventilation (SV) of both lungs. If, during AV, the inflated lung expands partly via compression of the opposite lung, mean lung volume will be smaller during AV than SV. As a consequence, mean intrathoracic pressure (as cited in the literature), and therefore, central venous pressure will be smaller. The experiments were performed in seven anaesthetized and paralyzed piglets using a double-piston ventilator. Minute ventilation was the same during AV and SV. Starting at SV, we alternated three times between AV and SV for periods of 10 min. During AV, central venous pressure was decreased by 0.7 mmHg and cardiac output was increased by 10 +/- 4.4% (mean, +/-SD) compared with SV. AV also resulted in increased arterial pressure. During one-sided inflation with closed outlet of the opposite lung, a pressure rise occurred in the opposite lung, indicating compression. The higher cardiac output during AV than SV can be explained by the fact that central venous pressure is lower during AV. This lower central venous pressure is very probably due to the lower mean intrathoracic pressure caused by compression of the opposite lung during unilateral inflation.

Anisotropic Reinforcement of Acute Anteroapical Infarcts Improves Pump Function

PubMed Central

Fomovsky, Gregory M.; Clark, Samantha A.; Parker, Katherine M.; Ailawadi, Gorav; Holmes, Jeffrey W.

2012-01-01

Background We hypothesize that a therapy that improves LV pump function early after infarction should decrease the need for compensation through sympathetic activation and dilation, thereby reducing the risk of developing heart failure. The mechanical properties of healing myocardial infarcts are an important determinant of left ventricular (LV) function, yet improving function by altering infarct properties has proven unexpectedly difficult. Using a computational model, we recently predicted that stiffening a large anterior infarct anisotropically (in only one direction) would improve LV function, while isotropic stiffening, the focus of previous studies and therapies, would not. The goal of this study was to test the novel strategy of anisotropic infarct reinforcement. Methods and Results We tested the effects of anisotropic infarct reinforcement in 10 open-chest dogs with large anteroapical infarcts that depressed LV pump function. We measured regional mechanics, LV volumes, and cardiac output at a range of preloads at Baseline, 45 minutes after coronary ligation (Ischemia), and 30 minutes later, following surgical reinforcement in the longitudinal direction (Anisotropic). Ischemia shifted the end-systolic pressure-volume relationship (ESPVR) and cardiac output curves rightward, decreasing cardiac output at matched end-diastolic pressure (EDP) by 44%. Anisotropic reinforcement significantly improved systolic function without impairing diastolic function, recovering half the deficit in overall LV function. Conclusions We conclude that anisotropic reinforcement is a promising new approach to improving LV function following a large myocardial infarction. PMID:22665716

Angiotensin II and CRF receptors in the central nucleus of the amygdala mediate hemodynamic response variability to cocaine in conscious rats.

PubMed

Watanabe, Mari A; Kucenas, Sarah; Bowman, Tamara A; Ruhlman, Melissa; Knuepfer, Mark M

2010-01-14

Stress or cocaine evokes either a large increase in systemic vascular resistance (SVR) or a smaller increase in SVR accompanied by an increase in cardiac output (designated vascular and mixed responders, respectively) in Sprague-Dawley rats. We hypothesized that the central nucleus of the amygdala (CeA) mediates this variability. Conscious, freely-moving rats, instrumented for measurement of arterial pressure and cardiac output and for drug delivery into the CeA, were given cocaine (5 mg/kg, iv, 4-6 times) and characterized as vascular (n=15) or mixed responders (n=10). Subsequently, we administered cocaine after bilateral microinjections (100 nl) of saline or selective agents in the CeA. Muscimol (80 pmol), a GABA(A) agonist, or losartan (43.4 pmol), an AT(1) receptor antagonist, attenuated the cocaine-induced increase in SVR in vascular responders, selectively, such that vascular responders were no longer different from mixed responders. The corticotropin releasing factor (CRF) antagonist, alpha-helical CRF(9-41) (15.7 pmol), abolished the difference between cardiac output and SVR in mixed and vascular responders. We conclude that greater increases in SVR observed in vascular responders are dependent on AT(1) receptor activation and, to a lesser extent on CRF receptors. Therefore, AT(1) and CRF receptors in the CeA contribute to hemodynamic response variability to intravenous cocaine.

Angiotensin II and CRF Receptors in the Central Nucleus of the Amygdala Mediate Hemodynamic Response Variability to Cocaine in Conscious Rats

PubMed Central

Watanabe, Mari A.; Kucenas, Sarah; Bowman, Tamara A.; Ruhlman, Melissa; Knuepfer, Mark M.

2009-01-01

Stress or cocaine evokes either a large increase in systemic vascular resistance (SVR) or a smaller increase in SVR accompanied by an increase in cardiac output (designated vascular and mixed responders, respectively) in Sprague-Dawley rats. We hypothesized that the central nucleus of the amygdala (CeA) mediates this variability. Conscious, freely-moving rats, instrumented for measurement of arterial pressure and cardiac output and for drug delivery into the CeA, were given cocaine (5 mg/kg, iv, 4-6 times) and characterized as vascular (n=15) or mixed responders (n=10). Subsequently, we administered cocaine after bilateral microinjections (100 nl) of saline or selective agents in the CeA. Muscimol (80 pmol), a GABAA agonist, or losartan (43.4 pmol), an AT1 receptor antagonist, attenuated the cocaine-induced increase in SVR in vascular responders, selectively, such that vascular responders were no longer different from mixed responders. The corticotropin releasing factor (CRF) antagonist, α-helical CRF9-41 (15.7 pmol), abolished the difference between cardiac output and SVR in mixed and vascular responders. We conclude that greater increases in SVR observed in vascular responders are dependent on AT1 receptor activation and, to a lesser extent on CRF receptors. Therefore, AT1 and CRF receptors in the CeA contribute to hemodynamic response variability to intravenous cocaine. PMID:19879859

Effect of exercise, heat stress and dehydration on myocardial performance.

PubMed

Fehling, P C; Haller, J M; Lefferts, W K; Hultquist, E M; Wharton, M; Rowland, T W; Smith, D L

2015-06-01

Myocardial dysfunction is a well-documented outcome of extended periods of high cardiac output. Whether similar effects occur during firefighting, an occupation characterized by repeated periods of work compounded by dehydration and heat stress, is uncertain. To investigate the independent and combined effects of moderate heat stress and dehydration on indicators of myocardial performance following intermittent, submaximal treadmill exercise while wearing personal protective equipment (PPE). Twelve aerobically fit young men (age 21.5±2.6 years; maximal oxygen uptake [VO2max] 60.3±4.4ml kg(-1) min(-1)) performed intermittent treadmill walking exercise consisting of three 20min bouts at an intensity of ~40% VO2max separated by two periods of rest in four different conditions in random order: (i) no heat stress-euhydrated, (ii) heat stress-euhydrated (heat stress created by wearing PPE, (iii) no heat stress-dehydrated and (iv) heat stress-dehydrated. We measured core temperature by a telemetric gastrointestinal pill. We determined cardiac variables by standard echocardiographic techniques immediately before and ~30min after exercise. We recorded no significant changes in markers of systolic (ejection fraction, shortening fraction, tissue Doppler-S) or diastolic (mitral peak E velocity, tissue Doppler-E' and E/E') function following exercise in any of the four conditions. In this model of exercise designed to mimic the work, heat stress and dehydration associated with firefighting activities, we observed no negative effects on myocardial inotropic or lusitropic function. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

An overview of the issues: physiological effects of bed rest and restricted physical activity

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Bloomfield, S. A.; Greenleaf, J. E.

1997-01-01

Reduction of exercise capacity with confinement to bed rest is well recognized. Underlying physiological mechanisms include dramatic reductions in maximal stroke volume, cardiac output, and oxygen uptake. However, bed rest by itself does not appear to contribute to cardiac dysfunction. Increased muscle fatigue is associated with reduced muscle blood flow, red cell volume, capillarization and oxidative enzymes. Loss of muscle mass and bone density may be reflected by reduced muscle strength and higher risk for injury to bones and joints. The resultant deconditioning caused by bed rest can be independent of the primary disease and physically debilitating in patients who attempt to reambulate to normal active living and working. A challenge to clinicians and health care specialists has been the identification of appropriate and effective methods to restore physical capacity of patients during or after restricted physical activity associated with prolonged bed rest. The examination of physiological responses to bed rest deconditioning and exercise training in healthy subjects has provided significant information to develop effective rehabilitation treatments. The successful application of acute exercise to enhance orthostatic stability, daily endurance exercise to maintain aerobic capacity, or specific resistance exercises to maintain musculoskeletal integrity rather than the use of surgical, pharmacological, and other medical treatments for clinical conditions has been enhanced by investigation and understanding of underlying mechanisms that distinguish physical deconditioning from the disease. This symposium presents an overview of cardiovascular and musculoskeletal deconditioning associated with reduced physical work capacity following prolonged bed rest and exercise training regimens that have proven successful in ameliorating or reversing these adverse effects.

Ventilation and gas exchange management after cardiac arrest.

PubMed

Sutherasan, Yuda; Raimondo, Pasquale; Pelosi, Paolo

2015-12-01

For several decades, physicians had integrated several interventions aiming to improve the outcomes in post-cardiac arrest patients. However, the mortality rate after cardiac arrest is still as high as 50%. Post-cardiac arrest syndrome is associated with high morbidity and mortality due to not only poor neurological outcome and cardiovascular failure but also respiratory dysfunction. To minimize ventilator-associated lung injury, protective mechanical ventilation by using low tidal volume ventilation and driving pressure may decrease pulmonary complications and improve survival. Low level of positive end-expiratory pressure (PEEP) can be initiated and titrated with careful cardiac output and respiratory mechanics monitoring. Furthermore, optimizing gas exchange by avoiding hypoxia and hyperoxia as well as maintaining normocarbia may improve neurological and survival outcome. Early multidisciplinary cardiac rehabilitation intervention is recommended. Minimally invasive monitoring techniques, that is, echocardiography, transpulmonary thermodilution method measuring extravascular lung water, as well as transcranial Doppler ultrasound, might be useful to improve appropriate management of post-cardiac arrest patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impaired chronotropic and vasodilator reserves limit exercise capacity in patients with heart failure and a preserved ejection fraction.

PubMed

Borlaug, Barry A; Melenovsky, Vojtech; Russell, Stuart D; Kessler, Kristy; Pacak, Karel; Becker, Lewis C; Kass, David A

2006-11-14

Nearly half of patients with heart failure have a preserved ejection fraction (HFpEF). Symptoms of exercise intolerance and dyspnea are most often attributed to diastolic dysfunction; however, impaired systolic and/or arterial vasodilator reserve under stress could also play an important role. Patients with HFpEF (n=17) and control subjects without heart failure (n=19) generally matched for age, gender, hypertension, diabetes mellitus, obesity, and the presence of left ventricular hypertrophy underwent maximal-effort upright cycle ergometry with radionuclide ventriculography to determine rest and exercise cardiovascular function. Resting cardiovascular function was similar between the 2 groups. Both had limited exercise capacity, but this was more profoundly reduced in HFpEF patients (exercise duration 180+/-71 versus 455+/-184 seconds; peak oxygen consumption 9.0+/-3.4 versus 14.4+/-3.4 mL x kg(-1) x min(-1); both P<0.001). At matched low-level workload, HFpEF subjects displayed approximately 40% less of an increase in heart rate and cardiac output and less systemic vasodilation (all P<0.05) despite a similar rise in end-diastolic volume, stroke volume, and contractility. Heart rate recovery after exercise was also significantly delayed in HFpEF patients. Exercise capacity correlated with the change in cardiac output, heart rate, and vascular resistance but not end-diastolic volume or stroke volume. Lung blood volume and plasma norepinephrine levels rose similarly with exercise in both groups. HFpEF patients have reduced chronotropic, vasodilator, and cardiac output reserve during exercise compared with matched subjects with hypertensive cardiac hypertrophy. These limitations cannot be ascribed to diastolic abnormalities per se and may provide novel therapeutic targets for interventions to improve exercise capacity in this disorder.

Effects of cholinergic and beta-adrenergic blockade on orthostatic tolerance in healthy subjects

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Sather, T. M.

2000-01-01

Cardiovascular responses during a graded lower body negative pressure (LBNP) protocol were compared before and after atropine and propranolol administration to test the hypothesis that both sympathetic and parasympathetic control of cardio-acceleration are associated with syncopal predisposition to orthostatic stress in healthy subjects. Eleven men were categorized into two groups having high (HT, N = 6) or low (LT, N = 5) tolerance based on their total time before the onset of presyncopal symptoms. HT and LT groups were similar in physical characteristics, fitness, and baseline cardiovascular measurements. Atropine treatment had no effect on LBNP tolerance or mean arterial pressure at presyncope, despite an atropine-induced increase in heart rate. Propranolol treatment reduced (p<0.05) LBNP tolerance in both groups. Diminished LBNP tolerance after propranolol administration was associated with reductions in cardiac output, whereas increase in systemic peripheral resistance from baseline to presyncope was unaffected by propranolol. Reduction in cardiac output and LBNP tolerance after beta blockade reflected a chronotropic effect because lower LBNP tolerance for the HT (-50%) and LT (-39%) groups was associated with dramatic reductions (p <0.05) in the magnitude of LBNP-induced tachycardia without significant effects on stroke volume at presyncope. Absence of an atropine-induced difference in cardiac output and systemic peripheral resistance between HT and LT groups failed to support the notion that cardiac vagal withdrawal represents a predominant mechanism that could account for differences in orthostatic tolerance. Because a reduction in LBNP tolerance in both HT and LT groups after propranolol treatment was most closely associated with reduced tachycardia, the data suggest that a primary autonomically mediated mechanism for maintenance of mean arterial pressure and orthostatic tolerance in healthy subjects is beta adrenergic-induced tachycardia.

Conversion of cardiac performance data in analog form for digital computer entry

NASA Technical Reports Server (NTRS)

Miller, R. L.

1972-01-01

A system is presented which will reduce analog cardiac performance data and convert the results to digital form for direct entry into a commercial time-shared computer. Circuits are discussed which perform the measurement and digital conversion of instantaneous systolic and diastolic parameters from the analog blood pressure waveform. Digital averaging over a selected number of heart cycles is performed on these measurements, as well as those of flow and heart rate. The determination of average cardiac output and peripheral resistance, including trends, is the end result after processing by digital computer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartmann, A.; Frenkel, J.; Hopf, R.

Amyloidosis is a systemic disease frequently involving the myocardium and leading to functional disturbances of the heart. Amyloidosis can mimic other cardiac diseases. A conclusive clinical diagnosis of cardiac involvement can only be made by a combination of different diagnostic methods. In 7 patients with myocardial amyloidosis we used a combined first-pass and static scintigraphy with technetium-99 m-pyrophosphate. There was only insignificant myocardial uptake of the tracer. The first-pass studies however revealed reduced systolic function in 4/7 patients and impaired diastolic function in 6/7 patients. Therefore, although cardiac amyloid could not be demonstrated in the static scintigraphy due to amyloidmore » fibril amount and composition, myocardial functional abnormalities were seen in the first-pass study.« less

Cardiac involvement in facio-scapulo-humeral muscular dystrophy: a family study using Thallium-201 single-photon-emission-computed tomography.

PubMed

Faustmann, P M; Farahati, J; Rupilius, B; Dux, R; Koch, M C; Reiners, C

1996-12-01

Fifteen persons from two consecutive generations of one family affected with facio-scapulo-humeral muscular dystrophy (FSHD) were clinically and neurophysiologically examined. Diagnostic muscle biopsies were obtained from two members. Linkage analysis showed that all four affected members of the family inherit the same 4q35 haplotype giving a lod score of z = +1.44. Six family members were examined by ECG at rest and under stress, by two-dimensional echocardiography, and by cardiac Thallium-201 single-photon-emission computed tomography (Tl-201-SPECT) under dobutamine stress and at rest. Abnormal reduced Tl-201 uptake in cardiac SPECT was only found in the affected members of the family. Therefore we suggest that cardiac Tl-201-SPECT abnormalities in FSHD reflect cardiomyogenic changes in this type of muscular disease.

Percent Emphysema and Right Ventricular Structure and Function

PubMed Central

Grau, Maria; Lima, Joao A.; Hoffman, Eric A.; Bluemke, David A.; Carr, J. Jeffrey; Chahal, Harjit; Enright, Paul L; Jain, Aditya; Prince, Martin R.; Kawut, Steven M.

2013-01-01

Background: Severe COPD can lead to cor pulmonale and emphysema and is associated with impaired left ventricular (LV) filling. We evaluated whether emphysema and airflow obstruction would be associated with changes in right ventricular (RV) structure and function and whether these associations would differ by smoking status. Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) performed cardiac MRI on 5,098 participants without clinical cardiovascular disease aged 45 to 84 years. RV and emphysema measures were available for 4,188 participants. Percent emphysema was defined as the percentage of voxels below −910 Hounsfield units in the lung windows on cardiac CT scans. Generalized additive models were used to control for confounders and adjust for respective LV parameters. Results: Participants consisted of 13% current smokers, 36% former smokers, and 52% never smokers. Percent emphysema was inversely associated with RV end-diastolic volume, stroke volume, cardiac output, and mass prior to adjustment for LV measures. After adjustment for LV end-diastolic volume, greater percent emphysema was associated with greater RV end-diastolic volume (+1.5 mL, P = .03) among current smokers, smaller RV end-diastolic volume (−0.8 mL, P = .02) among former smokers, and similar changes among never smokers. Conclusions: Percent emphysema was associated with smaller RV volumes and lower mass. The relationship of emphysema to cardiac function is complex but likely involves increased pulmonary vascular resistance, predominantly with reduced cardiac output, pulmonary hyperinflation, and accelerated cardiopulmonary aging. PMID:23450302

Understanding changes in cardiovascular pathophysiology.

PubMed

Chummun, Harry

Cardiovascular pathophysiological changes, such as hypertension and enlarged ventricles, reflect the altered functions of the heart and its circulation during ill-health. This article examines the normal and altered anatomy of the cardiac valves, the contractile elements and enzymes of the myocardium, the significance of the different factors associated with cardiac output, and the role of the autonomic nervous system in the heart beat. It also explores how certain diseases alter these functions and result in cardiac symptoms. Nurses can benefit from knowledge of these specific changes, for example, by being able to ask relevant questions in order to ascertain the nature of a patients condition, by being able to take an effective patient history and by being able to read diagnostic results, such as electrocardiograms and cardiac enzyme results. All this will help nurses to promote sound cardiac care based on a physiological rationale.

Skin temperature and core-peripheral temperature gradient as markers of hemodynamic status in critically ill patients: a review.

PubMed

Schey, Bernadette M; Williams, David Y; Bucknall, Tracey

2010-01-01

To examine the evidential basis underpinning the monitoring of skin temperature and core-peripheral temperature gradient as elements of hemodynamic assessment in critically ill and adult cardiac surgical patients. Twenty-six studies examining the efficacy of skin temperature or temperature gradient as markers of hemodynamic status were selected as part of an integrative review. Evidence pertaining to the efficacy of these parameters as markers of cardiac function is equivocal and has not been well appraised in the adult cardiac surgical population. Skin temperature and systemic vascular resistance are also affected by factors other than cardiac output. Skin temperature and core-peripheral temperature gradient should not be considered in isolation from other hemodynamic parameters when assessing cardiac status until they are validated by further large-scale prospective studies. 2010. Published by Mosby, Inc.

The effect of the oxygen uptake-power output relationship on the prediction of supramaximal oxygen demands.

PubMed

Muniz-Pumares, Daniel; Pedlar, Charles; Godfrey, Richard; Glaister, Mark

2017-01-01

The aim of this study was to investigate the relationship between oxygen uptake (V̇O2) and power output at intensities below and above the lactate threshold (LT) in cyclists; and to determine the reliability of supramaximal power outputs linearly projected from these relationships. Nine male cyclists (mean±standard deviation age: 41±8 years; mass: 77±6 kg, height: 1.79±0.05 m and V̇O2max: 54±7 mL∙kg-1∙min-1) completed two cycling trials each consisting of a step test (10×3 min stages at submaximal incremental intensities) followed by a maximal test to exhaustion. The lines of best fit for V̇O2 and power output were determined for: the entire step test; stages below and above the LT, and from rolling clusters of five consecutive stages. Lines were projected to determine a power output predicted to elicit 110% peak V̇O2. There were strong linear correlations (r≥0.953; P<0.01) between V̇O2 and power output using the three approaches; with the slope, intercept, and projected values of these lines unaffected (P≥0.05) by intensity. The coefficient of variation of the predicted power output at 110% V̇O2max was 6.7% when using all ten submaximal stages. Cyclists exhibit a linear V̇O2 and power output relationship when determined using 3 min stages, which allows for prediction of a supramaximal intensity with acceptable reliability.

US Army Institute of Surgical Research Annual Research Progress Report for Fiscal Year 1987.

DTIC Science & Technology

1987-10-01

oases, respiratory rate, chest roentgenograms), cardiovascular (blood pressure, central venous pressure, cardiac output), and renal (urine output, urine...Monitoring includes the precordial and/or esophageal stethoscope, peripheral pulse, blood pressure, central venous pressure, Swan-Ganz catheter... central venous , peripheral venous , and Swan-Ganz (7F, American Edward Laboratories, Irvine CA) catheters and an esophageal balloon were inserted. After a 2

A secondary meta-synthesis of qualitative studies of gender and access to cardiac rehabilitation.

PubMed

Angus, Jan E; King-Shier, Kathryn M; Spaling, Melisa A; Duncan, Amanda S; Jaglal, Susan B; Stone, James A; Clark, Alexander M

2015-08-01

To discuss issues in the theorization and study of gender observed during a qualitative meta-synthesis of influences on uptake of secondary prevention and cardiac rehabilitation services. Women and men can equally benefit from secondary prevention/cardiac rehabilitation and there is a need to understand gender barriers to uptake. Meta-method analysis secondary to meta-synthesis. For the meta-synthesis, a systematic search was performed to identify and retrieve studies published as full papers during or after 1995 and contained: a qualitative research component wholly or in a mixed method design, extractable population specific data or themes for referral to secondary prevention programmes and adults ≥18 years. Databases searched between January 1995-31 October 2011 included: CSA Sociological Abstracts, EBSCOhost CINAHL, EBSCOhost Gender Studies, EBSCOhost Health Source Nursing: Academic Edition, EBSCOhost SPORTDiscus, EBSCOhost SocINDEX. Studies were reviewed against inclusion/exclusion criteria. Included studies were subject to quality appraisal and standardized data extraction. Of 2264 screened articles, 69 were included in the meta-method analysis. Only four studies defined gender or used gender theories. Findings were mostly presented as inherently the characteristic of gendered worldviews of participants. The major themes suggest a mismatch between secondary prevention/cardiac rehabilitation services and consumers' needs, which are usually portrayed as differing according to gender but may also be subject to intersecting influences such as age or socioeconomic status. There is a persistent lack of theoretically informed gender analysis in qualitative literature in this field. Theory-driven gender analysis will improve the conceptual clarity of the evidence base for gender-sensitive cardiac rehabilitation programme development. © 2015 John Wiley & Sons Ltd.

Transient Receptor Potential Vanilloid 2 Regulates Myocardial Response to Exercise

PubMed Central

Naticchioni, Mindi; Karani, Rajiv; Smith, Margaret A.; Onusko, Evan; Robbins, Nathan; Jiang, Min; Radzyukevich, Tatiana; Fulford, Logan; Gao, Xu; Apel, Ryan; Heiny, Judith; Rubinstein, Jack; Koch, Sheryl E.

2015-01-01

The myocardial response to exercise is an adaptive mechanism that permits the heart to maintain cardiac output via improved cardiac function and development of hypertrophy. There are many overlapping mechanisms via which this occurs with calcium handling being a crucial component of this process. Our laboratory has previously found that the stretch sensitive TRPV2 channels are active regulators of calcium handling and cardiac function under baseline conditions based on our observations that TRPV2-KO mice have impaired cardiac function at baseline. The focus of this study was to determine the cardiac function of TRPV2-KO mice under exercise conditions. We measured skeletal muscle at baseline in WT and TRPV2-KO mice and subjected them to various exercise protocols and measured the cardiac response using echocardiography and molecular markers. Our results demonstrate that the TRPV2-KO mouse did not tolerate forced exercise although they became increasingly exercise tolerant with voluntary exercise. This occurs as the cardiac function deteriorates further with exercise. Thus, our conclusion is that TRPV2-KO mice have impaired cardiac functional response to exercise. PMID:26356305

Blood flow regulation and oxygen uptake during high-intensity forearm exercise.

PubMed

Nyberg, S K; Berg, O K; Helgerud, J; Wang, E

2017-04-01

The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25 ± 2 yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound, and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO 2diff ) during 6-min bouts of 60, 80, and 100% of maximal work rate (WR max ), respectively. Blood flow and oxygen uptake increased ( P < 0.05) from 60%WR max [557 ± 177(SD) ml/min; 56.0 ± 21.6 ml/min] to 80%WR max (679 ± 190 ml/min; 70.6 ± 24.8 ml/min), but no change was seen from 80%WR max to 100%WR max Blood velocity (49.5 ± 11.5 to 58.1 ± 11.6 cm/s) and brachial diameter (0.49 ± 0.05 to 0.50 ± 0.06 cm) showed concomitant increases ( P < 0.05) with blood flow from 60% to 80%WR max, whereas no differences were observed in a-vO 2diff Shear rate also increased ( P < 0.05) from 60% (822 ± 196 s -1 ) to 80% (951 ± 234 s -1 ) of WR max The mean response time (MRT) was slower ( P < 0.05) for blood flow (60%WR max 50 ± 22 s; 80%WR max 51 ± 20 s; 100%WR max 51 ± 23 s) than a-vO 2diff (60%WR max 29 ± 9 s; 80%WR max 29 ± 5 s; 100%WR max 20 ± 5 s), but not different from oxygen uptake (60%WR max 44 ± 25 s; 80%WR max 43 ± 14 s; 100%WR max 41 ± 32 s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WR max and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations. NEW & NOTEWORTHY This study evaluated blood flow regulation and oxygen uptake during small muscle mass forearm exercise with high to maximal intensity. Despite utilizing only a fraction of cardiac output, blood flow reached a plateau at 80% of maximal work rate and regulated peak oxygen uptake. Furthermore, the results revealed that muscle contractions dictated bulk oxygen delivery and yielded three times higher peak blood flow in the relaxation phase compared with mean values. Copyright © 2017 the American Physiological Society.

Inhaled anaesthetics and nitrous oxide: Complexities overlooked: things may not be what they seem.

PubMed

Hendrickx, Jan; Peyton, Philip; Carette, Rik; De Wolf, Andre

2016-09-01

This review re-examines existing pharmacokinetic and pharmacodynamic concepts of inhaled anaesthetics. After showing where uptake is hidden in the classic FA/FI curve, it is argued that target-controlled delivery of inhaled agents warrants a different interpretation of the factors affecting this curve (cardiac output, ventilation and blood/gas partition coefficient). Blood/gas partition coefficients of modern agents may be less important clinically than generally assumed. The partial pressure cascade from delivered to inspired to end-expired is re-examined to better understand the effect of rebreathing during low-flow anaesthesia, including the possibility of developing a hypoxic inspired mixture despite existing machine standards. Inhaled agents are easy to administer because they are transferred according to partial pressure gradients. In addition, the narrow dose-response curves for the three end points of general anaesthesia (loss of response to verbal command, immobility and autonomic reflex control) allow the clinical use of MACawake, MAC and MACBAR to determine depth of anaesthesia. Opioids differentially affect these clinical effects of inhaled agents. The effect of ventilation-perfusion relationships on gas uptake is discussed, and it is shown how moving beyond Riley's useful but simplistic model allows us to better understand both the concept and the magnitude of the second gas effect of nitrous oxide. It is argued that nitrous oxide remains a clinically useful drug. We hope to bring old (but ignored) and new (but potentially overlooked) information into the educational and clinical arenas to stimulate discussion among clinicians and researchers. We should not let technology pass by our all too engrained older concepts.

Seeking an explanation for the poor uptake of in-hospital AED programs.

PubMed

Laws, Tom A; Zeitz, Kathryn; Fiedler, Brenton A

2004-09-01

The automated external defibrillator (AED) has been adopted by emergency service personnel as a first-line intervention in the management of out-of-hospital cardiac arrest (OHCA). AED leads to more successful Advanced Cardiac Life Support; consequently, national resuscitation organisations worldwide have recommended that nurses and doctors also integrate AEDs as a component of their basic life-support response to cardiac arrest. Despite these recommendations, the implementation of AED programs within hospitals has been generally sporadic and isolated. A continuation of this situation will most likely disturb and perplex nurses and patients, as they are key stakeholders with respect to upholding recommended BLS practices. In the absence of any explanation from change agents within hospitals, this paper seeks, by way of a pilot study and a review of the literature, to identify the extent of the problem and identify factors contributing to the relatively slow uptake of this device. We argue that nurses and other first responders to in-hospital cardiac arrest (CA) have much to gain, in the context of Occupational Health Safety and Welfare (OHS and W), from ready access to AEDs. Cost factors are also considered, with initial cost of AED purchase likely to be a major concern for managers of hospital budgets. The issues we discuss in this paper clearly support the need for further research to (a) explain the nature of public hospital resistance to AEDs and (b) to consider whether AEDs will provide practical advantages to public hospitals from an occupational, social and economic perspective.

Oxygen uptake efficiency slope and peak oxygen consumption predict prognosis in children with tetralogy of Fallot.

PubMed

Tsai, Yun-Jeng; Li, Min-Hui; Tsai, Wan-Jung; Tuan, Sheng-Hui; Liao, Tin-Yun; Lin, Ko-Long

2016-07-01

Oxygen uptake efficiency slope (OUES) and peak oxygen consumption (VO2peak) are exercise parameters that can predict cardiac morbidity in patients with numerous heart diseases. But the predictive value in patients with tetralogy of Fallot is still undetermined, especially in children. We evaluated the prognostic value of OUES and VO2peak in children with total repair of tetralogy of Fallot. Retrospective cohort study. Forty tetralogy of Fallot patients younger than 12 years old were recruited. They underwent a cardiopulmonary exercise test during the follow-up period after total repair surgery. The results of the cardiopulmonary exercise test were used to predict the cardiac related hospitalization in the following two years after the test. OUES normalized by body surface area (OUES/BSA) and the percentage of predicted VO2peak appeared to be predictive for two-year cardiac related hospitalization. Receiver operating characteristic curve analysis demonstrated that the best threshold value for OUES/BSA was 1.029 (area under the curve = 0.70, p = 0.03), and for VO2peak was 74% of age prediction (area under the curve = 0.72, p = 0.02). The aforementioned findings were confirmed by Kaplan-Meier plots and log-rank test. OUES/BSA and VO2peak are useful predictors of cardiac-related hospitalization in children with total repair of tetralogy of Fallot. © The European Society of Cardiology 2015.

Assessing acute coronary syndrome patients' cardiac-related beliefs, motivation and mood over time to predict non-attendance at cardiac rehabilitation.

PubMed

Herber, Oliver R; Jones, Martyn C; Smith, Karen; Johnston, Derek W

2012-12-01

This research protocol describes and justifies a study to assess patients' cardiac-related beliefs (i.e. illness representations, knowledge/misconceptions, cardiac treatment beliefs), motivation and mood over time to predict non-attendance at a cardiac rehabilitation programme by measuring weekly/monthly changes in these key variables. Heart disease is the UK's leading cause of death. Evidence from meta-analyses suggests that cardiac rehabilitation facilitates recovery following acute cardiac events. However, 30-60% of patients do not attend cardiac rehabilitation. There is some evidence from questionnaire studies that a range of potentially modifiable psychological variables including patients' cardiac-related beliefs, motivation and mood may influence attendance. Mixed-methods. In this study, during 2012-2013, electronic diary data will be gathered weekly/monthly from 240 patients with acute coronary syndrome from discharge from hospital until completion of the cardiac rehabilitation programme. This will identify changes and interactions between key variables over time and their power to predict non-attendance at cardiac rehabilitation. Data will be analysed to examine the relationship between patients' illness perceptions, cardiac treatment beliefs, knowledge/misconceptions, mood and non-attendance of the cardiac rehabilitation programme. The qualitative component (face-to-face interviews) seeks to explore why patients decide not to attend, not complete or complete the cardiac rehabilitation programme. The identification of robust predictors of (non-)attendance is important for the design and delivery of interventions aimed at optimizing cardiac rehabilitation uptake. Funding for the study was granted in February 2011 by the Scottish Government Chief Scientist Office (CZH/4/650). © 2012 Blackwell Publishing Ltd.

The effects of hindlimb unweighting on the capacitance of rat small mesenteric veins

NASA Technical Reports Server (NTRS)

Dunbar, S. L.; Berkowitz, D. E.; Brooks-Asplund, E. M.; Shoukas, A. A.

2000-01-01

Microgravity is associated with an impaired cardiac output response to orthostatic stress. Mesenteric veins are critical in modulating cardiac filling through venoconstriction. The purpose of this study was to determine the effects of simulated microgravity on the capacitance of rat mesenteric small veins. We constructed pressure-diameter relationships from vessels of 21-day hindlimb-unweighted (HLU) rats and control rats by changing the internal pressure and measuring the external diameter. Pressure-diameter relationships were obtained both before and after stimulation with norepinephrine (NE). The pressure-diameter curves of HLU vessels were shifted to larger diameters than control vessels. NE (10(-4) M) constricted veins from control animals such that the pressure-diameter relationship was significantly shifted downward (i.e., to smaller diameters at equal pressure). NE had no effect on vessels from HLU animals. These results indicate that, after HLU, unstressed vascular volume may be increased and can no longer decrease in response to sympathetic stimulation. This may partially underlie the mechanism leading to the exaggerated fall in cardiac output and stroke volume seen in astronauts during an orthostatic stress after exposure to microgravity.

Effect of a perioperative, cardiac output-guided hemodynamic therapy algorithm on outcomes following major gastrointestinal surgery: a randomized clinical trial and systematic review.

PubMed

Pearse, Rupert M; Harrison, David A; MacDonald, Neil; Gillies, Michael A; Blunt, Mark; Ackland, Gareth; Grocott, Michael P W; Ahern, Aoife; Griggs, Kathryn; Scott, Rachael; Hinds, Charles; Rowan, Kathryn

2014-06-04

Small trials suggest that postoperative outcomes may be improved by the use of cardiac output monitoring to guide administration of intravenous fluid and inotropic drugs as part of a hemodynamic therapy algorithm. To evaluate the clinical effectiveness of a perioperative, cardiac output-guided hemodynamic therapy algorithm. OPTIMISE was a pragmatic, multicenter, randomized, observer-blinded trial of 734 high-risk patients aged 50 years or older undergoing major gastrointestinal surgery at 17 acute care hospitals in the United Kingdom. An updated systematic review and meta-analysis were also conducted including randomized trials published from 1966 to February 2014. Patients were randomly assigned to a cardiac output-guided hemodynamic therapy algorithm for intravenous fluid and inotrope (dopexamine) infusion during and 6 hours following surgery (n=368) or to usual care (n=366). The primary outcome was a composite of predefined 30-day moderate or major complications and mortality. Secondary outcomes were morbidity on day 7; infection, critical care-free days, and all-cause mortality at 30 days; all-cause mortality at 180 days; and length of hospital stay. Baseline patient characteristics, clinical care, and volumes of intravenous fluid were similar between groups. Care was nonadherent to the allocated treatment for less than 10% of patients in each group. The primary outcome occurred in 36.6% of intervention and 43.4% of usual care participants (relative risk [RR], 0.84 [95% CI, 0.71-1.01]; absolute risk reduction, 6.8% [95% CI, -0.3% to 13.9%]; P = .07). There was no significant difference between groups for any secondary outcomes. Five intervention patients (1.4%) experienced cardiovascular serious adverse events within 24 hours compared with none in the usual care group. Findings of the meta-analysis of 38 trials, including data from this study, suggest that the intervention is associated with fewer complications (intervention, 488/1548 [31.5%] vs control, 614/1476 [41.6%]; RR, 0.77 [95% CI, 0.71-0.83]) and a nonsignificant reduction in hospital, 28-day, or 30-day mortality (intervention, 159/3215 deaths [4.9%] vs control, 206/3160 deaths [6.5%]; RR, 0.82 [95% CI, 0.67-1.01]) and mortality at longest follow-up (intervention, 267/3215 deaths [8.3%] vs control, 327/3160 deaths [10.3%]; RR, 0.86 [95% CI, 0.74-1.00]). In a randomized trial of high-risk patients undergoing major gastrointestinal surgery, use of a cardiac output-guided hemodynamic therapy algorithm compared with usual care did not reduce a composite outcome of complications and 30-day mortality. However, inclusion of these data in an updated meta-analysis indicates that the intervention was associated with a reduction in complication rates. isrctn.org Identifier: ISRCTN04386758.

Care assessment platform: an ICT-enabled home care model for secondary prevention of cardiovascular diseases.

PubMed

Karunanithi, Mohanraj; Varnfield, Marlien; Ding, Hang; Garcia, Elsa; Whittaker, Frank; Sarela, Antti

2010-01-01

Cardiovascular disease (CVD) is the leading chronic diseases affecting developed countries. Traditional approach to secondary prevention of CVD through hospital-based cardiac rehabilitation (CR) is hampered by the lack of uptake and adherence.

Increased cardiac work provides a link between systemic hypertension and heart failure.

PubMed

Wilson, Alexander J; Wang, Vicky Y; Sands, Gregory B; Young, Alistair A; Nash, Martyn P; LeGrice, Ian J

2017-01-01

The spontaneously hypertensive rat (SHR) is an established model of human hypertensive heart disease transitioning into heart failure. The study of the progression to heart failure in these animals has been limited by the lack of longitudinal data. We used MRI to quantify left ventricular mass, volume, and cardiac work in SHRs at age 3 to 21 month and compared these indices to data from Wistar-Kyoto (WKY) controls. SHR had lower ejection fraction compared with WKY at all ages, but there was no difference in cardiac output at any age. At 21 month the SHR had significantly elevated stroke work (51 ± 3 mL.mmHg SHR vs. 24 ± 2 mL.mmHg WKY; n = 8, 4; P < 0.001) and cardiac minute work (14.2 ± 1.2 L.mmHg/min SHR vs. 6.2 ± 0.8 L.mmHg/min WKY; n = 8, 4; P < 0.001) compared to control, in addition to significantly larger left ventricular mass to body mass ratio (3.61 ± 0.15 mg/g SHR vs. 2.11 ± 0.008 mg/g WKY; n = 8, 6; P < 0.001). SHRs showed impaired systolic function, but developed hypertrophy to compensate and successfully maintained cardiac output. However, this was associated with an increase in cardiac work at age 21 month, which has previously demonstrated fibrosis and cell death. The interplay between these factors may be the mechanism for progression to failure in this animal model. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

The Toxicity of Inhaled Sulphur Mustard

DTIC Science & Technology

2012-03-01

Pulse oximetry Mean arterial pressure Central venous pressure Blood Chemistry (arterial and venous ) pH pO2 pCO2 Sodium Potassium Calcium...Cardiovascular Parameters − CFI – Cardiac Function Index − CO – Cardiac Output − CvO2 – Mixed Venous Oxygenation − CVP – Central Venous Pressure...Data are expressed as mean ± SEM. Changes in central venous pressure following exposure to HD: HD controls () and HD + NAC (). Data are

Assessing the effect of preoperative levosimendan on renal function in patients with right ventricular dysfunction.

PubMed

Guerrero Orriach, Jose L; Galán Ortega, M; Ramírez Fernandez, A; Ariza Villanueva, D; Florez Vela, A; Moreno Cortés, I; Rubio Navarro, M; Cruz Mañas, J

2017-02-01

The Acute Kidney Injury Network (AKIN) classification considers SCr values, urea and urine output in order to improve timely diagnose ARF and improve patient prognosis by early treatment. Preoperative levosimendan is a new way for cardiac and kidney protection, we try to evaluate this drug in fifteen patients comparing values of AKIN scale parameters pre and post cardiac surgery in patients with right ventricle dysfunction.

Evaluation of a new arterial pressure-based cardiac output device requiring no external calibration

PubMed Central

Prasser, Christopher; Bele, Sylvia; Keyl, Cornelius; Schweiger, Stefan; Trabold, Benedikt; Amann, Matthias; Welnhofer, Julia; Wiesenack, Christoph

2007-01-01

Background Several techniques have been discussed as alternatives to the intermittent bolus thermodilution cardiac output (COPAC) measurement by the pulmonary artery catheter (PAC). However, these techniques usually require a central venous line, an additional catheter, or a special calibration procedure. A new arterial pressure-based cardiac output (COAP) device (FloTrac™, Vigileo™; Edwards Lifesciences, Irvine, CA, USA) only requires access to the radial or femoral artery using a standard arterial catheter and does not need an external calibration. We validated this technique in critically ill patients in the intensive care unit (ICU) using COPAC as the method of reference. Methods We studied 20 critically ill patients, aged 16 to 74 years (mean, 55.5 ± 18.8 years), who required both arterial and pulmonary artery pressure monitoring. COPAC measurements were performed at least every 4 hours and calculated as the average of 3 measurements, while COAP values were taken immediately at the end of bolus determinations. Accuracy of measurements was assessed by calculating the bias and limits of agreement using the method described by Bland and Altman. Results A total of 164 coupled measurements were obtained. Absolute values of COPAC ranged from 2.80 to 10.80 l/min (mean 5.93 ± 1.55 l/min). The bias and limits of agreement between COPAC and COAP for unequal numbers of replicates was 0.02 ± 2.92 l/min. The percentage error between COPAC and COAP was 49.3%. The bias between percentage changes in COPAC (ΔCOPAC) and percentage changes in COAP (ΔCOAP) for consecutive measurements was -0.70% ± 32.28%. COPAC and COAP showed a Pearson correlation coefficient of 0.58 (p < 0.01), while the correlation coefficient between ΔCOPAC and ΔCOAP was 0.46 (p < 0.01). Conclusion Although the COAP algorithm shows a minimal bias with COPAC over a wide range of values in an inhomogeneous group of critically ill patients, the scattering of the data remains relative wide. Therefore, the used algorithm (V 1.03) failed to demonstrate an acceptable accuracy in comparison to the clinical standard of cardiac output determination. PMID:17996086

Oxygen Uptake Efficiency Plateau Best Predicts Early Death in Heart Failure

PubMed Central

Hansen, James E.; Stringer, William W.

2012-01-01

Background: The responses of oxygen uptake efficiency (ie, oxygen uptake/ventilation = V˙o2/V˙e) and its highest plateau (OUEP) during incremental cardiopulmonary exercise testing (CPET) in patients with chronic left heart failure (HF) have not been previously reported. We planned to test the hypothesis that OUEP during CPET is the best single predictor of early death in HF. Methods: We evaluated OUEP, slope of V˙o2 to log(V˙e) (oxygen uptake efficiency slope), oscillatory breathing, and all usual resting and CPET measurements in 508 patients with low-ejection-fraction (< 35%) HF. Each had further evaluations at other sites, including cardiac catheterization. Outcomes were 6-month all-reason mortality and morbidity (death or > 24 h cardiac hospitalization). Statistical analyses included area under curve of receiver operating characteristics, ORs, univariate and multivariate Cox regression, and Kaplan-Meier plots. Results: OUEP, which requires only moderate exercise, was often reduced in patients with HF. A low % predicted OUEP was the single best predictor of mortality (P < .0001), with an OR of 13.0 (P < .001). When combined with oscillatory breathing, the OR increased to 56.3, superior to all other resting or exercise parameters or combinations of parameters. Other statistical analyses and morbidity analysis confirmed those findings. Conclusions: OUEP is often reduced in patients with HF. Low % predicted OUEP (< 65% predicted) is the single best predictor of early death, better than any other CPET or other cardiovascular measurement. Paired with oscillatory breathing, it is even more powerful. PMID:22030802

Diagnostic value of quantitative assessment of cardiac 18F-fluoro-2-deoxyglucose uptake in suspected cardiac sarcoidosis.

PubMed

Lebasnier, Adrien; Legallois, Damien; Bienvenu, Boris; Bergot, Emmanuel; Desmonts, Cédric; Zalcman, Gérard; Agostini, Denis; Manrique, Alain

2018-06-01

The identification of cardiac sarcoidosis is challenging as there is no gold standard consensually admitted for its diagnosis. The aim of this study was to evaluate the diagnostic value of the assessment of cardiac dynamic 18 F-fluoro-2-deoxyglucose positron emission tomography ( 18 F-FDG PET/CT) and net influx constant (Ki) in patients suspected of cardiac sarcoidosis. Data obtained from 30 biopsy-proven sarcoidosis patients suspected of cardiac sarcoidosis who underwent a 50-min list-mode cardiac dynamic 18 F-FDG PET/CT after a 24 h high-fat and low-carbohydrate diet were analyzed. A normalized coefficient of variation of quantitative glucose influx constant, calculated as the ratio: standard deviation of the segmental Ki (min -1 )/global Ki (min -1 ) was determined using a validated software (Carimas ® 2.4, Turku PET Centre). Cardiac sarcoidosis was diagnosed according to the Japanese Ministry of Health and Welfare criteria. Receiving operating curve analysis was performed to determine sensitivity and specificity of cardiac dynamic 18 F-FDG PET/CT analysis to diagnose cardiac sarcoidosis. Six out of 30 patients (20%) were diagnosed as having cardiac sarcoidosis. Myocardial glucose metabolism was significantly heterogeneous in patients with cardiac sarcoidosis who showed significantly higher normalized coefficient of variation values compared to patients without cardiac sarcoidosis (0.513 ± 0.175 vs. 0.205 ± 0.081; p = 0.0007). Using ROC curve analysis, we found a cut-off value of 0.38 for the diagnosis of cardiac sarcoidosis with a sensitivity of 100% and a specificity of 91%. Our results suggest that quantitative analysis of cardiac dynamic 18 F-FDG PET/CT could be a useful tool for the diagnosis of cardiac sarcoidosis.

Cardiac hypoxia imaging: second-generation analogues of 64Cu-ATSM.

PubMed

Handley, Maxwell G; Medina, Rodolfo A; Mariotti, Erika; Kenny, Gavin D; Shaw, Karen P; Yan, Ran; Eykyn, Thomas R; Blower, Philip J; Southworth, Richard

2014-03-01

Myocardial hypoxia is an attractive target for diagnostic and prognostic imaging, but current approaches are insufficiently sensitive for clinical use. The PET tracer copper(II)-diacetyl-bis(N4-methylthiosemicarbazone) ((64)Cu-ATSM) has promise, but its selectivity and sensitivity could be improved by structural modification. We have therefore evaluated a range of (64)Cu-ATSM analogs for imaging hypoxic myocardium. Isolated rat hearts (n = 5/group) were perfused with normoxic buffer for 30 min and then hypoxic buffer for 45 min within a custom-built triple-γ-detector system to quantify radiotracer infusion, hypoxia-dependent cardiac uptake, and washout. A 1-MBq bolus of each candidate tracer (and (18)F-fluoromisonidazole for comparative purposes) was injected into the arterial line during normoxia, and during early and late hypoxia, and their hypoxia selectivity and pharmacokinetics were evaluated. The in vivo pharmacokinetics of promising candidates in healthy rats were then assessed by PET imaging and biodistribution. All tested analogs exhibited hypoxia sensitivity within 5 min. Complexes less lipophilic than (64)Cu-ATSM provided significant gains in hypoxic-to-normoxic contrast (14:1 for (64)Cu-2,3-butanedione bis(thiosemicarbazone) (ATS), 17:1 for (64)Cu-2,3-pentanedione bis(thiosemicarbazone) (CTS), 8:1 for (64)Cu-ATSM, P < 0.05). Hypoxic first-pass uptake was 78.2% ± 7.2% for (64)Cu-ATS and 70.7% ± 14.5% for (64)Cu-CTS, compared with 63.9% ± 11.7% for (64)Cu-ATSM. Cardiac retention of (18)F-fluoromisonidazole increased from 0.44% ± 0.17% during normoxia to 2.24% ± 0.08% during hypoxia. In vivo, normoxic cardiac retention of (64)Cu-CTS was significantly lower than that of (64)Cu-ATSM and (64)Cu-ATS (0.13% ± 0.02% vs. 0.25% ± 0.04% and 0.24% ± 0.03% injected dose, P < 0.05), with retention of all 3 tracers falling to less than 0.7% injected dose within 6 min. (64)Cu-CTS also exhibited lower uptake in liver and lung. (64)Cu-ATS and (64)Cu-CTS exhibit better cardiac hypoxia selectivity and imaging characteristics than the current lead hypoxia tracers, (64)Cu-ATSM and (18)F-fluoromisonidazole.

An ANN-based HRV classifier for cardiac health prognosis.

PubMed

Sunkaria, Ramesh Kumar; Kumar, Vinod; Saxena, Suresh Chandra; Singhal, Achala M

2014-01-01

A multi-layer artificial neural network (ANN)-based heart rate variability (HRV) classifier has been proposed, which gives the cardiac health status as the output based on HRV of the patients independently of the cardiologists' view. The electrocardiogram (ECG) data of 46 patients were recorded in the out-patient department (OPD) of a hospital and HRV was evaluated using self-designed autoregressive-model-based technique. These patients suspected to be suffering from cardiac abnormalities were thoroughly examined by experienced cardiologists. On the basis of symptoms and other investigations, the attending cardiologists advised them to be classified into four categories as per the severity of cardiac health. Out of 46, the HRV data of 28 patients were used for training and data of 18 patients were used for testing of the proposed classifier. The cardiac health classification of each tested patient with the proposed classifier matches with the medical opinion of the cardiologists.

High-throughput cardiac science on the Grid.

PubMed

Abramson, David; Bernabeu, Miguel O; Bethwaite, Blair; Burrage, Kevin; Corrias, Alberto; Enticott, Colin; Garic, Slavisa; Gavaghan, David; Peachey, Tom; Pitt-Francis, J; Pueyo, E; Rodriguez, Blanca; Sher, Anna; Tan, Jefferson

2010-08-28

Cardiac electrophysiology is a mature discipline, with the first model of a cardiac cell action potential having been developed in 1962. Current models range from single ion channels, through very complex models of individual cardiac cells, to geometrically and anatomically detailed models of the electrical activity in whole ventricles. A critical issue for model developers is how to choose parameters that allow the model to faithfully reproduce observed physiological effects without over-fitting. In this paper, we discuss the use of a parametric modelling toolkit, called Nimrod, that makes it possible both to explore model behaviour as parameters are changed and also to tune parameters by optimizing model output. Importantly, Nimrod leverages computers on the Grid, accelerating experiments by using available high-performance platforms. We illustrate the use of Nimrod with two case studies, one at the cardiac tissue level and one at the cellular level.

With age a lower individual breathing reserve is associated with a higher maximal heart rate.

PubMed

Burtscher, Martin; Gatterer, Hannes; Faulhaber, Martin; Burtscher, Johannes

2018-01-01

Maximal heart rate (HRmax) is linearly declining with increasing age. Regular exercise training is supposed to partly prevent this decline, whereas sex and habitual physical activity do not. High exercise capacity is associated with a high cardiac output (HR x stroke volume) and high ventilatory requirements. Due to the close cardiorespiratory coupling, we hypothesized that the individual ventilatory response to maximal exercise might be associated with the age-related HRmax. Retrospective analyses have been conducted on the results of 129 consecutively performed routine cardiopulmonary exercise tests. The study sample comprised healthy subjects of both sexes of a broad range of age (20-86 years). Maximal values of power output, minute ventilation, oxygen uptake and heart rate were assessed by the use of incremental cycle spiroergometry. Linear multivariate regression analysis revealed that in addition to age the individual breathing reserve at maximal exercise was independently predictive for HRmax. A lower breathing reserve due to a high ventilatory demand and/or a low ventilatory capacity, which is more pronounced at a higher age, was associated with higher HRmax. Age explained the observed variance in HRmax by 72% and was improved to 83% when the variable "breathing reserve" was entered. The presented findings indicate an independent association between the breathing reserve at maximal exercise and maximal heart rate, i.e. a low individual breathing reserve is associated with a higher age-related HRmax. A deeper understanding of this association has to be investigated in a more physiological scenario. Copyright © 2017 Elsevier B.V. All rights reserved.

Lethal Cardiomyopathy in Mice Lacking Transferrin Receptor in the Heart.

PubMed

Xu, Wenjing; Barrientos, Tomasa; Mao, Lan; Rockman, Howard A; Sauve, Anthony A; Andrews, Nancy C

2015-10-20

Both iron overload and iron deficiency have been associated with cardiomyopathy and heart failure, but cardiac iron utilization is incompletely understood. We hypothesized that the transferrin receptor (Tfr1) might play a role in cardiac iron uptake and used gene targeting to examine the role of Tfr1 in vivo. Surprisingly, we found that decreased iron, due to inactivation of Tfr1, was associated with severe cardiac consequences. Mice lacking Tfr1 in the heart died in the second week of life and had cardiomegaly, poor cardiac function, failure of mitochondrial respiration, and ineffective mitophagy. The phenotype could only be rescued by aggressive iron therapy, but it was ameliorated by administration of nicotinamide riboside, an NAD precursor. Our findings underscore the importance of both Tfr1 and iron in the heart, and may inform therapy for patients with heart failure. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Computational Quantification of the Cardiac Energy Consumption during Intra-Aortic Balloon Pumping Using a Cardiac Electromechanics Model

PubMed Central

Lim, Ki Moo; Lee, Jeong Sang; Gyeong, Min-Soo; Choi, Jae-Sung; Choi, Seong Wook

2013-01-01

To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure-volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes. When the IABP was used at inflation level 5, the cardiac output and stroke volume increased 11%, the ejection fraction increased 21%, the stroke work decreased 1%, the mean arterial pressure increased 10%, and the ATP consumption decreased 12%. These results show that although the ATP consumption is decreased significantly, stroke work is decreased only slightly, which indicates that the IABP helps the failed ventricle to pump blood efficiently. PMID:23341718

Computational quantification of the cardiac energy consumption during intra-aortic balloon pumping using a cardiac electromechanics model.

PubMed

Lim, Ki Moo; Lee, Jeong Sang; Gyeong, Min-Soo; Choi, Jae-Sung; Choi, Seong Wook; Shim, Eun Bo

2013-01-01

To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure-volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes. When the IABP was used at inflation level 5, the cardiac output and stroke volume increased 11%, the ejection fraction increased 21%, the stroke work decreased 1%, the mean arterial pressure increased 10%, and the ATP consumption decreased 12%. These results show that although the ATP consumption is decreased significantly, stroke work is decreased only slightly, which indicates that the IABP helps the failed ventricle to pump blood efficiently.

Cardiac index is associated with brain aging: the Framingham Heart Study.

PubMed

Jefferson, Angela L; Himali, Jayandra J; Beiser, Alexa S; Au, Rhoda; Massaro, Joseph M; Seshadri, Sudha; Gona, Philimon; Salton, Carol J; DeCarli, Charles; O'Donnell, Christopher J; Benjamin, Emelia J; Wolf, Philip A; Manning, Warren J

2010-08-17

Cardiac dysfunction is associated with neuroanatomic and neuropsychological changes in aging adults with prevalent cardiovascular disease, theoretically because systemic hypoperfusion disrupts cerebral perfusion, contributing to subclinical brain injury. We hypothesized that cardiac function, as measured by cardiac index, would be associated with preclinical brain magnetic resonance imaging (MRI) and neuropsychological markers of ischemia and Alzheimer disease in the community. Brain MRI, cardiac MRI, neuropsychological, and laboratory data were collected on 1504 Framingham Offspring Cohort participants free of clinical stroke, transient ischemic attack, or dementia (age, 61+/-9 years; 54% women). Neuropsychological and brain MRI variables were related to cardiac MRI-assessed cardiac index (cardiac output/body surface area). In multivariable-adjusted models, cardiac index was positively related to total brain volume (P=0.03) and information processing speed (P=0.02) and inversely related to lateral ventricular volume (P=0.048). When participants with clinically prevalent cardiovascular disease were excluded, the relation between cardiac index and total brain volume remained (P=0.02). Post hoc comparisons revealed that participants in the bottom cardiac index tertile (values <2.54) and middle cardiac index tertile (values between 2.54 and 2.92) had significantly lower brain volumes (P=0.04) than participants in the top cardiac index tertile (values >2.92). Although observational data cannot establish causality, our findings are consistent with the hypothesis that decreasing cardiac function, even at normal cardiac index levels, is associated with accelerated brain aging.

Cardiac index is associated with brain aging: The Framingham Heart Study

PubMed Central

Jefferson, Angela L.; Himali, Jayandra J.; Beiser, Alexa S.; Au, Rhoda; Massaro, Joseph M.; Seshadri, Sudha; Gona, Philimon; Salton, Carol J.; DeCarli, Charles; O’Donnell, Christopher J.; Benjamin, Emelia J.; Wolf, Philip A.; Manning, Warren J.

2010-01-01

Background Cardiac dysfunction is associated with neuroanatomic and neuropsychological changes in aging adults with prevalent cardiovascular disease (CVD), theoretically because systemic hypoperfusion disrupts cerebral perfusion, contributing to subclinical brain injury. We hypothesized that cardiac function, as measured by cardiac index, would be associated with pre-clinical brain magnetic resonance imaging (MRI) and neuropsychological markers of ischemia and Alzheimer’s disease in the community. Methods and Results Brain MRI, cardiac MRI, neuropsychological, and laboratory data were collected on 1504 Framingham Offspring Cohort participants free from clinical stroke, transient ischemic attack, or dementia (61±9 years; 54% women). Neuropsychological and brain MRI variables were related to cardiac MRI-assessed cardiac index (cardiac output/body surface area). In multivariable-adjusted models, cardiac index was positively related to total brain volume (P=0.03) and information processing speed (P=0.02) and inversely related to lateral ventricular volume (P=0.048). When participants with clinically prevalent CVD were excluded, the relation between cardiac index and total brain volume remained (P=0.02). Post-hoc comparisons revealed that participants in the bottom cardiac index tertile (values<2.54) and middle cardiac index tertile (values between 2.54 and 2.92) had significantly lower brain volumes (P=0.04) than participants in the top cardiac index tertile (values>2.92). Conclusions Although observational data cannot establish causality, our findings are consistent with the hypothesis that decreasing cardiac function, even at normal cardiac index levels, is associated with accelerated brain aging. PMID:20679552

Feasibility of FDG-PET in myocarditis: Comparison to CMR using integrated PET/MRI.

PubMed

Nensa, Felix; Kloth, Julia; Tezgah, Ercan; Poeppel, Thorsten D; Heusch, Philipp; Goebel, Juliane; Nassenstein, Kai; Schlosser, Thomas

2018-06-01

Besides cardiac sarcoidosis, FDG-PET is rarely used in the diagnosis of myocardial inflammation, while cardiac MRI (CMR) is the actual imaging reference for the workup of myocarditis. Using integrated PET/MRI in patients with suspected myocarditis, we prospectively compared FDG-PET to CMR and the feasibility of integrated FDG-PET/MRI in myocarditis. A total of 65 consecutive patients with suspected myocarditis were prospectively assessed using integrated cardiac FDG-PET/MRI. Studies comprised T2-weighted imaging, late gadolinium enhancement (LGE), and simultaneous PET acquisition. Physiological glucose uptake in the myocardium was suppressed using dietary preparation. FDG-PET/MRI was successful in 55 of 65 enrolled patients: two patients were excluded due to claustrophobia and eight patients due to failed inhibition of myocardial glucose uptake. Compared with CMR (LGE and/or T2), sensitivity and specificity of PET was 74% and 97%. Overall spatial agreement between PET and CMR was κ = 0.73. Spatial agreement between PET and T2 (κ = 0.75) was higher than agreement between PET and LGE (κ = 0.64) as well as between LGE and T2 (κ = 0.56). In patients with suspected myocarditis, FDG-PET is in good agreement with CMR findings.

Management of Complex Cardiac Issues in the Pregnant Patient.

PubMed

Hu, Huayong; Pasca, Ioana

2016-01-01

Management of peripartum heart disease in the intensive care unit requires optimization of maternal hemodynamics and maintenance of fetal perfusion. This requires fetal monitoring and should address the parturient's oxygen saturation, hemoglobin, and cardiac output as it relates to uterine blood flow. Pharmacologic strategies have limited evidence pertaining to hemodynamic stabilization and fetal perfusion. There is some evidence that surgical management of critical mitral stenosis should be percutaneous when possible because cardiac bypass is associated with increased fetal mortality. Fetal monitoring strategies should address central organ perfusion because peripheral scalp pH has not been associated with improved fetal outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

Glucagon-like peptide-1 reduces contractile function and fails to boost glucose utilization in normal hearts in the presence of fatty acids.

PubMed

Nguyen, T Dung; Shingu, Yasushige; Amorim, Paulo A; Schwarzer, Michael; Doenst, Torsten

2013-10-09

GLP-1 and exendin-4, which are used as insulin sensitizers or weight reducing drugs, were shown to improve glucose uptake in the heart. However, the direct effects of GLP-1 or exendin-4 on normal hearts in the presence of fatty acids, the main cardiac substrates, have never been investigated. We therefore assessed the effects of GLP-1 or exendin-4 on myocardial glucose uptake (GU), glucose oxidation (GO) and cardiac performance (CP) under conditions of fatty acid utilization. Rat hearts were perfused with only glucose (5 mM) or glucose (5 mM) plus oleate (0.4 mM) as substrates for 60 min. After 30 min, GLP-1 or exendin-4 (0.5 nM or 5 nM) was added. In the absence of oleate, GLP-1 increased both GU and GO. Exendin-4 increased GO but showed no effect on GU. Neither GLP-1 nor exendin-4 affected CP. However, when oleate was present, GLP-1 failed to stimulate glucose utilization and exendin-4 even decreased GU. Furthermore, now GLP-1 reduced CP. In contrast to prior reports, this negative inotropic effect could not be blocked by the protein kinase A inhibitor H-89. We then measured myocardial GO and CP in rats receiving a 4-week GLP-1 infusion. Interestingly, this chronic treatment resulted in a significant reduction in both GO and CP. Under the influence of oleate, GLP-1 reduces contractile function and fails to stimulate glucose utilization in normal hearts. Exendin-4 may acutely reduce cardiac glucose uptake but not contractility. We suggest advanced investigation of heart function and metabolism in patients treating with these peptides. © 2013.

Antioxidant treatment improves neonatal survival and prevents impaired cardiac function at adulthood following neonatal glucocorticoid therapy

PubMed Central

Niu, Youguo; Herrera, Emilio A; Evans, Rhys D; Giussani, Dino A

2013-01-01

Glucocorticoids are widely used to treat chronic lung disease in premature infants but their longer-term adverse effects on the cardiovascular system raise concerns. We reported that neonatal dexamethasone treatment in rats induced in the short term molecular indices of cardiac oxidative stress and cardiovascular tissue remodelling at weaning, and that neonatal combined antioxidant and dexamethasone treatment was protective at this time. In this study, we investigated whether such effects of neonatal dexamethasone have adverse consequences for NO bioavailability and cardiovascular function at adulthood, and whether neonatal combined antioxidant and dexamethasone treatment is protective in the adult. Newborn rat pups received daily i.p. injections of a human-relevant tapering dose of dexamethasone (D; n= 8; 0.5, 0.3, 0.1 μg g−1) or D with vitamins C and E (DCE; n= 8; 200 and 100 mg kg−1, respectively) on postnatal days 1–3 (P1–3); vitamins were continued from P4 to P6. Controls received equal volumes of vehicle from P1 to P6 (C; n= 8). A fourth group received vitamins alone (CCE; n= 8). At P100, plasma NO metabolites (NOx) was measured and isolated hearts were assessed under both Working and Langendorff preparations. Relative to controls, neonatal dexamethasone therapy increased mortality by 18% (P < 0.05). Surviving D pups at adulthood had lower plasma NOx concentrations (10.6 ± 0.8 vs. 28.0 ± 1.5 μm), an increased relative left ventricular (LV) mass (70 ± 2 vs. 63 ± 1%), enhanced LV end-diastolic pressure (14 ± 2 vs. 8 ± 1 mmHg) and these hearts failed to adapt output with increased preload (Δcardiac output: 2.9 ± 2.0 vs. 10.6 ± 1.2 ml min−1) or afterload (Δcardiac output: −5.3 ± 2.0 vs.1.4 ± 1.2 ml min−1); all P < 0.05. Combined neonatal dexamethasone with antioxidant vitamins improved postnatal survival, restored plasma NOx and protected against cardiac dysfunction at adulthood. In conclusion, neonatal dexamethasone therapy promotes cardiac dysfunction at adulthood. Combined neonatal treatment with antioxidant vitamins is an effective intervention. PMID:23940378

Association of physical examination with pulmonary artery catheter parameters in acute lung injury.

PubMed

Grissom, Colin K; Morris, Alan H; Lanken, Paul N; Ancukiewicz, Marek; Orme, James F; Schoenfeld, David A; Thompson, B Taylor

2009-10-01

To correlate physical examination findings, central venous pressure, fluid output, and central venous oxygen saturation with pulmonary artery catheter parameters. Retrospective study. Data from the multicenter Fluid and Catheter Treatment Trial of the National Institutes of Health Acute Respiratory Distress Syndrome Network. Five hundred thirteen patients with acute lung injury randomized to treatment with a pulmonary artery catheter. Correlation of physical examination findings (capillary refill time >2 secs, knee mottling, or cool extremities), central venous pressure, fluid output, and central venous oxygen saturation with parameters from a pulmonary artery catheter. We determined association of baseline physical examination findings and on-study parameters of central venous pressure and central venous oxygen saturation with cardiac index <2.5 L/min/m2 and mixed venous oxygen saturation <60%. We determined correlation of baseline central venous oxygen saturation and mixed venous oxygen saturation and predictive value of a low central venous oxygen saturation for a low mixed venous oxygen saturation. Prevalence of cardiac index <2.5 and mixed venous oxygen saturation <60% was 8.1% and 15.5%, respectively. Baseline presence of all three physical examination findings had low sensitivity (12% and 8%), high specificity (98% and 99%), low positive predictive value (40% and 56%), but high negative predictive value (93% and 86%) for cardiac index <2.5 and mixed venous oxygen saturation <60%, respectively. Central venous oxygen saturation <70% predicted a mixed venous oxygen saturation <60% with a sensitivity 84%,specificity 70%, positive predictive value 31%, and negative predictive value of 96%. Low cardiac index correlated with cool extremities, high central venous pressure, and low 24-hr fluid output; and low mixed venous oxygen saturation correlated with knee mottling and high central venous pressure, but these correlations were not found to be clinically useful. In this subset of patients with acute lung injury, there is a high prior probability that cardiac index and mixed venous oxygen saturation are normal and physical examination findings of ineffective circulation are not useful for predicting low cardiac index or mixed venous oxygen saturation. Central venous oxygen saturation <70% does not accurately predict mixed venous oxygen saturation <60%, but a central venous oxygen saturation >or=70% may be useful to exclude mixed venous oxygen saturation <60%.

Content validation of the operational definitions of the nursing diagnoses of activity intolerance, excess fluid volume, and decreased cardiac output in patients with heart failure.

PubMed

de Souza, Vanessa; Zeitoun, Sandra Salloum; Lopes, Camila Takao; de Oliveira, Ana Paula Dias; Lopes, Juliana de Lima; de Barros, Alba Lucia Botura Leite

2014-06-01

To consensually validate the operational definitions of the nursing diagnoses activity intolerance, excessive fluid volume, and decreased cardiac output in patients with decompensated heart failure. Consensual validation was performed in two stages: analogy by similarity of defining characteristics, and development of operational definitions and validation with experts. A total of 38 defining characteristics were found. Operational definitions were developed and content-validated. One hundred percent of agreement was achieved among the seven experts after five rounds. "Ascites" was added in the nursing diagnosis excessive fluid volume. The consensual validation improves interpretation of human response, grounding the selection of nursing interventions and contributing to improved nursing outcomes. Support the assessment of patients with decompensated heart failure. © 2013 NANDA International.

Comparison of superior vena caval and inferior vena caval access using a radioisotope technique during normal perfusion and cardiopulmonary resuscitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dalsey, W.C.; Barsan, W.G.; Joyce, S.M.

1984-10-01

Recent studies of thoracic pressure changes during external cardiopulmonary resuscitation (CPR) suggest that there may be a significant difference in the rate of delivery of intravenous drugs when they are administered through the extrathoracic inferior vena cava (IVC) rather than the intrathoracic superior vena cava (SVC). Comparison of delivery of a radionuclide given using superior and inferior vena caval access sites was made during normal blood flow and during CPR. Mean times from injection to peak emission count in each ventricle were determined. There were no significant differences between mean peak times for SVC or IVC routes during normal flowmore » or CPR. When peak times were corrected for variations in cardiac output, there were no significant differences between IVC and SVC peak times during normal flow. During CPR, however, mean left ventricular peak time, when corrected for cardiac output, was significantly shorter (P less than .05) when the SVC route was used. The mean time for the counts to reach half the ventricular peak was statistically shorter (P less than .05) in both ventricles with the SVC route during the low flow of CPR. This suggests that during CPR, increased drug dispersion may occur when drugs are infused by the IVC route and thus may modify the anticipated effect of the drug bolus. These results suggest that during CPR, both the cardiac output and the choice of venous access are important variables for drug delivery.« less

Decreased peak arteriovenous oxygen difference during treadmill exercise testing in individuals infected with the human immunodeficiency virus.

PubMed

Cade, W Todd; Fantry, Lori E; Nabar, Sharmila R; Keyser, Randall E

2003-11-01

To determine if arteriovenous oxygen difference was lower in asymptomatic individuals with human immunodeficiency virus (HIV) infection than in sedentary but otherwise healthy controls. Quasi-experimental cross-sectional. Clinical exercise laboratory. Fifteen subjects (10 men, 5 women) with HIV and 15 healthy gender- and activity level-matched controls (total N=30). Participants performed an incremental maximal exercise treadmill test to exhaustion. Electrocardiogram, metabolic, and noninvasive cardiac output measurements were evaluated at rest and throughout the tests. Data were analyzed by using analysis of covariance. Peak oxygen consumption (Vo(2)), cardiac output, stroke volume, and arteriovenous oxygen difference. The arteriovenous oxygen difference was determined indirectly using the Fick equation. Peak VO(2) was significantly lower (P<.0005) in participants with HIV (24.6+/-1.2mL.kg(-1).min(-1)) compared with controls (32.0+/-1.2mL.kg(-1).min(-1)). There were no significant intergroup differences in cardiac output or stroke volume at peak exercise. Peak arteriovenous oxygen difference was significantly lower (P<.04) in those infected with HIV (10.8+/-0.5 volume %) than in controls (12.4+/-0.5 volume %). The observed deficit in aerobic capacity in the participants with HIV appeared to be the result of a peripheral tissue oxygen extraction or utilization limitation. In addition to deconditioning, potential mechanisms for this significant attenuation may include HIV infection and inflammation, highly active antiretroviral therapy medication regimens, or a combination of these factors.

Low level CO2 effects on pulmonary function in humans

NASA Technical Reports Server (NTRS)

Sexton, J.; Mueller, K.; Elliott, A.; Gerzer, D.; Strohl, K. P.; West, J. B. (Principal Investigator)

1998-01-01

The purpose of the study was to determine whether chamber exposure to low levels of CO2 results in functional alterations in gas mixing and closing volume in humans. Four healthy volunteer subjects were exposed to 0.7% CO2 and to 1.2% CO2. Spirometry, lung volumes, single breath nitrogen washout, diffusing capacity for carbon monoxide (DLCO) by two methods, and cardiac output were measured in triplicate. Values were obtained over two non-consecutive days during the training period (control) and on days 2 or 3, 4, 6, 10, 13, and 23 of exposure to each CO2 level. Measurements were made during the same time of day. There was one day of testing after exposure, while still in the chamber but off carbon dioxide. The order of testing, up until measurements of DLCO and cardiac output, were randomized to avoid presentation effects. The consistent findings were a reduction in diffusing capacity for carbon monoxide and a fall in cardiac output, occurring to a similar degree with both exposures. For the group as a whole, there was no indication of major effects on spirometry, lung volumes, gas mixing or dead space. We conclude that small changes may occur in the function of distal gas exchanging units; however, these effects were not associated with any adverse health effects. The likelihood of pathophysiologic changes in lung function or structure with 0.7 or 1.2% CO2 exposure for this period of time, is therefore, low.

Advanced hemodynamic monitoring in intensive care medicine : A German web-based survey study.

PubMed

Saugel, B; Reese, P C; Wagner, J Y; Buerke, M; Huber, W; Kluge, S; Prondzinsky, R

2018-04-01

Advanced hemodynamic monitoring is recommended in patients with complex circulatory shock. To evaluate the current attitudes and beliefs among German intensivists, regarding advanced hemodynamic monitoring, the actual hemodynamic management in clinical practice, and the barriers to using it. Web-based survey among members of the German Society of Medical Intensive Care and Emergency Medicine. Of 284 respondents, 249 (87%) agreed that further hemodynamic assessment is needed to determine the type of circulatory shock if no clear clinical diagnosis can be made. In all, 281 (99%) agreed that echocardiography is helpful for this purpose (transpulmonary thermodilution: 225 [79%]; pulmonary artery catheterization: 126 [45%]). More than 70% of respondents agreed that blood flow variables (cardiac output, stroke volume) should be measured in patients with hemodynamic instability. The parameters most respondents agreed should be assessed in a patient with hemodynamic instability were mean arterial pressure, cardiac output, and serum lactate. Echocardiography is available in 99% of ICUs (transpulmonary thermodilution: 91%; pulmonary artery catheter: 63%). The respondents stated that, in clinical practice, invasive arterial pressure measurements and serum lactate measurements are performed in more than 90% of patients with hemodynamic instability (cardiac output monitoring in about 50%; transpulmonary thermodilution in about 40%). The respondents did not feel strong barriers to the use of advanced hemodynamic monitoring in clinical practice. This survey study shows that German intensivists deem advanced hemodynamic assessment necessary for the differential diagnosis of circulatory shock and to guide therapy with fluids, vasopressors, and inotropes in ICU patients.

A newly synthetic chromium complex-chromium (D-phenylalanine)3 activates AMP-activated protein kinase and stimulates glucose transport.

PubMed

Zhao, Peng; Wang, Jingying; Ma, Heng; Xiao, Yao; He, Leilei; Tong, Chao; Wang, Zhenhua; Zheng, Qiusheng; Dolence, E Kurt; Nair, Sreejayan; Ren, Jun; Li, Ji

2009-03-15

We synthesized the chromium (phenylalanine)(3) [Cr(D-phe)(3)] by chelating chromium(III) with D-phenylalanine ligand in aqueous solution to improve the bioavailability of chromium, and reported that Cr(D-phe)(3) improved insulin sensitivity. AMP-activated protein kinase (AMPK) is a key mediator for glucose uptake and insulin sensitivity. To address the molecular mechanisms by which Cr(d-phe)(3) increases insulin sensitivity, we investigated whether Cr(D-phe)(3) stimulates glucose uptake via activation of AMPK signaling pathway. H9c2 myoblasts and isolated cardiomyocytes were treated with Cr(D-phe)(3) (25microM). Western blotting was used for signaling determination. The glucose uptake was determined by 2-deoxy-D-glucose-(3)H accumulation. HPLC measured concentrations of AMP. The mitochondrial membrane potential (Deltapsi) was detected by JC-1 fluorescence assay. Cr(D-phe)(3) stimulated the phosphorylation of alpha catalytic subunit of AMPK at Thr(172), as well the downstream targets of AMPK, acetyl-CoA carboxylase (ACC, Ser(212)) and eNOS (Ser(1177)). Moreover, Cr(D-phe)(3) significantly stimulated glucose uptake in both H9c2 cells and cardiomyocytes. AMPK inhibitor compound C (10microM) dramatically inhibited the glucose uptake stimulated by Cr(D-phe)(3), while it did not affect insulin stimulation of glucose uptake. Furthermore, in vivo studies showed that Cr(D-phe)(3) also activated cardiac AMPK signaling pathway. The increase of cardiac AMP concentration and the decrease of mitochondrial membrane potential (Deltapsi) may contribute to the activation of AMPK induced by Cr(D-phe)(3). Cr(D-phe)(3) is a novel compound that activates AMPK signaling pathway, which contributes to the regulation of glucose transport during stress conditions that may be associated the role of AMPK in increasing insulin sensitivity.

Cardiac Pressure Changes with Venous Gas Embolism and Decompression

DTIC Science & Technology

1994-04-01

inferior vena cava via the left femoral vein for venous access. Airway pressure was measured from a connector at the proximal end of the endotracheal...Hartley), mount- ed in a 7-9 m acrylic cuff was surgically placed around the inferior vena cava via laparotomy, approximately 1-2 cm above the renal...pressure and decreasing cardiac output which in return may cause the left atrial pressure to fall below that of the right atrium . Recent studies have

Cardiac responses to hypoxia and reoxygenation in Drosophila.

PubMed

Zarndt, Rachel; Piloto, Sarah; Powell, Frank L; Haddad, Gabriel G; Bodmer, Rolf; Ocorr, Karen

2015-12-01

An adequate supply of oxygen is important for the survival of all tissues, but it is especially critical for tissues with high-energy demands, such as the heart. Insufficient tissue oxygenation occurs under a variety of conditions, including high altitude, embryonic and fetal development, inflammation, and thrombotic diseases, often affecting multiple organ systems. Responses and adaptations of the heart to hypoxia are of particular relevance in human cardiovascular and pulmonary diseases, in which the effects of hypoxic exposure can range in severity from transient to long-lasting. This study uses the genetic model system Drosophila to investigate cardiac responses to acute (30 min), sustained (18 h), and chronic (3 wk) hypoxia with reoxygenation. Whereas hearts from wild-type flies recovered quickly after acute hypoxia, exposure to sustained or chronic hypoxia significantly compromised heart function upon reoxygenation. Hearts from flies with mutations in sima, the Drosophila homolog of the hypoxia-inducible factor alpha subunit (HIF-α), exhibited exaggerated reductions in cardiac output in response to hypoxia. Heart function in hypoxia-selected flies, selected over many generations for survival in a low-oxygen environment, revealed reduced cardiac output in terms of decreased heart rate and fractional shortening compared with their normoxia controls. Hypoxia-selected flies also had smaller hearts, myofibrillar disorganization, and increased extracellular collagen deposition, consistent with the observed reductions in contractility. This study indicates that longer-duration hypoxic insults exert deleterious effects on heart function that are mediated, in part, by sima and advances Drosophila models for the genetic analysis of cardiac-specific responses to hypoxia and reoxygenation. Copyright © 2015 the American Physiological Society.

Sleep in heart failure.

PubMed

Naughton, Matthew T; Lorenzi-Filho, Geraldo

2009-01-01

Sleep plays a large role in patients with heart failure. In normal subjects, sleep is usually in a supine position with reduced sympathetic drive, elevated vagal tone and as such a relatively lower cardiac output and minute ventilation, allowing for recuperation. Patients with heart failure may not experience the same degree of autonomic activity change and the supine position may place a large strain on the pulmonary system. More than half of all heart failure patients have one of two types of sleep apnea: either obstructive or central sleep apnea. Some patients have both types. Obstructive sleep apnea is likely to be a cause of heart failure due to large negative intrathoracic pressures, apnea related hypoxemia and hypercapnia, terminated by an arousal and surge in systemic blood pressure associated with endothelial damage and resultant premature atherosclerosis. Reversal of obstructive sleep apnea improves blood pressure, systolic contraction and autonomic dysfunction however mortality studies are lacking. Central sleep apnea with Cheyne Stokes pattern of respiration (CSA-CSR) occurs as a result of increased central controller (brainstem driving ventilation) and plant (ventilation driving CO2) gain in the setting of a delayed feed back (i.e., low cardiac output). It is thought this type of apnea is a result of moderately to severely impaired cardiac function and is possibly indicative of high mortality. Treatment of CSA-CSR is best undertaken by treating the underlying cardiac condition which may include with medications, pacemakers, transplantation or continuous positive airway pressure (CPAP). In such patients CPAP exerts unique effects to assist cardiac function and reduce pulmonary edema. Whether CPAP improves survival in this heart failure population remains to be determined.

PM101: a cyclodextrin-based intravenous formulation of amiodarone devoid of adverse hemodynamic effects.

PubMed

Cushing, Daniel J; Kowey, Peter R; Cooper, Warren D; Massey, Bill W; Gralinski, Michael R; Lipicky, Raymond J

2009-04-01

Intravenous amiodarone (Amiodarone i.v.) is widely used to treat cardiac arrhythmias. The most frequent clinical adverse event associated with Amiodarone i.v. administration is systemic hypotension which has been attributed to the cosolvents used in the formulation, polysorbate 80 and benzyl alcohol. To minimize hypotension Amiodarone i.v. is diluted in 5% dextrose in water prior to administration and slowly infused. PM101 is a novel intravenous formulation that uses sulfobutylether-7-beta-cyclodextrin to solubilize amiodarone, and thus should be devoid of the untoward hemodynamic effects associated with polysorbate 80 and benzyl alcohol. Beagle dogs (n=7/group) were anesthetized with morphine and alpha-chloralose and instrumented to assess aortic blood pressure, cardiac output, cardiac contractility, and heart rate. Animals were treated with the U.S. approved human-equivalent loading dose (2.14 mg/kg) of Amiodarone i.v., PM101, and their respective vehicle controls. Administration of Amiodarone i.v. rapidly and significantly decreased mean aortic pressure, cardiac output, and cardiac contractility. A significant increase in heart rate was also observed as was a transient, but not significant, decrease in systemic vascular resistance. A similar pattern of rapid and significant hemodynamic changes was produced by the Amiodarone i.v. Vehicle (polysorbate 80/benzyl alcohol) alone. In marked contrast, PM101 and its vehicle produced no significant hemodynamic effects. This study provides a useful model for the continued search for a safe and effective intravenous amiodarone formulation devoid of the hypotensive risk associated with the current commercial formulation.

Increases in Cardiac Output and Oxygen Consumption During Enhanced External Counterpulsation.

PubMed

Ahlbom, Magnus; Hagerman, Inger; Ståhlberg, Marcus; Manouras, Aristomenis; Förstedt, Gunilla; Wu, Eline; Lund, Lars H

2016-11-01

Regular enhanced external counterpulsation (EECP) improves exercise capacity possibly through a training effect, but the roles of oxygen consumption (VO 2 ) vs. direct EECP effects (diastolic augmentation, DA-ratio), and their relation to cardiac index (CI) during EECP are unknown. We studied eight patients with angina pectoris (median [range] age 72 [53-85], 25% women), who underwent EECP for 35 daily sessions. Before, during and after the first and last sessions, we assessed VO 2 , DA-ratio and CI. At first EECP, CI increased from 2.2 (1.7-2.9) L/min/m 2 prior to EECP to 3.0 (2.2-3.8) during EECP (p=0.011), and returned to 2.4 (0.8-3.0). Similarly, VO 2 increased during EECP and returned to baseline after EECP. These patterns were reproduced at the last EECP session. Absolute values of CI and VO 2 correlated with each other during but not prior to or after EECP. The increase in CI correlated with the increase in VO 2 by trend: (first session, r 0.52, p=0.19; second session r 0.69, p=0.09), but not with DA-ratio. Acutely during EECP, there is an increase in cardiac output that is unrelated to direct EECP effects but related to, and may be secondary to, an increase in peripheral O 2 demand. This may represent a training effect. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Methods and apparatus for determining cardiac output

NASA Technical Reports Server (NTRS)

Cohen, Richard J. (Inventor); Sherman, Derin A. (Inventor); Mukkamala, Ramakrishna (Inventor)

2010-01-01

The present invention provides methods and apparatus for determining a dynamical property of the systemic or pulmonary arterial tree using long time scale information, i.e., information obtained from measurements over time scales greater than a single cardiac cycle. In one aspect, the invention provides a method and apparatus for monitoring cardiac output (CO) from a single blood pressure signal measurement obtained at any site in the systemic or pulmonary arterial tree or from any related measurement including, for example, fingertip photoplethysmography.According to the method the time constant of the arterial tree, defined to be the product of the total peripheral resistance (TPR) and the nearly constant arterial compliance, is determined by analyzing the long time scale variations (greater than a single cardiac cycle) in any of these blood pressure signals. Then, according to Ohm's law, a value proportional to CO may be determined from the ratio of the blood pressure signal to the estimated time constant. The proportional CO values derived from this method may be calibrated to absolute CO, if desired, with a single, absolute measure of CO (e.g., thermodilution). The present invention may be applied to invasive radial arterial blood pressure or pulmonary arterial blood pressure signals which are routinely measured in intensive care units and surgical suites or to noninvasively measured peripheral arterial blood pressure signals or related noninvasively measured signals in order to facilitate the clinical monitoring of CO as well as TPR.

Experimental myocardial infarction

PubMed Central

Kumar, Raj; Joison, Julio; Gilmour, David P.; Molokhia, Farouk A.; Pegg, C. A. S.; Hood, William B.

1971-01-01

The hemodynamic effects of tachycardia induced by atrial pacing were investigated in left ventricular failure of acute and healing experimental myocardial infarction in 20 intact, conscious dogs. Myocardial infarction was produced by gradual inflation of a balloon cuff device implanted around the left anterior descending coronary artery 10-15 days prior to the study. 1 hr after acute myocardial infarction, atrial pacing at a rate of 180 beats/min decreased left ventricular end-diastolic pressure from 19 to 8 mm Hg and left atrial pressure from 17 to 12 mm Hg, without change in cardiac output. In the healing phase of myocardial infarction 1 wk later, atrial pacing decreased left ventricular end-diastolic pressure from 17 to 9 mm Hg and increased the cardiac output by 37%. This was accompanied by evidence of peripheral vasodilation. In two dogs with healing anterior wall myocardial infarction, left ventricular failure was enhanced by partial occlusion of the circumflex coronary artery. Both the dogs developed pulmonary edema. Pacing improved left ventricular performance and relieved pulmonary edema in both animals. In six animals propranolol was given after acute infarction, and left ventricular function deteriorated further. However the pacing-induced augmentation of cardiac function was unaltered and, hence, is not mediated by sympathetics. The results show that the spontaneous heart rate in left ventricular failure of experimental canine myocardial infarction may be less than optimal and that maximal cardiac function may be achieved at higher heart rates. Images PMID:4395910

The Differential Effect of Two Types of Direct Written Corrective Feedback on Noticing and Uptake: Reformulation vs. Error Correction

ERIC Educational Resources Information Center

Santos, Maria; Lopez-Serrano, Sonia; Manchon, Rosa M.

2010-01-01

Framed in a cognitively-oriented strand of research on corrective feedback (CF) in SLA, the controlled three-stage (composition/comparison-noticing/revision) study reported in this paper investigated the effects of two forms of direct CF (error correction and reformulation) on noticing and uptake, as evidenced in the written output produced by a…

Problems in aerial application. II, Effects of chlorinated hydrocarbons on substrate-linked phosphorylation.

DOT National Transportation Integrated Search

1963-03-01

In a search for an explanation of an earlier finding that dieldrin decreased the rate of methionine uptake by cardiac muscle, chickens and rats were exposed to this compound and the substrate-linked phosphorylation phenomenon was studied during the a...

Daily inspiratory muscle training lowers blood pressure and vascular resistance in healthy men and women.

PubMed

DeLucia, Claire M; De Asis, Roxanne M; Bailey, E Fiona

2018-02-01

What is the central question of this study? What impact does inspiratory muscle training have on systemic vascular resistance, cardiac output and baroreflex sensitivity in adult men and women? What is the main finding and its importance? Inspiratory muscle training exerts favorable effects on blood pressure, vascular resistance and perception of stress. This exercise format is well-tolerated and equally effective whether implemented in men or women. Previous work has shown that inspiratory muscle training (IMT) lowers blood pressure after a mere 6 weeks, identifying IMT as a potential therapeutic intervention to prevent or treat hypertension. Here, we explore the effects of IMT on respiratory muscle strength and select cardiovascular parameters in recreationally active men and women. Subjects were randomly assigned to IMT (n = 12, 75% maximal inspiratory pressure) or sham training (n = 13, 15% maximal inspiratory pressure) groups and underwent a 6-week intervention comprising 30 breaths day -1 , 5 days week -1 . Pre- and post-training measures included maximal inspiratory pressure and resting measures of blood pressure, cardiac output, heart rate, spontaneous cardiac baroreflex sensitivity and systemic vascular resistance. We evaluated psychological and sleep status via administration of the Cohen-Hoberman inventory of physical symptoms and the Epworth sleepiness scale. Male and female subjects in the IMT group showed declines in systolic/diastolic blood pressures (-4.3/-3.9 mmHg, P < 0.025) and systemic vascular resistance (-3.5 mmHg min l -1 , P = 0.008) at week 6. There was no effect of IMT on cardiac output (P = 0.722), heart rate (P = 0.795) or spontaneous cardiac baroreflex sensitivity (P = 0.776). The IMT subjects also reported fewer stress-related symptoms (pre- versus post-training, 12.5 ± 8.5 versus 7.2 ± 9.7, P = 0.025). Based on these results, we suggest that a short course of IMT confers significant respiratory and cardiovascular improvements and parallel (modest) psychological benefits in healthy men and women. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Effects of levosimendan on glomerular filtration rate, renal blood flow, and renal oxygenation after cardiac surgery with cardiopulmonary bypass: a randomized placebo-controlled study.

PubMed

Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

2013-10-01

Acute kidney injury develops in a large proportion of patients after cardiac surgery because of the low cardiac output syndrome. The inodilator levosimendan increases cardiac output after cardiac surgery with cardiopulmonary bypass, but a detailed analysis of its effects on renal perfusion, glomerular filtration, and renal oxygenation in this group of patients is lacking. We therefore evaluated the effects of levosimendan on renal blood flow, glomerular filtration rate, renal oxygen consumption, and renal oxygen demand/supply relationship, i.e., renal oxygen extraction, early after cardiac surgery with cardiopulmonary bypass. Prospective, placebo-controlled, and randomized trial. Cardiothoracic ICU of a tertiary center. Postcardiac surgery patients (n=30). The patients were randomized to receive levosimendan, 0.1 µg/kg/min after a loading dose of 12 µg/kg (n=15), or placebo (n=15). The experimental procedure started 4-6 hours after surgery in the ICU during propofol sedation and mechanical ventilation. Systemic hemodynamic were evaluated by a pulmonary artery thermodilution catheter. Renal blood flow and glomerular filtration rate were measured by the renal vein retrograde thermodilution technique and by renal extraction of Cr-EDTA, respectively. Central venous pressure was kept constant by colloid/crystalloid infusion. Compared to placebo, levosimendan increased cardiac index (22%), stroke volume index (15%), and heart rate (7%) and decreased systemic vascular resistance index (21%), whereas mean arterial pressure was not affected. Levosimendan induced significant increases in renal blood flow (12%, p<0.05) and glomerular filtration rate (21%, p<0.05), decreased renal vascular resistance (18%, p<0.05) but caused no significant changes in filtration fraction, renal oxygen consumption, or renal oxygen extraction, compared to placebo. After cardiac surgery with cardiopulmonary bypass, levosimendan induces a vasodilation, preferentially of preglomerular resistance vessels, increasing both renal blood flow and glomerular filtration rate without jeopardizing renal oxygenation. Due to its pharmacodynamic profile, levosimendan might be an interesting alternative for treatment of postoperative heart failure complicated by acute kidney injury in postcardiac surgery patients.

Inter- and Intraobserver Agreement of 18F-FDG PET/CT Image Interpretation in Patients Referred for Assessment of Cardiac Sarcoidosis.

PubMed

Ohira, Hiroshi; Ardle, Brian Mc; deKemp, Robert A; Nery, Pablo; Juneau, Daniel; Renaud, Jennifer M; Klein, Ran; Clarkin, Owen; MacDonald, Karen; Leung, Eugene; Nair, Girish; Beanlands, Rob; Birnie, David

2017-08-01

Recent studies have reported the usefulness of 18 F-FDG PET in aiding with the diagnosis and management of patients with cardiac sarcoidosis (CS). However, image interpretation of 18 F-FDG PET for CS is sometimes challenging. We sought to investigate the inter- and intraobserver agreement and explore factors that led to important discrepancies between readers. Methods: We studied consecutive patients with no significant coronary artery disease who were referred for assessment of CS. Two experienced readers masked to clinical information, imaging reports, independently reviewed 18 F-FDG PET/CT images. 18 F-FDG PET/CT images were interpreted according to a predefined standard operating procedure, with cardiac 18 F-FDG uptake patterns categorized into 5 patterns: none, focal, focal on diffuse, diffuse, and isolated lateral wall or basal uptake. Overall image assessment was classified as either consistent with active CS or not. Results: One hundred scans were included from 71 patients. Of these, 46 underwent 18 F-FDG PET/CT with a no-restriction diet (no-restriction group), and 54 underwent 18 F-FDG PET/CT with a low-carbohydrate, high-fat and protein-permitted diet (low-carb group). There was agreement of the interpretation category in 74 of 100 scans. The κ-value of agreement among all 5 categories was 0.64, indicating moderate agreement. For overall clinical interpretation, there was agreement in 93 of 100 scans (κ = 0.85). When scans were divided into the preparation groups, there was a trend toward higher agreement in the low-carb group versus the no-restriction group (80% vs. 67%, P = 0.08). Regarding the overall clinical interpretation, there was also a trend toward greater agreement in the low-carb group versus the no-restriction group (96% vs. 89%, P = 0.08). Conclusion : The interobserver agreement of cardiac 18 F-FDG uptake image patterns was moderate. However, agreement was better regarding overall interpretation of CS. Detailed prescan dietary preparation seemed to improve interobserver agreement. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Scintigraphic evaluation of Lyme disease: Gallium-67 imaging of Lyme myositis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kengen, R.A.; v.d. Linde, M.; Sprenger, H.G.

1989-10-01

A patient suffering from Lyme disease had cardiac conduction abnormalities, symptoms of arthritis, and myalgia. A Ga-67 image showed evidence of endomyocarditis, but intense skeletal muscle uptake pointed to Lyme myositis. Reference is made to two other case reports of Lyme myositis.

[Summary of the consensus document: "Clinical practice guide for the management of low cardiac output syndrome in the postoperative period of heart surgery"].

PubMed

Pérez Vela, J L; Martín Benitez, J C; Carrasco Gonzalez, M; de la Cal López, M A; Hinojosa Pérez, R; Sagredo Meneses, V; del Nogal Saez, F

2012-05-01

Low cardiac output syndrome is a potential complication in cardiac surgery patients and is associated with increased morbidity and mortality. This guide provides recommendations for the management of these patients, immediately after surgery and following admission to the ICU. The recommendations are grouped into different sections, addressing from the most basic concepts such as definition of the disorder to the different sections of basic and advanced monitoring, and culminating with the complex management of this syndrome. We propose an algorithm for initial management, as well as two others for ventricular failure (predominantly left or right). Most of the recommendations are based on expert consensus, due to the lack of randomized trials of adequate design and sample size in patients of this kind. The quality of evidence and strength of the recommendations were based on the GRADE methodology. The guide is presented as a list of recommendations (with the level of evidence for each recommendation) for each question on the selected topic. For each question, justification of the recommendations is then provided. Copyright © 2011 Elsevier España, S.L. y SEMICYUC. All rights reserved.

[Clinical practice guide for the management of low cardiac output syndrome in the postoperative period of heart surgery].

PubMed

Pérez Vela, J L; Martín Benítez, J C; Carrasco González, M; de la Cal López, M A; Hinojosa Pérez, R; Sagredo Meneses, V; del Nogal Saez, F

2012-05-01

The low cardiac output syndrome is a potential complication in cardiac surgery patients and associated with increased morbidity and mortality. This guide is to provide recommendations for the management of these patients, immediately after surgery, admitted to the ICU. The recommendations are grouped into different sections, trying to answer from the most basic concepts such as the definition to the different sections of basic and advanced monitoring and ending with the complex management of this syndrome. We propose an algorithm for initial management, as well as two other for ventricular failure (predominantly left or right). Most of the recommendations are based on expert consensus because of the lack of randomized trials of adequate design and sample size in this group of patients. The quality of evidence and strength of the recommendations were made following the GRADE methodology. The guide is presented as a list of recommendations (and level of evidence for each recommendation) for each question on the selected topic. Then for each question, we proceed to the justification of the recommendations. Copyright © 2011 Elsevier España, S.L. y SEMICYUC. All rights reserved.

Construct, concurrent and discriminant validity of Type D personality in the general population: associations with anxiety, depression, stress and cardiac output.

PubMed

Howard, Siobhán; Hughes, Brian M

2012-01-01

The Type D personality, identified by high negative affectivity paired with high social inhibition, has been associated with a number of health-related outcomes in (mainly) cardiac populations. However, despite its prevalence in the health-related literature, how this personality construct fits within existing personality theory has not been directly tested. Using a sample of 134 healthy university students, this study examined the Type D personality in terms of two well-established personality traits; introversion and neuroticism. Construct, concurrent and discriminant validity of this personality type was established through examination of the associations between the Type D personality and psychometrically assessed anxiety, depression and stress, as well as measurement of resting cardiovascular function. Results showed that while the Type D personality was easily represented using alternative measures of both introversion and neuroticism, associations with anxiety, depression and stress were mainly accounted for by neuroticism. Conversely, however, associations with resting cardiac output were attributable to the negative affectivity-social inhibition synergy, explicit within the Type D construct. Consequently, both the construct and concurrent validity of this personality type were confirmed, with discriminant validity evident on examination of physiological indices of well-being.

A New Frontier for Cardiac Monitoring

NASA Technical Reports Server (NTRS)

2001-01-01

CardioDynamics International Corporation (CDIC) has created the BioZ(TM) System through a Small Business Innovation Research (SBIR) award from Johnson Space Center, providing patients and physicians with a cost-effective and highly accurate monitoring system.The BioZ non-invasive heart monitor is based on a technology known as Impedance Cardiography (ICG). BioZ provides the physician with vital information about the heart's ability to deliver blood to the body, the force one's heart exerts with each beat, and the amount of fluid in the chest. Specially designed bioimpedance sensors placed on the neck and chest monitor 12 different parameters, including cardiac output, contractility, systemic vascular resistance, and thoracic fluid content. These sensors monitor the electrical conductivity of the body-information that is converted into blood flow data and is displayed in real time on a monitoring screen. BioZ.com(TM) and BioZ.pc(TM) are two additional products that incorporate the same sensors present in the original BioZ system. The "com" in BioZ.com stands for cardiac output monitor. This fully integrated system is essentially a smaller version of the BioZ, combining the same abilities with a compact, lightweight design, while providing greater portability.

A novel handheld device for use in remote patient monitoring of heart failure patients--design and preliminary validation on healthy subjects.

PubMed

Pollonini, Luca; Rajan, Nithin O; Xu, Shuai; Madala, Sridhar; Dacso, Clifford C

2012-04-01

Remote patient monitoring (RPM) holds great promise for reducing the burden of congestive heart failure (CHF). Improved sensor technology and effective predictive algorithms can anticipate sudden decompensation events. Enhanced telemonitoring systems would promote patient independence and facilitate communication between patients and their physicians. We report the development of a novel hand-held device, called Blue Box, capable of collecting and wirelessly transmitting key cardiac parameters derived from three integrated biosensors: 2 lead electrocardiogram (ECG), photoplethysmography and bioelectrical impedance (bioimpedance). Blue Box measurements include time intervals between consecutive ECG R-waves (RR interval), time duration of the ECG complex formed by the Q, R and S waves (QRS duration), bioimpedance, heart rate and systolic time intervals. In this study, we recruited 24 healthy subjects to collect several parameters measured by Blue Box and assess their value in correlating with cardiac output measured with Echo-Doppler. Linear correlation between the heart rate measured with Blue Box and cardiac output from Echo-Doppler had a group average correlation coefficient of 0.80. We found that systolic time intervals did not improve the model significantly. However, STIs did inversely correlate with increasing workloads.

Influence of Gravity on Blood Volume and Flow Distribution

NASA Technical Reports Server (NTRS)

Pendergast, D.; Olszowka, A.; Bednarczyk, E.; Shykoff, B.; Farhi, L.

1999-01-01

In our previous experiments during NASA Shuttle flights SLS 1 and 2 (9-15 days) and EUROMIR flights (30-90 days) we observed that pulmonary blood flow (cardiac output) was elevated initially, and surprisingly remained elevated for the duration of the flights. Stroke volume increased initially and then decreased, but was still above 1 Gz values. As venous return was constant, the changes in SV were secondary to modulation of heart rate. Mean blood pressure was at or slightly below 1 Gz levels in space, indicating a decrease in total peripheral resistance. It has been suggested that plasma volume is reduced in space, however cardiac output/venous return do not return to 1 Gz levels over the duration of flight. In spite of the increased cardiac output, central venous pressure was not elevated in space. These data suggest that there is a change in the basic relationship between cardiac output and central venous pressure, a persistent "hyperperfusion" and a re-distribution of blood flow and volume during space flight. Increased pulmonary blood flow has been reported to increase diffusing capacity in space, presumably due to the improved homogeneity of ventilation and perfusion. Other studies have suggested that ventilation may be independent of gravity, and perfusion may not be gravity- dependent. No data for the distribution of pulmonary blood volume were available for flight or simulated microgravity. Recent studies have suggested that the pulmonary vascular tree is influenced by sympathetic tone in a manner similar to that of the systemic system. This implies that the pulmonary circulation is dilated during microgravity and that the distribution of blood flow and volume may be influenced more by vascular control than by gravity. The cerebral circulation is influenced by sympathetic tone similarly to that of the systemic and pulmonary circulations; however its effects are modulated by cerebral autoregulation. Thus it is difficult to predict if cerebral perfusion is increased and if there is edema in space. Anecdotal evidence suggests there may be cerebral edema early in flight. Cerebral artery velocity has been shown to be elevated in simulated microgravity. The elevated cerebral artery velocity during simulated microgravity may reflect vasoconstriction of the arteries and not increased cerebral blood flow. The purpose of our investigations was to evaluate the effects of alterations in simulated gravity (+/-), resulting in changes in cardiac output (+/-), and on the blood flow and volume distribution in the lung and brain of human subjects. The first hypothesis of these studies was that blood flow and volume would be affected by gravity, but their distribution in the lung would be independent of gravity and due to vasoactivity changing vascular resistance in lung vessels. The vasodilitation of the lung vasculature (lower resistance) along with increased "compliance" of the heart could account for the absence of increased central venous pressure in microgravity. Secondly, we postulate that cerebral blood velocity is increased in microgravity due to large artery vasoconstriction, but that cerebral blood flow would be reduced due to autoregulation.

Electrostimulation of muscles as a method for the treatment and prophylaxis of hemodynamic disturbances during prolonged hypokinesia

NASA Technical Reports Server (NTRS)

Dukhin, Y. O.; Zhukovskyy, L. Y.

1980-01-01

Hemodynamic and periopheral circulation indexes were recorded before, at the end of, and 5 days after 10 days of electrostimulation for 45 min daily, at rest and after a physical loading test. It was found that stroke and minute volume, cardiac output, and regional circulation improved and heart rate and peripheral resistance decreased. The functional state of the cardiac muscle and vascular tone are improved by electrostimulation of selected groups of skeletal muscles.

Hemodynamic effects of aerosol propellants. I. Cardiac depression in the dog.

PubMed

Simaan, J A; Aviado, D M

1975-11-01

The inhalation of fluorocarbons caused a depression of myocardial contractility, aortic hypotension, a decrease in cardiac output and an increase in pulmonary vascular resistance. The minimal concentrations that elicited these changes are as follows: 1% trichlorofluoromethane (FC11); 2.5% dichlorotetrafluoroethane (FC114); and 10% dichlorodifluoromethane (FC12). Inhalation of 20% octafluorocyclobutane (FC318) and difluoroethane (FC152a) did not influence these hemodynamic parameters. As in previous comparisons, the most widely used aerosol propellants are potentially cardiotoxic in the anesthetized dog.

Cardiovascular research in space - Considerations for the design of the human research facility of the United States Space Station

NASA Technical Reports Server (NTRS)

Charles, J. B.; Bungo, M. W.

1986-01-01

The design of the Space Station's Human Research Facility for the collection of information on the long-time physiological adjustments of humans to space is described. The Space Life Sciences-1 mission will carry a rack-mounted echocardiograph for cardiac imaging, a mass spectrometer for cardiac output and respiratory function assessments at rest and during exercise, and a device to stimulate the carotid sinus baroreceptors and measure the resulting changes in heart rate.

Structural identifiability analyses of candidate models for in vitro Pitavastatin hepatic uptake.

PubMed

Grandjean, Thomas R B; Chappell, Michael J; Yates, James W T; Evans, Neil D

2014-05-01

In this paper a review of the application of four different techniques (a version of the similarity transformation approach for autonomous uncontrolled systems, a non-differential input/output observable normal form approach, the characteristic set differential algebra and a recent algebraic input/output relationship approach) to determine the structural identifiability of certain in vitro nonlinear pharmacokinetic models is provided. The Organic Anion Transporting Polypeptide (OATP) substrate, Pitavastatin, is used as a probe on freshly isolated animal and human hepatocytes. Candidate pharmacokinetic non-linear compartmental models have been derived to characterise the uptake process of Pitavastatin. As a prerequisite to parameter estimation, structural identifiability analyses are performed to establish that all unknown parameters can be identified from the experimental observations available. Copyright © 2013. Published by Elsevier Ireland Ltd.

Measuring the mechanical efficiency of a working cardiac muscle sample at body temperature using a flow-through calorimeter.

PubMed

Taberner, Andrew J; Johnston, Callum M; Pham, Toan; June-Chiew Han; Ruddy, Bryan P; Loiselle, Denis S; Nielsen, Poul M F

2015-08-01

We have developed a new `work-loop calorimeter' that is capable of measuring, simultaneously, the work-done and heat production of isolated cardiac muscle samples at body temperature. Through the innovative use of thermoelectric modules as temperature sensors, the development of a low-noise fluid-flow system, and implementation of precise temperature control, the heat resolution of this device is 10 nW, an improvement by a factor of ten over previous designs. These advances have allowed us to conduct the first flow-through measurements of work output and heat dissipation from cardiac tissue at body temperature. The mechanical efficiency is found to vary with peak stress, and reaches a peak value of approximately 15 %, a figure similar to that observed in cardiac muscle at lower temperatures.

Regulation of pumping function of the heart in developing body under changing regimens of motor activity.

PubMed

Vafina, E Z; Abzalov, R A; Abzalov, N I; Nikitin, A S; Gulyakov, A A

2014-06-01

We analyzed parameters of the pumping function of the heart in rats subjected to enhanced motor activity after a preliminary 70-day hypokinesia under conditions of α- and β-adrenergic receptor stimulation with norepinephrine followed by blockade of β-adrenergic receptor with propranolol (obsidian) and α1-adrenergic receptors with doxazosin. After norepinephrine administration, the HR and cardiac output were higher in rats with enhanced physical activity after preliminary hypokinesia than in rats with low physical activity. After propranolol administration, stroke volume and cardiac output in 100-day-old rats with limited activity were lower, and HR higher was than in rats with enhanced physical activity after preliminary 70-day hypokinesia. After administration of doxazosin, rats with limited motor activity demonstrated more pronounced changes in HR than rats with enhanced physical activity after preliminary 70-day hypokinesia.

Piezoelectric extraction of ECG signal

NASA Astrophysics Data System (ADS)

Ahmad, Mahmoud Al

2016-11-01

The monitoring and early detection of abnormalities or variations in the cardiac cycle functionality are very critical practices and have significant impact on the prevention of heart diseases and their associated complications. Currently, in the field of biomedical engineering, there is a growing need for devices capable of measuring and monitoring a wide range of cardiac cycle parameters continuously, effectively and on a real-time basis using easily accessible and reusable probes. In this paper, the revolutionary generation and extraction of the corresponding ECG signal using a piezoelectric transducer as alternative for the ECG will be discussed. The piezoelectric transducer pick up the vibrations from the heart beats and convert them into electrical output signals. To this end, piezoelectric and signal processing techniques were employed to extract the ECG corresponding signal from the piezoelectric output voltage signal. The measured electrode based and the extracted piezoelectric based ECG traces are well corroborated. Their peaks amplitudes and locations are well aligned with each other.

Reversal of pulmonary hypertension after percutaneous closure of congenital renal arteriovenous fistula in a 74-year old woman.

PubMed

Brar, Vijaywant; Bernardo, Nelson; Suddath, William; Weissman, Gaby; Asch, Federico; Campia, Umberto

2015-01-01

We report the case of a large right renal arteriovenous fistula (AVF) in a 74-year old woman who presented with heart failure. Transthoracic echocardiography revealed normal left ventricular size and systolic function (ejection fraction 60-65%), moderately dilated right ventricle with severely depressed systolic function, and severe pulmonary hypertension. Right heart catheterization confirmed the elevated pulmonary pressures and showed a high cardiac output. Physical examination was remarkable for a right flank bruit. An abdominal ultrasound revealed an AVF originating from the distal right renal artery and dilated suprarenal inferior vena cava and hepatic veins. These findings were confirmed with an abdominal MRI. Percutaneous endovascular closure of the right renal AVF was successfully performed, with immediate reduction of pulmonary pressures and normalization of cardiac output. The patient's symptoms improved, and a post intervention echocardiogram revealed normalization of right ventricular size. Copyright © 2015 Elsevier Inc. All rights reserved.

Action of acetylstrophanthidin on experimental myocardial infarction.

NASA Technical Reports Server (NTRS)

Nola, G. T.; Pope, S. E.; Harrison, D. C.

1972-01-01

An experimental animal model with acute myocardial infarction of a size insufficient to produce profound heart failure or shock was used to study the effects of acute infarction on digitalis tolerance and the hemodynamic changes produced by moderate and large doses of acetylstrophanthidin. With acute myocardial infarction, digitalis toxic arrhythmias could be precipitated with significantly lower doses of digitalis than in animals without myocardial infarction. There was no precise correlation between the size of infarction and the toxic dose of glycoside. Coronary artery ligation produced a stable but relatively depressed circulatory state, as evidenced by lowered cardiac output and stroke volume and elevated systemic vascular resistance and left atrial mean pressure. When digitalis was infused, the following significant changes were observed at nontoxic doses: (1) elevation of aortic and left ventricular pressures; (2) further decline in cardiac output; and (3) decreased left atrial mean pressure.

Non-invasive measurement of the haemodynamic effects of inhaled salbutamol, intravenous L-arginine and sublingual nitroglycerin

PubMed Central

Tahvanainen, Anna; Leskinen, Miia; Koskela, Jenni; Ilveskoski, Erkki; Alanko, Juha; Kähönen, Mika; Kööbi, Tiit; Lehtimäki, Lauri; Moilanen, Eeva; Mustonen, Jukka; Pörsti, Ilkka

2009-01-01

AIMS To examine the effects of salbutamol and L-arginine, two compounds acting largely on the endothelium, and the endothelium-independent agent nitroglycerin on blood pressure, arterial compliance, cardiac function and vascular resistance. METHODS Continuous radial pulse wave analysis, whole-body impedance cardiography, and plethysmographic blood pressure from fingers in the supine position and during head-up tilt were recorded in nine healthy subjects. Data were captured before and after L-arginine (10 mg mg−1 min−1) or saline infusion, salbutamol (400 µg) or placebo inhalation, and sublingual nitroglycerin (0.25 mg) or placebo resoriblet. RESULTS The results of all measurements were comparable before drug administration. The effects of inhaled salbutamol were apparent in the supine position: systemic vascular resistance (−9.2 ± 2.6%) and augmentation index (−4.0 ± 1.5%) decreased, and heart rate (8.6 ± 2.5%) and cardiac output (8.8 ± 3.1%) increased. L-arginine had no clear effects on supine haemodynamics, but during head-up tilt blood pressure was moderately decreased and reduction in aortic reflection time prevented, indicating improved large arterial compliance. Nitroglycerin reduced supine vascular resistance (−6.7 ± 1.8%) and augmentation index (−7.4 ± 1.6%), and increased cardiac output (+9.2 ± 2.7%). During head-up tilt, nitroglycerin increased cardiac output (+10.6 ± 5.6%) and heart rate (+40 ± 7.5%), decreased vascular resistance (−7.8 ± 5.8%) and augmentation index (−18.7 ± 3.2%), and prevented the decrease in aortic reflection time. CONCLUSIONS Inhaled salbutamol predominantly changed supine haemodynamics, whereas the moderate effects of L-arginine were observed during the head-up tilt. In contrast, small doses of nitroglycerin induced major changes in haemodynamics both supine and during the head-up tilt. Altogether, these results emphasize the importance of haemodynamic measurements in both the supine and upright positions. PMID:19660000

Cardiac myofibrillar contractile properties during the progression from hypertension to decompensated heart failure.

PubMed

Hanft, Laurin M; Emter, Craig A; McDonald, Kerry S

2017-07-01

Heart failure arises, in part, from a constellation of changes in cardiac myocytes including remodeling, energetics, Ca 2+ handling, and myofibrillar function. However, little is known about the changes in myofibrillar contractile properties during the progression from hypertension to decompensated heart failure. The aim of the present study was to provide a comprehensive assessment of myofibrillar functional properties from health to heart disease. A rodent model of uncontrolled hypertension was used to test the hypothesis that myocytes in compensated hearts exhibit increased force, higher rates of force development, faster loaded shortening, and greater power output; however, with progression to overt heart failure, we predicted marked depression in these contractile properties. We assessed contractile properties in skinned cardiac myocyte preparations from left ventricles of Wistar-Kyoto control rats and spontaneous hypertensive heart failure (SHHF) rats at ~3, ~12, and >20 mo of age to evaluate the time course of myofilament properties associated with normal aging processes compared with myofilaments from rats with a predisposition to heart failure. In control rats, the myofilament contractile properties were virtually unchanged throughout the aging process. Conversely, in SHHF rats, the rate of force development, loaded shortening velocity, and power all increased at ~12 mo and then significantly fell at the >20-mo time point, which coincided with a decrease in left ventricular fractional shortening. Furthermore, these changes occurred independent of changes in β-myosin heavy chain but were associated with depressed phosphorylation of myofibrillar proteins, and the fall in loaded shortening and peak power output corresponded with the onset of clinical signs of heart failure. NEW & NOTEWORTHY This novel study systematically examined the power-generating capacity of cardiac myofilaments during the progression from hypertension to heart disease. Previously undiscovered changes in myofibrillar power output were found and were associated with alterations in myofilament proteins, providing potential new targets to exploit for improved ventricular pump function in heart failure. Copyright © 2017 the American Physiological Society.

Comparison of Levosimendan, Milrinone and Dobutamine in treating Low Cardiac Output Syndrome Following Valve Replacement Surgeries with Cardiopulmonary Bypass

PubMed Central

Sunny; Karim, Habib Md Reazaul; Saikia, Manuj Kumar; Bhattacharyya, Prithwis; Dey, Samarjit

2016-01-01

Introduction Low Cardiac Output Syndrome (LCOS) following Cardiopulmonary Bypass (CPB) is common and associated with increased mortality. Maintenance of adequate cardiac output is one of the primary objectives in management of such patients. Aim To compare Levosimendan, Milrinone and Dobutamine for the treatment of LCOS after CPB in patients who underwent valve replacement surgeries. Materials and Methods Sixty eligible patients meeting LCOS were allocated into three treatment groups: Group A-Levosimendan (loading dose 10μg/kg over 10 minutes, followed by 0.1μg/kg/min); Group B-Milrinone (loading dose 50 mcg/kg over 10 minutes followed by 0.5mcg/kg/min) and Group C-Dobutamine @ 5μg/kg/min to achieve target cardiac index (CI) of > 2.5 L/min/m2. In case of failure, other drugs were added as required. Hemodynamic parameters were monitored using EV1000TM clinical platform till 30 minutes post CPB. INSTAT software was used for statistics and p<0.05 was considered significant. Results The mean±standard deviation of time taken by Dobutamine, Levosimendan and Milrinone to bring the CI to target were 11.1±8.79, 11.3±6.34 and 16.62±9.33 minutes respectively (p=0.064). Levosimendan was equally effective in increasing and maintaining adequate CI as compared to Dobutamine (p>0.05). Levosimendan and Milrinone increased MAP (Mean Arterial Pressure) equally while Dobutamine was more effective as compared to both Levosimendan and Milrinone 20th minute onwards (p<0.01). Milrinone was less effective in increasing the stroke volume as compared to Dobutamine and Levosimendan while Dobutamine and Levosimendan were equally effective. There was no difference in the HR (Heart Rate) achieved with all these three drugs. Conclusion Levosimendan is equally effective to Dobutamine and better than Milrinone for the treatment of LCOS following CPB in patients undergoing valve replacement surgeries. PMID:28208977

Pulmonary ventilation-perfusion mismatch: a novel hypothesis for how diving vertebrates may avoid the bends.

PubMed

Garcia Párraga, Daniel; Moore, Michael; Fahlman, Andreas

2018-04-25

Hydrostatic lung compression in diving marine mammals, with collapsing alveoli blocking gas exchange at depth, has been the main theoretical basis for limiting N 2 uptake and avoiding gas emboli (GE) as they ascend. However, studies of beached and bycaught cetaceans and sea turtles imply that air-breathing marine vertebrates may, under unusual circumstances, develop GE that result in decompression sickness (DCS) symptoms. Theoretical modelling of tissue and blood gas dynamics of breath-hold divers suggests that changes in perfusion and blood flow distribution may also play a significant role. The results from the modelling work suggest that our current understanding of diving physiology in many species is poor, as the models predict blood and tissue N 2 levels that would result in severe DCS symptoms (chokes, paralysis and death) in a large fraction of natural dive profiles. In this review, we combine published results from marine mammals and turtles to propose alternative mechanisms for how marine vertebrates control gas exchange in the lung, through management of the pulmonary distribution of alveolar ventilation ([Formula: see text]) and cardiac output/lung perfusion ([Formula: see text]), varying the level of [Formula: see text] in different regions of the lung. Man-made disturbances, causing stress, could alter the [Formula: see text] mismatch level in the lung, resulting in an abnormally elevated uptake of N 2 , increasing the risk for GE. Our hypothesis provides avenues for new areas of research, offers an explanation for how sonar exposure may alter physiology causing GE and provides a new mechanism for how air-breathing marine vertebrates usually avoid the diving-related problems observed in human divers. © 2018 The Authors.

Beta2- and beta3-adrenergic receptor polymorphisms and exercise hemodynamics in postmenopausal women.

PubMed

McCole, Steve D; Shuldiner, Alan R; Brown, Michael D; Moore, Geoffrey E; Ferrell, Robert E; Wilund, Kenneth R; Huberty, Andrea; Douglass, Larry W; Hagberg, James M

2004-02-01

We sought to determine whether common genetic variations at the beta2 (beta2-AR, Gln27Glu) and beta3 (beta3-AR, Trp64Arg) adrenergic receptor gene loci were associated with cardiovascular (CV) hemodynamics during maximal and submaximal exercise. CV hemodynamics were assessed in 62 healthy postmenopausal women (20 sedentary, 22 physically active, and 20 endurance athletes) during treadmill exercise at 40, 60, 80, and 100% maximal O2 uptake using acetylene rebreathing to quantify cardiac output. The beta2-AR genotype and habitual physical activity (PA) levels interacted to significantly associate with arteriovenous O2 difference (a-vDO2) during submaximal exercise (P = 0.05), with the highest submaximal exercise a-vDO2 in sedentary women homozygous for the beta2-AR Gln allele and no genotype-dependent differences in submaximal exercise a-vDO2 in physically active and athletic women. The beta2-AR genotype also was independently associated with a-vDO2 during submaximal (P = 0.004) and approximately 100% maximal O2 uptake exercise (P = 0.006), with a 1.2-2 ml/100 ml greater a-vDO2 in the Gln/Gln than in the Glu/Glu genotype women. The beta3-AR genotype, independently or interacting with habitual PA levels, was not significantly associated with any CV hemodynamic variables during submaximal or maximal exercise. Thus it appears that the beta2-AR genotype, both independently and interacting with habitual PA levels, is significantly associated with a-vDO2 during exercise in postmenopausal women, whereas the beta3-AR genotype does not appear to be associated with any maximal or submaximal exercise CV hemodynamic responses in postmenopausal women.

A Forty-Year Follow-Up of the Dallas Bed Rest and Training Study: The Effect of Age on the Cardiovascular Response to Exercise in Men

PubMed Central

McGavock, Jonathan M.; Hastings, Jeffrey L.; Snell, Peter G.; McGuire, Darren K.; Pacini, Eric L.; Mitchell, Jere H.

2009-01-01

Background In 1966, five 20-year-old men underwent a comprehensive physiological evaluation of the capacity for adaptation of the cardiovascular system in response to 3 weeks of bed rest and 8 weeks of heavy endurance training; these same participants were reevaluated before and after training at the age of 50. The aim of the present study was to reexamine these same men 40 years following the original assessments. Methods and Results In all three studies, minute ventilation and expired gases were analyzed during exercise testing with Douglas bag collection. Cardiac output (CO) was determined using the acetylene rebreathing technique. Compared with the original 30-year interval, the decline in maximal oxygen uptake (VO2max) (−11% vs −25%), maximal CO (+6% vs −11%), and maximal stroke volume (+10% vs −10%) were greater between 50 and 60 years of age. The annualized decline in VO2max (55 mL/min/y) between ages 50 and 60 was approximately fourfold higher than the decline between 20 and 50 years (12 mL/min/y). Conclusions In the original five participants of the Dallas Bed Rest and Training Study, VO2max declined after 40 years of living due to a balanced decrease in central and peripheral determinants of oxygen uptake. The rate of decline in VO2max and its components accelerated after the age of 50 years secondary to age and clinical comorbidities. The net proportional decline in VO2max for a period of 40 years of life was comparable with that experienced after 3 weeks of strict bed rest at the age of 20 (27% vs 26%, respectively). PMID:19196908

The effects of combined versus selective adrenergic blockade on left ventricular and systemic hemodynamics, myocardial substrate preference, and regional perfusion in conscious dogs with dilated cardiomyopathy.

PubMed

Nikolaidis, Lazaros A; Poornima, Indu; Parikh, Pratik; Magovern, Megan; Shen, You-Tang; Shannon, Richard P

2006-05-02

Given that adverse effects of chronic sympathetic activation are mediated by all three adrenergic receptor subtypes (beta1, beta2, alpha1), we examined the effects of standard doses of carvedilol and metoprolol succinate (metoprolol controlled release/extended release [CR/XL]) on hemodynamics, myocardial metabolism, and regional organ perfusion. Both beta1 selective and combined adrenergic blockade reduce morbidity and mortality in heart failure. Whether there are advantages of one class over the other remains controversial, even in the wake of the Carvedilol Or Metoprolol European Trial (COMET). Similarly, the mechanistic basis for the relative differences is incompletely understood. Thirty-three conscious, chronically instrumented dogs with pacing-induced (240 min(-1) for 4 weeks) dilated cardiomyopathy (DCM) were randomized to carvedilol (25 mg twice daily, Coreg, Glaxo Smith Kline, Research Triangle, North Carolina) or metoprolol succinate (100 mg qd, Toprol XL, Astra Zeneca, Wilmington, Delaware). Left ventricular and systemic hemodynamics, myocardial substrate uptake, and norepinephrine spillover were measured before and after three days of treatment. Regional (renal, hepatic, skeletal muscle) blood flows were measured using neutron-activated microspheres. Both agents had comparable heart rate effects. However, carvedilol-treated dogs showed significantly greater increases in stroke volume and cardiac output and decreases in left ventricular end-diastolic pressure and systemic vascular resistance. Carvedilol increased renal, hepatic, and skeletal muscle blood flow. Carvedilol increased myocardial glucose uptake and suppressed norepinephrine and glucagon. Carvedilol antagonized the response to exogenous norepinephrine to a greater extent than metoprolol CR/XL. At doses inducing comparable heart rate reductions, short-term treatment with carvedilol had superior hemodynamic and metabolic effects compared with metoprolol CR/XL. These data suggest important advantages of blocking all three adrenergic receptor subtypes in DCM.

Increased temperature tolerance of the air-breathing Asian swamp eel Monopterus albus after high-temperature acclimation is not explained by improved cardiorespiratory performance.

PubMed

Lefevre, S; Findorf, I; Bayley, M; Huong, D T T; Wang, T

2016-01-01

This study investigated the hypothesis that in the Asian swamp eel Monopterus albus, an air-breathing fish from south-east Asia that uses the buccopharyngeal cavity for oxygen uptake, the upper critical temperature (TU) is increased by acclimation to higher temperature, and that the increased TU is associated with improved cardiovascular and respiratory function. Monopterus albus were therefore acclimated to 27° C (current average) and 32° C (current maximum temperature as well as projected average within 100-200 years), and both the effect of acclimation and acute temperature increments on cardiovascular and respiratory functions were investigated. Two weeks of heat acclimation increased upper tolerated temperature (TU ) by 2° C from 36·9 ± 0·1° C to 38·9 ± 0·1° C (mean ± s.e.). Oxygen uptake (M˙O2) increased with acclimation temperature, accommodated by increases in both aerial and aquatic respiration. Overall, M˙O2 from air (M˙O2a ) was predominant, representing 85% in 27° C acclimated fish and 80% in 32° C acclimated fish. M˙O2 increased with acute increments in temperature and this increase was entirely accommodated by an increase in air-breathing frequency and M˙O2a . Monopterus albus failed to upregulate stroke volume; rather, cardiac output was maintained through increased heart rate with rising temperature. Overall, acclimation of M. albus to 32° C did not improve its cardiovascular and respiratory performance at higher temperatures, and cardiovascular adaptations, therefore, do not appear to contribute to the observed increase in TU. © 2015 The Fisheries Society of the British Isles.

Bymixer system can measure O2 uptake and CO2 elimination in the anesthesia circle circuit.

PubMed

Rosenbaum, Abraham; Kirby, Christopher W; Breen, Peter H

2007-06-01

The ability to measure carbon dioxide elimination (Vco(2)), oxygen uptake (Vo(2)), and R (respiratory exchange ratio, Vco(2)/Vo(2)) during anesthesia may help the non-invasive detection of critical events (e.g., abrupt decrease in cardiac output) and metabolic upset (e.g., onset of anaerobic metabolism). We have developed a new clinical bymixer (inline mixing chamber) that can measure mixed inspired and expired gas fractions in the anesthesia circle circuit. The addition of a standard anesthesia gas analyzer and flowmeter, and a new airway temperature and humidity sensor, allow determinations of Vco(2) and Vo(2) at the airway opening of the circle circuit. Over a range of tidal volume and frequency, Vco(2) and Vo(2) were compared to reference values generated by the combustion of metered liquid ethanol in a new metabolic lung simulator. By linear regression, bymixer-flow measurements of Vco(2) (slope = 1.02, Y-intercept = -5.31, coefficient of determination, R(2) = 0.998) and Vo(2) (slope = 1.05, Y-intercept = -4.34, R(2) = 0.993) correlated closely to the reference values generated by the metabolic lung simulator. Limits of agreement analysis generated percent errors (mean +/- 1.96 SD) of -1.2 +/- 7.2% for Vco(2) and 2.5 +/- 9.8% for Vo(2). The new clinical bymixer is compact, lightweight, disposable, inexpensive, and has a fast and adjustable response time (time constant about 14 sec). Anesthesia circle circuit integrity is maintained. Bymixer-flow measurements of Vco(2) and Vo(2) are accurate and may add to clinical monitoring under anesthesia and surgery.

Convective and Diffusive O2 Transport Components of Peak Oxygen Uptake Following Long-duration Spaceflight

NASA Technical Reports Server (NTRS)

Ade, Carl J.; Moore, A. D.

2014-01-01

Spaceflight reduces aerobic capacity and may be linked with maladaptations in the O2 transport pathway. The aim was to 1) evaluate the cardiorespiratory adaptations following 6 months aboard the International Space Station and 2) model the contributions of convective (Q (raised dot) O2) and peripheral diffusive (DO2) components of O2 transport to changes in peak O2 uptake (V (raised dot) O2PEAK). To date, 1 male astronaut (XX yrs) completed an incremental exercise test to measure V (raised dot) O2PEAK prior to and 2 days post-flight. Cardiac output (Q (raised dot) ) was measured at three submaximal work rates via carbon dioxide rebreathing. The Q (raised dot) :V (raised dot) O2 relationship was extrapolated to V (raised dot) O2PEAK to determine Q (raised dot) PEAK. Hemoglobin concentration was measured at rest via a venous blood sample. These measurements were used to model the changes in Q (raised dot) O2 and DO2 using Fick's principle of mass conservation and Law of Diffusion as established by Wagner and colleagues (Annu. Rev. Physiol 58: 21-50, 1996 and J. Appl. Physiol. 73: 1067-1076, 1992). V (raised dot) O2PEAK decreased postflight from 3.72 to 3.45 l min-1, but Q (raised dot) PEAK increased from 24.5 to 27.7 l min-1. The decrease in V (raised dot) O2PEAK post-flight was associated with a 21.2% decrease in DO2, an 18.6% decrease in O2 extraction, but a 3.4% increase in Q (raised dot) O2. These preliminary data suggest that long-duration spaceflight reduces peripheral diffusing capacity and that it largely contributes to the post-flight decrease in aerobic capacity.

Sex differences in the oxygen delivery, extraction, and uptake during moderate-walking exercise transition.

PubMed

Beltrame, Thomas; Villar, Rodrigo; Hughson, Richard L

2017-09-01

Previous studies in children and older adults demonstrated faster oxygen uptake (V̇O 2 ) kinetics in males compared with females, but young healthy adults have not been studied. We hypothesized that young men would have faster aerobic system dynamics in response to the onset of exercise than women. Interactions between oxygen supply and utilization were characterized by the dynamics of V̇O 2 , deoxyhemoglobin (HHb), tissue saturation index (TSI), cardiac output (Q̇), and calculated arteriovenous O 2 difference (a-vO 2 diff ) in women and men. Eighteen healthy active young women and men (9 of each sex) with similar aerobic fitness levels volunteered for this study. Participants performed an incremental cardiopulmonary treadmill exercise test and 3 moderate-intensity treadmill exercise tests (at 80% V̇O 2 of gas exchange threshold). Data related to the moderate exercise were submitted to exponential data modelling to obtain parameters related to the aerobic system dynamics. The time constants of V̇O 2 , a-vO 2 diff , HHb, and TSI (30 ± 6, 29 ± 1, 16 ± 1, and 15 ± 2 s, respectively) in women were statistically (p < 0.05) faster than the time constants in men (42 ± 10, 49 ± 21, 19 ± 3, and 20 ± 4 s, respectively). Although Q̇ dynamics were not statistically different (p = 0.06) between groups, there was a trend to slower Q̇ dynamics in men corresponding with the slower V̇O 2 kinetics. These results indicated that the peripheral and pulmonary oxygen extraction dynamics were remarkably faster in women. Thus, contrary to the hypothesis, V̇O 2 dynamics measured at the mouth at the onset of submaximal treadmill walking were faster in women compared with men.

Manual vs. automatic capture management in implantable cardioverter defibrillators and cardiac resynchronization therapy defibrillators.

PubMed

Murgatroyd, Francis D; Helmling, Erhard; Lemke, Bernd; Eber, Bernd; Mewis, Christian; van der Meer-Hensgens, Judith; Chang, Yanping; Khalameizer, Vladimir; Katz, Amos

2010-06-01

The Secura ICD and Consulta CRT-D are the first defibrillators to have automatic right atrial (RA), right ventricular (RV), and left ventricular (LV) capture management (CM). Complete CM was evaluated in an implantable cardioverter defibrillator (ICD) population. Two prospective clinical studies were conducted in 28 centres in Europe and Israel. Automatic CM data were compared with manual threshold measurements, the CM applicability was determined, and adjustments to pacing outputs were analysed. In total, 160 patients [age 64.6 +/- 10.4 years, 77% male, 80 ICD and 80 cardiac resynchronization therapy defibrillator (CRT-D)] were included. The differences between automatic and manual measurements were 2.5 V) due to raised RA threshold in seven (4.4%), high RV threshold in nine (5.6%), and high LV threshold in three patients (3.8%). All high threshold detections and all automatic modulations of pacing output were adjudicated appropriate. Complete CM adjusts pacing output appropriately, permitting a reduction in office visits while it may maximize device longevity. The study was registered at ClinicalTrials.gov identifiers: NCT00526227 and NCT00526162.

Robotic cardiac surgery: an anaesthetic challenge.

PubMed

Wang, Gang; Gao, Changqing

2014-08-01

Robotic cardiac surgery with the da Vinci robotic surgical system offers the benefits of a minimally invasive procedure, including a smaller incision and scar, reduced risk of infection, less pain and trauma, less bleeding and blood transfusion requirements, shorter hospital stay and decreased recovery time. Robotic cardiac surgery includes extracardiac and intracardiac procedures. Extracardiac procedures are often performed on a beating heart. Intracardiac procedures require the aid of peripheral cardiopulmonary bypass via a minithoracotomy. Robotic cardiac surgery, however, poses challenges to the anaesthetist, as the obligatory one-lung ventilation (OLV) and CO2 insufflation may reduce cardiac output and increase pulmonary vascular resistance, potentially resulting in hypoxaemia and haemodynamic compromise. In addition, surgery requires appropriate positioning of specialised cannulae such as an endopulmonary vent, endocoronary sinus catheter, and endoaortic clamp catheter under the guidance of transoesophageal echocardiography. Therefore, cardiac anaesthetists should have a working knowledge of these systems, OLV and haemodynamic support. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Comparison of multiple non-invasive methods of measuring cardiac output during pregnancy reveals marked heterogeneity in the magnitude of cardiac output change between women.

PubMed

Petersen, John W; Liu, Jing; Chi, Yueh-Yun; Lingis, Melissa; Williams, R Stan; Rhoton-Vlasak, Alice; Segal, Mark S; Conrad, Kirk P

2017-04-01

Various non-invasive methods are available to measure cardiac output (CO) during pregnancy. We compared serial measures of CO using various methods to determine which provided the least variability. Ten patients with spontaneous pregnancy had estimation of CO at baseline prior to becoming pregnant and at the end of the first and third trimesters. Echocardiographic data were used to estimate CO using the Teichholz method, Simpson's biplane method, and the Doppler determined velocity time integral (VTI) method. In addition, a Bioz Dx device was used to estimate CO by impedance cardiography. CO estimated with the VTI method had the lowest beat-to-beat variability. CO estimated with the VTI method was higher than CO estimated with the 2D-Teichholz method and Simpson's method. The percent change in CO during pregnancy was similar for all echo methods (VTI, Teichholz, and Simpson's biplane). Baseline CO determined with impedance cardiography was higher than CO determined with the VTI method. However, change in CO during pregnancy was significantly lower when measured with impedance cardiography. There was marked heterogeneity in the degree of rise in CO during the first trimester (-3 to 55%). The wide variation in the gestational rise in CO was unexpected, and at least in part secondary to variable increase in heart rate. We recommend the use of the Doppler determined VTI method for the estimation of CO in pregnancy. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

The Effect of Overweight/Obesity on Cardiovascular Responses to Acute Psychological Stress in Men Aged 50-70 Years

PubMed Central

Torres, Susan J.; Turner, Anne I.; Jayasinghe, Sisitha U.; Reynolds, John; Nowson, Caryl A.

2014-01-01

Background To determine the effect of adiposity in males aged 50-70 years on cardiovascular responses to acute psychological stress. Methods Lean (BMI 20-25 kg/m2) (n = 21) and overweight/obese (BMI 27-35 kg/m2) (n = 21) men aged 50-70 years were subjected to psychological stress. Systolic blood pressure, diastolic blood pressure, heart rate, total peripheral resistance, and cardiac output were measured by a Finometer during resting (60 min), stress (30 min), and recovery (90 min). Results The lean group had a significantly higher SBP stress reactivity when compared to the overweight/obese group (51.5 ± 3.7% vs. 41.0 ± 2.9% (mean ± SEM); p < 0.05). A significant effect of time was observed for systolic blood pressure, diastolic blood pressure, heart rate, total peripheral resistance, and cardiac output (p < 0.0001 for all). There were significant time × body type interactions for systolic blood pressure, diastolic blood pressure, heart rate, total peripheral resistance, and cardiac output (p < 0.05 for all). Total peripheral resistance during recovery was higher in the lean compared to the overweight/obese group (p < 0.05). In the lean group, systolic and diastolic blood pressure variability remained elevated after stress (p < 0.05) but returned to resting levels in the overweight/obese group (p > 0.05). Conclusion Moderate adiposity in men was associated with reduced systolic blood pressure % reactivity, total peripheral resistance, and blood pressure variability after psychological stress. Overweight/obese men appear to be at no greater risk of unfavorable cardiovascular responses to stress. PMID:25428119

Cold physiology: postprandial blood flow dynamics and metabolism in the Antarctic fish Pagothenia borchgrevinki.

PubMed

Sandblom, Erik; Davison, William; Axelsson, Michael

2012-01-01

Previous studies on metabolic responses to feeding (i.e. the specific dynamic action, SDA) in Antarctic fishes living at temperatures below zero have reported long-lasting increases and small peak responses. We therefore hypothesized that the postprandial hyperemia also would be limited in the Antarctic fish Pagothenia borchgrevinki. The proportion of cardiac output directed to the splanchnic circulation in unfed fish was 18%, which is similar to temperate fish species. Contrary to our prediction, however, gastrointestinal blood flow had increased by 88% at twenty four hours after feeding due to a significant increase in cardiac output and a significant decrease in gastrointestinal vascular resistance. While gastric evacuation time appeared to be longer than in comparable temperate species, digestion had clearly commenced twenty four hours after feeding as judged by a reduction in mass of the administered feed. Even so, oxygen consumption did not increase suggesting an unusually slowly developing SDA. Adrenaline and angiotensin II was injected into unfed fish to investigate neuro-humoral control mechanisms of gastrointestinal blood flow. Both agonists increased gastrointestinal vascular resistance and arterial blood pressure, while systemic vascular resistance was largely unaffected. The hypertension was mainly due to increased cardiac output revealing that the heart and the gastrointestinal vasculature, but not the somatic vasculature, are important targets for these agonists. It is suggested that the apparently reduced SDA in P. borchgrevinki is due to a depressant effect of the low temperature on protein assimilation processes occurring outside of the gastrointestinal tract, while the gastrointestinal blood flow responses to feeding and vasoactive substances resemble those previously observed in temperate species.

Variations in Alveolar Partial Pressure for Carbon Dioxide and Oxygen Have Additive Not Synergistic Acute Effects on Human Pulmonary Vasoconstriction

PubMed Central

Croft, Quentin P. P.; Formenti, Federico; Talbot, Nick P.; Lunn, Daniel; Robbins, Peter A.; Dorrington, Keith L.

2013-01-01

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, −4 and −9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So 2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So 2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output. PMID:23935847

Variations in alveolar partial pressure for carbon dioxide and oxygen have additive not synergistic acute effects on human pulmonary vasoconstriction.

PubMed

Croft, Quentin P P; Formenti, Federico; Talbot, Nick P; Lunn, Daniel; Robbins, Peter A; Dorrington, Keith L

2013-01-01

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, -4 and -9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output.

Nasal continuous positive airway pressure (n-CPAP) does not change cardiac output in preterm infants.

PubMed

Moritz, Barbara; Fritz, Michael; Mann, Christian; Simma, Burkhard

2008-02-01

Our objective was to study how invasive mechanical ventilation impairs cardiac output (CO) in children and adults. Although the application of continuous positive airway pressure (CPAP) is widely practiced in neonatal intensive care, its hemodynamic consequences have not yet been investigated. A prospective study to assess the hemodynamic effects was conducted in 21 preterm infants < 1500 g using two-dimensional M-mode and pulsed Doppler echocardiography during and 1 hour after discontinuation of nasal CPAP (n-CPAP). Gestational age was 28.0 +/- 1.9 weeks (mean +/- standard deviation); birthweight, 1000 +/- 238 g; age at study entry, 200 +/- 155 hours; total maintenance fluid, 154 +/- 42 mL/kg/day; and n-CPAP level, 4.4 +/- 0.9 cm H(2)O. None of the infants received inotropic support, and n-CPAP did not cause any significant difference in the parameters measured: stroke volume, 3.1 +/- 1.0 mL (with n-CPAP) versus 3.1 +/- 1.0 mL (without n-CPAP); cardiac output, 487 +/- 156 mL/minute versus 500 +/- 176 mL/minute; left ventricular diastolic diameter, 1.22 +/- 0.15 cm versus 1.24 +/- 0.14 cm; fractional shortening, 0.30 +/- 0.05% versus 0.29 +/- 0.04%; and aortic velocity-time integral, 8.64 +/- 1.80 cm versus 8.70 +/- 1.65 cm. The n-CPAP level did not influence CO; n-CPAP (up to 7 cm H (2)O) has no echocardiographically detectable hemodynamic effect in preterm infants. Our data imply there is no need to withhold n-CPAP support to prevent circulatory compromise in these infants.

Computational simulation of passive leg-raising effects on hemodynamics during cardiopulmonary resuscitation.

PubMed

Shin, Dong Ah; Park, Jiheum; Lee, Jung Chan; Shin, Sang Do; Kim, Hee Chan

2017-03-01

The passive leg-raising (PLR) maneuver has been used for patients with circulatory failure to improve hemodynamic responsiveness by increasing cardiac output, which should also be beneficial and may exert synergetic effects during cardiopulmonary resuscitation (CPR). However, the impact of the PLR maneuver on CPR remains unclear due to difficulties in monitoring cardiac output in real-time during CPR and a lack of clinical evidence. We developed a computational model that couples hemodynamic behavior during standard CPR and the PLR maneuver, and simulated the model by applying different angles of leg raising from 0° to 90° and compression rates from 80/min to 160/min. The simulation results showed that the PLR maneuver during CPR significantly improves cardiac output (CO), systemic perfusion pressure (SPP) and coronary perfusion pressure (CPP) by ∼40-65% particularly under the recommended range of compression rates between 100/min and 120/min with 45° of leg raise, compared to standard CPR. However, such effects start to wane with further leg lifts, indicating the existence of an optimal angle of leg raise for each person to achieve the best hemodynamic responses. We developed a CPR-PLR model and demonstrated the effects of PLR on hemodynamics by investigating changes in CO, SPP, and CPP under different compression rates and angles of leg raising. Our computational model will facilitate study of PLR effects during CPR and the development of an advanced model combined with circulatory disorders, which will be a valuable asset for further studies. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Hemodynamic effects of intravenous nicardipine in severely pre-eclamptic women with a hypertensive crisis.

PubMed

Cornette, J; Buijs, E A B; Duvekot, J J; Herzog, E; Roos-Hesselink, J W; Rizopoulos, D; Meima, M; Steegers, E A P

2016-01-01

Nicardipine permits rapid control of blood pressure in women with severe pre-eclampsia (PE) and hypertensive crisis. Our objective was to investigate its maternal and fetal hemodynamic effects. Ten severely pre-eclamptic pregnant women who required intravenous nicardipine for severe hypertension were included in this prospective observational trial. Maternal macrocirculation was assessed by transthoracic echocardiography. Maternal microcirculatory perfusion was examined sublingually with the sidestream dark field imaging technique. Fetal hemodynamics were assessed by Doppler examinations of the uteroplacental and fetal circulations. Maternal cardiac output, total vascular resistance, mitral E/A ratio and capillary heterogeneity index, uterine artery pulsatility index and fetal cerebroplacental ratio were considered primary outcomes. Paired measurements, obtained before administration of nicardipine infusion and after stabilization of blood pressure, were compared. Administration of nicardipine significantly reduced the mean arterial blood pressure (median difference, 26 mmHg; P = 0.002) and total vascular resistance (median difference, 791 dynes × s/cm(5) ; P = 0.002) in all included women. This induced a reflex tachycardia with consequent increase in cardiac output of 1.55 L/min (P  =  0.004). There were no significant changes in the other determinants of maternal or fetal hemodynamic parameters. Nicardipine effectively reduces blood pressure through selective afterload reduction that triggers an increase in cardiac output, without affecting maternal diastolic function, or microcirculatory, uteroplacental or fetal perfusion. This hemodynamic response is uniform and predictable. Fetomaternal cardiovascular profiling can be achieved by combining transthoracic echocardiography with obstetric Doppler. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Levosimendan for Perioperative Cardioprotection: Myth or Reality?

PubMed

Santillo, Elpidio; Migale, Monica; Massini, Carlo; Incalzi, Raffaele Antonelli

2018-03-21

Levosimendan is a calcium sensitizer drug causing increased contractility in the myocardium and vasodilation in the vascular system. It is mainly used for the therapy of acute decompensated heart failure. Several studies on animals and humans provided evidence of the cardioprotective properties of levosimendan including preconditioning and anti-apoptotic. In view of these favorable effects, levosimendan has been tested in patients undergoing cardiac surgery for the prevention or treatment of low cardiac output syndrome. However, initial positive results from small studies have not been confirmed in three recent large trials. To summarize levosimendan mechanisms of action and clinical use and to review available evidence on its perioperative use in cardiac surgery setting. We searched two electronic medical databases for randomized controlled trials studying levosimendan in cardiac surgery patients, ranging from January 2000 to August 2017. Meta-analyses, consensus documents and retrospective studies were also reviewed. In the selected interval of time, 54 studies on the use of levosimendan in heart surgery have been performed. Early small size studies and meta-analyses have suggested that perioperative levosimendan infusion could diminish mortality and other adverse outcomes (i.e. intensive care unit stay and need for inotropic support). Instead, three recent large randomized controlled trials (LEVO-CTS, CHEETAH and LICORN) showed no significant survival benefits from levosimendan. However, in LEVO-CTS trial, prophylactic levosimendan administration significantly reduced the incidence of low cardiac output syndrome. Based on most recent randomized controlled trials, levosimendan, although effective for the treatment of acute heart failure, can't be recommended as standard therapy for the management of heart surgery patients. Further studies are needed to clarify whether selected subgroups of heart surgery patients may benefit from perioperative levosimendan infusion. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Random forests ensemble classifier trained with data resampling strategy to improve cardiac arrhythmia diagnosis.

PubMed

Ozçift, Akin

2011-05-01

Supervised classification algorithms are commonly used in the designing of computer-aided diagnosis systems. In this study, we present a resampling strategy based Random Forests (RF) ensemble classifier to improve diagnosis of cardiac arrhythmia. Random forests is an ensemble classifier that consists of many decision trees and outputs the class that is the mode of the class's output by individual trees. In this way, an RF ensemble classifier performs better than a single tree from classification performance point of view. In general, multiclass datasets having unbalanced distribution of sample sizes are difficult to analyze in terms of class discrimination. Cardiac arrhythmia is such a dataset that has multiple classes with small sample sizes and it is therefore adequate to test our resampling based training strategy. The dataset contains 452 samples in fourteen types of arrhythmias and eleven of these classes have sample sizes less than 15. Our diagnosis strategy consists of two parts: (i) a correlation based feature selection algorithm is used to select relevant features from cardiac arrhythmia dataset. (ii) RF machine learning algorithm is used to evaluate the performance of selected features with and without simple random sampling to evaluate the efficiency of proposed training strategy. The resultant accuracy of the classifier is found to be 90.0% and this is a quite high diagnosis performance for cardiac arrhythmia. Furthermore, three case studies, i.e., thyroid, cardiotocography and audiology, are used to benchmark the effectiveness of the proposed method. The results of experiments demonstrated the efficiency of random sampling strategy in training RF ensemble classification algorithm. Copyright © 2011 Elsevier Ltd. All rights reserved.

Cardiac cycle-synchronized electrical muscle stimulator for lower limb training with the potential to reduce the heart's pumping workload

PubMed Central

Matsuse, Hiroo; Akimoto, Ryuji; Kamiya, Shiro; Moritani, Toshio; Sasaki, Motoki; Ishizaki, Yuta; Ohtsuka, Masanori; Nakayoshi, Takaharu; Ueno, Takafumi; Shiba, Naoto; Fukumoto, Yoshihiro

2017-01-01

Background The lower limb muscle may play an important role in decreasing the heart’s pumping workload. Aging and inactivity cause atrophy and weakness of the muscle, leading to a loss of the heart-assisting role. An electrical lower limb muscle stimulator can prevent atrophy and weakness more effectively than conventional resistance training; however, it has been reported to increase the heart’s pumping workload in some situations. Therefore, more effective tools should be developed. Methods We newly developed a cardiac cycle-synchronized electrical lower limb muscle stimulator by combining a commercially available electrocardiogram monitor and belt electrode skeletal muscle electrical stimulator, making it possible to achieve strong and wide but not painful muscle contractions. Then, we tested the stimulator in 11 healthy volunteers to determine whether the special equipment enabled lower limb muscle training without harming the hemodynamics using plethysmography and a percutaneous cardiac output analyzer. Results In 9 of 11 subjects, the stimulator generated diastolic augmentation waves on the dicrotic notches and end-diastolic pressure reduction waves on the plethysmogram waveforms of the brachial artery, showing analogous waveforms in the intra-aortic balloon pumping heart-assisting therapy. The heart rate, stroke volume, and cardiac output significantly increased during the stimulation. There was no change in the systolic or diastolic blood pressure during the stimulation. Conclusion Cardiac cycle-synchronized electrical muscle stimulation for the lower limbs may enable muscle training without harmfully influencing the hemodynamics and with a potential to reduce the heart’s pumping workload, suggesting a promising tool for effectively treating both locomotor and cardiovascular disorders. PMID:29117189

Effects of hypertrophic and dilated cardiomyopathy mutations on power output by human β-cardiac myosin.

PubMed

Spudich, James A; Aksel, Tural; Bartholomew, Sadie R; Nag, Suman; Kawana, Masataka; Yu, Elizabeth Choe; Sarkar, Saswata S; Sung, Jongmin; Sommese, Ruth F; Sutton, Shirley; Cho, Carol; Adhikari, Arjun S; Taylor, Rebecca; Liu, Chao; Trivedi, Darshan; Ruppel, Kathleen M

2016-01-01

Hypertrophic cardiomyopathy is the most frequently occurring inherited cardiovascular disease, with a prevalence of more than one in 500 individuals worldwide. Genetically acquired dilated cardiomyopathy is a related disease that is less prevalent. Both are caused by mutations in the genes encoding the fundamental force-generating protein machinery of the cardiac muscle sarcomere, including human β-cardiac myosin, the motor protein that powers ventricular contraction. Despite numerous studies, most performed with non-human or non-cardiac myosin, there is no clear consensus about the mechanism of action of these mutations on the function of human β-cardiac myosin. We are using a recombinantly expressed human β-cardiac myosin motor domain along with conventional and new methodologies to characterize the forces and velocities of the mutant myosins compared with wild type. Our studies are extending beyond myosin interactions with pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin, the roles of regulatory light chain phosphorylation on the functions of the system, and the possible roles of myosin binding protein-C and titin, important regulatory components of both cardiac and skeletal muscles. © 2016. Published by The Company of Biologists Ltd.

A flatness-based control approach to drug infusion for cardiac function regulation

NASA Astrophysics Data System (ADS)

Rigatos, Gerasimos; Zervos, Nikolaos; Melkikh, Alexey

2016-12-01

A new control method based on differential flatness theory is developed in this article, aiming at solving the problem of regulation of haemodynamic parameters, Actually control of the cardiac output (volume of blood pumped out by heart per unit of time) and of the arterial blood pressure is achieved through the administered infusion of cardiovascular drugs, such as dopamine and sodium nitroprusside. Time delays between the control inputs and the system's outputs are taken into account. Using the principle of dynamic extension, which means that by considering certain control inputs and their derivatives as additional state variables, a state-space description for the heart's function is obtained. It is proven that the dynamic model of the heart is a differentially flat one. This enables its transformation into a linear canonical and decoupled form, for which the design of a stabilizing feedback controller becomes possible. The proposed feedback controller is of proven stability and assures fast and accurate tracking of the reference setpoints by the outputs of the heart's dynamic model. Moreover, by using a Kalman Filter-based disturbances' estimator, it becomes possible to estimate in real-time and compensate for the model uncertainty and external perturbation inputs that affect the heart's model.

Is there a place for intra-aortic balloon counterpulsation support in acute right ventricular failure by pressure-overload?

PubMed

Vanden Eynden, Frederic; Mets, Gilles; De Somer, Filip; Bouchez, Stefaan; Bove, Thierry

2015-10-15

Most therapeutic strategies for acute right ventricular failure (RVF) by pressure-overload are directed to improve cardiac output and coronary perfusion pressure by vasopressive agents. The eventual role of intra-aortic balloon counterpulsation (IABP) support remains questionable. This study investigates the contribution of IABP for acute RVF by pressure-overload, in comparison with phenylephrine (PE) and norepinephrine (NOR). Acute RVF is induced by fixed pulmonary artery constriction in 6 pigs, pursuing a 50% reduction of cardiac output. Assessment of the treatment interventions included biventricular PV-loop analysis, and continuous measurement of aortic and right coronary artery flow. Restoration of baseline cardiac output was only observed by administration of NOR (Baseline=3.82±1.52ml/min - RVF=2.03±0.59ml/min - IABP=2.45±0.62ml/min - PE=2.98±0.63ml/min - NOR=3.95±0.73ml/min, p<0.001). NOR had most effect on biventricular contractility (PRSW-slope-RV: IABP +24% - PE +59% - NOR +208%, p<0.001 and PRSW-slope-LV: IABP +36% - PE +53% - NOR +196%, p<0.001), heart rate acceleration (IABP +7% - PE +12% - NOR +51%, p<0.001), and RCA flow (IABP +31% - PE +58% - NOR +180%, p<0.001), concomitant to a higher increase of LV-to-RV pressure ratio (IABP: +7% versus -3%, PE: +36% versus +8%, NOR: +101% versus 42%). The hemodynamic contribution of IABP was limited, unless a modest improvement of LV compliance during PE and NOR infusion. In a model of acute pressure-overload RV failure, IABP appears to offer limited hemodynamic benefit. The administration of norepinephrine is most effective to correct systemic output and myocardial perfusion through adding an inotropic and chronotropic effect to systemic vasopression. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Decreases in maximal oxygen uptake following long-duration spaceflight: Role of convective and diffusive O2 transport mechanisms.

PubMed

Ade, C J; Broxterman, R M; Moore, A D; Barstow, T J

2017-04-01

We have previously predicted that the decrease in maximal oxygen uptake (V̇o 2max ) that accompanies time in microgravity reflects decrements in both convective and diffusive O 2 transport to the mitochondria of the contracting myocytes. The aim of this investigation was therefore to quantify the relative changes in convective O 2 transport (Q̇o 2 ) and O 2 diffusing capacity (Do 2 ) following long-duration spaceflight. In nine astronauts, resting hemoglobin concentration ([Hb]), V̇o 2max , maximal cardiac output (Q̇ Tmax ), and differences in arterial and venous O 2 contents ([Formula: see text]-[Formula: see text]) were obtained retrospectively for International Space Station Increments 19-33 (April 2009-November 2012). Q̇o 2 and Do 2 were calculated from these variables via integration of Fick's Principle of Mass Conservation and Fick's Law of Diffusion. V̇o 2max significantly decreased from pre- to postflight (-53.9 ± 45.5%, P = 0.008). The significant decrease in Q̇ Tmax (-7.8 ± 9.1%, P = 0.05), despite an unchanged [Hb], resulted in a significantly decreased Q̇o 2 (-11.4 ± 10.5%, P = 0.02). Do 2 significantly decreased from pre- to postflight by -27.5 ± 24.5% ( P = 0.04), as did the peak [Formula: see text]-[Formula: see text] (-9.2 ± 7.5%, P = 0.007). With the use of linear regression analysis, changes in V̇o 2max were significantly correlated with changes in Do 2 ( R 2  = 0.47; P = 0.04). These data suggest that spaceflight decreases both convective and diffusive O 2 transport. These results have practical implications for future long-duration space missions and highlight the need to resolve the specific mechanisms underlying these spaceflight-induced changes along the O 2 transport pathway. NEW & NOTEWORTHY Long-duration spaceflight elicited a significant decrease in maximal oxygen uptake. Given the adverse physiological adaptations to microgravity along the O 2 transport pathway that have been reported, an integrative approach to the determinants of postflight maximal oxygen uptake is needed. We demonstrate that both convective and diffusive oxygen transport are decreased following ~6 mo International Space Station missions. Copyright © 2017 the American Physiological Society.

Hemodynamic responses to external counterbalancing of auto-positive end-expiratory pressure in mechanically ventilated patients with chronic obstructive pulmonary disease.

PubMed

Baigorri, F; de Monte, A; Blanch, L; Fernández, R; Vallés, J; Mestre, J; Saura, P; Artigas, A

1994-11-01

To study the effect of positive end-expiratory pressure (PEEP) on right ventricular hemodynamics and ejection fraction in patients with chronic obstructive pulmonary disease and positive alveolar pressure throughout expiration by dynamic hyperinflation (auto-PEEP). Open, prospective, controlled trial. General intensive care unit of a community hospital. Ten patients sedated and paralyzed with an acute exacerbation of chronic obstructive pulmonary disease undergoing mechanical ventilation. Insertion of a pulmonary artery catheter modified with a rapid response thermistor and a radial arterial catheter. PEEP was then increased from 0 (PEEP 0) to auto-PEEP level (PEEP = auto-PEEP) and 5 cm H2O above that (PEEP = auto-PEEP +5). At each level of PEEP, airway pressures, flow and volume, hemodynamic variables (including right ventricular ejection fraction by thermodilution technique), and blood gas analyses were recorded. The mean auto-PEEP was 6.6 +/- 2.8 cm H2O and the total PEEP reached was 12.2 +/- 2.4 cm H2O. The degree of lung inflation induced by PEEP averaged 145 +/- 87 mL with PEEP = auto-PEEP and 495 +/- 133 mL with PEEP = auto-PEEP + 5. The PEEP = auto-PEEP caused a right ventricular end-diastolic pressure increase, but there was no other significant hemodynamic change. With PEEP = auto-PEEP + 5, there was a significant increase in intravascular pressures; this amount of PEEP reduced cardiac output (from 4.40 +/- 1.38 L/min at PEEP 0 to 4.13 +/- 1.48 L/min; p < .05). The cardiac output reduction induced by PEEP = auto-PEEP + 5 was > 10% in only five cases and this group of patients had significantly lower right ventricular volumes than the group with less cardiac output variation (right ventricular end-diastolic volume: 64 +/- 9 vs. 96 +/- 26 mL/m2; right ventricular end-systolic volume: 38 +/- 6 vs. 65 +/- 21 mL/m2; p < .05) without significant difference in the other variables that were measured. Neither right ventricular ejection fraction nor right ventricle volumes changed as PEEP increased, but there were marked interpatient differences and also pronounced changes in volume between stages in individual patients. In the study conditions, PEEP application up to values approaching auto-PEEP did not result in the impairment of right ventricular hemodynamics, while higher levels reduced cardiac output in selected patients.

Echocardiographic dimensions and function in adults with primary growth hormone resistance (Laron syndrome).

PubMed

Feinberg, M S; Scheinowitz, M; Laron, Z

2000-01-15

Patients with primary growth hormone (GH) resistance-Laron Syndrome (LS)-have no GH signal transmission, and thus, no generation of circulating insulin-like growth factor-I (IGF-I), and should serve as a unique model to explore the controversies concerning the longterm effect of GH/IGF-I deficiency on cardiac dimension and function. We assessed 8 patients with LS (4 men, 4 women) with a mean (+/- SD) age of 38+/-7 years (range 22 to 45), and 8 aged-matched controls (4 men, 4 women) with a mean age of 38+/-9 years (range 18 to 47) by echocardiography at rest, following exercise, and during dobutamine administration. Left ventricular (LV) septum, posterior wall, and end-diastolic diameter were significantly reduced in untreated patients with LS compared with the control group (p<0.05 for all). Systolic Doppler-derived parameters, including LV stroke volume, stroke index, cardiac output, and cardiac index, were significantly lower (p<0.05 for all) than in the control subjects, whereas LV diastolic Doppler parameters, including mitral valve waves E, A, E/A ratio, and E deceleration time, were similar in both groups. LV ejection fraction at rest as well as the stress-induced increment of the LV ejection fraction were similar in both groups. Our results show that untreated patients with long-term IGF-I deficiency have reduced cardiac dimensions and output but normal LV ejection fraction at rest and LV contractile reserve following stress.

Extracorporeal cardiopulmonary resuscitation for blunt cardiac rupture.

PubMed

Kudo, Shunsuke; Tanaka, Keiji; Okada, Kunihiko; Takemura, Takahiro

2017-11-01

Extracorporeal cardiopulmonary resuscitation (ECPR) followed by operating room sternotomy, rather than resuscitative thoracotomy, might be life-saving for patients with blunt cardiac rupture and cardiac arrest who do not have multiple severe traumatic injuries. A 49-year-old man was injured in a vehicle crash and transferred to the emergency department. On admission, he was hemodynamically stable, but a plain chest radiograph revealed a widened mediastinum, and echocardiography revealed hemopericardium. A computed tomography scan revealed hemopericardium and mediastinal hematoma, without other severe traumatic injuries. However, the patient's pulse was lost soon after he was transferred to the intensive care unit, and cardiopulmonary resuscitation was initiated. We initiated ECPR using femorofemoral veno-arterial extracorporeal membrane oxygenation (ECMO) with heparin administration, which achieved hemodynamic stability. He was transferred to the operating room for sternotomy and cardiac repair. Right ventricular rupture and pericardial sac laceration were identified intraoperatively, and cardiac repair was performed. After repairing the cardiac rupture, the cardiac output recovered spontaneously, and ECMO was discontinued intraoperatively. The patient recovered fully and was discharged from the hospital on postoperative day 7. In this patient, ECPR rapidly restored brain perfusion and provided enough time to perform operating room sternotomy, allowing for good surgical exposure of the heart. Moreover, open cardiac massage was unnecessary. ECPR with sternotomy and cardiac repair is advisable for patients with blunt cardiac rupture and cardiac arrest who do not have severe multiple traumatic injuries. Copyright © 2017 Elsevier Inc. All rights reserved.

Is There Evidence that Runners can Benefit from Wearing Compression Clothing?

PubMed

Engel, Florian Azad; Holmberg, Hans-Christer; Sperlich, Billy

2016-12-01

Runners at various levels of performance and specializing in different events (from 800 m to marathons) wear compression socks, sleeves, shorts, and/or tights in attempt to improve their performance and facilitate recovery. Recently, a number of publications reporting contradictory results with regard to the influence of compression garments in this context have appeared. To assess original research on the effects of compression clothing (socks, calf sleeves, shorts, and tights) on running performance and recovery. A computerized research of the electronic databases PubMed, MEDLINE, SPORTDiscus, and Web of Science was performed in September of 2015, and the relevant articles published in peer-reviewed journals were thus identified rated using the Physiotherapy Evidence Database (PEDro) Scale. Studies examining effects on physiological, psychological, and/or biomechanical parameters during or after running were included, and means and measures of variability for the outcome employed to calculate Hedges'g effect size and associated 95 % confidence intervals for comparison of experimental (compression) and control (non-compression) trials. Compression garments exerted no statistically significant mean effects on running performance (times for a (half) marathon, 15-km trail running, 5- and 10-km runs, and 400-m sprint), maximal and submaximal oxygen uptake, blood lactate concentrations, blood gas kinetics, cardiac parameters (including heart rate, cardiac output, cardiac index, and stroke volume), body and perceived temperature, or the performance of strength-related tasks after running. Small positive effect sizes were calculated for the time to exhaustion (in incremental or step tests), running economy (including biomechanical variables), clearance of blood lactate, perceived exertion, maximal voluntary isometric contraction and peak leg muscle power immediately after running, and markers of muscle damage and inflammation. The body core temperature was moderately affected by compression, while the effect size values for post-exercise leg soreness and the delay in onset of muscle fatigue indicated large positive effects. Our present findings suggest that by wearing compression clothing, runners may improve variables related to endurance performance (i.e., time to exhaustion) slightly, due to improvements in running economy, biomechanical variables, perception, and muscle temperature. They should also benefit from reduced muscle pain, damage, and inflammation.

TRPM2 Channels Protect against Cardiac Ischemia-Reperfusion Injury

PubMed Central

Miller, Barbara A.; Hoffman, Nicholas E.; Merali, Salim; Zhang, Xue-Qian; Wang, JuFang; Rajan, Sudarsan; Shanmughapriya, Santhanam; Gao, Erhe; Barrero, Carlos A.; Mallilankaraman, Karthik; Song, Jianliang; Gu, Tongda; Hirschler-Laszkiewicz, Iwona; Koch, Walter J.; Feldman, Arthur M.; Madesh, Muniswamy; Cheung, Joseph Y.

2014-01-01

Cardiac TRPM2 channels were activated by intracellular adenosine diphosphate-ribose and blocked by flufenamic acid. In adult cardiac myocytes the ratio of GCa to GNa of TRPM2 channels was 0.56 ± 0.02. To explore the cellular mechanisms by which TRPM2 channels protect against cardiac ischemia/reperfusion (I/R) injury, we analyzed proteomes from WT and TRPM2 KO hearts subjected to I/R. The canonical pathways that exhibited the largest difference between WT-I/R and KO-I/R hearts were mitochondrial dysfunction and the tricarboxylic acid cycle. Complexes I, III, and IV were down-regulated, whereas complexes II and V were up-regulated in KO-I/R compared with WT-I/R hearts. Western blots confirmed reduced expression of the Complex I subunit and other mitochondria-associated proteins in KO-I/R hearts. Bioenergetic analyses revealed that KO myocytes had a lower mitochondrial membrane potential, mitochondrial Ca2+ uptake, ATP levels, and O2 consumption but higher mitochondrial superoxide levels. Additionally, mitochondrial Ca2+ uniporter (MCU) currents were lower in KO myocytes, indicating reduced mitochondrial Ca2+ uptake was likely due to both lower ψm and MCU activity. Similar to isolated myocytes, O2 consumption and ATP levels were also reduced in KO hearts. Under a simulated I/R model, aberrant mitochondrial bioenergetics was exacerbated in KO myocytes. Reactive oxygen species levels were also significantly higher in KO-I/R compared with WT-I/R heart slices, consistent with mitochondrial dysfunction in KO-I/R hearts. We conclude that TRPM2 channels protect the heart from I/R injury by ameliorating mitochondrial dysfunction and reducing reactive oxygen species levels. PMID:24492610

Diagnosis of Myocardial Viability by Fluorodeoxyglucose Distribution at the Border Zone of a Low Uptake Region

PubMed Central

Sone, Teruki; Yoshikawa, Kunihiko; Mimura, Hiroaki; Hayashida, Akihiro; Wada, Nozomi; Obase, Kikuko; Imai, Koichiro; Saito, Ken; Maehama, Tomoko; Fukunaga, Masao; Yoshida, Kiyoshi

2010-01-01

Purpose In cardiac 2-[F-18]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) examination, interpretation of myocardial viability in the low uptake region (LUR) has been difficult without additional perfusion imaging. We evaluated distribution patterns of FDG at the border zone of the LUR in the cardiac FDG-PET and established a novel parameter for diagnosing myocardial viability and for discriminating the LUR of normal variants. Materials and Methods Cardiac FDG-PET was performed in patients with a myocardial ischemic event (n = 22) and in healthy volunteers (n = 22). Whether the myocardium was not a viable myocardium (not-VM) or an ischemic but viable myocardium (isch-VM) was defined by an echocardiogram under a low dose of dobutamine infusion as the gold standard. FDG images were displayed as gray scaled-bull's eye mappings. FDG-plot profiles for LUR (= true ischemic region in the patients or normal variant region in healthy subjects) were calculated. Maximal values of FDG change at the LUR border zone (a steepness index; Smax scale/pixel) were compared among not-VM, isch-VM, and normal myocardium. Results Smax was significantly higher for n-VM compared to those with isch-VM or normal myocardium (ANOVA). A cut-off value of 0.30 in Smax demonstrated 100% sensitivity and 83% specificity for diagnosing n-VM and isch-VM. Smax less than 0.23 discriminated LUR in normal myocardium from the LUR in patients with both n-VM and isch-VM with a 94% sensitivity and a 93% specificity. Conclusion Smax of the LUR in cardiac FDG-PET is a simple and useful parameter to diagnose n-VM and isch-VM, as well as to discriminate thr LUR of normal variants. PMID:20191007

Risk model for deaths and renal replacement therapy dependence in patients with acute kidney injury after cardiac surgery.

PubMed

Sun, Shiren; Ma, Feng; Li, Qiaoneng; Bai, Ming; Li, Yangping; Yu, Yan; Huang, Chen; Wang, Hanmin; Ning, Xiaoxuan

2017-10-01

Acute kidney injury (AKI) is a serious complication after cardiac surgery and is associated with increased in-hospital deaths. Renal replacement therapy (RRT) is becoming a routine strategy for severe AKI. Our goal was to evaluate the risk factors for death and RRT dependence in patients with AKI after cardiac surgery. We included 190 eligible adult patients who had AKI following cardiac surgery and who required RRT at our centre from November 2010 to March 2015. We collected preoperative, intraoperative, postoperative and RRT data for all patients. In this cohort, 87 patients had successful RRT in the hospital, whereas 103 patients had RRT that failed (70 deaths and 33 cases of RRT dependence). The multivariable logistic analysis identified old age [odds ratio (OR): 1.042, 95% confidence interval (CI): 1.012-1.074; P = 0.011], serum uric acid (OR: 1.015, 95% CI: 1.003-1.031; P = 0.024), intraoperative concentrated red blood cell transfusions (OR: 1.144, 95% CI: 1.006-1.312; P = 0.041), postoperative low cardiac output syndrome (OR: 3.107, 95% CI: 1.179-8.190; P = 0.022) and multiple organ failure (OR: 5.786, 95% CI: 2.115-15.832; P = 0.001) as factors associated with a higher risk for RRT failure. The prediction model (-4.3 + 0.002 × preuric acid + 0.10 × concentrated red blood cells + 0.04 × age + 1.12 × [low cardiac output syndrome = 1] + 1.67 × [multiple organ failure = 1]) based on the multivariate analysis had statistically significant different incriminatory power with an area under the curve of 0.786. The prediction model may serve as a simple, accurate tool for predicting in-hospital RRT failure for patients with AKI following cardiac surgery. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Automated processing of first-pass radionuclide angiocardiography by factor analysis of dynamic structures.

PubMed

Cavailloles, F; Bazin, J P; Capderou, A; Valette, H; Herbert, J L; Di Paola, R

1987-05-01

A method for automatic processing of cardiac first-pass radionuclide study is presented. This technique, factor analysis of dynamic structures (FADS) provides an automatic separation of anatomical structures according to their different temporal behaviour, even if they are superimposed. FADS has been applied to 76 studies. A description of factor patterns obtained in various pathological categories is presented. FADS provides easy diagnosis of shunts and tricuspid insufficiency. Quantitative information derived from the factors (cardiac output and mean transit time) were compared to those obtained by the region of interest method. Using FADS, a higher correlation with cardiac catheterization was found for cardiac output calculation. Thus compared to the ROI method, FADS presents obvious advantages: a good separation of overlapping cardiac chambers is obtained; this operator independant method provides more objective and reproducible results. A number of parameters of the cardio-pulmonary function can be assessed by first-pass radionuclide angiocardiography (RNA) [1,2]. Usually, they are calculated using time-activity curves (TAC) from regions of interest (ROI) drawn on the cardiac chambers and the lungs. This method has two main drawbacks: (1) the lack of inter and intra-observers reproducibility; (2) the problem of crosstalk which affects the evaluation of the cardio-pulmonary performance. The crosstalk on planar imaging is due to anatomical superimposition of the cardiac chambers and lungs. The activity measured in any ROI is the sum of the activity in several organs and 'decontamination' of the TAC cannot easily be performed using the ROI method [3]. Factor analysis of dynamic structures (FADS) [4,5] can solve the two problems mentioned above. It provides an automatic separation of anatomical structures according to their different temporal behaviour, even if they are superimposed. The resulting factors are estimates of the time evolution of the activity in each structure (underlying physiological components), and the associated factor images are estimates of the spatial distribution of each factor. The aim of this study was to assess the reliability of FADS in first pass RNA and compare the results to those obtained by the ROI method which is generally considered as the routine procedure.

Hepatic function imaging using dynamic Gd-EOB-DTPA enhanced MRI and pharmacokinetic modeling.

PubMed

Ning, Jia; Yang, Zhiying; Xie, Sheng; Sun, Yongliang; Yuan, Chun; Chen, Huijun

2017-10-01

To determine whether pharmacokinetic modeling parameters with different output assumptions of dynamic contrast-enhanced MRI (DCE-MRI) using Gd-EOB-DTPA correlate with serum-based liver function tests, and compare the goodness of fit of the different output assumptions. A 6-min DCE-MRI protocol was performed in 38 patients. Four dual-input two-compartment models with different output assumptions and a published one-compartment model were used to calculate hepatic function parameters. The Akaike information criterion fitting error was used to evaluate the goodness of fit. Imaging-based hepatic function parameters were compared with blood chemistry using correlation with multiple comparison correction. The dual-input two-compartment model assuming venous flow equals arterial flow plus portal venous flow and no bile duct output better described the liver tissue enhancement with low fitting error and high correlation with blood chemistry. The relative uptake rate Kir derived from this model was found to be significantly correlated with direct bilirubin (r = -0.52, P = 0.015), prealbumin concentration (r = 0.58, P = 0.015), and prothrombin time (r = -0.51, P = 0.026). It is feasible to evaluate hepatic function by proper output assumptions. The relative uptake rate has the potential to serve as a biomarker of function. Magn Reson Med 78:1488-1495, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Glucose inhibits cardiac muscle maturation through nucleotide biosynthesis.

PubMed

Nakano, Haruko; Minami, Itsunari; Braas, Daniel; Pappoe, Herman; Wu, Xiuju; Sagadevan, Addelynn; Vergnes, Laurent; Fu, Kai; Morselli, Marco; Dunham, Christopher; Ding, Xueqin; Stieg, Adam Z; Gimzewski, James K; Pellegrini, Matteo; Clark, Peter M; Reue, Karen; Lusis, Aldons J; Ribalet, Bernard; Kurdistani, Siavash K; Christofk, Heather; Nakatsuji, Norio; Nakano, Atsushi

2017-12-12

The heart switches its energy substrate from glucose to fatty acids at birth, and maternal hyperglycemia is associated with congenital heart disease. However, little is known about how blood glucose impacts heart formation. Using a chemically defined human pluripotent stem-cell-derived cardiomyocyte differentiation system, we found that high glucose inhibits the maturation of cardiomyocytes at genetic, structural, metabolic, electrophysiological, and biomechanical levels by promoting nucleotide biosynthesis through the pentose phosphate pathway. Blood glucose level in embryos is stable in utero during normal pregnancy, but glucose uptake by fetal cardiac tissue is drastically reduced in late gestational stages. In a murine model of diabetic pregnancy, fetal hearts showed cardiomyopathy with increased mitotic activity and decreased maturity. These data suggest that high glucose suppresses cardiac maturation, providing a possible mechanistic basis for congenital heart disease in diabetic pregnancy.

Glucose inhibits cardiac muscle maturation through nucleotide biosynthesis

PubMed Central

Nakano, Haruko; Minami, Itsunari; Braas, Daniel; Pappoe, Herman; Wu, Xiuju; Sagadevan, Addelynn; Vergnes, Laurent; Fu, Kai; Morselli, Marco; Dunham, Christopher; Ding, Xueqin; Stieg, Adam Z; Gimzewski, James K; Pellegrini, Matteo; Clark, Peter M; Reue, Karen; Lusis, Aldons J; Ribalet, Bernard; Kurdistani, Siavash K; Christofk, Heather; Nakatsuji, Norio

2017-01-01

The heart switches its energy substrate from glucose to fatty acids at birth, and maternal hyperglycemia is associated with congenital heart disease. However, little is known about how blood glucose impacts heart formation. Using a chemically defined human pluripotent stem-cell-derived cardiomyocyte differentiation system, we found that high glucose inhibits the maturation of cardiomyocytes at genetic, structural, metabolic, electrophysiological, and biomechanical levels by promoting nucleotide biosynthesis through the pentose phosphate pathway. Blood glucose level in embryos is stable in utero during normal pregnancy, but glucose uptake by fetal cardiac tissue is drastically reduced in late gestational stages. In a murine model of diabetic pregnancy, fetal hearts showed cardiomyopathy with increased mitotic activity and decreased maturity. These data suggest that high glucose suppresses cardiac maturation, providing a possible mechanistic basis for congenital heart disease in diabetic pregnancy. PMID:29231167