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1

The Determinants of Cardiac Output  

NSDL National Science Digital Library

Part of the Gross Physiology of the Cardiovascular System site, this 22-minute video presentation explains fundamental but often misunderstood concepts about the determinants of cardiac output, using Dr. Anderson's hydraulic model of the cardiovascular system. It is a useful summary and overview of the concepts presented in greater detail in the online text. A transcript of the video presentation is available.

Anderson, Robert M.

2012-01-25

2

Mathematics and the Heart: Understanding Cardiac Output  

ERIC Educational Resources Information Center

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…

Champanerkar, Jyoti

2013-01-01

3

Pulmonary artery thermodilution cardiac output vs. transpulmonary thermodilution cardiac output in two patients with intrathoracic pathology.  

PubMed

In two adult patients, one with a severe hemorrhage and one with a partial anomalous pulmonary vein, cardiac output (CO) measurements were performed simultaneously by means of the bolus transpulmonary thermodilution technique (COao) and continuous pulmonary artery thermodilution method (CCOpa). In both cases, the methods revealed clinically significant different cardiac output values based upon the site of measurement and the underlying pathology. The assessment of cardiac output (CO) is considered an important part of cardiovascular monitoring of the critically ill patient. Cardiac output is most commonly determined intermittently by the bolus thermodilution technique with a pulmonary artery catheter (COpa). As continuous monitoring of CO is preferable to this intermittent technique, two major techniques have been proposed. Firstly, a nearly continuous thermodilution method (CCOpa) using a heating filament mounted on a pulmonary artery catheter (Baxter Edwards Laboratories, Irvine, CA), with a clinically acceptable accuracy compared with the intermittent bolus technique. Based on these results we assumed CCOpa equivalent to real CO during hemodynamically stable conditions, and secondly, a continuous cardiac output system based on pulse contour analysis (PCCO), such as the PiCCO system (Pulsion Medical System, Munchen, Germany). To calibrate this device, which uses a derivation of the algorithm of Wesseling and colleagues, an independently obtained value of CO by the transpulmonary thermodilution method (COao) is used. Clinical validation studies in patients without underlying intrathoracic pathology, comparing transpulmonary COao with the pulmonary technique (COpa), mostly yielded good agreement. PMID:15101866

Breukers, R B G E; Jansen, J R C

2004-05-01

4

Are the arms and legs in competition for cardiac output?  

PubMed

Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value. Despite this similarity between arm and leg VO2max, when arm exercise is added to leg exercise, VO2max is not markedly elevated, which suggests a central or cardiac limitation. In fact, when intense arm exercise is added to leg exercise, leg blood flow at a given work rate is approximately 10% less than during leg exercise alone. Similarly, when intense leg exercise is added to arm exercise, arm blood flow and muscle oxygenation are reduced by approximately 10%. Such reductions in regional blood flow are mainly attributed to peripheral vasoconstriction induced by the arterial baroreflex to support the prevailing blood pressure. This putative mechanism is also demonstrated when the ability to increase cardiac output is compromised; during exercise, the prevailing blood pressure is established primarily by an increase in cardiac output, but if the contribution of the cardiac output is not sufficient to maintain the preset blood pressure, the arterial baroreflex increases peripheral resistance by augmenting sympathetic activity and restricting blood flow to working skeletal muscles. PMID:17019302

Secher, Niels H; Volianitis, Stefanos

2006-10-01

5

Methods and apparatus for determining cardiac output  

NASA Technical Reports Server (NTRS)

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.

Cohen, Richard J. (Inventor); Mukkamala, Ramakrishna (Inventor); Sherman, Derin A. (Inventor)

2010-01-01

6

Cardiac output monitoring: basic science and clinical application: Cardiac output monitoring  

Microsoft Academic Search

Summary Derangements in the circulation are a common feature of sepsis, trauma, major surgery and other critical illnesses. Detailed evaluation of the circulation is therefore an essential aspect of the clinical management of such patients. The use of cardiac output monitoring technology is an increasingly important aspect of evaluating patients in the operating theatre, critical care unit and elsewhere. There

S. Jhanji; J. Dawson; R. M. Pearse

2008-01-01

7

Newer methods of cardiac output monitoring.  

PubMed

Cardiac output (CO) is the volume of blood ejected by each ventricle per minute and is the product of stroke volume and heart rate. CO can thus be manipulated by alteration in heart rate or rhythm, preload, contractility and afterload. Moreover it gives important information about tissue perfusion and oxygen delivery. CO can be measured by various methods and thermodilution method using pulmonary artery catheter (PAC) is till date considered as gold standard method. Complications associated with PAC led to development of newer methods which are minimally or non-invasive. Newer methods fulfil other properties like continuous and reproducible reading, cost effective, reliable during various physiological states and have fast response time. These methods are validated against the gold standard with good level agreement. In this review we have discussed various newer methods of CO monitoring and their effectiveness in clinical use. PMID:25276302

Mehta, Yatin; Arora, Dheeraj

2014-09-26

8

Newer methods of cardiac output monitoring  

PubMed Central

Cardiac output (CO) is the volume of blood ejected by each ventricle per minute and is the product of stroke volume and heart rate. CO can thus be manipulated by alteration in heart rate or rhythm, preload, contractility and afterload. Moreover it gives important information about tissue perfusion and oxygen delivery. CO can be measured by various methods and thermodilution method using pulmonary artery catheter (PAC) is till date considered as gold standard method. Complications associated with PAC led to development of newer methods which are minimally or non-invasive. Newer methods fulfil other properties like continuous and reproducible reading, cost effective, reliable during various physiological states and have fast response time. These methods are validated against the gold standard with good level agreement. In this review we have discussed various newer methods of CO monitoring and their effectiveness in clinical use.

Mehta, Yatin; Arora, Dheeraj

2014-01-01

9

Non-invasive assessment of cardiac output in children  

Microsoft Academic Search

BACKGROUND: Stroke distance, the systolic velocity integral of aortic blood flow, is a linear analogue of stroke volume; its product with heart rate is minute distance, analogous to cardiac output. OBJECTIVE: To investigate the feasibility of assessing cardiac output in children with a simple non-invasive Doppler ultrasound technique, and to determine the normal range of values. METHODS: Peak aortic blood

J R Richardson; J Ferguson; J Hiscox; J Rawles

1998-01-01

10

Cardiac output estimation using arterial blood pressure waveforms  

E-print Network

Cardiac output (CO) is a cardinal parameter of cardiovascular state, and a fundamental determinant of global oxygen delivery. Historically, measurement of CO has been limited to critically-ill patients, using invasive ...

Sun, James Xin

2006-01-01

11

Assessment of cardiac output by the Doppler ultrasound technique alone  

Microsoft Academic Search

The normal range of aortic blood velocity was established in 140 healthy adults, using a non-invasive Doppler ultrasound technique. Integration of the area under the velocity-time curve for each heart beat gave stroke distance, which, when multiplied by heart rate, gave minute distance. Stroke distance and minute distance are an indication of stroke volume and cardiac output respectively and both

N E Haites; F M McLennan; D H Mowat; J M Rawles

1985-01-01

12

Reduced cardiac output in imported Plasmodium falciparum malaria  

PubMed Central

Background Volume substitution remains subject of controversy in the light of effusions and oedema potentially complicating this highly febrile disease. Understanding the role of myocardial and circulatory function appears to be essential for clinical management. In the present study, cardiac function and cardiac proteins have been assessed and correlated with parasitological and immunologic parameters in patients with imported Plasmodium falciparum malaria. Methods In a prospective case-control study, 28 patients with uncomplicated and complicated P. falciparum malaria were included and findings were compared with 26 healthy controls. Cardiac function parameters were assessed by an innovative non-invasive method based on the re-breathing technique. In addition, cardiac enzymes and pro- and anti-inflammatory cytokines were measured and assessed with respect to clinical symptoms and conditions of malaria. Results Cardiac index (CI) as a measurement of cardiac output (CO) was 21% lower in malaria patients than in healthy controls (2.7 l/min/m2 versus 3.4 l/min/m2; P < 0.001). In contrast, systemic vascular resistance index (SVRI) was increased by 29% (32.6 mmHg?m2/(l/min) versus 23.2 mmHg?m2/(l/min); P < 0.001). This correlated with increased cardiac proteins in patients versus controls: pro-BNP 139.3 pg/ml versus 60.4 pg/ml (P = 0.03), myoglobin 43.6 ?g/l versus 27.8 ?g/l (P = < 0.001). All measured cytokines were significantly increased in patients with malaria. CI, SVRI as well as cytokine levels did not correlate with blood parasite density. Conclusions The results support previous reports suggesting impaired cardiac function contributing to clinical manifestations in P. falciparum malaria. Findings may be relevant for fluid management and should be further explored in endemic regions. PMID:21658247

2011-01-01

13

Transthoracic electrical bioimpedance versus thermodilution technique for cardiac output measurement during mechanical ventilation  

Microsoft Academic Search

To study the possible influence of mechanical ventilation on the accurracy of thoracic electrical bioimpedance (TEI) in the measurement of cardiac output, we determined cardiac output concurrently by TEI using Kubicek's equation and by thermodilution in 8 acutely ill patients who were mechanically ventilated (assist\\/control mode) but who had no underlying respiratory failure. Cardiac outputs were lower with TEI than

J. C. Preiser; A. Daper; J.-N. Parquier; B. Contempré; J.-L. Vincent

1989-01-01

14

Continuous cardiac output and mixed venous oxygen saturation monitoring.  

PubMed

Continuous assessment of cardiac output and SVO2 in the critically ill may be helpful in both the monitoring variations in the patient's cardiovascular state and in determining the efficacy of therapy. Commercially available continuous cardiac output (CCO) monitoring systems are based on the pulsed warm thermodilution technique. In vitro validation studies have demonstrated that this method provides higher accuracy and greater resistance to thermal noise than standard bolus thermodilution techniques. Numerous clinical studies comparing bolus with continuous thermodilution techniques have shown this technique similarly accurate to track each other and to have negligible bias between them. The comparison between continuous thermal and other cardiac output methods also demonstrates good precision of the continuous thermal technique. Accuracy of continuous oximetry monitoring using reflectance oximetry via fiberoptics has been assessed both in vitro and in vivo. Most of the studies testing agreement between continuous SVO2 measurements and pulmonary arterial blood samples measured by standard oximetry have shown good correlation. Continuous SVO2 monitoring is often used in the management of critically ill patients. The most recently designed pulmonary artery catheters are now able to simultaneously measure either SVO2 and CCO or SVO2 and right ventricular ejection fraction. This ability to view simultaneous trends of SVO2 and right ventricular performance parameters will probably allow the clinician to graphically see the impact of volume loading or inotropic therapy over time, as well as the influence of multiple factors, including right ventricular dysfunction, on SVO2. However, the cost-effectiveness of new pulmonary artery catheters application remains still questionable because no established utility or therapeutic guidelines are available. PMID:9869547

Cariou, A; Monchi, M; Dhainaut, J F

1998-12-01

15

Noninvasive estimation of cardiac output with nonprescribed breathing  

Microsoft Academic Search

A noninvasive method to estimate cardiac output\\u000a $$\\\\dot Q$$\\u000a without special patient cooperation was developed by modifying a previous acetylene-helium (C2H2?He) rebreathing technique (ART). Estimation of\\u000a $$\\\\dot Q$$\\u000a using ART is based on a single-compartment model that is valid only under prescribed breathing; e.g., fast, deep breathing,\\u000a and emptying of the rebreathing bag on each breath. To make the ART

Marco E. Cabrera; Gerald M. Saidel; Mark H. Cohen

1991-01-01

16

Hibernator Citellus undulatus maintains safe cardiac conduction and is protected against tachyarrhythmias  

E-print Network

of Sciences, Puschino, Russia. BACKGROUND Most mammals experience cardiac arrest during hypothermia reserved. doi:10.1016/j.hrthm.2005.06.012 #12;succumbs to cardiac arrest due to atrial and ventricularHibernator Citellus undulatus maintains safe cardiac conduction and is protected against

17

A rebreathing method for measuring lung volume, diffusing capacity and cardiac output in conscious small animals  

Microsoft Academic Search

We developed a multiple gas rebreathing technique for measuring lung diffusing capacity (DLCO), lung volume (VL) and cardiac output simultaneously in conscious spontaneously breathing small animals. Lung volume was measured from the dilution of methane (CH4) or sulfur hexafluoride (SF6) and verified independently by a helium washout technique. Cardiac output and DLCO were estimated from the uptake of acetylene and

Cuneyt Yilmaz; Robert L. Johnson; Connie C. W. Hsia

2005-01-01

18

Equipment review: An appraisal of the LiDCO(TM)plus method of measuring cardiac output  

PubMed Central

The LiDCO™plus system is a minimally/non-invasive technique of continuous cardiac output measurement. In common with all cardiac output monitors this technology has both strengths and weaknesses. This review discusses the technological basis of the device and its clinical application. PMID:15153237

2004-01-01

19

Comparison of cardiac output measurement using the CardioQP oesophageal Doppler with cardiac output measurement using thermodilution technique in children during heart catheterisation.  

PubMed

The minimally invasive CardioQP oesophageal Doppler probe estimates cardiac output by measuring blood flow velocity in the descending aorta. Individual variables to enter are patient's age, weight and height. We measured cardiac output simultaneously with CardioQP and pulmonary artery catheter thermodilution techniques during heart catheterisation in 40 paediatric patients with congenital heart defects. Median [range] age was 8.2 years [0.5-16.7 years], cardiac output values measured by thermodilution and CardioQP were 3.6 l.min(-1) [1.2-7.1 l.min(-1)] and 3.0 l.min(-1) [0.7-6.7 l.min(-1)], respectively. These values showed only moderate correlation (r = 0.809; p < 0.0001). Bias and precision were 0.66 l.min(-1) and 1.79 l.min(-1) (95% limits of agreement: -1.13 to +2.45 l.min(-1)). Based on our preliminary experience, cardiac output values measured by CardioQP in children do not reliably represent cardiac output values compared with the thermodilution technique. We suggest measurement of individual aortic diameter to improve performance of the CardioQP. PMID:18557743

Knirsch, W; Kretschmar, O; Tomaske, M; Stutz, K; Nagdyman, N; Balmer, C; Schmitz, A; Berger, F; Bauersfeld, U; Weiss, M

2008-08-01

20

Measurement of cardiac output by carbon dioxide rebreathing methods.  

PubMed

Cardiac output may be measured noninvasively by applying the Fick principle to CO2; CO2 output is measured by expired gas analysis and the veno-arterial CO2 content difference is obtained from estimates of PVCO2 and PaCO2. PVCO2 is determined using the lung as a tonometer for the equilibration of CO2; two main methods are available. In the Defares or exponential method, a low concentration of CO2 is initially rebreathed. Complete equilibration is not reached between the lung and rebreathing bag and the PvCO2 is calculated as the asymptote of the exponential rise in PETCO2 during rebreathing and prior to recirculation. Even though several mathematical methods can be used to calculate PvCO2, the most precise is an iterative statistical analysis to obtain the best-fit curve for PETCO2 with time, from which PvCO2 is obtained from PETCO2 at 20 seconds after the start of rebreathing. In the Collier or equilibrium method, a bag having CO2 concentration higher than PvCO2 is rebreathed. If an appropriate initial bag volume CO2 has been selected, equilibration will occur in the lung-bag system, recognized as a plateau in the PCO2 rebreathing record. If a plateau is not obtained, PvCO2 can be estimated by extrapolating the line joining the points of expired PCO2 during the 8th and 12th seconds of rebreathing to that of the 20th second. With the equilibrium method, the plateau PCO2 is systematically higher than PvCO2 (downstream effect) and a correction is applied to obtain PvCO2. PaCO2 can be estimated from PETCO2 or from the mixed-expired PCO2 and an assumed physiologic dead space, except in patients with abnormal lung function, in whom PaCO2 must be measured directly. The content of CO2 in blood may be calculated from PCO2 by the equation: In(CCO2) = [0.396 X In(PCO2)] + 2.38 More complex algorithms are available to calculate CCO2 if the pH, hemoglobin, and arterial O2 saturation are widely divergent from resting values. The indirect Fick method applied to CO2 during exercise can be used to obtain a valid and reproducible measurement of Q comparable to that obtained by invasive methods. PMID:2500297

Heigenhauser, G J; Jones, N L

1989-06-01

21

Measurement of cardiac output by use of noninvasively measured transient hemodilution curves with photoacoustic technology.  

PubMed

We present the theoretical basis and experimental verification for cardiac output measurements using noninvasively measured hemodilution curves afforded with an indicator dilution technique and the emerging photoacoustic technology. A photoacoustic system noninvasively tracks a transient hemodilution effect induced by a bolus of isotonic saline as an indicator. As a result, a photoacoustic indicator dilution curve is obtained, which allows to estimate cardiac output from the developed algorithm. The experiments with a porcine blood circulatory phantom system demonstrated the feasibility of this technology towards the development of a noninvasive cardiac output measurement system for patient monitoring. PMID:24877007

Kang, Dongyel; Huang, Qiaojian; Li, Youzhi

2014-05-01

22

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

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

23

Cardiac output estimation from arterial blood pressure waveforms using the MIMIC II database  

E-print Network

The effect of signal quality on the accuracy of cardiac output (CO) estimation from arterial blood pressure (ABP) was evaluated using data from the Multi-Parameter Intelligent Patient Monitoring for Intensive Care (MIMIC) ...

Chen, Tiffany

2009-01-01

24

Application of bioreactance for cardiac output assessment during exercise in healthy individuals  

Microsoft Academic Search

In patients with cardiac failure, bioreactance-based cardiac output (CO) monitoring provides a valid non-invasive method for\\u000a assessing cardiac performance during exercise. The purpose of this study was to evaluate the efficacy of this technique during\\u000a strenuous exercise in healthy, trained individuals. Fourteen recreational cyclists, mean (SD) age of 34 (8) years and relative\\u000a peak oxygen uptake of (VO2) 56 (6) ml kg?1 min?1,

Adrian Elliott; James H. Hull; David Nunan; Djordje G. Jakovljevic; David Brodie; Lesley Ansley

2010-01-01

25

Cardiac Output and Central Distribution of Blood Flow in the Human Fetus  

Microsoft Academic Search

Background—The objectives of this study were to establish reference ranges for left and right cardiac output and to investigate blood flow distribution through the foramen ovale, ductus arteriosus, and pulmonary bed in human fetuses. Methods and Results—A prospective study was performed in 222 normal fetuses from 13 to 41 weeks of gestation with high-resolution color Doppler ultrasound. Cardiac output and

Gunther Mielke; Norbert Benda

2010-01-01

26

A critical review of the ability of continuous cardiac output monitors to measure trends in cardiac output.  

PubMed

Numerous cardiac output (CO) monitors have been produced that provide continuous rather than intermittent readings. Bland and Altman has become the standard method for validating their performance against older standards. However, the Bland and Altman method only assesses precision and does not assess how well a device detects serial changes in CO (trending ability). Currently, there is no consensus on how trending ability, or trend analysis, should be performed. Therefore, we performed a literature review to identify articles published between 1997 and 2009 that compared methods of continuous CO measurement. Identified articles were grouped according to measurement technique and statistical methodology. Articles that analyzed trending ability were reviewed with the aim of finding an acceptable statistical method. Two hundred two articles were identified. The most popular methods were pulse contour (69 articles), Doppler (54), bioimpedance (38), and transpulmonary or continuous thermodilution (27). Forty-one articles addressed trending, and of these only 23 provided an in-depth analysis. Several common statistical themes were identified: time plots, regression analysis, Bland and Altman using change in CO (?CO), and the 4-quadrant plot, which used direction of change of ?CO to determine the concordance. This plot was further refined by exclusion of data when values were small. Receiver operating characteristic curves were used to define the exclusion zone. In animal studies, a reliable reference standard such as an aortic flowprobe was frequently used, and regression or time plots could be used to show trending. Clinical studies were more problematic because data collection points were fewer (8-10 per subject). The consensus was to use the 4-quadrant plot with exclusion zones and apply concordance analysis. A concordance rate of >92% when using a 15% zone indicated good trending. A new method of presenting trend data (?CO) on a polar plot is proposed. Agreement was shown by the angle with the horizontal axis and ?CO by the distance from the center. Trending can be assessed by the vertical limits of the data, similar to the Bland and Altman method. PMID:20736431

Critchley, Lester A; Lee, Anna; Ho, Anthony M-H

2010-11-01

27

The effect of cardiac denervation and beta-blockade on control of cardiac output in exercising dogs  

Microsoft Academic Search

Summary  Normal and cardiac denervated dogs, with an electromagnetic aortic flowprobe implanted at least 14 days before the experiments,\\u000a ran at different speeds on a 25% graded treadmill. The experiments were carried out before and after blockade of betareceptors\\u000a in the heart by PO administration of 125 mg·kg?1 practolol per day. Changes in stroke volume, heart rate, and cardiac output were

P. G. A. Versteeg; M. I. M. Noble; J. Stubbs; G. Elzinga

1983-01-01

28

Comparison of bioimpedance versus thermodilution cardiac output during cardiac surgery: Evaluation of a second-generation bioimpedance device  

Microsoft Academic Search

Objective: To compare a second-generation thoracic electrical bioimpedance (TEB) hemodynamic monitoring system with the clinically used pulmonary artery catheter thermodilution (TD-PAC) system. Design: Blinded, simultaneous measurements at specified key time points during surgery. Setting: University teaching hospital cardiac surgical operating rooms. Participants: Forty-seven patients undergoing primary elective coronary artery bypass surgery. Interventions: Timed cardiac output measurements by thermodilution and continuous

Bruce D. Spiess; Muhammad A. Patel; Louise O. Soltow; Ian H. Wright

2001-01-01

29

Type D personality and cardiac output in response to stress  

Microsoft Academic Search

Type D personality is predictive of adverse clinical outcome and psychological distress in cardiac patients. However, the mechanisms by which Type D affects health are largely unknown. This study (1) investigated the relationship between Type D and cardiovascular reactivity to experimentally induced stress and (2) tested the influence of Type D on subjective feelings of stress. Eighty four healthy young

Lynn Williams; Ronan E. O’Carroll; Rory C. O’Connor

2009-01-01

30

Non-invasive measurement of cardiac output by a single breath constant expiratory technique.  

PubMed

A new single breath test has been developed that measures pulmonary blood flow (Qc) and pulmonary tissue volume by using the fact that Qc is proportional to the relationship between the absorption rate of acetylene (C2H2) from the alveolar gas and the rate of change of lung volume during constant expiratory flow. To make these measurements a bag in bottle system with a rolling seal spirometer, a mass spectrometer, and a minicomputer with analogue to digital conversion have been used. Qc was compared with cardiac output measured by the thermodilution technique in 20 patients with cardiac disease; some also had mild chronic obstructive pulmonary disease. The mean (SD) resting Qc for the group was 5.27 (1.22) l/min and the cardiac output measured by thermodilution was 5.30 (1.31) l/min. The mean difference between the two estimations of cardiac output was 0.03 l and the standard deviation of this difference was 0.76 l. The Qc technique was not successful in patients with an FEV1/FVC less than 60%, but seemed to be accurate in those with higher FEV1/FVC values. Correction of Qc for the effect of venous admixture in 14 patients resulted in an average 19% overestimation of cardiac output (6.01 (2.52) l/min v 5.05 (1.64) l/min). It is concluded that cardiac output can be accurately measured in patients with cardiac or mild pulmonary disease. No correction for venous admixture due to ventilation-perfusion mismatch was necessary in these patients, presumably because the large breath used by the technique overcomes most mild ventilation-perfusion maldistribution. These findings, in addition to the non-invasive nature of the technique, suggest potential value for the measurement of cardiac output in various clinical conditions. PMID:6701821

Elkayam, U; Wilson, A F; Morrison, J; Meltzer, P; Davis, J; Klosterman, P; Louvier, J; Henry, W L

1984-02-01

31

Validation of a modified one-step rebreathing technique for measuring exercise cardiac output.  

PubMed

A modification of the Farhi one-step rebreathing technique (1) is described for determining submaximal exercise cardiac output (Q). Factors critical in the estimation of Q are initial rebreathing bag volume and constant bag volume during the maneuver. By substituting a high flow rate analyzer (500 ml.min-1) for the recommended low flow rate mass spectrometer (60 ml.min-1), adding a recirculation circuit from the outlet of the analyzer to an inlet at the base of the rebreathing bag, and reducing the length of sample tubing to the analyzer, we were able to recirculate the subject's expired gas and achieve no loss of bag volume. No statistically significant differences in estimate of cardiac output were noted between the mass spectrometer and LB-2 analyzer with recirculation circuit during submaximal cycling. Heart rate and oxygen uptake were highly correlated with cardiac output and agreed well with the literature, irrespective of the CO2 analyzer system used. A unique feature of our method is that the subject's tidal volume is measured prior to the maneuver and then used as the initial rebreathing bag volume. Varying the bag volume by +/- 0.2 L from the tidal volume had no significant effect on the estimate of cardiac output during exercise. Now quick, reliable, and noninvasive measurements of cardiac output are feasible in subjects--not only in the laboratory but also in the field where a mass spectrometer is not readily portable. PMID:3149188

Szlyk, P C; Evans, K C; Sils, I V

1988-12-01

32

Cardiac power output and its response to exercise in athletes and non-athletes.  

PubMed

Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow- and pressure-generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non-athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age- and gender-matched healthy sedentary controls participated in this study. CPO was calculated as the product of cardiac output and mean arterial pressure, expressed in watts. Measures of hemodynamic status, cardiac structure and pumping capability were assessed by echocardiography. CPO was assessed at rest and after peak bicycle exercise. At rest, the two groups had similar values of cardiac power output (1·08 ± 0·2 W versus 1·1 ± 0·24 W, P>0·05), but the athletes demonstrated lower systolic blood pressure (109·5 ± 6·2 mmHg versus 117·2 ± 8·2 mmHg, P<0·05) and thicker posterior wall of the left ventricle (9·8 ± 1 mm versus 9 ± 1·1 mm, P<0·05). Peak CPO was higher in athletes (5·87 ± 0·75 W versus 5·4 ± 0·69 W, P<0·05) as was cardiac reserve (4·92 ± 0·66 W versus 4·26 ± 0·61 W, P<0·05), respectively. Peak exercise CPO and reserve were only moderately correlated with end-diastolic volume (r = 0·54; r = 0·46, P<0·05) and end-diastolic left ventricular internal diameter (r = 0·48; r = 0·42, P<0·05), respectively. Athletes demonstrated greater maximal cardiac pumping capability and reserve than non-athletes. The study provides new evidence that resting measures of cardiac structure and function need to be considered with caution in interpretation of maximal cardiac performance. PMID:23522013

Klasnja, Aleksandar V; Jakovljevic, Djordje G; Barak, Otto F; Popadic Gacesa, Jelena Z; Lukac, Damir D; Grujic, Nikola G

2013-05-01

33

Epi-aortic Doppler measurement of cardiac output in univentricular connection  

PubMed Central

Background In the initial postoperative period after a Fontan-type operation for a univentricular circulation, cardiac output information is important, but cannot be provided by conventional methods due to the surgical reconstruction of the heart. In this regard we investigated the feasibility of epi-aortic Doppler measurements in order to calculate cardiac output. Methods : Epi-aortic cardiac output measurement was compared with Fick measurements as the gold standard in eight patients with a univentricular circulation after a Fontan-type operation. Results The mean diameter of the aorta by epi-aortic measurement was 18 mm (range 14 to 25), by angiography 17 mm (range 10 to 24), correlation coefficient 0.88 (p < 0.05). The mean cardiac output by epi-aortic measurement was 2.8 l.min?1 (range 1.2 to 6.3), by the Fick calculations 1.8 l.min?1 (range 0.8 to 5.0). The correlation coefficient for cardiac output data in aortic diameters up to 20 millimeter in diameter was 0.55 (p < 0.05). Conclusions Epi-aortic Doppler measurement of cardiac output after Fontan type reconstructions could be applied in aortas up to 20 millimeter in diameter. A reasonable correlation with Fick calculations was found. This was supported by Bland–Altman plotting. The method is intrinsically invasive, but application and removal of the device were easy and no complications related to the system were observed. An important restriction is the often present abnormal anatomy, either congenitally or after surgery. PMID:22915911

Bogers, Ad J J C; van den Burg, Martin; Schepp, Ronald; Klein, Jan

2009-01-01

34

Stroke volume and cardiac output hypoxemic hypoxia produced by intravenous infusion of carbon dioxide.  

PubMed

Hypoxia produced by intravenous infusion of gaseous carbon dioxide was associated in conscious rabbits with decreases in cardiac output and stroke volume. At the same time the arterial blood pressure, oxygen uptake and blood pH decreased, whereas carbon dioxide pressure and lactate level in the arterial blood increased. Pulmonary ventilation increased too, due to the rise in the respiratory frequency and tidal volume. The fall in cardiac output and stroke volume explains a great fall of oxygen uptake in response to decrease of oxygen pressure in the blood. PMID:6787834

Lyszczarz, J; Boruta, E

1980-01-01

35

A comparison of transoesophageal echocardiographic Doppler across the aortic valve and the thermodilution technique for estimating cardiac output.  

PubMed

This study was undertaken in order to elucidate the differences between various planes of measurement and Doppler techniques (pulsed- vs. continuous-wave Doppler) across the aortic valve to estimate cardiac output. In 45 coronary artery bypass patients, cardiac output was measured each time using four different Doppler techniques (transverse and longitudinal plane, pulsed- and continuous-wave Doppler) and compared with the thermodilution technique. Measurements were performed after induction of anaesthesia and shortly after arrival in the intensive care unit. Optimal imaging was obtained in 91% of the patients, in whom a total of 82 measurements of cardiac output were performed. The respective mean (SD) areas of the aortic valve were 3.77 (0.71) cm2 in the transverse plane and 3.86 (0.89) cm2 in the longitudinal plane. A correlation of 0.87 was found between pulsed-wave Doppler cardiac output and the thermodilution technique in either transverse or longitudinal plane. Correlation coefficients of 0.82 and 0.84 were found between thermodilution cardiac output and transverse and longitudinal continuous-wave Doppler cardiac output, respectively. Although thermodilution cardiac output is a widely accepted clinical standard, transoesophageal Doppler echocardiography across the aortic valve offers adequate estimations of cardiac output. In particular, pulsed-wave Doppler cardiac output in both the transverse and longitudinal plane provides useful data. PMID:10215707

Poelaert, J; Schmidt, C; Van Aken, H; Hinder, F; Mollhoff, T; Loick, H M

1999-02-01

36

Continuous cardiac output measurement - Aspects of Doppler frequency analysis  

NASA Technical Reports Server (NTRS)

From the suprasternal notch blood flow velocity in the aorta can be measured non-invasively by a Doppler probe. Integration over systole after frequency analysis gives a measure of stroke volume if a separate diameter observation is incorporated. Frequency analysis by a zero crossing counter or by a set of parallel phaselock loops was less effective than a set of bandpass filters. Observations on dogs, baboons and humans before and after exercise or surgery suggest the indications to be useful. Application to judging heart failure by the effect of introducing a volume load is indicated. Changes in output also are measured in freely moving subjects.

Mackay, R. S.; Hechtman, H. B.

1975-01-01

37

Doppler Ultrasound Determination of the Distribution of Human Cardiac Output: Effects of Age and Physical Stresses  

Microsoft Academic Search

Due to its high spatial, temporal, and dynamic resolution, noninvasive Doppler ultrasound can be used to determine the distribution of phasic cardiac output in humans. The effects of ageing and various common physical stresses on combined human major central and regional blood flows have not been reported. We tested the hypothesis that there are no significant age-related differences in steady-state

E. R. Greene; R. C. Roach

2004-01-01

38

Serial changes in cardiac output during normal pregnancy: a Doppler ultrasound study  

Microsoft Academic Search

Objectives: To determine the direction and magnitude of change in cardiac output (CO) during pregnancy. Study design: We performed serial measurements of CO on five occasions from 24 weeks gestation to term and once during the puerperium in 26 normal pregnancies (156 measurements) using Doppler ultrasound measurement of flow velocity profiles and aortic root cross sectional area. Result: CO increased

Terence G. Hennessy; Dermot MacDonald; Marie S. Hennessy; Margaret Maguire; Sean Blake; Hugh A. McCann; Declan D. Sugrue

1996-01-01

39

Real-time cardiac output estimation of the circulatory system under left ventricular assistance  

Microsoft Academic Search

A method for indirect and real-time estimation of the cardiac output of the circulatory system supported by the left ventricular assist device (LVAD) is proposed. This method has low invasiveness and is useful for clinical applications of the LVAD since it needs only two measurements: the rate of blood outflow from the LVAD and the aortic pressure. The method is

Makoto Yoshizawa; Hiroshi Takeda; Makoto Miura; Tomoyuki Yambe; Yoshiaki Katahira; Shin-ichi Nitta

1993-01-01

40

Bioimpedance versus thermodilution cardiac output measurement: The bomed NCCOM3 after coronary bypass surgery  

Microsoft Academic Search

Values obtained for cardiac output (CO) were compared using thermodilution (TD) with those obtained using bioimpedance (Bi) as measured using the Bomed NCCOM3 (Revision 6) in 28 consecutive patients in the first 24h after coronary artery bypass surgery (CABS). In 46 paired measurements made in the first 12 h after CABS Bi values for CO were significantly lower than TD

A. N. Thomas; J. Ryan; B. R. H. Doran; B. J. Pollard

1991-01-01

41

CARDIAC OUTPUT AND BLOOD FLOW DISTRIBUTION DURING SWIMMING AND VOLUNTARY DIVING OF THE TUFTED DUCK (AYTHYA FULIGULA)  

Microsoft Academic Search

Summary Cardiac output (Kb) and blood flow distribution were continuously measured in the tufted duck when diving voluntarily. Blood flows through pulmonary, ischiadic, carotid and brachiocephalic arteries were recorded using miniature pulsed Doppler flow probes. By measuring these flows, cardiac output and blood flow to the leg muscles and to the flight muscles could be calculated. Heart rate and Vb

R. M. BEVAN; P. J. BUTLER

42

THE EFFECT OF EXERCISE ON THE CARDIAC OUTPUT AND BLOOD FLOW DISTRIBUTION OF THE LARGESCALE SUCKER CATOSTOMUS MACROCHEILUS  

Microsoft Academic Search

Summary Cardiac output (Q. ) and blood flow distribution were measured in adult largescale suckers at rest and while swimming. Cardiac output was directly measured using an ultrasonic flowprobe in f ish during the summer (16?C), fall (10?C) and winter (5?C). Largescale suckers were adept at holding station against a current without swimming and, when engaged in this behavior, they

ALAN S. KOLOK; R. MICHAEL SPOONER; ANTHONY P. FARRELL

43

Techniques for maintaining design efficiency when operating klystron amplifiers at levels below the maximum output power  

NASA Astrophysics Data System (ADS)

Some accelerator designs require that the amount of RF power supplied to the accelerating cavities be varied along the accelerator length. In order to minimize operating expense for a high-power, CW system, it is also desirable to maximize RF-generator efficiency. Klystrons are the traditional source used for RF-accelerator applications, but a high-efficiency klystron design is optimized to provide high efficiency at only one operating point, usually at saturation. Different klystron designs could be used for different power levels to maintain high efficiency; however, this approach would increase the capital costs of the accelerator. We discuss several methods of varying the output power of a klystron and show semi-empirically a way to preserve klystron efficiency. We derive two semi-empirical methods to predict the variations in power and efficiency under nonoptimum operating conditions. Experimental data from a 1.25 MW klystron are also shown. These data support our hypothesis and our models.

Tallerico, Paul; Rees, Daniel; Young, Andrew; Laycock, Don; Symons, Robert

1995-04-01

44

Long-term stable timing distribution of an ultrafast optical pulse train over multiple fiber links with polarization maintaining output  

E-print Network

The distribution of an ultrafast optical pulse train over multiple fiber links with long-term stable timing precision within 2 femtoseconds rms is accomplished by integrating a polarization maintaining output with 300 meter ...

Cox, Jonathan A.

45

Sarcalumenin is essential for maintaining cardiac function during endurance exercise training  

PubMed Central

Sarcalumenin (SAR), a Ca2+-binding protein located in the longitudinal sarcoplasmic reticulum (SR), regulates Ca2+ reuptake into the SR by interacting with cardiac sarco(endo)plasmic reticulum Ca2+-ATPase 2a (SERCA2a). We have previously demonstrated that SAR deficiency induced progressive heart failure in response to pressure overload, despite mild cardiac dysfunction in sham-operated SAR knockout (SARKO) mice (26). Since responses to physiological stresses often differ from those to pathological stresses, we examined the effects of endurance exercise on cardiac function in SARKO mice. Wild-type (WT) and SARKO mice were subjected to endurance treadmill exercise training (?65% of maximal exercise ability for 60 min/day) for 12 wk. After exercise training, maximal exercise ability was significantly increased by 5% in WT mice (n = 6), whereas it was significantly decreased by 37% in SARKO mice (n = 5). Cardiac function assessed by echocardiographic examination was significantly decreased in accordance with upregulation of biomarkers of cardiac stress in SARKO mice after training. After training, expression levels of SERCA2a protein were significantly downregulated by 30% in SARKO hearts, whereas they were significantly upregulated by 59% in WT hearts. Consequently, SERCA2 activity was significantly decreased in SARKO hearts after training. Furthermore, the expression levels of other Ca2+-handling proteins, including phospholamban, ryanodine receptor 2, calsequestrin 2, and sodium/calcium exchanger 1, were significantly decreased in SARKO hearts after training. These results indicate that SAR plays a critical role in maintaining cardiac function under physiological stresses, such as endurance exercise, by regulating Ca2+ transport activity into the SR. SAR may be a primary target for exercise-related adaptation of the Ca2+ storage system in the SR to preserve cardiac function. PMID:19502553

Jiao, Qibin; Bai, Yunzhe; Akaike, Toru; Takeshima, Hiroshi; Ishikawa, Yoshihiro; Minamisawa, Susumu

2009-01-01

46

Sarcalumenin is essential for maintaining cardiac function during endurance exercise training.  

PubMed

Sarcalumenin (SAR), a Ca(2+)-binding protein located in the longitudinal sarcoplasmic reticulum (SR), regulates Ca(2+) reuptake into the SR by interacting with cardiac sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a). We have previously demonstrated that SAR deficiency induced progressive heart failure in response to pressure overload, despite mild cardiac dysfunction in sham-operated SAR knockout (SARKO) mice (26). Since responses to physiological stresses often differ from those to pathological stresses, we examined the effects of endurance exercise on cardiac function in SARKO mice. Wild-type (WT) and SARKO mice were subjected to endurance treadmill exercise training ( approximately 65% of maximal exercise ability for 60 min/day) for 12 wk. After exercise training, maximal exercise ability was significantly increased by 5% in WT mice (n = 6), whereas it was significantly decreased by 37% in SARKO mice (n = 5). Cardiac function assessed by echocardiographic examination was significantly decreased in accordance with upregulation of biomarkers of cardiac stress in SARKO mice after training. After training, expression levels of SERCA2a protein were significantly downregulated by 30% in SARKO hearts, whereas they were significantly upregulated by 59% in WT hearts. Consequently, SERCA2 activity was significantly decreased in SARKO hearts after training. Furthermore, the expression levels of other Ca(2+)-handling proteins, including phospholamban, ryanodine receptor 2, calsequestrin 2, and sodium/calcium exchanger 1, were significantly decreased in SARKO hearts after training. These results indicate that SAR plays a critical role in maintaining cardiac function under physiological stresses, such as endurance exercise, by regulating Ca(2+) transport activity into the SR. SAR may be a primary target for exercise-related adaptation of the Ca(2+) storage system in the SR to preserve cardiac function. PMID:19502553

Jiao, Qibin; Bai, Yunzhe; Akaike, Toru; Takeshima, Hiroshi; Ishikawa, Yoshihiro; Minamisawa, Susumu

2009-08-01

47

Changes in cardiac output during swimming and aquatic hypoxia in the air-breathing Pacific tarpon.  

PubMed

Pacific tarpon (Megalops cyprinoides) use a modified gas bladder as an air-breathing organ (ABO). We examined changes in cardiac output (V(b)) associated with increases in air-breathing that accompany exercise and aquatic hypoxia. Juvenile (0.49 kg) and adult (1.21 kg) tarpon were allowed to recover in a swim flume at 27 degrees C after being instrumented with a Doppler flow probe around the ventral aorta to monitor V(b) and with a fibre-optic oxygen sensor in the ABO to monitor air-breathing frequency. Under normoxic conditions and in both juveniles and adults, routine air-breathing frequency was 0.03 breaths min(-1) and V(b) was about 15 mL min(-1) kg(-1). Normoxic exercise (swimming at about 1.1 body lengths s(-1)) increased air-breathing frequency by 8-fold in both groups (reaching 0.23 breaths min(-1)) and increased V(b) by 3-fold for juveniles and 2-fold for adults. Hypoxic exposure (2 kPa O2) at rest increased air-breathing frequency 19-fold (to around 0.53 breaths min(-1)) in both groups, and while V(b) again increased 3-fold in resting juvenile fish, V(b) was unchanged in resting adult fish. Exercise in hypoxia increased air-breathing frequency 35-fold (to 0.95 breaths min(-1)) in comparison with resting normoxic fish. While juvenile fish increased V(b) nearly 2-fold with exercise in hypoxia, adult fish maintained the same V(b) irrespective of exercise state and became agitated in comparison. These results imply that air-breathing during exercise and hypoxia can benefit oxygen delivery, but to differing degrees in juvenile and adult tarpon. We discuss this difference in the context of myocardial oxygen supply. PMID:17869150

Clark, T D; Seymour, R S; Christian, K; Wells, R M G; Baldwin, J; Farrell, A P

2007-11-01

48

Embryonic and adult-derived resident cardiac macrophages are maintained through distinct mechanisms at steady state and during inflammation.  

PubMed

Cardiac macrophages are crucial for tissue repair after cardiac injury but are not well characterized. Here we identify four populations of cardiac macrophages. At steady state, resident macrophages were primarily maintained through local proliferation. However, after macrophage depletion or during cardiac inflammation, Ly6c(hi) monocytes contributed to all four macrophage populations, whereas resident macrophages also expanded numerically through proliferation. Genetic fate mapping revealed that yolk-sac and fetal monocyte progenitors gave rise to the majority of cardiac macrophages, and the heart was among a minority of organs in which substantial numbers of yolk-sac macrophages persisted in adulthood. CCR2 expression and dependence distinguished cardiac macrophages of adult monocyte versus embryonic origin. Transcriptional and functional data revealed that monocyte-derived macrophages coordinate cardiac inflammation, while playing redundant but lesser roles in antigen sampling and efferocytosis. These data highlight the presence of multiple cardiac macrophage subsets, with different functions, origins, and strategies to regulate compartment size. PMID:24439267

Epelman, Slava; Lavine, Kory J; Beaudin, Anna E; Sojka, Dorothy K; Carrero, Javier A; Calderon, Boris; Brija, Thaddeus; Gautier, Emmanuel L; Ivanov, Stoyan; Satpathy, Ansuman T; Schilling, Joel D; Schwendener, Reto; Sergin, Ismail; Razani, Babak; Forsberg, E Camilla; Yokoyama, Wayne M; Unanue, Emil R; Colonna, Marco; Randolph, Gwendalyn J; Mann, Douglas L

2014-01-16

49

Accuracy and Reliability of Non-invasive Cardiac Output: The Future in Cardiology?  

E-print Network

A new generation of non-invasive cardiac output monitors provides an alternative to using conventional invasive methods such as thermodilution and direct Fick. The Bioz.com measures changes in thoracic electrical bioimpedance (TEB) of the descending aorta. The Innocor uses the principle of inert gas rebreathing. Simultaneous TEB and thermodilution cardiac output measurements were taken from 27 patients undergoing right heart catheterisation. Linear regression analysis showed good correlation between thermodilution and TEB about the line y=0.85x + 0.63 (r=0.91, P<0.0001). Preliminary data from the Innocor suggest comparable accuracy, continuous monitoring, portability, ease of use and low cost for a variety of applications in cardiology. 1.

S Faddy; J Bol; Dwm Muller; St. Vincent’s Hospital

50

Cardiac Remodeling in Fish: Strategies to Maintain Heart Function during Temperature Change  

PubMed Central

Rainbow trout remain active in waters that seasonally change between 4°C and 20°C. To explore how these fish are able to maintain cardiac function over this temperature range we characterized changes in cardiac morphology, contractile function, and the expression of contractile proteins in trout following acclimation to 4°C (cold), 12°C (control), and 17°C (warm). The relative ventricular mass (RVM) of the cold acclimated male fish was significantly greater than that of males in the control group. In addition, the compact myocardium of the cold acclimated male hearts was thinner compared to controls while the amount of spongy myocardium was found to have increased. Cold acclimation also caused an increase in connective tissue content, as well as muscle bundle area in the spongy myocardium of the male fish. Conversely, warm acclimation of male fish caused an increase in the thickness of the compact myocardium and a decrease in the amount of spongy myocardium. There was also a decrease in connective tissue content in both myocardial layers. In contrast, there was no change in the RVM or connective tissue content in the hearts of female trout with warm or cold acclimation. Cold acclimation also caused a 50% increase in the maximal rate of cardiac AM Mg2+-ATPase but did not influence the Ca2+ sensitivity of this enzyme. To identify a mechanism for this change we utilized two-dimensional difference gel electrophoresis to characterize changes in the cardiac contractile proteins. Cold acclimation caused subtle changes in the phosphorylation state of the slow skeletal isoform of troponin T found in the heart, as well as of myosin binding protein C. These results demonstrate that acclimation of trout to warm and cold temperatures has opposing effects on cardiac morphology and tissue composition and that this results in distinct warm and cold cardiac phenotypes. PMID:21915331

Klaiman, Jordan M.; Fenna, Andrew J.; Shiels, Holly A.; Macri, Joseph; Gillis, Todd E.

2011-01-01

51

Evaluation of cardiac output from a tidally ventilated homogeneous lung model  

Microsoft Academic Search

We used the direct Fick measurements to validate a method for estimating cardiac output by iteratively fitting \\u000a at the mouth to lung model values. This model was run using a series of 50, 30 and 10 breaths to test sensitivity to number of breaths used for fitting. The lung was treated as a catenary two-compartment lung model consisting of a

Habib Benallal; Kenneth C. Beck; Bruce D. Johnson; Thierry Busso

2005-01-01

52

Influence of vagal cooling on cardiac output in normal and beta-blocked exercising dogs  

Microsoft Academic Search

Summary  To study the relative influence of parasympathetic and sympathetic innervation on the early adaptation of cardiac output (CO) to exercise, we determined the time constant and amplitude of the CO change in dogs following a stepwise increase in treadmill velocity. The animals were studied during control conditions, beta-blockade, vagal blockade and combined beta-blockade and vagal blockade. To measure CO, an

P. G. A. Versteeg; P. Borgdorff

1986-01-01

53

Continuous intraoperative noninvasive cardiac output monitoring using a new thoracic bioimpedance device  

Microsoft Academic Search

Objectives: To compare a new noninvasive bioimpedance device with the standard thermodilution method during the intraoperative period in high-risk patients undergoing oncological surgery.Design: Prospectively collected data with retrospective analysis.Setting: The study was undertaken at a university hospital, single institution.Participants: Twenty-three selected adults undergoing extensive, ablative oncological surgery.Interventions: Simultaneous measurements of cardiac output by a new bioimpedance method and the standard

Duraiyah Thangathurai; Christopher Charbonnet; Peter Roessler; Charles C. J. Wo; Maged Mikhail; Roland Yoshida; William C. Shoemaker

1997-01-01

54

Cardiac output measurement: Lack of agreement between thermodilution and thoracic electric bioimpedance in two clinical settings  

Microsoft Academic Search

Study objective: To determine the agreement between thermodilution (TD) and thoracic electric bioimpedance (TEB) techniques in cardiac output (CO) measurements in hyperdynamic kidney recipients and normodynamic patients subjected to radical cystectomy. The main objective was to determine the reliability of TEB in CO measurement.Design: Open two-group study.Setting: Unïversity hospital.Patients: 19 kidney recipients and 5 radical cystectomy patients.Interventions: Radial artery cannula

Mohamed M. Atallah; Atef D. Demain

1995-01-01

55

Comparison of cardiac output determined by different rebreathing methods at rest and at peak exercise  

Microsoft Academic Search

Several rebreathing methods are available for cardiac output (Q\\u000a T) measurement. The aims of this study were threefold: first, to compare values for resting Q\\u000a T produced by the equilibrium-CO2, exponential-CO2 and inert gas-N2O rebreathing methods and, second, to evaluate the reproducibility of these three methods at rest. The third aim was to assess\\u000a the agreement between estimates of peak

Djordje G. Jakovljevic; David Nunan; Gay Donovan; Lynette D. Hodges; Gavin R. H. Sandercock; David A. Brodie

2008-01-01

56

Evaluation of the tracking potential of a noninvasive estimator of cardiac output.  

PubMed

A robust, automatic measurement system for calculating cardiac output noninvasively has recently been developed. The proposed method relies on fast Fourier transform (FFT) analysis of pulses measured externally at the carotid and femoral pressure points. A transfer function of the aorta is computed from these (calibrated) pressure measurements, and a tapered model of the aorta is parametrically adapted so that its transfer function matches that derived experimentally. Incorporated in the system are a custom routine for digitally filtering pressure data and a simplex optimization algorithm for identification of aortic parameters essential to the calculation of impedance and aortic flow. Once flow has been reconstructed in the time domain it is averaged to a stroke volume and multiplied by the heart rate to yield cardiac output. Flow measurements are computed over several pulses and compared against the standard, invasive procedure of thermodilution. Preliminary results for a dynamic investigation of the method indicate a strong potential for tracking changes in cardiac output over time, thus advocating its use in monitoring hemodynamically unstable patients. PMID:8814389

Redling, J; Akay, M

1996-07-01

57

The Circadian Clock Maintains Cardiac Function by Regulating Mitochondrial Metabolism in Mice  

PubMed Central

Cardiac function is highly dependent on oxidative energy, which is produced by mitochondrial respiration. Defects in mitochondrial function are associated with both structural and functional abnormalities in the heart. Here, we show that heart-specific ablation of the circadian clock gene Bmal1 results in cardiac mitochondrial defects that include morphological changes and functional abnormalities, such as reduced enzymatic activities within the respiratory complex. Mice without cardiac Bmal1 function show a significant decrease in the expression of genes associated with the fatty acid oxidative pathway, the tricarboxylic acid cycle, and the mitochondrial respiratory chain in the heart and develop severe progressive heart failure with age. Importantly, similar changes in gene expression related to mitochondrial oxidative metabolism are also observed in C57BL/6J mice subjected to chronic reversal of the light-dark cycle; thus, they show disrupted circadian rhythmicity. These findings indicate that the circadian clock system plays an important role in regulating mitochondrial metabolism and thereby maintains cardiac function. PMID:25389966

Kohsaka, Akira; Das, Partha; Hashimoto, Izumi; Nakao, Tomomi; Deguchi, Yoko; Gouraud, Sabine S.; Waki, Hidefumi; Muragaki, Yasuteru; Maeda, Masanobu

2014-01-01

58

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

PubMed Central

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

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

2012-01-01

59

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 Central

OBJECTIVES 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. METHODS 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. RESULTS 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. CONCLUSIONS 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. PMID:22761126

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

2012-01-01

60

The validity of trans-esophageal Doppler ultrasonography as a measure of cardiac output in critically ill adults  

Microsoft Academic Search

ObjectiveTo determine the validity of the esophageal Doppler monitor (EDM) and echo-esophageal Doppler (Echo-ED) in measuring cardiac output in the critically ill.DesignSystematic search of relevant international literature and data synthesis.Search strategyLiterature search (1989–2003) using Ovid interface to Medline, Embase and Cochrane databases aimed at finding studies comparing EDM or Echo-ED cardiac output with that derived from simultaneous pulmonary artery thermodilution

Paul M. Dark; Mervyn Singer

2004-01-01

61

Automated non-invasive measurement of cardiac output: comparison of electrical bioimpedance and carbon dioxide rebreathing techniques  

Microsoft Academic Search

Two commercial automated, non-invasive systems for estimation of cardiac output were evaluated. Values of cardiac output obtained by electrical bioimpedance cardiography (BoMed NCCOM3 machine) were compared with values derived from an indirect Fick technique that uses carbon dioxide rebreathing (Gould 9000 IV system) during 103 simultaneous measurements made at rest in 19 randomly selected subjects and on exercise in 11

S A Smith; A E Russell; M J West; J Chalmers

1988-01-01

62

Effect of inspiration of 12% O? (balance N?) on cardiac output, respiration, oxygen saturation, and oxygen delivery.  

PubMed

Low arterial oxygen saturation (SaO(2)) will result in a reduced rate of arterial oxygen delivery to the tissues (DO(2)), unless there is a compensatory increase in cardiac output (CO) or haemoglobin concentration (Hb). An adequate DO(2) can therefore be maintained by increasing ventilation, CO, or both. Sustaining a tissue specific oxygen extraction is thought to play an important part in overall compensation. The present study has examined responses to acute hypoxic exposure in 8 volunteers (breathing 12% oxygen, balance nitrogen) and describes changes in CO, ventilation and the SaO(2). Aims included: examination of the extent of intersubject variations and seeing whether DO(2) was maintained. SaO(2), PCO(2), respiration (via stethograph) and Finapress (non-invasive) arterial blood pressure (BP) were recorded, firstly on air and then on 12% oxygen. CO was derived, off-line, from the BP record. CO was increased in 5 subjects (22%-45%) but was virtually unchanged in 3, and yet comparison for all 8 subjects showed that DO(2) on 12% oxygen was not significantly different from DO(2) on air (mean on air 1017 ml. min(-1); hypoxia 1080 ml. min(-1), p = 0.27). SaO(2) on 12% oxygen ranged between 85% and 93%. In conclusion, exposure to the same hypoxic gas mixture resulted in differing individual ventilatory and CO responses. However, DO(2) was well maintained. PMID:21445805

Bell, M; Thake, C D; Wolff, C B

2011-01-01

63

NOTE: Increasing cardiac output and decreasing oxygenation sequence in pump twins of acardiac twin pregnancies  

NASA Astrophysics Data System (ADS)

An acardiac twin pregnancy is a rare but serious complication of monochorionic twinning and consists of an acardiac twin and a pump twin. The acardiac twin is a severely malformed fetus that lacks most organs, particularly a heart, but grows during pregnancy because it is perfused by the developmentally normal pump twin via a set of arterioarterial and venovenous placental anastomoses. Pump twins die intrauterine or neonatally in about 50% of the cases. Because the effects of an acardiac mass on the pump twin's development are incompletely known, methods for outcome prognosis are currently not available. We sought to derive simple relations for the pump twin's excess cardiac output and decreased oxygenation and to use available clinical cases for a preliminary test of the model. As a method, we used a theoretical flow model to represent the fetoplacental circulation of an acardiac twin pregnancy and estimated blood deoxygenation and reoxygenation following perfusion of the two bodies and placentas, respectively. The results show the pump twin's excess cardiac output and decrease of venous oxygen saturation to depend on the ratio of pump twin to acardiac twin umbilical blood flow, whose ratio can be measured by ultrasonography. The clinical cases show a decreasing umbilical flow ratio with gestation. In conclusion, prospective serial study is necessary to test whether measurement of umbilical flow ratios allows monitoring the pump twin's pathophysiologic development, possibly resulting in a guideline for prognosis of pump twin survival.

van Gemert, Martin J. C.; Umur, Asli; van den Wijngaard, Jeroen P. H. M.; Van Bavel, Ed; Vandenbussche, Frank P. H. A.; Nikkels, Peter G. J.

2005-02-01

64

The use of electrical cardiometry for continuous cardiac output monitoring in preterm neonates: a validation study.  

PubMed

Background?Electrical cardiometry (EC) is a continuous noninvasive method for measuring cardiac output (CO), but there are limited data on premature infants. We evaluated the utility of EC monitoring by comparing the results obtained using EC to measurements of CO and systemic blood flow using echocardiography (ECHO). Methods?In this prospective observational study, 40 preterm neonates underwent 108-paired EC and ECHO measurements. Results?There were correlations between EC-CO and left ventricular output (LVO, p?output (RVO, p?

Song, R; Rich, W; Kim, J H; Finer, N N; Katheria, A C

2014-12-01

65

A fMRI Study of Verbal Working Memory, Cardiac Output, and Ejection Fraction in Elderly Patients with Cardiovascular Disease  

Microsoft Academic Search

Cardiovascular disease (CVD) is associated with cognitive deficits even in the absence of stroke. We examined the relationship\\u000a between cardiac performance, as measured by cardiac output (CO) and ejection fraction (EF), and brain activity during a verbal\\u000a working memory (VWM) task in elderly CVD patients who tend to be at increased risk for vascular cognitive impairments. Seventeen\\u000a patients were recruited

Farzin Irani; Lawrence H. Sweet; Andreana P. Haley; John J. Gunstad; Beth A. Jerskey; Richard C. Mulligan; Angela L. Jefferson; Athena Poppas; Ronald A. Cohen

2009-01-01

66

Improved noninvasive method for measurement of cardiac output and evaluation of left-sided cardiac valve incompetence  

SciTech Connect

A time-saving method was developed to label red blood cells in vitro with /sup 99m/Tc while avoiding centrifugation. After tin incubation, extracellular tin was oxidized by sodium hypochlorite, and EDTA was added for stabilizing the complex prior to /sup 99m/Tc incubation. Labeling yields were 95%, and in vivo decay showed a high stability with a mean biologic half-life of eleven hours. The first-passage radionuclide technique for determination of cardiac output using the above-mentioned tracer was evaluated by using the left ventricle as area-of-interest with individual background correction after complete mixing of the tracer. This technique showed a high level of agreement with invasive methods. By combining this method for measurement of the forward stroke volume with the multigated equilibrium principle for determination of the total left ventricular stroke volume using similar background corrections, an exact evaluation of regurgitation fractions was obtained. In patients with aortic and mitral valve disease the noninvasive radionuclide technique gave similar but probably more accurate results as compared with contrast aortography and ventriculography. The radionuclide technique may be suitable for monitoring and selecting patients for surgical treatment.

Kelbaek, H.

1989-05-01

67

Effect of prednisolone treatment on selected respiratory parameters and cardiac output in prematurely delivered neonatal lambs.  

PubMed Central

Lambs were delivered by hysterotomy on days 142 and 143 postcoitum and were assigned to either a control group or a prednisolone-treated group (10 mg/kg daily for four days). On days 1 through 3 of life erythrocyte 2,3-diphosphoglycerate values were significantly increased in the treated group. Prednisolone treatment did not result in significantly increased P50 values. Mean plasma corticoid values in the control group decreased gradually postpartum. The prednisolone-treated lambs compared to the control lambs had depressed corticoid values, differing significantly on day 4. Body weight gains were significantly depressed by treatment and this effect lasted beyond the treatment period. On day 1 of life (24 hours postinitial treatment) oxygen consumption and cardiac output were significantly elevated in the treated group. PMID:647453

Thompson, F N; van Kampen, M; Culver, D H

1978-01-01

68

Low Cardiac Output Secondary to a Malpositioned Umbilical Venous Catheter: Value of Targeted Neonatal Echocardiography  

PubMed Central

Systemic hypotension is common in very low birthweight preterm infants but the nature of the precipitating cause may be unclear. Targeted neonatal echocardiography (TnEcho) is being increasingly used to support hemodynamic decisions in the neonatal intensive care unit (NICU), including identifying impairments in the transitional circulation of preterm infants, providing timely re-evaluation after institution of therapies and evaluating the placement of indwelling catheters. We present a case of a preterm infant with systemic hypotension and low cardiac output secondary to a large transatrial shunt induced by a malpositioned umbilical venous catheter. Repositioning of the line led to resolution of the hemodynamic disturbance and clinical instability, highlighting the utility of TnEcho in the NICU. PMID:25032055

Weisz, Dany E.; Poon, Wei Bing; James, Andrew; McNamara, Patrick J.

2014-01-01

69

Management of perioperative low cardiac output state without extracorporeal life support: What is feasible?  

PubMed Central

A transient and reversible reduction in cardiac output–low cardiac output state (LCOS) often occurs following surgery for congenital heart disease. Inappropriately managed LCOS is a risk factor for increased morbidity and death. LCOS may occasionally be progressive and refractory needing a period of “myocardial rest” with extracorporeal life support (ECLS). ECLS is currently considered a routine tool available for rapid deployment in most industrialized countries. Accumulated experience and refinements in technology have led to improving survivals – discharge survivals of 35%–50%, with almost 100% survival in select groups on elective left ventricular assist device. Thus, there is an increasing trend to initiate ECLS “early or electively in the operating room” in high-risk patients. India has a huge potential need for ECLS given the large number of infants presenting late with preexisting ventricular dysfunction or in circulatory collapse. ECLS is an expensive and resource consuming treatment modality and is not a viable therapeutic option in our country. The purpose of this paper is to reiterate an anticipatory, proactive approach to LCOS: (1) methods for early detection of evolving LCOS and (2) timely initiation of individualized therapy. This paper also explores what is feasible with the refinement of “simple, conventional, inexpensive strategies” for the management of LCOS. Therapy for LCOS should be multimodal based on the type of circulation and physiology. Our approach to LCOS includes: (1) intraoperative strategies, (2) aggressive afterload reduction, (3) lusitropy, (4) exclusion of structural defects, (5) harnessing cardiopulmonary interactions, and (6) addressing metabolic and endocrine abnormalities. We have achieved a discharge survival rate of greater than 97% with these simple methods. PMID:21234194

Kumar, Girish; Iyer, Parvathi U

2010-01-01

70

Age and sex influence the balance between maximal cardiac output and peripheral vascular reserve.  

PubMed

We evaluated the influence of age and sex on the relationship between central and peripheral vasodilatory capacity. Healthy men (19 younger, 12 older) and women (17 younger, 17 older) performed treadmill and knee extensor exercise to fatigue on separate days while maximal cardiac output (Q, acetylene uptake) and peak femoral blood flow (FBF, Doppler ultrasound) were measured, respectively. Maximal Q was reduced with age similarly in men (Y: 23.6 +/- 2.7 vs. O: 17.4 +/- 3.5 l/min; P < 0.05) and women (Y: 17.7 +/- 1.9 vs. O: 12.3 +/- 1.6 l/min; P < 0.05). Peak FBF was similar between younger (Y) and older (O) men (Y: 2.1 +/- 0.5 vs. O: 2.2 +/- 0.7 l/min) but was lower in older women compared with younger women (Y: 1.9 +/- 0.4 vs. O: 1.4 +/- 0.4 l/min; P < 0.05). Maximal Q was positively correlated with peak FBF in men (Y: r = 0.55, O: r = 0.74; P < 0.05) but not in women (Y: r = 0.34, O: r = 0.10). Normalization of cardiac output to appendicular muscle mass and peak FBF to quadriceps mass reduced the correlation between these variables in younger men (r = 0.30), but the significant association remained in older men (r = 0.68; P < 0.05), with no change in women. These data suggest that 1) aerobic capacity is associated with peripheral vascular reserve in men but not women, and 2) aging is accompanied by a more pronounced sex difference in this relationship. PMID:19959767

Ridout, Samuel J; Parker, Beth A; Smithmyer, Sandra L; Gonzales, Joaquin U; Beck, Kenneth C; Proctor, David N

2010-03-01

71

Non-invasive cardiac output assessment during moderate exercise: pulse contour compared with CO2 rebreathing.  

PubMed

The arterial pulse contour method called Modelflow 2.1 calculates stroke volume continuously, beat to beat, from the non-invasive blood pressure signal measured by Finapres or Portapres. Portapres is the portable version of Finapres. The purpose of this study was to compare cardiac output (CO) calculated using Modelflow 2.1 (COmf) with CO obtained by the CO2 rebreathing method (COre) during steady state at moderate exercise levels. Twelve subjects visited the laboratory twice and performed submaximal exercise on a bicycle ergometer at 20%, 40% and 60% of their individual peak power output (POpeak). The averaged correlation between COmf and COre gives an r-value of 0.69, whereas the slope and intercept of the regression line were 1.06 and 1.65 respectively. The averaged difference between COmf and COre was 2.27 +/- 3.91 min-1 (mean +/- standard deviation). However, the test-retest difference between COmf and COre was 2.5 +/- 3.1 and 0.5 +/- 1.31 min-1 respectively. These results suggest that Modelflow 2.1 is not an accurate method for estimating CO from non-invasive blood pressure data collected by Portapres during exercise at up to 60% of the individual POpeak corresponding with daily life activity. PMID:10361613

Houtman, S; Oeseburg, B; Hopman, M T

1999-05-01

72

Non-invasive beat-to-beat cardiac output monitoring by an improved method of transthoracic bioimpedance measurement  

Microsoft Academic Search

The report describes a method of impedance cardiography using an improved estimate of thoracic volume. The formulas and their implementation in hardware and software are explained and new shortband electrodes are described which generate a good homogeneous thoracic field. Examples of stroke volume and cardiac output curves underline the capabilities of the monitoring system “Task Force® Monitor”. In several experiments,

J. Fortin; W. Habenbacher; A. Heller; A. Hacker; R. Grüllenbergera; J. Innerhofer; H. Passath; Ch. Wagner; G. Haitchi; D. Flotzinger; R. Pacher; P. Wach

2006-01-01

73

Cardiac output and shunt during voluntary activity at different temperatures in the turtle, Trachemys scripta.  

PubMed

Red-eared slider turtles (Trachemys scripta) were chronically instrumented with blood flow probes for a long-term study of voluntary behavior in an enriched laboratory setting. Cardiovascular measures consisting of total cardiac output (Q(tot)), pulmonary blood flow (Q(pul)), systemic blood flow (Q(sys)), net cardiac shunt (Q(shunt)), heart rate (HR), and stroke volume (SV) were obtained during spontaneous activity at a constant body temperature (Tb=2 degrees C) and at unstable (variable) T(b)'s ranging from 19 degrees to 37 degrees C. The effects of temperature and activity differed between the pulmonary and systemic circuits, with increases in Q(sys) due to HR alone, while both HR and SV contributed to gains in Q(pul). At stable 20 degrees C, cardiovascular responses during diving, submerged swimming, and walking were qualitatively similar, and increases in Q(tot) during activity ( approximately 2 x resting levels) were due to greater gains in Q(pul) than Q(sys). At unstable T(b)'s and in general, net Q(shunt) while active depended on the integration of individual physiological influences such as heating, cooling, and initial behavioral state acting on the cardiovascular system. During activity, net left-to-right (L-R) shunts predominated at constant T(b) of 20 degrees C (mean shunt fraction approximately 30%-40%), while both net L-R and right-to-left (R-L) shunts of varying size were found at unstable T(b)'s (19 degrees - 37 degrees C). PMID:14671716

Krosniunas, Egle H; Hicks, James W

2003-01-01

74

Cardiac Output is Not a Significant Source of Low Frequency Mean Arterial Pressure Variability  

PubMed Central

Spontaneous mean arterial pressure (MAP) variability may be mainly due to fluctuations in cardiac output (CO) and total peripheral resistance (TPR). While high frequency (HF ~ 0.25 Hz) oscillations in MAP are ultimately driven by respiration, the source of low frequency (LF ~ 0.1 Hz) fluctuations has not been fully elucidated. It is known that CO buffers these oscillations, but there is no evidence on its potential role in also generating them. The main goal was to determine whether CO is a source of LF variability in MAP. Six dogs were chronically instrumented to obtain beat-to-beat measurements of CO and MAP while the dogs were fully awake and at rest. A causal dynamic model was identified to relate the fluctuations in CO to MAP. The model was then used to predict the MAP fluctuations from the CO fluctuations. The CO fluctuations were able to predict about 70% of the MAP oscillations in the HF band but showed no predictive value in the LF band. Hence, respiration induces CO fluctuations in the HF band that, in turn, cause MAP oscillations, while TPR fluctuations appear to be the dominant mediator of LF fluctuations of MAP. CO is not a significant source of these oscillations, and it may only be responsible for dampening them, likely through the baroreflex. PMID:23969898

Aletti, F; Hammond, RL; Sala-Mercado, JA; Chen, X; O'Leary, DS; Baselli, G; Mukkamala, R

2013-01-01

75

Cardiac output and contractility indices: establishing a standard in response to low-to-moderate level exercise in healthy men.  

PubMed

Measurement by impedance cardiography (ZCG) of cardiac output and contractility indices during exercise is a recent addition to exercise testing of the cardiac patient. To provide a needed standard of normal responses to exercise at integrals of resting oxygen consumption (METS), 10 healthy men were tested. Basal oxygen consumption (1MET) under standardized conditions was measured by mass spectrometry. Over several days the subjects were exercised on a treadmill at 2METS through 6METS with monitoring of heart rate, electrocardiogram, oxygen consumption per minute (VO2) and ZCG. The exercise routine was then repeated to look for test-retest effect. Values closely approximating presently accepted basal oxygen consumptions were achieved under these standardized but practical conditions. Cardiac output during sitting, fully supported rest was slightly higher than that at 2METS on treadmill owing to higher stroke volume. From 2METS through 6METS the curvilinear mean heart rate and stroke volume were mirror images, producing a linear increase in mean cardiac output which at 6METS was 145% of basal and 160% of the 2MET value, while the contractility index increased to 217% of basal. Comparison of the 2 trials revealed no significant test-retest effect. PMID:518263

Mancini, R; Kottke, F J; Patterson, R; Kubicek, W; Olson, M

1979-12-01

76

Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients  

Microsoft Academic Search

Purpose  Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However,\\u000a concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate\\u000a the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance\\u000a (TSVR) is low.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Fifty-eight septic patients were

Daniel De Backer; Gernot Marx; Andrew Tan; Christopher Junker; Marc Van Nuffelen; Lars Hüter; Willy Ching; Frédéric Michard; Jean-Louis Vincent

2011-01-01

77

Heterotrimeric G proteins regulate a non-canonical function of septate junction proteins to maintain cardiac integrity in Drosophila  

PubMed Central

Summary The gene networks regulating heart morphology and cardiac integrity are largely unknown. We previously reported a role for the heterotrimeric G protein ? subunit 1 (G?1) in mediating cardial-pericardial cell adhesion in Drosophila. Here we show G-o?47A and G?13F cooperate with G?1 to maintain cardiac integrity. Cardial-pericardial cell adhesion also relies on the septate junction (SJ) proteins Neurexin-IV (Nrx-IV), Sinuous, Coracle, and Nervana2, and which together function in a common pathway with G?1. Furthermore, G?1 signaling is required for proper SJ protein localization, and loss of at least one SJ protein, Nrx-IV, induces cardiac lumen collapse. These results are surprising because the embryonic heart lacks SJs and suggest that SJ proteins perform non-canonical functions to maintain cardiac integrity in Drosophila. Our findings unveil the components of a previously unrecognized network of genes that couple G-protein signaling with novel structural constituents of the heart. PMID:19000835

Yi, Peng; Johnson, Aaron N.; Han, Zhe; Wu, Jiang; Olson, Eric N.

2009-01-01

78

Increased cardiac output contributes to the development of chronic intermittent hypoxia-induced hypertension.  

PubMed

Chronic intermittent hypoxia (CIH) in animal models has been shown to result in hypertension and elevation of sympathetic nervous system activity. Sympathetically mediated vasoconstriction is believed to be the primary mechanism underpinning CIH-induced hypertension; however, the potential contribution of the heart is largely overlooked. We sought to determine the contribution of cardiac output (CO) and lumbar sympathetic control of the hindlimb circulation to CIH-induced hypertension. Male Wistar rats (n = 64) were exposed to 2 weeks of CIH [cycles of 90 s hypoxia (5% O2 nadir) and 210 s normoxia] or normoxia for 8 h day(-1). Under urethane anaesthesia, CIH-treated animals developed hypertension (81.4 ± 2.2 versus 91.6 ± 2.4 mmHg; P < 0.001), tachycardia (397 ± 8 versus 445 ± 7 beats min(-1); P < 0.001) and an increased haematocrit (42.4 ± 0.4 versus 45.0 ± 0.4%; P < 0.001). Echocardiography revealed that CIH exposure increased the CO [19.3 ± 1.7 versus 25.8 ± 2.6 ml min(-1) (100 g)(-1); P = 0.027] with no change in total peripheral resistance (4.93 ± 0.49 versus 4.17 ± 0.34 mmHg ml(-1) min(-1); P = 0.123). Sympathetic ganglionic blockade revealed that sympathetic control over blood pressure was not different (-27.7 ± 1.6 versus -32.3 ± 2.9 mmHg; P = 0.095), and no chronic vasoconstriction was found in the hindlimb circulation of CIH-treated animals (39.4 ± 2.5 versus 38.0 ± 2.4 ?l min(-1) mmHg(-1); P = 0.336). Lumbar sympathetic control over the hindlimb circulation was unchanged in CIH-treated animals (P = 0.761), although hindlimb arterial sympathetic density was increased (P = 0.012) and vascular sensitivity to phenylephrine was blunted (P = 0.049). We conclude that increased CO is sufficient to explain the development of CIH-induced hypertension, which may be an early adaptive response to raise O2 flow. We propose that sustained elevated cardiac work may ultimately lead to heart failure. PMID:25063839

Lucking, Eric F; O'Halloran, Ken D; Jones, James F X

2014-10-01

79

Monitoring non-invasive cardiac output and stroke volume during experimental human hypovolaemia and resuscitation  

PubMed Central

Background Multiple methods for non-invasive measurement of cardiac output (CO) and stroke volume (SV) exist. Their comparative capabilities are not clearly established. Methods Healthy human subjects (n=21) underwent central hypovolaemia through progressive lower body negative pressure (LBNP) until the onset of presyncope, followed by termination of LBNP, to simulate complete resuscitation. Measurement methods were electrical bioimpedance (EBI) of the thorax and three measurements of CO and SV derived from the arterial blood pressure (ABP) waveform: the Modelflow (MF) method, the long-time interval (LTI) method, and pulse pressure (PP). We computed areas under receiver-operating characteristic curves (ROC AUCs) for the investigational metrics, to determine how well they discriminated between every combination of LBNP levels. Results LTI and EBI yielded similar reductions in SV during progressive hypovolaemia and resuscitation (correlation coefficient 0.83) with ROC AUCs for distinguishing major LBNP (?60 mm Hg) vs resuscitation (0 mm Hg) of 0.98 and 0.99, respectively. MF yielded very similar reductions and ROC AUCs during progressive hypovolaemia, but after resuscitation, MF-CO did not return to baseline, yielding lower ROC AUCs (?ROC AUC range, ?0.18 to ?0.26, P<0.01). PP declined during hypovolaemia but tended to be an inferior indicator of specific LBNP levels, and PP did not recover during resuscitation, yielding lower ROC curves (P<0.01). Conclusions LTI, EBI, and MF were able to track progressive hypovolaemia. PP decreased during hypovolaemia but its magnitude of reduction underestimated reductions in SV. PP and MF were inferior for the identification of resuscitation. PMID:21051492

Reisner, A. T.; Xu, D.; Ryan, K. L.; Convertino, V. A.; Rickards, C. A.; Mukkamala, R.

2011-01-01

80

Carotid baroreflex pressor responses at rest and during exercise: cardiac output vs. regional vasoconstriction.  

PubMed

The arterial baroreflex mediates changes in arterial pressure via reflex changes in cardiac output (CO) and regional vascular conductance, and the relative roles may change between rest and exercise and across workloads. Therefore, we quantified the contribution of CO and regional vascular conductances to carotid baroreflex-mediated increases in mean arterial pressure (MAP) at rest and during mild to heavy treadmill exercise (3.2 kph; 6.4 kph, 10% grade; and 8 kph, 15% grade). Dogs (n = 8) were chronically instrumented to measure changes in MAP, CO, hindlimb vascular conductance, and renal vascular conductance in response to bilateral carotid occlusion (BCO). At rest and at each workload, BCO caused similar increases in MAP (average 35 +/- 2 mmHg). In response to BCO, neither at rest nor at any workload were there significant increases in CO; therefore, the pressor response occurred via peripheral vasoconstriction. At rest, 10.7 +/- 1.4% of the rise in MAP was due to vasoconstriction in the hindlimb, whereas 4.0 +/- 0.7% was due to renal vasoconstriction. Linear regression analysis revealed that, with increasing workloads, relative contributions of the hindlimb increased and those of the kidney decreased. At the highest workload, the decrease in hindlimb vascular conductance contributed 24.3 +/- 3.4% to the pressor response, whereas the renal contribution decreased to only 1.6 +/- 0.3%. We conclude that the pressor response during BCO was mediated solely by peripheral vasoconstriction. As workload increases, a progressively larger fraction of the pressor response is mediated via vasoconstriction in active skeletal muscle and the contribution of vasoconstriction in inactive beds (e.g., renal) becomes progressively smaller. PMID:11158962

Collins, H L; Augustyniak, R A; Ansorge, E J; O'Leary, D S

2001-02-01

81

Does left ventricular tissue Doppler peak systolic velocity (Sm) reflect cardiac output in the critically ill?  

PubMed

Cardiac output (CO) is dependent on a number of factors, in particular, the systolic function of the heart. Tissue Doppler (TD) is a modality in echocardiography that measures myocardial velocity and is related to contractility. TD can therefore be used to measure the systolic function of the heart. This study sought to establish whether the systolic component of TD can be used to estimate CO in critically ill patients. Retrospective data was obtained from a total of 80 patients: 29 patients with a normal echocardiogram, and 51 intensive care unit patients; 28 septic and 23 with heart failure. The mean TD peak systolic velocity (Sm) was significantly lower in the heart failure patients (P <0.05) compared to both normal and septic group. The mean CO was significantly higher in septic patients when compared to heart failure patients. A mild to moderate positive correlation was found between Sm and CO in the heart failure group and with all patients combined (r2=0.19, P <0.001). Subsequent analysis of Sm versus stroke volume again showed a mild positive correlation in the heart failure group and combined results (r2=0.18, P <0.001). Sm was weakly correlated to heart rate only in the normal group but not in the combined cohort. Our data confirms a weak to moderate correlation between Sm and CO, probably resulting from a positive correlation of Sm and stroke volume. This correlation is not strong enough to support the use of an individual's Sm to estimate CO in intensive care patients. PMID:23808508

Golowenko, A R; Nalos, M; Huang, S J

2013-07-01

82

Subject-specific Model Estimation of Cardiac Output and Blood Volume During Hemorrhage  

PubMed Central

We have developed a novel method for estimating subject-specific hemodynamics during hemorrhage. First, a mathematical model representing a closed-loop circulation and baroreceptor feedback system was parameterized to match the baseline physiology of individual experimental subjects by fitting model results to 1 min of pre-injury data. This automated parameterization process matched pre-injury measurements within 1.4 ± 1.3% SD. Tuned parameters were then used in similar open-loop models to simulate dynamics post-injury. Cardiac output (CO) estimates were obtained continuously using post-injury measurements of arterial blood pressure (ABP) and heart rate (HR) as inputs to the first open-loop model. Secondarily, total blood volume (TBV) estimates were obtained by summing the blood volumes in all the circulatory segments of a second open-loop model that used measured CO as an additional input. We validated the estimation method by comparing model CO results to flowprobe measurements in 14 pigs. Overall, CO estimates had a Bland-Altman bias of ?0.30 l/min with upper and lower limits of agreement 0.80 and ?1.40 l/min. The negative bias is likely due to overestimation of the peripheral resistance response to hemorrhage. There was no reference measurement of TBV; however, the estimates appeared reasonable and clearly predicted survival versus death during the post-hemorrhage period. Both open-loop models ran in real time on a computer with a 2.4 GHz processor, and their clinical applicability in emergency care scenarios is discussed. PMID:17846886

Neal, Maxwell Lewis; Bassingthwaighte, James B.

2010-01-01

83

A comparative evaluation of electrical velocimetry and inert gas rebreathing for the non-invasive assessment of cardiac output  

Microsoft Academic Search

Background  When assessing the function of the cardiovascular system, cardiac output (CO) is a substantial parameter. For its determination,\\u000a numerous non-invasive techniques have been proposed in the recent years including inert gas rebreathing (IGR) and impedance\\u000a cardiography (ICG). The aim of our study was to evaluate whether a novel ICG algorithm (electrical velocimetry) and IGR can\\u000a be used interchangeably in the

Frederik Trinkmann; Manuel Berger; Ursula Hoffmann; Martin Borggrefe; Jens J. Kaden; Joachim Saur

84

RETRACTED ARTICLE: Noninvasive assessment of cardiac output using thoracic electrical bioimpedance in hemodynamically stable and unstable patients after cardiac surgery: a comparison with pulmonary artery thermodilution  

Microsoft Academic Search

Objective  To compare noninvasive cardiac output (CO)measurement obtained with a new thoracic electrical bioimpedance (TEB) device, using\\u000a a proprietary modification of the impedance equation, with invasive measurement obtained via pulmonary artery thermodilution.\\u000a \\u000a \\u000a \\u000a \\u000a Design  Prospective, observational study.\\u000a \\u000a \\u000a \\u000a Setting  Surgical intensive care unit (ICU) of a university-affiliated community hospital.\\u000a \\u000a \\u000a \\u000a Patients and participants  Seventy-four adult patients undergoing elective cardiac surgery with routine pulmonary artery catheter placement.\\u000a \\u000a \\u000a \\u000a Interventions  None.\\u000a \\u000a \\u000a \\u000a Measurements and results  Simultaneous

Stefan Suttner; Thilo Schöllhorn; Joachim Boldt; Jochen Mayer; Kerstin D. Röhm; Katrin Lang; Swen N. Piper

2006-01-01

85

Effect of analyzer on determination of mixed venous PCO2 and cardiac output during exercise.  

PubMed

Cardiac output (CO) during exercise can be determined noninvasively by using the indirect Fick CO2-rebreathing technique. CO2 measurements for this technique are usually performed with an infrared analyzer (IA) or mass spectrometer (MS). However, IA CO2 measurements are susceptible to underreading in the face of high O2 concentrations because of collision broadening. We compared an IA (Ametek model CD-3A) with a MS (Marquette model MGA-1100) to see the effect this would have on mixed venous PCO2 (PVCO2) and CO measurements. After calibration with room air and a gas mixture of 5% CO2-12% O2-83% N2, both devices were tested with three different gas mixtures of CO2 in O2. For each gas mixture, IA gave lower CO2 values than did the MS (4.1% CO2: IA, 3.85 +/- 0.01% and MS, 4.13 +/- 0.01%; 9.2% CO2: IA, 8.44 +/- 0.07% and MS, 9.19 +/- 0.01%; 13.8% CO2: IA, 12.57 +/- 0.15% and MS, 13.82 +/- 0.01%). Warming and humidifying the gases did not alter the results. The IA gave lower values than did the MS for eight other medical gases in lower concentrations of O2 (40-50%). Equilibrium and exponential rebreathing procedures were performed. Values determined by the IA were > 10% higher than those determined by the MS for both rebreathing methods. We conclude that all IAs must be checked for collision broadening if they are to be used in environments where the concentration of O2 is > 21%. If collision broadening is present, then either a special high O2-CO2 calibration curve must be constructed, or the IA should not be used for both arterial PCO2 and PVCO2 estimates because it may produce erroneously low PVCO2 values, with resultant overestimation of CO. PMID:8567499

Hornby, L; Coates, A L; Lands, L C

1995-09-01

86

Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise  

NASA Technical Reports Server (NTRS)

Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p< 0.05. RESULTS: Artery diameter did not change from baseline. BF increased (p<0.05) after exercise in each condition except LBFR(sub SBP) in the order of HL (12.73+/-1.42 cm3,mean+/-SE) > LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of that observed in LL, which supports the hypothesis that local ischemia stimulates the LBFR hypertrophic response. As the cuff did not compress the artery, the ischemia may have occurred because of the blunted rise in CO or because arterial BP cannot overcome the cuff pressure. As LBFR(sub DBP) effectively reduced BF and CO with cuff pressures less than systolic BP, future studies should investigate the hypertrophic potential of LBFR at even lower cuff pressures.

Everett, M. E.; Hackney, K.; Ploutz-Snyder, L.

2011-01-01

87

The comparison of a novel continuous cardiac output monitor based on pulse wave transit time and echo Doppler during exercise.  

PubMed

A new technology called estimated continuous cardiac output (esCCO) uses pulse wave transit time (PWTT) obtained from an electrocardiogram and pulse oximeter to measure cardiac output (CO) non-invasively and continuously. This study was performed to evaluate the accuracy of esCCO during exercise testing. We compared esCCO with CO measured by the echo Doppler aortic velocity-time integral (VTIao_CO). The correlation coefficient between esCCO and VTIao_CO was r= 0.87 (n= 72). Bias and precision were 0.33 ± 0.95 L/min and percentage error was 31%. The esCCO could detect change in VTIao_CO larger than 1 L/min with a concordance rate of 88%. In polar plot, 83% of data are within 0.5 L/min, and 100% of data are within 1 L/min. Those results show the acceptable accuracy and trend ability of esCCO. Change in pre-ejection period (PEP) measured by using M-mode of Diagnostic Ultrasound System accounted for approximately half of change in PWTT. This indicates that PEP included in PWTT has an impact on the accuracy of esCCO measurement. In this study, the validity of esCCO during exercise testing was assessed and shown to be acceptable. The result of this study suggests that we can expand its application. PMID:23365874

Sugo, Yoshihiro; Sakai, Tomoyuki; Terao, Mami; Ukawa, Teiji; Ochiai, Ryoichi

2012-01-01

88

Effects of Dobutamine on Left Ventricular Performance, Coronary Dynamics, and Distribution of Cardiac Output in Conscious Dogs  

PubMed Central

The effects of dobutamine ([±]-4-[2-[[3-(p-hydroxyphenyl)-1-methyl propyl] amino] ethyl] pyrocatechol hydrochloride), a new synthetic cardioactive sympathomimetic amine, were examined on direct and continuous measurements of left ventricular (LV) diameter (D), pressures (P), velocity of shortening (V), dP/dt, dP/dt/P, arterial pressure, cardiac output, and regional blood flows in the left circumflex coronary, mesenteric, renal, and iliac beds in healthy, conscious dogs. At the highest dose of dobutamine examined, 40 ?g/kg/min, the drug increased dP/dt/P from 65±3 to 128±4 s-1 and isolength velocity from 72±4 to 120±7 mm/s without affecting LV end diastolic D significantly. Mean arterial P rose from 92±2 to 104±3 mm Hg and heart rate from 78±3 to 111±7 beats/min, while LV end systolic D fell from 24.1±1.4 to 19.9±1.8 mm, reflecting a rise in stroke volume from 30±4 to 42±3 ml. Cardiac output rose from 2.41±0.23 to 4.35±0.28 liter/min, while calculated total peripheral resistance declined from 0.042±0.005 to 0.028±0.003 mm Hg/ml/min. The greatest increases in flow and decreases in calculated resistance occurred in the iliac and coronary beds, and the least occurred in the renal bed. Propranolol blocked the inotropic and beta2 dilator responses while vasoconstricting effects mediated by alpha adrenergic stimulation remained in each of the beds studied. When dobutamine was infused after a combination of practolol and phentolamine, dilatation occurred in each of the beds studied. These observations indicate that dobutamine is a potent positive inotropic agent with relatively slight effects on preload, afterload, or heart rate, and thus may be a potentially useful clinical agent. The one property of this drug which is not ideal is its tendency to cause a redistribution of cardiac output favoring the muscular beds at the expense of the kidney and visceral beds. Images PMID:4825224

Vatner, Stephen F.; McRitchie, Robert J.; Braunwald, Eugene

1974-01-01

89

Efficacy and safety of milrinone in preventing low cardiac output syndrome in infants and children after corrective surgery for congenital heart disease  

Microsoft Academic Search

Background—Low cardiac output syndrome (LCOS), affecting up to 25% of neonates and young children after cardiac surgery, contributes to postoperative morbidity and mortality. This study evaluated the efficacy and safety of prophylactic milrinone in pediatric patients at high risk for developing LCOS. Methods and Results—The study was a double-blind, placebo-controlled trial with 3 parallel groups (low dose, 25-g\\/kg bolus over

Timothy M. Hoffman; Gil Wernovsky; Andrew M. Atz

2003-01-01

90

Analysis of interobserver and intraobserver variation of interpretation of the echocardiographic and Doppler flow determination of cardiac output by the mitral orifice method.  

PubMed Central

The variability of the interpretation by two individuals of a combined echocardiographic and Doppler method of calculating output was studied in 30 normal adults. In each subject three separate cardiac cycles were recorded to calculate maximal mitral valve orifice, the ratio of mean to maximal mitral valve leaflet separation, and the mean flow velocity through the mitral valve. The recordings were digitised twice by two independent observers. Estimates of cardiac output ranged from 3.2 to 8.11 1/min. Analysis of variance showed that interobserver and intraobserver variability for these measurements was 5.8% and 6.1% respectively. It is concluded that the reproducibility for interpreting this non-invasive method is adequate for clinical use in adults with cardiac outputs within the normal range. PMID:3707784

Nicolosi, G L; Pungercic, E; Cervesato, E; Modena, L; Zanuttini, D

1986-01-01

91

Training is required to improve the reliability of esophageal doppler to measure cardiac output in critically ill patients  

Microsoft Academic Search

Objectives: Assessment of and effect of training on reliability of esophageal Doppler (ED) versus thermodilution (TD) for cardiac output\\u000a (CO) measurement.\\u000a \\u000a \\u000a Design: Prospective study.\\u000a \\u000a \\u000a \\u000a \\u000a Setting: Intensive care unit of a university hospital.\\u000a \\u000a \\u000a \\u000a \\u000a Patients: 64 consecutive critically ill patients requiring a pulmonary artery catheter, sedation, and mechanical ventilation.\\u000a \\u000a \\u000a \\u000a \\u000a Interventions: Esophageal Doppler CO measurements were performed by the same operator, whereas TD

J. Y. Lefrant; P. Bruelle; A. G. M. Aya; G. Saïssi; M. Dauzat; J. E. de La Coussaye; J. J. Eledjam

1998-01-01

92

[Influence of cerebral perfusion pressure and cardiac output on brain oxygenation and metabolism].  

PubMed

The article contains results of examination of correlation between systemic hemodynamic and brain oxygenation and metabolism in patients with intracranial hemorrhage. Cardiac index (CI) and cerebral perfusion pressure (CPP) levels were compared to brain oxygenation and metabolism in 8 patients with intracranial hemorrhage (137 measurements). CI alterations didn't influence on PbrO2, glucose level or lactate/pyruvate ratio in the brain interstitial fluid in patients with traumatic brain injury. CPP elevation led to cerebral metabolism improvement. Optimal metabolic state was mentioned in CPP > 80 mm Hg. CPP elevation led to PbrO2 increasing in patients with subarachnoid hemorrhage due to aneurism rupture. This phenomenon can be explained by damage mechanisms of cerebral blood flow autoregulation. In these cases CI elevation was accompanied by worsening of aerobic metabolism in theoretically intact regions and improving it in injured brain regions. PMID:24341044

Titova, Iu V; Petrikov, S S; Solodov, A A; Krylov, V V

2013-01-01

93

Three-dimensional perfusion cultivation of human cardiac-derived progenitors facilitates their expansion while maintaining progenitor state.  

PubMed

The therapeutic application of autologous cardiac-derived progenitor cells (CPCs) requires a large cell quantity generated under defined conditions. Herein, we investigated the applicability of a three-dimensional (3D) perfusion cultivation system to facilitate the expansion of CPCs harvested from human heart biopsies and characterized by a relatively high percentage of c-kit(+) cells. The cells were seeded in macroporous alginate scaffolds and after cultivation for 7 days under static conditions, some of the constructs were transferred into a perfusion bioreactor, which was operated for an additional 14 days. A robust and highly reproducible human CPC (hCPC) expansion of more than seven-fold was achieved under the 3D perfusion culture conditions, while under static conditions, the expansion of CPCs was limited only to the first 7 days, after which it leveled-off. On day 21 of perfusion cultivation, the expanded cells exhibited a higher expression level of the progenitor marker c-kit, suggesting that the c-kit-positive CPCs are the main cell population undergoing proliferation. The profile of the spontaneous differentiation in the perfused construct was different from that in the static cultivated constructs; genes typical for cardiac and endothelial cell lineages were more widely expressed in the perfused constructs. By contrast, the differentiation to osteogenic (Von Kossa staining and alkaline phosphatase activity) and adipogenic (Oil Red staining) lineages was reduced in the perfused constructs compared with static cultivated constructs. Collectively, our results indicate that 3D perfusion cultivation mode is an appropriate system for robust expansion of human CPCs while maintaining their progenitor state and differentiation potential into the cardiovascular cell lineages. PMID:24568665

Kryukov, Olga; Ruvinov, Emil; Cohen, Smadar

2014-11-01

94

Effect of cardiac output on gas exchange in one-lung atelectasis.  

PubMed

To evaluate the effect of administration of dobutamine on gas exchange in patients with one-lung atelectasis during pneumonectomy, ten patients with normal pulmonary function and localized carcinoma of the lung were studied during pulmonary resection. With each patient in the lateral decubitus position, hemodynamic profiles and oxygen transport data were recorded before and after administration of dobutamine at 5 micrograms/kg/min. Patients were ventilated with one-lung anesthesia and administration of 100 percent oxygen. With infusion of dobutamine, the heart rate, cardiac index, and LVSWI significantly increased. Mean arterial pressure increased while PAP fell. Systemic and pulmonary vascular resistance also declined. Arterial oxygenization and delivery improved, while oxygen uptake was unchanged. Pulmonary shunt fraction was significantly reduced. While the mechanism for shunt reduction in our patients is unclear, operative factors may include pulmonary vasodilation with dobutamine inhibition of HPV. The negative impact of reduced HPV may have been lessened by gravitational distribution of blood flow and dobutamine-mediated reduction in PAP in our patients. PMID:2331907

Mathru, M; Dries, D J; Kanuri, D; Blakeman, B; Rao, T

1990-05-01

95

Roles for Cardiac MyBP-C in Maintaining Myofilament Lattice Rigidity and Prolonging Myosin Cross-Bridge Lifetime  

SciTech Connect

We investigated the influence of cardiac myosin binding protein-C (cMyBP-C) and its constitutively unphosphorylated status on the radial and longitudinal stiffnesses of the myofilament lattice in chemically skinned myocardial strips of the following mouse models: nontransgenic (NTG), effective null for cMyBP-C (t/t), wild-type cMyBP-C expressed into t/t (WT{sub t/t}), and constitutively unphosphorylated cMyBP-C (AllP{sub -t/t}). We found that the absence of cMyBP-C in the t/t and the unphosphorylated cMyBP-C in the AllP{sub -t/t} resulted in a compressible cardiac myofilament lattice induced by rigor not observed in the NTG and WT{sub t/t}. These results suggest that the presence and phosphorylation of the N-terminus of cMyBP-C provides structural support and radial rigidity to the myofilament lattice. Examination of myofilament longitudinal stiffness under rigor conditions demonstrated a significant reduction in cross-bridge-dependent stiffness in the t/t compared with NTG controls, but not in the AllP{sub -t/t} compared with WT{sub t/t} controls. The absence of cMyBP-C in the t/t and the unphosphorylated cMyBP-C in the AllP{sub -t/t} both resulted in a shorter myosin cross-bridge lifetime when myosin isoform was controlled. These data collectively suggest that cMyBP-C provides radial rigidity to the myofilament lattice through the N-terminus, and that disruption of the phosphorylation of cMyBP-C is sufficient to abolish this structural role of the N-terminus and shorten cross-bridge lifetime. Although the presence of cMyBP-C also provides longitudinal rigidity, phosphorylation of the N-terminus is not necessary to maintain longitudinal rigidity of the lattice, in contrast to radial rigidity.

Palmer, B.M.; Sadayappan, S.; Wang, Y.; Weith, A.E.; Previs, M.J.; Bekyarova, T.; Irving, T.C.; Robbins, J.; Maughan, D.W. (Vermont)

2011-10-06

96

The "systolic volume balance" method for the noninvasive estimation of cardiac output based on pressure wave analysis.  

PubMed

Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several mathematical methods have been proposed for CO estimation based on pressure waveform analysis. Most of them depend on invasive recording of blood pressure and require repeated calibrations, and they suffer from decreased accuracy under specific conditions. A new systolic volume balance (SVB) method, including a simpler empirical form (eSVB), was derived from basic physical principles that govern blood flow and, in particular, a volume balance approach for the conservation of mass ejected into and flowed out of the arterial system during systole. The formulas were validated by a one-dimensional model of the systemic arterial tree. Comparisons of CO estimates between the proposed and previous methods were performed in terms of agreement and accuracy using "real" CO values of the model as a reference. Five hundred and seven different hemodynamic cases were simulated by altering cardiac period, arterial compliance, and resistance. CO could be accurately estimated by the SVB method as follows: CO = C × PP(ao)/(T - P(sm) × T(s)/P(m)) and by the eSVB method as follows: CO = k × C × PP(ao)/T, where C is arterial compliance, PP(ao) is aortic pulse pressure, T is cardiac period, P(sm) is mean systolic pressure, T(s) is systolic duration, P(m) is mean pressure, and k is an empirical coefficient. SVB applied on aortic pressure waves did not require calibration or empirical correction for CO estimation. An empirical coefficient was necessary for brachial pressure wave analysis. The difference of SVB-derived CO from model CO (for brachial waves) was 0.042 ± 0.341 l/min, and the limits of agreement were -0.7 to 0.6 l/min, indicating high accuracy. The intraclass correlation coefficient and root mean square error between estimated and "real" CO were 0.861 and 0.041 l/min, respectively, indicating very good accuracy. eSVB also provided accurate estimation of CO. An in vivo validation study of the proposed methods remains to be conducted. PMID:22427512

Papaioannou, Theodore G; Vardoulis, Orestis; Stergiopulos, Nikos

2012-05-15

97

Non-Invasive Cardiac Output Measurement in Low and Very Low Birth Weight Infants: A Method Comparison  

PubMed Central

Background: Cardiac output (CO) measurement in low (LBW) and very low (VLBW) birth weight infants is difficult. Hitherto, sporadical transthoracic echocardiography (TTE) is the only non-invasive measurement method. Electrical velocimetry (EV) has been evaluated as an alternative in normal weight newborns. Objectives: The study was designed to evaluate if EV could be interchangeable with TTE even in LBW and VLBW infants. Methods: In 28 (17 LBW, 11 VLBW) pre-mature newborns, n?=?228 simultaneous TTE (trans-aortic Doppler), and EV measurements (134 LBW, 94 VLBW) of stroke volume (SV) and heart rate (HR) were performed, thereof calculating body weight indexed SV (=SV*) and CO (=CO*) for all patients and the subgroups. Method comparison was performed by Bland–Altman plot, method precision expressed by calculation of the coefficient of variation (CV). Results: Mean CO* in all patients was 256.4?±?44.8 (TTE) and 265.3?±?48.8 (EV) ml/kg/min. Bias and precision were clinically acceptable, limits of agreement within the 30% criterion for method interchangeability (17). According to their different anatomic dimensions and pathophysiology, there were significant differences of SV(*), HR, and CO* for LBW and VLBW infants as well for inotropic treatment and ventilation mode. Conclusion: Extending recent publications on EV/TTE comparison in newborns, this study suggests that EV is also applicable in LWB/VLBW infants as a safe and easy to handle method for continuous CO monitoring in the NICU and PCICU. PMID:24724074

Grollmuss, Oswin; Gonzalez, Patricia

2014-01-01

98

Arterial pressure, cardiac output and systemic resistance before and after pithing in normotensive and spontaneously hypertensive rats.  

PubMed

After complete cardiovascular denervation mean arterial pressure (MAP) falls to almost equally low levels in spontaneously hypertensive rats (SHR) and normotensive control rats (NCR). This has earlier been suggested to indicate a dominance of neurogenic mechanisms in established SHR hypertension. -- In the present study, total peripheral resistance (TPR) remains, however, some 35 per cent higher in adult SHR than in NCR after pithing while cardiac output (CO), and stroke volume, is 35 per cent lower in SHR. These opposite differences in TPR and CO after denervation, resulting in equal MAP levels in SHR and NCR, seem rather to be a consequence of the rapidly established structural adaptation that affects all SHR high-pressure cardiovascular sections. Thus, the SHR precapillary resistance vessels display thickened walls and luminal narrowing, which keeps TPR higher than in NCR even during maximal vasodilatation. Due to hypertrophy, the SHR left ventricle exhibits a reduced myocardial stretch for a given filling pressure and stroke volume is consequently reduced more than in NCR after complete denervation. -- Paradoxically, therefore, rather than reflecting any dominance of neurogenic mechanisms in established SHR hypertension the MAP equalization in SHR and NCR after cardiovascular denervation emphasizes the hemodynamic importance of cardiovascular structural changes present in hypertension. PMID:1101646

Albrecht, I; Hallbäck, M; Julius, S; Lundgren, Y; Stage, L; Weiss, L; Folkow, B

1975-07-01

99

Cardiac output measured by acetylene rebreathing technique at rest and during exercise. Comparison of results obtained by various calculation procedures.  

PubMed

Cardiac output (Qc) was measured by a rebreathing technique, using acetylene and a mass-spectrometer for analyzing. In addition the rate of pulmonary uptake of O2 (VO2) during the rebreathing period and during a preceding steady-state period were determined. Measurements were made on 8 adult humans at rest and at different levels of exercise up to maximum at two occasions. The ratio (VO2 during steady-state/VO2 during rebreathing) was found to be significantly below 1 when the steady-state VO2 was below about 21 . min-1 and to be about 0.55 for subjects at rest. This indicates that VO2, and hence Qc, is increased by the rebreathing procedure when this involves deeper and more frequent respirations than those of the preceding period. Accordingly, when VO2 was below about 21 . min-1, the Qc value, calculated exclusively from acetylene concentrations recorded during rebreathing, was multiplied by the above-mentioned VO2-ratio. It is shown that this correcting procedure gives more reasonable values than those obtained by acetylene data alone. It is pointed out in what respects this correcting procedure of calculation deviates from that originally used by Grollman, and it is shown that there are only moderate differences between the results obtained by the two procedures. PMID:7195567

Kanstrup, I L; Hallbäck, I

1981-05-01

100

Quantification of Cardiac Sac Network Effects on a Movement-Related Parameter of Pyloric Network Output in the Lobster  

E-print Network

Quantification of Cardiac Sac Network Effects on a Movement- Related Parameter of Pyloric Network 29 September 2002 Thuma, Jeff B. and Scott L. Hooper. Quantification of cardiac sac network effects.1152/jn.00631.2002. Cardiac sac network activity (cycle period tens of seconds to minutes) has long been

Hooper, Scott

101

Comparing the accuracy of ES-BC, EIS-GS, and ES Oxi on body composition, autonomic nervous system activity, and cardiac output to standardized assessments  

PubMed Central

Background and purpose The Electro Sensor Complex (ESC) is software that combines three devices using bioelectrical impedance, galvanic skin response, and spectrophotometry: (1) ES-BC (Electro Sensor-Body Composition; LD Technology, Miami, FL) to assess body composition, (2) EIS-GS (Electro Interstitial Scan-Galvanic Skin; LD Technology) to predict autonomic nervous system activity, and (3) ES Oxi (Electro Sensor Oxi; LD Technology) to assess cardiac output. The objective of this study was to compare each to a standardized assessment: ES-BC to dual-energy X-ray absorptiometry (DXA), EIS-GS to heart rate variability, and ES Oxi to BioZ Dx Diagnostic System (BioZ Dx; SonoSite Inc, Bothell, WA). Patients and methods The study was conducted in two waves. Fifty subjects were assessed for body composition and autonomic nervous system activity. Fifty-one subjects were assessed for cardiac output. Results We found adequate relative and absolute agreement between ES-BC and DXA for fat mass (r = 0.97, P < 0.001) with ES-BC overestimating fat mass by 0.1 kg and for body fat percentage (r = 0.92, P < 0.001) with overestimation of fat percentage by 0.4%. For autonomic nervous system activity, we found marginal relative agreement between EIS-GS and heart rate variability by using EIS-GS as the predictor in a linear regression equation (adjusted R2 = 0.56, P = 0.03). For cardiac output, adequate relative and absolute agreement was found between ES Oxi and BioZ Dx at baseline (r = 0.60, P < 0.001), after the first exercise stage (r = 0.79, P < 0.001), and after the second exercise stage (r = 0.86, P < 0.001). Absolute agreement was found at baseline and after both bouts of exercise; ES Oxi overestimated baseline and stage 1 exercise cardiac output by 0.3 L/minute and 0.1 L/minute, respectively, but exactly estimated stage 2 exercise cardiac output. Conclusion ES-BC and ES Oxi accurately assessed body composition and cardiac output compared to standardized instruments, whereas EIS-GS showed marginal predictive ability for autonomic nervous system activity. The ESC software managing the three devices would be useful to help detect complications related to metabolic syndrome, diabetes, and cardiovascular disease and to noninvasively and rapidly manage treatment follow-up. PMID:22915943

Lewis, John E; Tannenbaum, Stacey L; Gao, Jinrun; Melillo, Angelica B; Long, Evan G; Alonso, Yaima; Konefal, Janet; Woolger, Judi M; Leonard, Susanna; Singh, Prabjot K; Chen, Lawrence; Tiozzo, Eduard

2011-01-01

102

Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients  

PubMed Central

Purpose Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low. Methods Fifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3–5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (COG2) and third-generation (COG3) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO). Results A total of 401 simultaneous measurements of iCO, COG2, COG3, and CCO were recorded. The mean (95%CI) biases between COG2 and iCO, COG3 and iCO, and CCO and iCO were ?10 (?15 to ?5)% [?0.8 (?1.1 to ?0.4) L/min], 0 (?4 to 4)% [0 (?0.3 to 0.3) L/min], and 9 (6–13)% [0.7 (0.5–1.0) L/min], respectively. The percentage errors were 29 (20–37)% for COG2, 30 (24–37)% for COG3, and 28 (22–34)% for CCO. The difference between iCO and COG2 was significantly correlated with TSVR (r2 = 0.37, p < 0.0001). A very weak (r2 = 0.05) relationship was also observed for the difference between iCO and COG3. Conclusions In patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software. Electronic supplementary material The online version of this article (doi:10.1007/s00134-010-2098-8) contains supplementary material, which is available to authorized users. PMID:21153399

Marx, Gernot; Tan, Andrew; Junker, Christopher; Van Nuffelen, Marc; Huter, Lars; Ching, Willy; Michard, Frederic; Vincent, Jean-Louis

2010-01-01

103

8-Oxoguanine DNA glycosylase 1 (ogg1) maintains the function of cardiac progenitor cells during heart formation in zebrafish  

SciTech Connect

Genomic damage may devastate the potential of progenitor cells and consequently impair early organogenesis. We found that ogg1, a key enzyme initiating the base-excision repair, was enriched in the embryonic heart in zebrafish. So far, little is known about DNA repair in cardiogenesis. Here, we addressed the critical role of ogg1 in cardiogenesis for the first time. ogg1 mainly expressed in the anterior lateral plate mesoderm (ALPM), the primary heart tube, and subsequently the embryonic myocardium by in situ hybridisation. Loss of ogg1 resulted in severe cardiac morphogenesis and functional abnormalities, including the short heart length, arrhythmia, decreased cardiomyocytes and nkx2.5{sup +} cardiac progenitor cells. Moreover, the increased apoptosis and repressed proliferation of progenitor cells caused by ogg1 deficiency might contribute to the heart phenotype. The microarray analysis showed that the expression of genes involved in embryonic heart tube morphogenesis and heart structure were significantly changed due to the lack of ogg1. Among those, foxh1 is an important partner of ogg1 in the cardiac development in response to DNA damage. Our work demonstrates the requirement of ogg1 in cardiac progenitors and heart development in zebrafish. These findings may be helpful for understanding the aetiology of congenital cardiac deficits. - Highlights: • A key DNA repair enzyme ogg1 is expressed in the embryonic heart in zebrafish. • We found that ogg1 is essential for normal cardiac morphogenesis in zebrafish. • The production of embryonic cardiomyocytes requires appropriate ogg1 expression. • Ogg1 critically regulated proliferation of cardiac progenitor cells in zebrafish. • foxh1 is a partner of ogg1 in the cardiac development in response to DNA damage.

Yan, Lifeng [State Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing 210029 (China); Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing 210029 (China); Zhou, Yong [Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai 200025 (China); Yu, Shanhe [Shanghai Institute of Hematology, RuiJin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025 (China); Ji, Guixiang [Nanjing Institute of Environmental Sciences/Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Ministry of Environmental Protection, Nanjing 210042 (China); Wang, Lei [Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai 200025 (China); Liu, Wei [State Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing 210029 (China); Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing 210029 (China); Gu, Aihua, E-mail: aihuagu@njmu.edu.cn [State Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing 210029 (China); Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing 210029 (China)

2013-11-15

104

PKPD modelling of the interrelationship between mean arterial BP, cardiac output and total peripheral resistance in conscious rats  

PubMed Central

Background and Purpose The homeostatic control of arterial BP is well understood with changes in BP resulting from changes in cardiac output (CO) and/or total peripheral resistance (TPR). A mechanism-based and quantitative analysis of drug effects on this interrelationship could provide a basis for the prediction of drug effects on BP. Hence, we aimed to develop a mechanism-based pharmacokinetic-pharmacodynamic (PKPD) model in rats that could be used to characterize the effects of cardiovascular drugs with different mechanisms of action (MoA) on the interrelationship between BP, CO and TPR. Experimental Approach The cardiovascular effects of six drugs with diverse MoA, (amlodipine, fasudil, enalapril, propranolol, hydrochlorothiazide and prazosin) were characterized in spontaneously hypertensive rats. The rats were chronically instrumented with ascending aortic flow probes and/or aortic catheters/radiotransmitters for continuous recording of CO and/or BP. Data were analysed in conjunction with independent information on the time course of drug concentration using a mechanism-based PKPD modelling approach. Key Results By simultaneous analysis of the effects of six different compounds, the dynamics of the interrelationship between BP, CO and TPR were quantified. System-specific parameters could be distinguished from drug-specific parameters indicating that the model developed is drug-independent. Conclusions and Implications A system-specific model characterizing the interrelationship between BP, CO and TPR was obtained, which can be used to quantify and predict the cardiovascular effects of a drug and to elucidate the MoA for novel compounds. Ultimately, the proposed PKPD model could be used to predict the effects of a particular drug on BP in humans based on preclinical data. PMID:23849040

Snelder, N; Ploeger, B A; Luttringer, O; Rigel, D F; Webb, R L; Feldman, D; Fu, F; Beil, M; Jin, L; Stanski, D R; Danhof, M

2013-01-01

105

Tidal volume, cardiac output and functional residual capacity determine end-tidal CO2 transient during standing up in humans  

PubMed Central

In man assuming the upright position, end-tidal PCO2 (PETCO2) decreases. With the rising interest in cerebral autoregulation during posture change, which is known to be affected by PETCO2, we sought to determine the factors leading to hypocapnia during standing up from the supine position. To study the contribution of an increase in tidal volume (VT) and breathing frequency, a decrease in stroke volume (SV), a ventilation–perfusion (V/Q) gradient and an increase in functional residual capacity (FRC) to hypocapnia in the standing position, we developed a mathematical model of the lung to follow breath-to-breath variations in PETCO2. A gravity-induced apical-to-basal V/Q gradient in the lung was modelled using nine lung segments. We tested the model using an eight-subject data set with measurements of VT, pulmonary O2 uptake and breath-to-breath lumped SV. On average, the PETCO2 decreased from 40 mmHg to 36 mmHg after 150 s standing. Results show that the model is able to track breath-to-breath PETCO2 variations (r2= 0.74, P < 0.05). Model parameter sensitivity analysis demonstrates that the decrease in PETCO2 during standing is due primarily to increased VT, and transiently to decreased SV and increased FRC; a slight gravity-induced V/Q mismatch also contributes to the hypocapnia. The influence of cardiac output on hypocapnia in the standing position was verified in experiments on human subjects, where first breathing alone, and then breathing, FRC and V/Q were controlled. PMID:14608002

Gisolf, Janneke; Wilders, Ronald; Immink, Rogier V; van Lieshout, Johannes J; Karemaker, John M

2004-01-01

106

Derivation of cardiac output and alveolar ventilation rate based on energy expenditure measurements in healthy males and females.  

PubMed

Physiologically based pharmacokinetic modeling and occupational exposure assessment studies often use minute ventilation rates (VE), alveolar ventilation rates (VA) and cardiac outputs (Q) that are not reflective of the physiological variations encountered during the aggregate daytime activities of individuals from childhood to adulthood. These variations of VE, VA and Q values were determined for healthy normal-weight individuals aged 5-96?years by using two types of published individual data that were measured in the same subjects (n?=?902), namely indirect calorimetry measurements and the disappearance rates of oral doses of deuterium (²H) and heavy-oxygen (¹?O) in urine monitored by gas-isotope-ratio mass spectrometry. Arteriovenous oxygen content differences (0.051-0.082?ml of O? consumed ml?¹ of blood) and ratios of the physiological dead space to the tidal volume (0.232-0.419) were determined for oxygen consumption rates (0.157-0.806?l min?¹) required by minute energy expenditures ranging from 0.76 to 3.91?kcal min?¹. Generally higher values for the 2.5th up to the 99th percentile for VE (0.132-0.774?l kg?¹ min?¹, 4.42-21.69?l m?² min?¹), VA (0.093-0.553?l kg?¹ min?¹, 3.09-15.53?l m?² min?¹), Q (0.065-0.330?l kg?¹ min?¹, 2.17 to 9.46?l m?² min?¹) and ventilation-perfusion ratios (1.12-2.16) were found in children and teenagers aged 5-<16.5?years compared with older individuals. The distributions of cardiopulmonary parameters developed in this study should be useful in facilitating a scientifically sound characterization of the inter-individual differences in the uptake and health risks of lipophilic air pollutants, particularly as they relate to younger children. PMID:21365669

Brochu, Pierre; Brodeur, Jules; Krishnan, Kannan

2012-08-01

107

Cardiac output and cardiac index measured with cardiovascular magnetic resonance in healthy subjects, elite athletes and patients with congestive heart failure  

PubMed Central

Background Cardiovascular Magnetic Resonance (CMR) enables non-invasive quantification of cardiac output (CO) and thereby cardiac index (CI, CO indexed to body surface area). The aim of this study was to establish if CI decreases with age and compare the values to CI for athletes and for patients with congestive heart failure (CHF). Methods CI was measured in 144 healthy volunteers (39?±?16?years, range 21–81?years, 68 females), in 60 athletes (29?±?6?years, 30 females) and in 157 CHF patients with ejection fraction (EF) below 40% (60?±?13?years, 33 females). CI was calculated using aortic flow by velocity-encoded CMR and is presented as mean?±?SD. Flow was validated in vitro using a flow phantom and in 25 subjects with aorta and pulmonary flow measurements. Results There was a slight decrease of CI with age in healthy subjects (8?ml/min/m2 per year, r2?=?0.07, p?=?0.001). CI in males (3.2?±?0.5?l/min/m2) and females (3.1?±?0.4?l/min/m2) did not differ (p?=?0.64). The mean?±?SD of CI in healthy subjects in the age range of 20–29 was 3.3?±?0.4?l/min/m2, in 30–39?years 3.3?±?0.5?l/min/m2, in 40–49?years 3.1?±?0.5?l/min/m2, 50–59?years 3.0?±?0.4?l/min/m2 and >60?years 3.0?±?0.4?l/min/m2. There was no difference in CI between athletes and age-controlled healthy subjects but HR was lower and indexed SV higher in athletes. CI in CHF patients (2.3?±?0.6?l/min/m2) was lower compared to the healthy population (p?

2012-01-01

108

8-Oxoguanine DNA glycosylase 1 (ogg1) maintains the function of cardiac progenitor cells during heart formation in zebrafish.  

PubMed

Genomic damage may devastate the potential of progenitor cells and consequently impair early organogenesis. We found that ogg1, a key enzyme initiating the base-excision repair, was enriched in the embryonic heart in zebrafish. So far, little is known about DNA repair in cardiogenesis. Here, we addressed the critical role of ogg1 in cardiogenesis for the first time. ogg1 mainly expressed in the anterior lateral plate mesoderm (ALPM), the primary heart tube, and subsequently the embryonic myocardium by in situ hybridisation. Loss of ogg1 resulted in severe cardiac morphogenesis and functional abnormalities, including the short heart length, arrhythmia, decreased cardiomyocytes and nkx2.5(+) cardiac progenitor cells. Moreover, the increased apoptosis and repressed proliferation of progenitor cells caused by ogg1 deficiency might contribute to the heart phenotype. The microarray analysis showed that the expression of genes involved in embryonic heart tube morphogenesis and heart structure were significantly changed due to the lack of ogg1. Among those, foxh1 is an important partner of ogg1 in the cardiac development in response to DNA damage. Our work demonstrates the requirement of ogg1 in cardiac progenitors and heart development in zebrafish. These findings may be helpful for understanding the aetiology of congenital cardiac deficits. PMID:23892003

Yan, Lifeng; Zhou, Yong; Yu, Shanhe; Ji, Guixiang; Wang, Lei; Liu, Wei; Gu, Aihua

2013-11-15

109

Cardiac function and architecture are maintained in a model of cardiorestricted overexpression of the prorenin-renin receptor.  

PubMed

The (pro)renin-renin receptor, (P)RR has been claimed to be a novel element of the renin-angiotensin system (RAS). The function of (P)RR has been widely studied in renal and vascular pathology but the cardio-specific function of (P)RR has not been studied in detail. We therefore generated a transgenic mouse (Tg) with cardio-restricted (P)RR overexpression driven by the alpha-MHC promotor. The mRNA expression of (P)RR was ? 170-fold higher (P<0.001) and protein expression ? 5-fold higher (P<0.001) in hearts of Tg mice as compared to non-transgenic (wild type, Wt) littermates. This level of overexpression was not associated with spontaneous cardiac morphological or functional abnormalities in Tg mice. To assess whether (P)RR could play a role in cardiac hypertrophy, we infused ISO for 28 days, but this caused an equal degree of cardiac hypertrophy and fibrosis in Wt and Tg mice. In addition, ischemia-reperfusion injury was performed in Langendorff perfused isolated mouse hearts. We did not observe differences in parameters of cardiac function or damage between Wt and Tg mouse hearts under these conditions. Finally, we explored whether the hypoxia sensing response would be modulated by (P)RR using HeLa cells with and without (P)RR overexpression. We did not establish any effect of (P)RR on expression of genes associated with the hypoxic response. These results demonstrate that cardio-specific overexpression of (P)RR does not provoke phenotypical differences in the heart, and does not affect the hearts' response to stress and injury. It is concluded that increased myocardial (P)RR expression is unlikely to have a major role in pathological cardiac remodeling. PMID:24587131

Mahmud, Hasan; Candido, Wellington Mardoqueu; van Genne, Linda; Vreeswijk-Baudoin, Inge; Yu, Hongjuan; van de Sluis, Bart; van Deursen, Jan; van Gilst, Wiek H; Silljé, Herman H W; de Boer, Rudolf A

2014-01-01

110

Effects of head-up tilt on mean arterial pressure, heart rate, and regional cardiac output distribution in aging rats  

E-print Network

Many senescent individuals demonstrate an inability to regulate mean arterial pressure (MAP) in response to standing or head-up tilt; however, whether this aging effect is the result of depressed cardiac function or an inability to reduce peripheral...

Ramsey, Michael Wiechmann

2006-04-12

111

Human cardiac stem cells exhibit mesenchymal features and are maintained through Akt/GSK-3{beta} signaling  

SciTech Connect

Recent evidence suggested that human cardiac stem cells (hCSCs) may have the clinical application for cardiac repair; however, their characteristics and the regulatory mechanisms of their growth have not been fully investigated. Here, we show the novel property of hCSCs with respect to their origin and tissue distribution in human heart, and demonstrate the signaling pathway that regulates their growth and survival. Telomerase-active hCSCs were predominantly present in the right atrium and outflow tract of the heart (infant > adult) and had a mesenchymal cell-like phenotype. These hCSCs expressed the embryonic stem cell markers and differentiated into cardiomyocytes to support cardiac function when transplanted them into ischemic myocardium. Inhibition of Akt pathway impaired the hCSC proliferation and induced apoptosis, whereas inhibition of glycogen synthase kinase-3 (GSK-3) enhanced their growth and survival. We conclude that hCSCs exhibit mesenchymal features and that Akt/GSK-3{beta} may be crucial modulators for hCSC maintenance in human heart.

Tateishi, Kento [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Ashihara, Eishi [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan); Honsho, Shoken [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Takehara, Naofumi [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan); Nomura, Tetsuyaital [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Takahashi, Tomosaburo [Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Ueyama, Tomomi [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan); Yamagishi, Masaaki; Yaku, Hitoshi [Department of Cardiovascular Surgery, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan); Matsubara, Hiroaki [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]|[Department of Cardiovascular Medicine, Kyoto Prefectural University School of Medicine, Kyoto 602-8566 (Japan)]. E-mail: matsubah@koto.kpu-m.ac.jp; Oh, Hidemasa [Department of Experimental Therapeutics, Translational Research Center, Kyoto University Hospital, Kyoto 606-8507 (Japan)]. E-mail: hidemasa@kuhp.kyoto-u.ac.jp

2007-01-19

112

In vertebrates, short-term imbalances in blood pressure are regulated by reflex changes in cardiac output and peripheral  

E-print Network

In vertebrates, short-term imbalances in blood pressure are regulated by reflex changes in cardiac identified in many vertebrate species (see review by Bagshaw, 1985). In reptiles, the anatomy, and probably birds, the existence of myelinated baroreceptors (with thresholds well below normal arterial

Altimiras, Jordi

113

The Transcriptional Coactivators, PGC-1? and ?, Cooperate to Maintain Cardiac Mitochondrial Function During the Early Stages of Insulin Resistance  

PubMed Central

We previously demonstrated a cardiac mitochondrial biogenic response in insulin resistant mice that requires the nuclear receptor transcription factor PPAR?. We hypothesized that the PPAR? coactivator peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1?) is necessary for mitochondrial biogenesis in insulin resistant hearts and that this response was adaptive. Mitochondrial phenotype was assessed in insulin resistant mouse models in wild-type (WT) versus PGC-1? deficient (PGC-1??/?) backgrounds. Both high fat-fed (HFD) WT and 6 week-old Ob/Ob animals exhibited a significant increase in myocardial mitochondrial volume density compared to standard chow fed or WT controls. In contrast, HFD PGC-1??/? and Ob/Ob-PGC-1??/? hearts lacked a mitochondrial biogenic response. PGC-1? gene expression was increased in 6 week-old Ob/Ob animals, followed by a decline in 8 week-old Ob/Ob animals with more severe glucose intolerance. Mitochondrial respiratory function was increased in 6 week-old Ob/Ob animals, but not in Ob/Ob-PGC-1??/? mice and not in 8 week-old Ob/Ob animals, suggesting a loss of the early adaptive response, consistent with the loss of PGC-1? upregulation. Animals that were deficient for PGC-1? and heterozygous for the related coactivator PGC-1? (PGC-1??/??+/?) were bred to the Ob/Ob mice. Ob/Ob-PGC-1??/??+/? hearts exhibited dramatically reduced mitochondrial respiratory capacity. Finally, the mitochondrial biogenic response was triggered in H9C2 myotubes by exposure to oleate, an effect that was blunted with shRNA-mediated PGC-1 “knockdown”. We conclude that PGC-1 signaling is important for the adaptive cardiac mitochondrial biogenic response that occurs during the early stages of insulin resistance. This response occurs in a cell autonomous manner and likely involves exposure to high levels of free fatty acids. PMID:22080103

Mitra, Riddhi; Nogee, Daniel P.; Zechner, Juliet F.; Yea, Kyungmoo; Gierasch, Carrie M.; Kovacs, Attila; Medeiros, Denis M.; Kelly, Daniel P.; Duncan, Jennifer G.

2012-01-01

114

CO(2)-Dependent vasomotor reactivity of cerebral arteries in patients with severe traumatic brain injury: time course and effect of augmentation of cardiac output with dobutamine.  

PubMed

Failing cerebral blood flow (CBF) autoregulation may contribute to cerebral damage after traumatic brain injury (TBI). The purpose of this study was to describe the time course of CO(2)-dependent vasoreactivity, measured as CBF velocity in response to hyperventilation (vasomotor reactivity [VMR] index). We included 13 patients who had had severe TBI, 8 of whom received norepinephrine (NE) based on clinical indication. In these patients, measurements were also performed after dobutamine administration, with a goal of increasing cardiac output by 30%. Blood flow velocity was measured with transcranial Doppler ultrasound in both hemispheres. All patients except one had an abnormal VMR index in at least one hemisphere within the first 24?h after TBI. In those patients who did not receive catecholamines, mean VMR index recovered within the first 48 to 72?h. In contrast, in patients who received NE within the first 48?h period, VMR index did not recover on the second day. Cardiac output and mean CBF velocity increased significantly during dobutamine administration, but VMR index did not change significantly. In conclusion, CO(2) vasomotor reactivity was abnormal in the first 24?h after TBI in most of the patients, but recovered within 48?h in those patients who did not receive NE, in contrast to those eventually receiving the drug. Addition of dobutamine to NE had variable but overall insignificant effects on CO(2) vasomotor reactivity. PMID:21501044

Haenggi, Matthias; Andermatt, Anna; Anthamatten, Claudia; Galimanis, Aikaterini; Mono, Marie-Luise; Alfieri, Alexander; Fung, Christian; Takala, Jukka; Jakob, Stephan M

2012-06-10

115

The feasibility and applications of non-invasive cardiac output monitoring, thromboelastography and transit-time flow measurement in living-related renal transplantation surgery: results of a prospective pilot observational study  

PubMed Central

Introduction Delayed graft function (DGF) remains a significant and detrimental postoperative phenomenon following living-related renal allograft transplantation, with a published incidence of up to 15%. Early therapeutic vasodilatory interventions have been shown to improve DGF, and modifications to immunosuppressive regimens may subsequently lessen its impact. This pilot study assesses the potential applicability of perioperative non-invasive cardiac output monitoring (NICOM), transit-time flow monitoring (TTFM) of the transplant renal artery and pre-/perioperative thromboelastography (TEG) in the early prediction of DGF and perioperative complications. Methods Ten consecutive living-related renal allograft recipients were studied. Non-invasive cardiac output monitoring commenced immediately following induction of anaesthesia and was maintained throughout the perioperative period. Doppler-based TTFM was performed during natural haemostatic pauses in the transplant surgery: immediately following graft reperfusion and following ureteric implantation. Central venous blood sampling for TEG was performed following induction of anaesthesia and during abdominal closure. Results A single incidence of DGF was seen within the studied cohort and one intra-operative (thrombotic) complication noted. NICOM confirmed a predictable trend of increased cardiac index (CI) following allograft reperfusion (mean CI - clamped: 3.17?±?0.29 L/min/m2, post-reperfusion: 3.50?±?0.35 L/min/m2; P?

2014-01-01

116

Non-invasive in vivo measurement of cardiac output in C57BL/6 mice using high frequency transthoracic ultrasound: evaluation of gender and body weight effects.  

PubMed

Even though mice are being increasingly used as models for human cardiovascular diseases, non-invasive monitoring of cardiovascular parameters such as cardiac output (CO) in this species is challenging. In most cases, the effects of gender and body weight (BW) on these parameters have not been studied. The objective of this study was to provide normal reference values for CO in C57BL/6 mice, and to describe possible gender and/or BW associated differences between them. We used 30-MHz transthoracic Doppler ultrasound to measure hemodynamic parameters in the ascending aorta [heart rate (HR), stroke volume (SV), stroke index (SI), CO, and cardiac index (CI)] in ten anesthetized mice of either sex. No differences were found for HR, SV, and CO. Both SI and CI were statistically lower in males. However, after normalization for BW, these differences disappeared. These results suggest that if comparisons of cardiovascular parameters are to be made between male and female mice, values should be standardized for BW. PMID:24852337

Domínguez, Elisabet; Ruberte, Jesús; Ríos, José; Novellas, Rosa; Del Alamo, Maria Montserrat Rivera; Navarro, Marc; Espada, Yvonne

2014-10-01

117

In emergently ventilated trauma patients, low end-tidal CO2 and low cardiac output are associated and correlate with hemodynamic instability, hemorrhage, abnormal pupils, and death  

PubMed Central

Background In a smaller experience, the authors previously demonstrated that end-tidal carbon dioxide (PetCO2) and cardiac output (CO) had a positive association in emergently intubated trauma patients during Emergency Department resuscitation. The aim of this larger study was to reassess the relationship of PetCO2 with CO and identify patient risk-conditions influencing PetCO2 and CO values. Methods The investigation consists of acutely injured trauma patients requiring emergency tracheal intubation. The study focuses on the prospective collection of PetCO2 and noninvasive CO monitor (NICOM®) values in the Emergency Department. Results From the end of March through August 2011, 73 patients had 318 pairs of PetCO2 (mm Hg) and CO (L/min.) values. Mean data included Injury Severity Score (ISS) ?15 in 65.2%, Glasgow Coma Score of 6.4?±?4.6, hypotension in 19.0%, and death in 34.3%. With PetCO2???25 (15.9?±?8.0), systolic blood pressure was 77.0?±?69, CO was 3.2?±?3.0, cardiac arrest was 60.4%, and mortality was 84.9%. During hypotension, CO was lower with major blood loss (1.9), than without major loss (5.0; P?=?0.0008). Low PetCO2 was associated with low CO (P??20, hypotension, bradycardia, major blood loss, abnormal pupils, cardiac arrest, and death. Low CO was associated (P???0.0059) with ISS?>?20, hypotension, bradycardia, major blood loss, abnormal pupils, cardiac arrest, and death. Conclusions During emergency department resuscitation, a decline in PetCO2 correlates with decreases in noninvasive CO in emergently intubated trauma patients. Decreasing PetCO2 and declining NICOM CO are associated with hemodynamic instability, hemorrhage, abnormal pupils, and death. The study indicates that NICOM CO values are clinically discriminate and have physiologic validity. PMID:24020798

2013-01-01

118

A model-free method for mass spectrometer response correction. [for oxygen consumption and cardiac output calculation  

NASA Technical Reports Server (NTRS)

A new method for correction of mass spectrometer output signals is described. Response-time distortion is reduced independently of any model of mass spectrometer behavior. The delay of the system is found first from the cross-correlation function of a step change and its response. A two-sided time-domain digital correction filter (deconvolution filter) is generated next from the same step response data using a regression procedure. Other data are corrected using the filter and delay. The mean squared error between a step response and a step is reduced considerably more after the use of a deconvolution filter than after the application of a second-order model correction. O2 consumption and CO2 production values calculated from data corrupted by a simulated dynamic process return to near the uncorrupted values after correction. Although a clean step response or the ensemble average of several responses contaminated with noise is needed for the generation of the filter, random noise of magnitude not above 0.5 percent added to the response to be corrected does not impair the correction severely.

Shykoff, Barbara E.; Swanson, Harvey T.

1987-01-01

119

Heart mass and the maximum cardiac output of birds and mammals: implications for estimating the maximum aerobic power input of flying animals  

PubMed Central

Empirical studies of cardiovascular variables suggest that relative heart muscle mass (relative Mh) is a good indicator of the degree of adaptive specialization for prolonged locomotor activities, for both birds and mammals. Reasonable predictions for the maximum oxygen consumption of birds during flight can be obtained by assuming that avian heart muscle has the same maximum physiological and biomechanical performance as that of terrestrial mammals. Thus, data on Mh can be used to provide quantitative estimates for the maximum aerobic power input (aerobic Pi,max) available to animals during intense levels of locomotor activity. The maximum cardiac output of birds and mammals is calculated to scale with respect to Mh (g) as 213 Mh0.88+-0.04 (ml min-1), while aerobic Pi,max is estimated to scale approximately as 11 Mh0.88+-0.09 (W). In general, estimated inter-species aerobic Pi,max, based on Mh for all bird species (excluding hummingbirds), is calculated to scale with respect to body mass (Mb in kg) as 81 Mb0.82+-0.11 (W). Comparison of family means for Mh indicate that there is considerable diversity in aerobic capacity among birds and mammals, for example, among the medium to large species of birds the Tinamidae have the smallest relative Mh (0.25 per cent) while the Otidae have unusually large relative Mh (1.6 per cent). Hummingbirds have extremely large relative Mh (2.28 per cent), but exhibit significant sexual dimorphism in their scaling of Mh and flight muscle mass, so that when considering hummingbird flight performance it may be useful to control for sexual differences in morphology. The estimated scaling of aerobic Pi,max (based on Mh and Mb in g) for male and female hummingbirds is 0.51 Mb0.83 +/-0.07 and 0.44 Mb0.85+- 0.11 (W), respectively. Locomotory muscles are dynamic structures and it might be anticipated that where additional energetic 'costs' occur seasonally (e.g. due to migratory fattening or the development of large secondary sexual characteristics) then the relevant cardiac and locomotor musculature might also be regulated seasonally. This is an important consideration, both due to the intrinsic interest of studying muscular adaptation to changes in energy demand, but also as a confounding variable in the practical use of heart rate to estimate the energetics of animals. Haemoglobin concentration (or haematocrit) may also be a confounding variable. Thus, it is concluded that data on the cardiovascular and flight muscle morphology of animals provides essential information regarding the behavioural, ecological and physiological significance of the flight performance of animals.

Bishop, C. M.

1997-01-01

120

STAT5 requires the N-domain to maintain hematopoietic stem cell repopulating function and appropriate lymphoid-myeloid lineage output  

PubMed Central

Objective STAT5 is a critical regulator of hematopoietic development and its impaired activation is associated with hematopoietic and immune cell defects. However, much of this information has been learned from knockout mice that still retain the potential for expression of STAT5 proteins that are N-terminally truncated due to alternative internal translation initiation codons. The goal of these studies was to use transplantation based assays to analyze the degree of STAT5?N activity in HSC and throughout lymphomyeloid development. Methods We have directly compared E14.5 fetal liver cells from mice with potential to express STAT5ab?N (STAT5ab?N/?N) with mice completely lacking STAT5a and STAT5b (STAT5abnull/null). We have also utilized retroviral complementation of STAT5abnull/null fetal liver hematopoietic stem cells (HSC) to enforce expression of full-length STAT5a or STAT5a lacking the first 136 amino acids (STAT5a? N). Results We report that STAT5 is required for HSC, lymphocyte, and erythrocyte development. We demonstrate that restored expression of STAT5a in STAT5abnull/null HSC provides a strong selective advantage, correcting T/B lymphocyte and erythrocyte development. Interestingly, Gr-1+ blood cells were inversely correlated with B-lymphocytes and both were normalized by STAT5a expression. In contrast, transduction of STAT5a?N only provided partial B-lymphocyte development. Conclusions These studies define the role of STAT5 in maintaining normal lymphoid vs. myeloid balance during hematopoiesis and highlight a major role for the N/domain in HSC function. The platform of retroviral complementation described here will be particularly useful for future studies to sub-define the N-domain regions that are critical for hematopoiesis. PMID:17976521

Li, Geqiang; Wang, Zhengqi; Zhang, Yi; Kang, Zizhen; Haviernikova, Eleonora; Cui, Yongzhi; Hennighausen, Lothar; Moriggl, Richard; Wang, Demin; Tse, William; Bunting, Kevin D.

2007-01-01

121

Increased cardiac output, not pulmonary artery systolic pressure, increases intrapulmonary shunt in healthy humans breathing room air and 40% O2.  

PubMed

Blood flow through intrapulmonary arteriovenous anastomoses (IPAVAs) has been demonstrated to increase in healthy humans during a variety of conditions; however, whether or not this blood flow represents a source of venous admixture (Q? VA /Q?T) that impairs pulmonary gas exchange efficiency (i.e. increases the alveolar-to-arterial PO2 difference (A-aDO2)) remains controversial and unknown. We hypothesized that blood flow through IPAVAs does provide a source of Q? VA /Q?T. To test this, blood flow through IPAVAs was increased in healthy humans at rest breathing room air and 40% O2: (1) during intravenous adrenaline (epinephrine) infusion at 320 ng kg(-1) min(-1) (320 ADR), and (2) with vagal blockade (2 mg atropine), before and during intravenous adrenaline infusion at 80 ng kg(-1) min(-1) (ATR + 80 ADR). When breathing room air the A-aDO2 increased by 6 ± 2 mmHg during 320 ADR and by 5 ± 2 mmHg during ATR + 80 ADR, and the change in calculated Q? VA /Q?T was +2% in both conditions. When breathing 40% O2, which minimizes contributions from diffusion limitation and alveolar ventilation-to-perfusion inequality, the A-aDO2 increased by 12 ± 7 mmHg during 320 ADR, and by 9 ± 6 mmHg during ATR + 80 ADR, and the change in calculated Q? VA /Q?T was +2% in both conditions. During 320 ADR cardiac output (Q?T) and pulmonary artery systolic pressure (PASP) were significantly increased; however, during ATR + 80 ADR only Q?T was significantly increased, yet blood flow through IPAVAs as detected with saline contrast echocardiography was not different between conditions. Accordingly, we suggest that blood flow through IPAVAs provides a source of intrapulmonary shunt, and is mediated primarily by increases in Q?T rather than PASP. PMID:25085889

Elliott, Jonathan E; Duke, Joseph W; Hawn, Jerold A; Halliwill, John R; Lovering, Andrew T

2014-10-15

122

Effects of levosimendan/furosemide infusion on Plasma Brain Natriuretic Peptide, echocardiographic parameters and cardiac output in end-stage heart failure patients  

PubMed Central

Summary Background Acute decompensation heart failure (ADHF) remains a cause of hospitalization in patients with end-stage congestive HF. The administration of levosimendan in comparison with a standard therapy in CHF patients admitted for ADHF was analysed. Material/Methods Consecutive patients admitted for ADHF (NYHA class III–IV) were treated with levosimendan infusion 0.1 ?g/kg/min or with furosemide infusion 100–160 mg per day for 48 hours (control group). All subjects underwent determination of brain natriuretic peptide (BNP), non-invasive cardiac output (CO), and echocardiogram at baseline, at the end of therapy and 1 week after therapy. Results Seven patients admitted for 20 treatments in 16 months (age 66 years; mean admission/year 5.4) were treated with levosimendan and compared with 7 patients admitted for 15 treatments (age 69.1 years; mean admission/year 6.1). At the end of levosimendan therapy, BNP decreased (from 679.7±512.1 pg/ml to 554.2±407.6 pg/ml p=0.03), and 6MWT and LVEF improved (from 217.6±97.7 m to 372.2±90.4 m p=0.0001; from 22.8±9.1% to 25.4±9.8% p=0.05). Deceleration time, E/A, E/E’, TAPSE, pulmonary pressure and CO did not change significantly after levosimendan therapy and after 1 week. At follow-up, only 6-min WT and NYHA class showed a significant improvement (p=0.0001, p=0.001 respectively). The furosemide infusion reduced NYHA class and body weight (from 3.4±0.6 to 2.3±0.5 p=0.001; from 77.5±8.6 kg to 76±6.6 kg p=0.04), but impaired renal function (clearances from 56.3±21.9 ml/min to 41.2±10.1 ml/min p=0.04). Conclusions Treating end-stage CHF patients with levosimendan improved BNP and LVEF, but this effect disappeared after 1 week. The amelioration of 6MWT and NYHA class lasted longer after levosimendan infusion. PMID:21358614

Feola, Mauro; Lombardo, Enrico; Taglieri, Camillo; Vallauri, Paola; Piccolo, Salvatore; Valle, Roberto

2011-01-01

123

Construct, concurrent and discriminant validity of Type D personality in the general population: Associations with anxiety, depression, stress and cardiac output  

Microsoft Academic Search

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

Siobhán Howard; Brian M. Hughes

2012-01-01

124

Construct, concurrent and discriminant validity of Type D personality in the general population: Associations with anxiety, depression, stress and cardiac output  

Microsoft Academic Search

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

Siobhán Howard; Brian M. Hughes

2011-01-01

125

Cardiac gated ventilation  

SciTech Connect

There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. The authors evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50 msec scan aperture. Multi slice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. The authors observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a non-failing model of the heart.

Hanson, C.W. III [Hospital of the Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. Anesthesia; Hoffman, E.A. [Univ. of Iowa College of Medicine, Iowa City, IA (United States). Div. of Physiologic Imaging

1995-12-31

126

Cardiac gated ventilation  

NASA Astrophysics Data System (ADS)

There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. We evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50msec scan aperture. Multislice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. We observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a nonfailing model of the heart.

Hanson, C. William, III; Hoffman, Eric A.

1995-05-01

127

Preoperative levosimendan decreases mortality and the development of low cardiac output in high-risk patients with severe left ventricular dysfunction undergoing coronary artery bypass grafting with cardiopulmonary bypass  

PubMed Central

BACKGROUND: The calcium sensitizer levosimendan has been used in cardiac surgery for the treatment of postoperative low cardiac output syndrome (LCOS) and difficult weaning from cardiopulmonary bypass (CPB). OBJECTIVES: To evaluate the effects of preoperative treatment with levosimendan on 30-day mortality, the risk of developing LCOS and the requirement for inotropes, vasopressors and intra-aortic balloon pumps in patients with severe left ventricular dysfunction. METHODS: Patient with severe left ventricular dysfunction and an ejection fraction <25% undergoing coronary artery bypass grafting with CPB were admitted 24 h before surgery and were randomly assigned to receive levosimendan (loading dose 10 ?g/kg followed by a 23 h continuous infusion of 0.1?g/kg/min) or a placebo. RESULTS: From December 1, 2002 to June 1, 2008, a total of 252 patients were enrolled (127 in the levosimendan group and 125 in the control group). Individuals treated with levosimendan exhibited a lower incidence of complicated weaning from CPB (2.4% versus 9.6%; P<0.05), decreased mortality (3.9% versus 12.8%; P<0.05) and a lower incidence of LCOS (7.1% versus 20.8%; P<0.05) compared with the control group. The levosimendan group also had a lower requirement for inotropes (7.9% versus 58.4%; P<0.05), vasopressors (14.2% versus 45.6%; P<0.05) and intra-aortic balloon pumps (6.3% versus 30.4%; P<0.05). CONCLUSION: Patients with severe left ventricle dysfunction (ejection fraction <25%) undergoing coronary artery bypass grafting with CPB who were pretreated with levosimendan exhibited lower mortality, a decreased risk for developing LCOS and a reduced requirement for inotropes, vasopressors and intra-aortic balloon pumps. Studies with a larger number of patients are required to confirm whether these findings represent a new strategy to reduce the operative risk in this high-risk patient population. PMID:23620700

Levin, Ricardo; Degrange, Marcela; Del Mazo, Carlos; Tanus, Eduardo; Porcile, Rafael

2012-01-01

128

Overload protection circuit for output driver  

Microsoft Academic Search

A protection circuit for preventing excessive power dissipation in an output transistor whose conduction path is connected between a power terminal and an output terminal. The protection circuit includes means for sensing the application of a turn on signal to the output transistor and the voltage at the output terminal. When the turn on signal is maintained for a period

Roger G

1982-01-01

129

Cardiac thin filament regulation  

PubMed Central

Myocardial contraction is initiated upon the release of calcium into the cytosol from the sarcoplasmic reticulum following membrane depolarization. The fundamental physiological role of the heart is to pump an amount blood that is determined by the prevailing requirements of the body. The physiological control systems employed to accomplish this task include regulation of heart rate, the amount of calcium release, and the response of the cardiac myofilaments to activator calcium ions. Thin filament activation and relaxation dynamics has emerged as a pivotal regulatory system tuning myofilament function to the beat-to-beat regulation of cardiac output. Maladaptation of thin filament dynamics, in addition to dysfunctional calcium cycling, is now recognized as an important cellular mechanism causing reduced cardiac pump function in a variety of cardiac diseases. Here, we review current knowledge regarding protein–protein interactions involved in the dynamics of thin filament activation and relaxation and the regulation of these processes by protein kinase-mediated phosphorylation. PMID:18421471

Kobayashi, Tomoyoshi; Jin, Lei; de Tombe, Pieter P.

2010-01-01

130

Cardiac lipofibromatosis.  

PubMed

We present a case of cardiac lipofibromatosis associated with atrial fibrillation and complete heart block requiring permanent pacemaker implantation. Multimodality cardiac imaging including transthoracic echocardiography and cardiac magnetic resonance were useful for tissue characterization of this rare cardiac diagnosis. PMID:23146562

Shen, Seeger; Rizkallah, Jacques; Kirkpatrick, Iain D C; Khadem, Ali; Jassal, Davinder S

2013-04-01

131

Design and testing of an MRI-compatible cycle ergometer for non-invasive cardiac assessments during exercise  

PubMed Central

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

2012-01-01

132

Dynamic cardiac mapping on patient-specific cardiac models.  

PubMed

Minimally invasive techniques for electrophysiological cardiac data mapping and catheter ablation therapy have been driven through advancements in computer-aided technologies, including magnetic tracking systems, and virtual and augmented-reality environments. The objective of this work is to extend current cardiac mapping techniques to collect and display data in the temporal domain, while mapping on patient-specific cardiac models. This paper details novel approaches to collecting spatially tracked cardiac electrograms, registering the data with a patient-specific cardiac model, and interpreting the data directly on the model surface, with the goal of giving a more comprehensive cardiac mapping system in comparison to current systems. To validate the system, laboratory studies were conducted to assess the accuracy of navigating to both physical and virtual landmarks. Subsequent to the laboratory studies, an in-vivo porcine experiment was conducted to assess the systems overall ability to collect spatial tracked electrophysiological data, and map directly onto a cardiac model. The results from these experiments show the new dynamic cardiac mapping system was able to maintain high accuracy of locating physical and virtual landmarks, while creating a dynamic cardiac map displayed on a dynamic cardiac surface model. PMID:18979839

Wilson, Kevin; Guiraudon, Gerard; Jones, Doug; Linte, Cristian A; Wedlake, Chris; Moore, John; Peters, Terry M

2008-01-01

133

Cardiac image segmentation for contrast agent videodensitometry  

Microsoft Academic Search

Indicator dilution techniques are widely used in the intensive care unit and operating room for cardiac parameter measurements. However, the invasiveness of current techniques represents a limitation for their clinical use. The development of stable ultrasound contrast agents allows new applications of the indicator dilution method. Ultrasound contrast agent dilutions permit an echographic noninvasive measurement of cardiac output, ejection fraction,

Massimo Mischi; Antonius A. C. M. Kalker; Henricus H. M. Korsten

2005-01-01

134

Cardiac metastases  

Microsoft Academic Search

Tumours metastatic to the heart (cardiac metastases) are among the least known and highly debated issues in oncology, and few systematic studies are devoted to this topic. Although primary cardiac tumours are extremely uncommon (various postmortem studies report rates between 0.001% and 0.28%), secondary tumours are not, and at least in theory, the heart can be metastasised by any malignant

R Bussani; F De-Giorgio; A Abbate; F Silvestri

2007-01-01

135

Cardiac asthma.  

PubMed

Cardiac dyspnea, especially if present only with exercise, is often confused with asthma and exercise-induced bronchospasm. Cardiac dyspnea or asthma is the consequence of pulmonary edema due to pulmonary venous hypertension and not due to asthmatic bronchoconstriction. In overt, acute congestive heart failure, the diagnosis may be readily made by history and physical examination and pertinent laboratory and imaging data. PMID:23337063

Buckner, Kern

2013-02-01

136

Maintaining a Healthy Weight  

MedlinePLUS

... and drink Other ways to maintian a healthy weight? Limit portion size to control calorie intake. Add ... Go4Life Maintaining a Healthy Weight Maintaining a healthy weight is important for overall health and well-being. ...

137

Redox Control of Cardiac Excitability  

PubMed Central

Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

138

Cardiac rhabdomyosarcoma.  

PubMed

Cardiac sarcoma is a very rare neoplasm and is difficult to diagnose. The case of a 51-year-old man with a left atrial tumour, locally recurrent three months after its surgical removal, is presented. Computed tomography showed metastatic spread to the lung parenchyma. On revised histology, the mass extirpated was a sarcoma. Because of the metastatic spread, further therapy was symptomatic only; the patient died 15 months after the first manifestation of his problems. Immunohistochemical staining confirmed cardiac rhabdomyosarcoma with metastatic spread to the lungs. Difficulty in diagnosing and treating cardiac tumours is discussed. PMID:20428274

Chlumský, J; Holá, D; Hlavácek, K; Michal, M; Svec, A; Spatenka, J; Dusek, J

2001-01-01

139

[Cardiac angiosarcoma].  

PubMed

The paper outlines the authors'case of cardiac angiosarcoma. It provides the gross and microscopic characteristics of this tumor and procedures for its clinical and immunomorphological diagnosis. PMID:21695990

Kir'ianov, N A; Terekhov, M V; Sukhanov, S A; Lozhkin, E A; Nikolaeva, N B

2011-01-01

140

Cardiac Cephalalgia  

Microsoft Academic Search

We report a patient with cardiac cephalalgia and review reported cases from the English-language literature based on the new diagnostic criteria published in the International Classification of Headache Disorders, ed 2. Twenty-two patients, including ours, with headaches of cardiac origin were reviewed. The cases fit three of the four new criteria well: Criteria B (acute myocardial ischemia has occurred, 100%),

Shih-Pin Chen; Jong-Ling Fuh; Wen-Chung Yu; Shuu-Jiun Wang

2004-01-01

141

Cardiac factors in orthostatic hypotension  

NASA Astrophysics Data System (ADS)

Cardiac function is determined by preload, afterload, heart rate and contractility. During orthostatic stress, the footward blood shift is compensated for by an increase of afterload. LBNP is widely used to analyze effects of volume displacement during orthostatic stress. Comparisons of invasive ( right heart catheterization) and non-invasive approach (echocardiography) yielded similar changes. Preload and afterload change with graded LBNP, heart rate increases, and stroke volume and cardiac output decrease. Thus, the working point on the left ventricular function curve is shifted to the left and downward, similar to hypovolemia. However, position on the Frank-Starling curve, the unchanged ejection fraction, and the constant Vcf indicate a normal contractile state during LBNP. A decrease of arterial oxygen partial pressure during LBNP shwos impaired ventilation/perfusion ratio. Finally, LBNP induced cardiac and hemodynamic changes can be effectively countermeasured by dihydroergotamine, a potent venoconstrictor. Comparison of floating catheter data with that of echocardiography resulted in close correlation for cardiac output and stroke volume. In addition, cardiac dimensions changed in a similar way during LBNP. From our findings, echocardiography as a non-invasive procedure can reliably used in LBNP and orthostatic stress tests. Some informations can be obtained on borderline values indicating collaps or orthostatic syncope. Early fainters can be differentiated from late fainters by stroke volume changes.

Löllgen, H.; Dirschedl, P.; Koppenhagen, K.; Klein, K. E.

142

Cardiac Regenerative Capacity and Mechanisms  

PubMed Central

The heart holds the monumental yet monotonous task of maintaining circulation. Although cardiac function is critical to other organs and to life itself, mammals are not equipped with significant natural capacity to replace heart muscle that has been lost by injury. This deficiency plays a role in leaving millions worldwide each year vulnerable to heart failure. By contrast, certain other vertebrate species like zebrafish are strikingly good at heart regeneration. A cellular and molecular understanding of endogenous regenerative mechanisms, combined with advances in methodology to transplant cells, together project a future in which cardiac muscle regeneration can be therapeutically stimulated in injured human hearts. This review will focus on what has been discovered recently about cardiac regenerative capacity and how natural mechanisms of heart regeneration in model systems are stimulated and maintained. PMID:23057748

Kikuchi, Kazu; Poss, Kenneth D.

2013-01-01

143

About Cardiac Arrest  

MedlinePLUS

... High Blood Pressure Tools & Resources Stroke More About Cardiac Arrest Updated:Sep 10,2014 What is cardiac arrest? ... to heart disease and stroke. Start exploring today ! Cardiac Arrest • Home • About Cardiac Arrest • Understand Your Risk for ...

144

Maintaining Plant Genebanks  

NSDL National Science Digital Library

This lesson explores the benefits and problems of maintaining plant genebanks globally. Students can plan a genebank or agricultural cryopreservation business venture, write a biography about a famous botanist, present views at a genebank symposium for developing nations and more!

Brian R. Shmaefsky (Kingwood College;)

2003-06-02

145

Cardiac Regeneration  

PubMed Central

The heart is a pump that is comprised of cardiac myocytes and other cell types and whose proper function is critical to quality of life. The ability to trigger regeneration of heart muscle following injury eludes adult mammals, a deficiency of great clinical impact. Major research efforts are attempting to change this through advances in cell therapy or activating endogenous regenerative mechanisms that exist only early in life. By contrast with mammals, lower vertebrates like zebrafish demonstrate an impressive natural capacity for cardiac regeneration throughout life. This review will cover recent progress in the field of heart regeneration with a focus on endogenous regenerative capacity and its potential manipulation. PMID:22449849

Choi, Wen-Yee; Poss, Kenneth D.

2012-01-01

146

Maintaining Bermudagrass Lawns  

E-print Network

System Maintaining Bermudagrass L a w ns L-5339 8/06 Bermudagrass (Cynodon dactylon [L.]) is a popular turfgrass for lawns, golf courses, athletic fields and general utility areas. Found in Australia, Africa, India, South America... System Maintaining Bermudagrass L a w ns L-5339 8/06 Bermudagrass (Cynodon dactylon [L.]) is a popular turfgrass for lawns, golf courses, athletic fields and general utility areas. Found in Australia, Africa, India, South America...

Chalmers, David; McAfee, James; Havlak, Roger

2006-08-08

147

Cardiac Rehabilitation  

MedlinePLUS

Cardiac rehabilitation (rehab) is a medically supervised program to help people who have A heart attack Angioplasty or coronary artery bypass grafting for coronary heart disease A heart valve repair or replacement A heart transplant or a lung transplant Angina Heart failure The ...

148

Software Maintainability Index Revisited  

SciTech Connect

For many years now, software practitioners have been collecting metrics from source code in an effort to better understand the software they are developing or changing. Maintainability Index (MI) is a composite metric that incorporates a number of traditional source code metrics into a single number that indicates relative maintainability. As originally proposed by Oman and Hagemeister, the MI is comprised of weighted Halstead metrics (effort or volume), McCabe's Cyclomatic Complexity, lines of code (LOC), and number of comments [1, 2]. Two equations were presented: one that considered comments and one that did not.

Welker, Kurt Dean

2001-08-01

149

A cortical potential reflecting cardiac function  

PubMed Central

Emotional trauma and psychological stress can precipitate cardiac arrhythmia and sudden death through arrhythmogenic effects of efferent sympathetic drive. Patients with preexisting heart disease are particularly at risk. Moreover, generation of proarrhythmic activity patterns within cerebral autonomic centers may be amplified by afferent feedback from a dysfunctional myocardium. An electrocortical potential reflecting afferent cardiac information has been described, reflecting individual differences in interoceptive sensitivity (awareness of one's own heartbeats). To inform our understanding of mechanisms underlying arrhythmogenesis, we extended this approach, identifying electrocortical potentials corresponding to the cortical expression of afferent information about the integrity of myocardial function during stress. We measured changes in cardiac response simultaneously with electroencephalography in patients with established ventricular dysfunction. Experimentally induced mental stress enhanced cardiovascular indices of sympathetic activity (systolic blood pressure, heart rate, ventricular ejection fraction, and skin conductance) across all patients. However, the functional response of the myocardium varied; some patients increased, whereas others decreased, cardiac output during stress. Across patients, heartbeat-evoked potential amplitude at left temporal and lateral frontal electrode locations correlated with stress-induced changes in cardiac output, consistent with an afferent cortical representation of myocardial function during stress. Moreover, the amplitude of the heartbeat-evoked potential in the left temporal region reflected the proarrhythmic status of the heart (inhomogeneity of left ventricular repolarization). These observations delineate a cortical representation of cardiac function predictive of proarrhythmic abnormalities in cardiac repolarization. Our findings highlight the dynamic interaction of heart and brain in stress-induced cardiovascular morbidity. PMID:17420478

Gray, Marcus A.; Taggart, Peter; Sutton, Peter M.; Groves, David; Holdright, Diana R.; Bradbury, David; Brull, David; Critchley, Hugo D.

2007-01-01

150

Diversity & Community: Maintaining Allegiances.  

ERIC Educational Resources Information Center

The quest for diversity must overcome the resistance of traditional White, male faculty to redefining the mission and curriculum of the liberal arts college. Change will be difficult, but it must occur if liberal arts colleges are to survive and maintain a central and relevant place in multicultural America. (MSE)

Pena, Devon G.

1990-01-01

151

Cardiac optogenetics  

PubMed Central

Optogenetics is an emerging technology for optical interrogation and control of biological function with high specificity and high spatiotemporal resolution. Mammalian cells and tissues can be sensitized to respond to light by a relatively simple and well-tolerated genetic modification using microbial opsins (light-gated ion channels and pumps). These can achieve fast and specific excitatory or inhibitory response, offering distinct advantages over traditional pharmacological or electrical means of perturbation. Since the first demonstrations of utility in mammalian cells (neurons) in 2005, optogenetics has spurred immense research activity and has inspired numerous applications for dissection of neural circuitry and understanding of brain function in health and disease, applications ranging from in vitro to work in behaving animals. Only recently (since 2010), the field has extended to cardiac applications with less than a dozen publications to date. In consideration of the early phase of work on cardiac optogenetics and the impact of the technique in understanding another excitable tissue, the brain, this review is largely a perspective of possibilities in the heart. It covers the basic principles of operation of light-sensitive ion channels and pumps, the available tools and ongoing efforts in optimizing them, overview of neuroscience use, as well as cardiac-specific questions of implementation and ideas for best use of this emerging technology in the heart. PMID:23457014

2013-01-01

152

Cardiac Surgery  

PubMed Central

Well into the first decades of the 20th century, medical opinion held that any surgical attempts to treat heart disease were not only misguided, but unethical. Despite such reservations, innovative surgeons showed that heart wounds could be successfully repaired. Then, extracardiac procedures were performed to correct patent ductus arteriosus, coarctation of the aorta, and tetralogy of Fallot. Direct surgery on the heart was accomplished with closed commissurotomy for mitral stenosis. The introduction of the heart-lung machine and cardiopulmonary bypass enabled the surgical treatment of other congenital and acquired heart diseases. Advances in aortic surgery paralleled these successes. The development of coronary artery bypass grafting greatly aided the treatment of coronary heart disease. Cardiac transplantation, attempts to use the total artificial heart, and the application of ventricular assist devices have brought us to the present day. Although progress in the field of cardiovascular surgery appears to have slowed when compared with the halcyon times of the past, substantial challenges still face cardiac surgeons. It can only be hoped that sufficient resources and incentive can carry the triumphs of the 20th century into the 21st. This review covers past developments and future opportunities in cardiac surgery. PMID:22163121

Weisse, Allen B.

2011-01-01

153

Visualization of Model Output  

NSDL National Science Digital Library

Visualization of output from mathematical or statistical models is one of the best ways to introduce introductory geoscience students to the results and behavior of sophisticated models. Example of good sites ...

154

What Is an Output?  

Microsoft Academic Search

A recurrent idea in the history of psychology is that one is conscious of outputs but not of the complex processes underlying the generation of outputs, which is evident in the out-of-the-blue, “eureka-like” experiences associated with intuition. We examine how this idea may suffer from a logical fallacy and may thus have inadvertently hindered progress on the study of the

Ezequiel Morsella; John A. Bargh

2010-01-01

155

Reproducibility of linear cardiac output measurement by Doppler ultrasound alone  

Microsoft Academic Search

Inclusion of a pig aorta in an artificial circulation with pulsed blood flow allowed correlation of minute distance, measured in the aorta by Doppler ultrasound, and absolute blood flow, measured by timed blood-volume collection. The correlation coefficient was 0.99 with a standard error of prediction that was 5.4% of the minute distance predicted at a standard flow rate of 5

F M McLennan; N E Haites; J D Mackenzie; M K Daniel; J M Rawles

1986-01-01

156

Regulation of the cardiac sodium pump.  

PubMed

In cardiac muscle, the sarcolemmal sodium/potassium ATPase is the principal quantitative means of active transport at the myocyte cell surface, and its activity is essential for maintaining the trans-sarcolemmal sodium gradient that drives ion exchange and transport processes that are critical for cardiac function. The 72-residue phosphoprotein phospholemman regulates the sodium pump in the heart: unphosphorylated phospholemman inhibits the pump, and phospholemman phosphorylation increases pump activity. Phospholemman is subject to a remarkable plethora of post-translational modifications for such a small protein: the combination of three phosphorylation sites, two palmitoylation sites, and one glutathionylation site means that phospholemman integrates multiple signaling events to control the cardiac sodium pump. Since misregulation of cytosolic sodium contributes to contractile and metabolic dysfunction during cardiac failure, a complete understanding of the mechanisms that control the cardiac sodium pump is vital. This review explores our current understanding of these mechanisms. PMID:22955490

Fuller, W; Tulloch, L B; Shattock, M J; Calaghan, S C; Howie, J; Wypijewski, K J

2013-04-01

157

Linear accelerator output variability.  

PubMed

The Wellington Cancer Centre is equipped with two matched linear accelerators (Varian 2100CD) linear accelerators (identified as SN1027 and SN42). Each morning, before treatments commence, a radiation therapist carries out an output constancy check of the radiation output and every fortnight a physicist measures, in a phantom, the delivered radiation dose to check on the machine calibration. The daily output checks have been recorded into a database (Argus QA for Radiation Oncology) since August 1997 and in June 1998 the fortnightly calibration measurements were added. The information in the database, up to April 2003, has been analysed to consider the quality of the daily constancy checks as compared with the fortnightly calibration measurements and whether the data contains useful information on machine performance. After allowance for the effects of machine recalibration the fortnightly calibration measurements had an average standard deviation of 0.4% and the daily constancy checks 0.8%. The daily constancy checks had a greater number of large deviations than would be expected assuming a normal distribution and were not a good predictor of the need for a recalibration. The fortnightly calibration measurements with a much lower spread give a reliable indication of the need for a recalibration allowing the adoption of a +/- 1% tolerance. Over the period analysed one accelerator (SN42) was relatively stable with the output generally drifting between +/- 1% while the other (SN1027) had a consistent increase in the average output of about 2.5% per year. PMID:15580846

Luketina, I A; Greig, L

2004-09-01

158

Linear output nitinol engine  

SciTech Connect

This patent describes a linear output nitinol engine consisting of a number of integrated communicating parts. The engine has an external support framework which is described in detail. The patent further describes a wire transport mechanism, a pair of linkage levers with a loom secured to them, a number of nitinol wires strung between the looms, and a power takeoff block secured to the linkage levers. A pulley positioned in a flip-flop supporting bracket and a power takeoff modality including a tension member connected to a power output cable in order to provide linear power output transmission is described. A method for biasing the timing and the mechanism for timing the synchronization of the throw over arms and the flip-flop of the pulley are also described.

Banks, R.M.

1986-01-14

159

The relationship between power output and endurance: a brief review  

Microsoft Academic Search

It is well established that for work requiring high power output, endurance time is short, and that low power outputs can be maintained for long periods. Parameters describing this relationship are important in characterising work performance and the capacity of humans as a source of mechanical power. The purpose of this paper is to provide a brief review of the

R. Hugh Morton; David J. Hodgson

1996-01-01

160

Reliable Gas Turbine Output: Attaining Temperature Independent Performance  

E-print Network

of availability, it is the major option for future power generation. One inherent disadvantage of gas turbines is the degradation of output as the ambient air temperature increases. This reduction in output during times of peak load create a reliability...% of the electric system, could create reliability and operational problems. This paper explores the potential for maintaining constant, reliable outputs from gas turbines by cooling ambient air temperatures before the air is used in the compressor section...

Neeley, J. E.; Patton, S.; Holder, F.

161

Different Contribution of Splanchnic Organs to Hyperlactatemia in Fecal Peritonitis and Cardiac Tamponade  

PubMed Central

Background. Changes in hepatosplanchnic lactate exchange are likely to contribute to hyperlactatemia in sepsis. We hypothesized that septic and cardiogenic shock have different effects on hepatosplanchnic lactate exchange and its contribution to hyperlactatemia. Materials and Methods. 24 anesthetized pigs were randomized to fecal peritonitis (P), cardiac tamponade (CT), and to controls (n = 8 per group). Oxygen transport and lactate exchange were calculated during 24 hours. Results. While hepatic lactate influx increased in P and in CT, hepatic lactate uptake remained unchanged in P and decreased in CT. Hepatic lactate efflux contributed 20% (P) and 33% (CT), respectively, to whole body venous efflux. Despite maintained hepatic arterial blood flow, hepatic oxygen extraction did not increase in CT. Conclusions. Whole body venous lactate efflux is of similar magnitude in hyperdynamic sepsis and in cardiogenic shock. Although jejunal mucosal pCO2 gradients are increased, enhanced lactate production from other tissues is more relevant to the increased arterial lactate. Nevertheless, the liver fails to increase hepatic lactate extraction in response to rising hepatic lactate influx, despite maintained hepatic oxygen consumption. In cardiac tamponade, regional, extrasplanchnic lactate production is accompanied by hepatic failure to increase oxygen extraction and net hepatic lactate output, despite maintained hepatic arterial perfusion. PMID:24228242

Gorrasi, Jose; Eleftheriadis, Anestis; Takala, Jukka; Brandt, Sebastian; Djafarzadeh, Siamak; Bruegger, Lukas E.; Bracht, Hendrik; Jakob, Stephan M.

2013-01-01

162

AN INTEGRATEDMICROELECTROMECHANICALRESONANT OUTPUT GYROSCOPE -  

E-print Network

AN INTEGRATEDMICROELECTROMECHANICALRESONANT OUTPUT GYROSCOPE - Ashwin A. Seshia*,Roger T. Howe vibratory rate gyroscope based on resonant sensing of the Coriolis force. The new design has several advantages over rate gyroscopes that utilize open-loop displacement sensing for rotation rate measurement

Tang, William C

163

Central Venous Saturation: A Prognostic Tool in Cardiac Surgery patients  

Microsoft Academic Search

Background: Central venous oxygen saturation (ScvO2) is a valuable prognostic marker in sepsis. However, its value in cardiac surgery has not been assessed yet. This study aimed at evaluating ScvO2 as a tool for predicting short-term organ dysfunction (OD) after cardiac surgery. Methods: A prospective cohort including cardiac surgery patients submitted to a goal-oriented therapy to maintain ScvO2 above 70%

Pedro M. Nogueira; Hugo T. Mendonça-Filho; Luiz Antonio Campos; Renato V. Gomes; Alexandre R. Felipe; Marco A. Fernandes; Cristiane A. Villela-Nogueira; José R. Rocco

2010-01-01

164

Origins of Cardiac Fibroblasts  

PubMed Central

Cardiac fibroblasts play a critical role in maintenance of normal cardiac function. They are indispensable for damage control and tissue remodeling on myocardial injury and principal mediators of pathological cardiac remodeling and fibrosis. Despite their manyfold functions, cardiac fibroblasts remain poorly characterized in molecular terms. Evidence is evolving that cardiac fibroblasts are a heterogeneous population and likely derive from various distinct tissue niches in health and disease. Here, we review our emerging understanding of where cardiac fibroblasts come from, as well as how we can possibly use this knowledge to develop novel therapies for cardiac fibrosis. PMID:21106947

Zeisberg, Elisabeth M.; Kalluri, Raghu

2011-01-01

165

Cardiac Cells Beating in Culture: A Laboratory Exercise  

ERIC Educational Resources Information Center

This article describes how to establish a primary tissue culture, where cells are taken directly from an organ of a living animal. Cardiac cells are taken from chick embryos and transferred to culture dishes. These cells are not transformed and therefore have a limited life span. However, the unique characteristics of cardiac cells are maintained

Weaver, Debora

2007-01-01

166

Nitric Oxide Synthase Inhibition Attenuates Cardiac Response to Hemodilution with Viscogenic Plasma Expander  

PubMed Central

Background and Objectives Increased vascular wall shear stress by elevated plasma viscosity significantly enhances the endothelial nitric oxide synthase (eNOS) activity during an acute isovolemic hemodilution. Also the modulation of plasma viscosity has effects on the cardiac function that were revealed if a left ventricular (LV) pressure-volume (PV) measurement was used. The aim of this study was to assess cardiac function responses to nitric oxide synthase (NOS) inhibitors with the presence of an elevated plasma viscosity but a low hematocrit level. Furthermore, systemic parameters were monitored in a murine model. Materials and Methods As test group five anesthetized hamsters were administered with N(G)-nitro-L-arginine methyl ester (L-NAME), NOS inhibitor, whereas five other hamsters were used as control group without L-NAME infusion. The dosage of L-NAME was 10 mg/kg. An isovolemic hemodilution was performed by 40% of estimated blood volume with 6% w/v dextran 2000 kDa, high viscosity plasma expanders (PEs) with viscosity 6.34 cP. LV function was measured and assessed using a 1.4 Fr PV conductance catheter. Results The study results demonstrated that NOS inhibition prevented the normal cardiac adaptive response after hemodilution. The endsystolic pressure increased 14% after L-NAME infusion and maintained higher than at the baseline after hemodilution, whereas it gradually decreased in the animals without L-NAME infusion. The admission of L-NAME significantly decreased the maximum rate of ventricular pressure rise (+dP/dtmax), stroke volume and cardiac output after hemodilution if compared to the control group (p<0.05). Conclusion This finding supports the presumption that nitric oxide induced by an increased plasma viscosity with the use of a high viscosity PE plays a major role in the cardiac function during an acute isovolemic hemodilution. PMID:24653740

Cabrales, Pedro

2014-01-01

167

Maintaining the unmethylated state  

PubMed Central

Background A remarkable correspondence exists between the cytogenetic locations of the known fragile sites and frequently reported sites of hypermethylation. The best-known features of fragile sites are sequence motifs that are prone to the spontaneous formation of a non-B DNA structure. These facts, coupled with the known enzymological specificities of DNA methyltransferase 1 (DNMT1), the ATP-dependent and actin-dependent helicases, and the ten-eleven translocation (TET) dioxygenases, suggest that these enzymes are involved in an epigenetic cycle that maintains the unmethylated state at these sites by resolving non-B structure, preventing both the sequestration of DNA methyltransferases (DNMTs) and hypermethylation in normal cells. Presentation of the hypothesis The innate tendency of DNA sequences present at fragile sites to form non-B DNA structures results in de novo methylation of DNA at these sites that is held in check in normal cells by the action of ATP-dependent and actin-dependent helicases coupled with the action of TET dioxygenases. This constitutes a previously unrecognized epigenetic repair cycle in which spontaneously forming non-B DNA structures formed at fragile sites are methylated by DNMTs as they are removed by the action of ATP-dependent and actin-dependent helicases, with the resulting nascent methylation rendered non-transmissible by TET dioxygenases. Testing the hypothesis A strong prediction of the hypothesis is that knockdown of ATP-dependent and actin-dependent helicases will result in enhanced bisulfite sensitivity and hypermethylation at non-B structures in multiple fragile sites coupled with global hypomethylation. Implications of the hypothesis A key implication of the hypothesis is that helicases, like the lymphoid-specific helicase and alpha thalassemia/mental retardation syndrome X-linked helicase, passively promote accurate maintenance of DNA methylation by preventing the sequestration of DNMTs at sites of unrepaired non-B DNA structure. When helicase action is blocked due to mutation or downregulation of the respective genes, DNMTs stall at unrepaired non-B structures in fragile sites after methylating them and are unable to methylate other sites in the genome, resulting in hypermethylation at non-B DNA-forming sites, along with hypomethylation elsewhere. PMID:24079333

2013-01-01

168

CARDIAC MUSCLE  

PubMed Central

With light and electron microscopy a comparison has been made of the morphology of ventricular (V) and Purkinje (P) fibers of the hearts of guinea pig, rabbit, cat, dog, goat, and sheep. The criteria, previously established for the rabbit heart, that V fibers are distinguished from P fibers by the respective presence and absence of transverse tubules is shown to be true for all animals studied. No evidence was found of a permanent connection between the sarcoplasmic reticulum and the extracellular space. The sarcoplasmic reticulum (SR) of V fibers formed couplings with the sarcolemma of a transverse tubule (interior coupling) and with the peripheral sarcolemma (peripheral coupling), whereas in P fibers the SR formed only peripheral couplings. The forms of the couplings were identical. The significance, with respect to excitation-contraction coupling, of the difference in the form of the couplings in cardiac versus skeletal muscle is discussed together with the electrophysiological implications of the differing geometries of bundles of P fibers from different animals. PMID:5645545

Sommer, Joachim R.; Johnson, Edward A.

1968-01-01

169

Pediatric Cardiac Surgery in Developing Countries  

Microsoft Academic Search

Pediatric cardiac surgery in developing countries is a major challenge. It is a challenge to employ evolving methods to cater\\u000a to the surgical needs of a very large number of children with congenital heart defects while dealing with severe budgetary\\u000a constraints, finding funding to maintain the program, and maintaining quality in the backdrop of constant turnover of trained\\u000a medical, nursing,

Suresh G. Rao

2007-01-01

170

Single-center experience with levosimendan in children undergoing cardiac surgery and in children with decompensated heart failure  

PubMed Central

Background Levosimendan has pharmacologic and hemodynamic advantages over conventional intravenous inotropic agents. It has been used mainly as a rescue drug in the pediatric intensive care unit or in the operating room. We present the largest single-center experience of levosimendan in children. Methods Retrospective analysis of all children who received levosimendan infusions between July 5, 2001 and July 4, 2010 in a pediatric intensive care unit. The results of a questionnaire for physicians (anesthesiologist/intensivists, cardiologists and cardiac surgeons) concerning their clinical perceptions of levosimendan are evaluated Results During the study period a total of 484 infusions were delivered to 293 patients 53% of whom were male. The median age of the patients was 0.4 years (4 hours-21.1 years) at the time of levosimendan administration. A majority of levosimendan infusions were administered to children who were undergoing cardiac surgery (72%), 14% to children with cardiomyopathy and 14% to children with cardiac failure. Eighty-nine out of the 293 patients (30.4%) received repeated doses of levosimendan (up to 11 infusions). The most common indication for the use of levosimendan (94%) was when the other inotropic agents were insufficient to maintain stable hemodynamics. Levosimendan was especially used in children with cardiomyopathy (100%) or with low cardiac output syndrome (94%). A majority (89%) of the respondents believed that levosimendan administration postponed the need for mechanical assist devices in some children with cardiomyopathy. Moreover, 44% of respondents thought that the mechanical support was totally avoided in some patients undergoing cardiac surgery after receiving levosimendan. Conclusion Levosimendan is widely used in our institution and many physicians believe that its use could decrease the need for mechanical support in children undergoing cardiac surgery or in children with decompensated heart failure. However, there is a lack of good empirical evidence in children to support this perception. PMID:21974814

2011-01-01

171

Cardiac Syndrome X  

MedlinePLUS

Related terms: angina, microvascular angina Cardiac syndrome X patients have the pain of angina , but they do not have coronary artery disease ( CAD ). So even though patients with cardiac syndrome X ...

172

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

PubMed

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. PMID:24314236

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

2014-11-01

173

An Unusual Cause of Cardiac Tamponade during Cardiac Catheterization Study  

PubMed Central

Introduction. Catheter-based diagnostic and therapeutic procedures are rapidly advancing. However, catheter related complications sometimes become life threatening. Cardiac tamponade is a rare but serious complication of this procedure. We have summarized one cardiac tamponade pejoration due to secondary coronary vessels laceration by the implanted pericardial drainage. Case report. A 4-year-old baby having Tetralogy of Fallot was posted for diagnostic catheterization study. Patient was induced with sevoflurane and spontaneous respiration was maintained. After catheter insertion to RV, dye was injected through the catheter which rapidly spread into the pericardial cavity indicating right ventricle perforation. Immediately, blood was aspirated under transthoracic echocardiographic guidance and hemodynamics started improving. For the provision of quick access to aspirate further collection, an intrapericardial sheath was inserted after multiple attempts. Patient's condition started deteriorating again. TTE revealed again some collection and it was increasing gradually. On exploration, it was found that there was continuous bleeding from a lacerated epicardial vessel which contributed to the pericardial collection leading to further tamponade effect. This second iatrogenic injury complicated the management of the first iatrogenic cardiac perforation and, thereby, created a life-threatening situation which needed immediate surgical exploration. Discussion. Usual cause of tamponade after right ventricular perforation is bleeding from the RV, but in our case the second tamponade was not due to bleeding from the RV, but was rather from new laceration injury of epicardial vessels which was remained undiagnosed till exploration.

Das, Deepanwita; Datta, Monalisa; Dey, Somnath; Parida, Jyotiranjan; Kumar, Rupesh; Pande, Arindam

2014-01-01

174

Titin-mediated control of cardiac myofibrillar function.  

PubMed

According to the Frank-Starling relationship, ventricular pressure or stroke volume increases with end-diastolic volume. This is regulated, in large part, by the sarcomere length (SL) dependent changes in cardiac myofibrillar force, loaded shortening, and power. Consistent with this, both cardiac myofibrillar force and absolute power fall at shorter SL. However, when Ca(2+) activated force levels are matched between short and long SL (by increasing the activator [Ca(2+)]), short SL actually yields faster loaded shortening and greater peak normalized power output (PNPO). A potential mechanism for faster loaded shortening at short SL is that, at short SL, titin becomes less taut, which increases the flexibility of the cross-bridges, a process that may be mediated by titin's interactions with thick filament proteins. We propose a more slackened titin yields greater myosin head radial and azimuthal mobility and these flexible cross-bridges are more likely to maintain thin filament activation, which would allow more force-generating cross-bridges to work against a fixed load resulting in faster loaded shortening. We tested this idea by measuring SL-dependence of power at matched forces in rat skinned cardiac myocytes containing either N2B titin or a longer, more compliant N2BA titin. We predicted that, in N2BA titin containing cardiac myocytes, power-load curves would not be shifted upward at short SL compared to long SL (when force is matched). Consistent with this, peak normalized power was actually less at short SL versus long SL (at matched force) in N2BA-containing myocytes (N2BA titin: ?PNPO (Short SL peak power minus long SL peak power)=-0.057±0.049 (n=5) versus N2B titin: ?PNPO=+0.012±0.012 (n=5). These findings support a model whereby SL per se controls mechanical properties of cross-bridges and this process is mediated by titin. This myofibrillar mechanism may help sustain ventricular power during periods of low preloads, and perhaps a breakdown of this mechanism is involved in impaired function of failing hearts. PMID:24269766

Hanft, Laurin M; Greaser, Marion L; McDonald, Kerry S

2014-06-15

175

Cardiac Disease in Pregnancy: Value of Echocardiography  

Microsoft Academic Search

Cardiovascular disease in women during pregnancy poses particular challenges. It continues to be a leading cause of maternal\\u000a mortality and contributes to significant morbidity. Echocardiography is essential in characterizing the extent and effects\\u000a of heart disease prior to, during, and after pregnancy. By understanding the physiologic adaptation in pregnancy with increases\\u000a in heart rate, blood volume, and cardiac output, and

Sarah Tsiaras; Athena Poppas

2010-01-01

176

[Malignant cardiac tumors].  

PubMed

Cardiac neoplasms are a rare occurrence in clinical practice. The various frequencies of primary and secondary malignant tumors vary from report to report, approximately 1% in most autopsy series and 4% in cancer patient's autopsies. Cardiac malignancies account for less 1% of cardiac surgery and about for 0.1% of cardiac echographic studies. The presence of metastatic tumor to the heart usually indicates widespread metastases. Lung carcinomas are the most commonly encountered tumor followed by breast and pancreas cancer and melanoma. Apart from primary pericardial mesothelioma, primary cardiac tumors are high-grade sarcomas with a high metastatic potency that often becomes evident early after surgery. Symptoms are non specific, occur late in the disease and affect few patients; especially secondary neoplasms of the heart take their course so fast that they cannot become symptomatic. The signs of cardiac neoplasms are divided into systemic symptoms (fever, arthralgias and myalgias), cardiac symptoms (congestive heart failure, arrhythmia, chest pain) and uncommon embolisms. Diagnosis is actually made easier with cardiac echography. Cardiac RMI is helpful to estimate vessels and pericardium involvement. Due to its poor prognosis, treatment of cardiac metastases is restricted to best supportive care. For primary cardiac neoplasms, surgery must be carefully discussed because operative intervention is often followed by rapid widespread metastases that adjuvant chemotherapy cannot avoid in most cases. PMID:15899620

Debourdeau, Philippe; Gligorov, Joseph; Teixeira, Luis; Aletti, Marc; Zammit, Christine

2004-11-01

177

Anesthesia with propofol induces insulin resistance systemically in skeletal and cardiac muscles and liver of rats  

SciTech Connect

Highlights: ? Propofol, as a model anesthetic drug, induced whole body insulin resistance. ? Propofol anesthesia decreased glucose infusion rate to maintain euglycemia. ? Propofol decreased insulin-mediated glucose uptake in skeletal and cardiac muscles. ? Propofol increased hepatic glucose output confirming hepatic insulin resistance. -- Abstract: Hyperglycemia together with hepatic and muscle insulin resistance are common features in critically ill patients, and these changes are associated with enhanced inflammatory response, increased susceptibility to infection, muscle wasting, and worsened prognosis. Tight blood glucose control by intensive insulin treatment may reduce the morbidity and mortality in intensive care units. Although some anesthetics have been shown to cause insulin resistance, it remains unknown how and in which tissues insulin resistance is induced by anesthetics. Moreover, the effects of propofol, a clinically relevant intravenous anesthetic, also used in the intensive care unit for sedation, on insulin sensitivity have not yet been investigated. Euglycemic hyperinsulinemic clamp study was performed in rats anesthetized with propofol and conscious unrestrained rats. To evaluate glucose uptake in tissues and hepatic glucose output [{sup 3}H]glucose and 2-deoxy[{sup 14}C]glucose were infused during the clamp study. Anesthesia with propofol induced a marked whole-body insulin resistance compared with conscious rats, as reflected by significantly decreased glucose infusion rate to maintain euglycemia. Insulin-stimulated tissue glucose uptake was decreased in skeletal muscle and heart, and hepatic glucose output was increased in propofol anesthetized rats. Anesthesia with propofol induces systemic insulin resistance along with decreases in insulin-stimulated glucose uptake in skeletal and heart muscle and attenuation of the insulin-mediated suppression of hepatic glucose output in rats.

Yasuda, Yoshikazu; Fukushima, Yuji; Kaneki, Masao [Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114 (United States)] [Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114 (United States); Martyn, J.A. Jeevendra, E-mail: jmartyn@partners.org [Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114 (United States)] [Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114 (United States)

2013-02-01

178

Psychological adjustment after cardiac transplantation.  

PubMed

Cardiac transplantation is viable therapeutic alternative for patients with end-stage heart disease, which offers a favourable short- and medium-term prognosis. The survival has improved from 20% of patients who survived at one year after transplantation in the 1960s to the present figures of 80%-85% of patients who are alive at one year, and 50%-70% of patients who are alive at five years, after transplantation. Therefore, it seems timely to focus attention on the psychological well-being of cardiac-transplant recipients. The medical literature is scant in regard to the psychiatric and the psychosocial impact of cardiac transplantation on recipients, and a systematic and prospective study of the psychosocial adaptation of recipients is lacking. Since 1984, we have been studying the emotional impact of cardiac transplantation on recipients and their families. This article presents the results for a group of recipients who have been assessed before transplantation, then followed-up at discharge from hospital and at four, eight and 12 months after transplantation. The study attempted to quantitate the recipients' anxiety, depression, body image and subjective quality of life by way of standardized self-assessment questionnaires. The recipients' satisfaction with relationships or their marital situation also was reported, as were their degree of rehabilitation at 12 months and their attitudes to various aspects of treatment after the transplantation. Before the transplantation, 53% of patients reported an increase in anxiety and 34% of patients recorded scores that indicated mild-to-moderate levels of depression. Thirty-seven per cent of patients showed a deterioration in the quality of their lives and 34% of patients had a negative body image. After the transplantation, significant improvements occurred in all parameters, which were maintained at follow-up. PMID:3041251

Jones, B M; Chang, V P; Esmore, D; Spratt, P; Shanahan, M X; Farnsworth, A E; Keogh, A; Downs, K

1988-08-01

179

Body size and work output.  

PubMed

The relationship between work output and anthropometric, biochemical, and socioeconomic varables was studied in 57 male industrial workers engaged in the production of detonator fuses. These workers were studied for 3 months and their daily work output was carefully measured. Work output was measured in terms of the number of fuses produced per day. Clinical and biochemical examination indicated that their current nutritional status was adequate. Among the parameters studied only body weight, height, and lean body weight were significantly correlated with work output. Body weight and lean body weight were significantly correlated (P less than 0.001) with work output even after removing the influence of height by partial correlation. Total daily work output was significantly higher (P less than 0.01) in those with higher body weight and lean body weight. The rate of work was also higher in the higher body weight group PMID:842484

Satyanarayana, K; Naidu, A N; Chatterjee, B; Rao, N

1977-03-01

180

Serial Input Output  

SciTech Connect

Serial Input/Output (SIO) is designed to be a long term storage format of a sophistication somewhere between simple ASCII files and the techniques provided by inter alia Objectivity and Root. The former tend to be low density, information lossy (floating point numbers lose precision) and inflexible. The latter require abstract descriptions of the data with all that that implies in terms of extra complexity. The basic building blocks of SIO are streams, records and blocks. Streams provide the connections between the program and files. The user can define an arbitrary list of streams as required. A given stream must be opened for either reading or writing. SIO does not support read/write streams. If a stream is closed during the execution of a program, it can be reopened in either read or write mode to the same or a different file. Records represent a coherent grouping of data. Records consist of a collection of blocks (see next paragraph). The user can define a variety of records (headers, events, error logs, etc.) and request that any of them be written to any stream. When SIO reads a file, it first decodes the record name and if that record has been defined and unpacking has been requested for it, SIO proceeds to unpack the blocks. Blocks are user provided objects which do the real work of reading/writing the data. The user is responsible for writing the code for these blocks and for identifying these blocks to SIO at run time. To write a collection of blocks, the user must first connect them to a record. The record can then be written to a stream as described above. Note that the same block can be connected to many different records. When SIO reads a record, it scans through the blocks written and calls the corresponding block object (if it has been defined) to decode it. Undefined blocks are skipped. Each of these categories (streams, records and blocks) have some characteristics in common. Every stream, record and block has a name with the condition that each stream, record or block name must be unique in its category (i.e. all streams must have different names, but a stream can have the same name as a record). Each category is an arbitrary length list which is handled by a 'manager' and there is one manager for each category.

Waite, Anthony; /SLAC

2011-09-07

181

Maintaining Subsurface Drip Irrigation Systems  

E-print Network

A subsurface drip irrigation system should last more than 20 years if properly maintained. Important maintenance procedures include cleaning the filters, flushing the lines, adding chlorine and injecting acids. Details of these procedures...

Enciso, Juan; Porter, Dana; Bordovsky, Jim; Fipps, Guy

2004-09-07

182

Emergency cardiac support with extracorporeal membrane oxygenation for cardiac arrest.  

PubMed

A 46-year-old woman with no major medical history presented to the emergency department with chest pain and evidence of anterior, anterolateral, and inferior ST-elevation myocardial infarction. Her condition quickly deteriorated into cardiogenic shock with ventricular arrhythmia. Despite revascularization of the left anterior descending artery and intravenous inotrope and antiarrhythmic therapy, her unstable hemodynamics and arrhythmias persisted. Early emergency initiation of venoarterial extracorporeal membrane oxygenation (ECMO) led to prompt hemodynamic and rhythm stability; however, adequate endogenous cardiac output did not ensue, and she was not able to be weaned from ECMO until hospital day 8. She subsequently recovered and continues to do well in the outpatient setting. This case demonstrates the remarkable hemodynamic and rhythm stability that early initiation of ECMO can provide in the setting of unstable myocardial infarction. PMID:23809321

Tweet, Marysia S; Schears, Gregory J; Cassar, Andrew; Sheldon, Seth H; McGlinch, Brian P; Sandhu, Gurpreet S

2013-07-01

183

Cardiac and vascular adaptation to 0g with and without thigh cuffs (Antares 14 and Altair 21 day Mir spaceflights)  

NASA Astrophysics Data System (ADS)

Cardiovascular Actaptation was evaluated on 2 astronauts: one wearing thigh cuffs from flight day 1 to 8 (14d flight), the second without cuffs (21d flight). Ultrasound investigations were performed at rest and during LBNP. Results: Without thigh cuffs the cardiovascular Actaptation consists in (1) the development of a hypovolemia with an increase of the heart rate and the cardiac output, (2) the decrease of the vascular tone in the deep (mesenteric and splanchnic) and peripheral (Lower limbs) vascular areas. The use of thigh cuffs maintains the volemia and the cardiac output at the preflight level (without heart rate increase) and prevents the loss of vascular tone in the deep and peripheral areas. Moreover the adaptative process changes since the cuffs are removed and even the volemia seems to be unaffected at this stage the vascular tone decreases to a comparable extend as during the flight without cuffs. Nevertheless during the flight without cuffs or 3 days after removing the cuffs hemodynamic signs of decreased orthostatic tolerance are present during the inflight and the 3 days post flight LBNP. Presently the possible contribution of the thigh cuffs to the reduction of the vascular deconditioning has not been tested yet.

Arbeille, Ph.; Fomina, G.; Achaibou, F.; Pottier, J.; Kotovskaya, A.

184

New output improvements for CLASSY  

NASA Technical Reports Server (NTRS)

Additional output data and formats for the CLASSY clustering algorithm were developed. Four such aids to the CLASSY user are described. These are: (1) statistical measures; (2) special map types; (3) formats for standard output; and (4) special cluster display method.

Rassbach, M. E. (principal investigator)

1981-01-01

185

Established and emerging dose reduction methods in cardiac computed tomography.  

PubMed

Cardiac computed tomography (CT) is a non-invasive modality that is commonly used as an alternative to invasive coronary angiography for the investigation of coronary artery disease. The enthusiasm for this technology has been tempered by a growing appreciation of the potential risks of malignancy associated with the use of ionising radiation. In the spirit of minimizing patient risk, the medical profession and industry have worked hard to developed methods and protocols to reduce patient radiation exposure while maintaining excellent diagnostic accuracy. A complete understanding of radiation reduction techniques will allow clinicians to reduce patient risk while providing an important diagnostic service. This review will consider the established and emerging techniques that may be adopted to reduce patient absorbed doses from x-ray CT. By modifying (1) x-ray tube output, (2) imaging time (scan duration), (3) imaging distance (scan length) and (4) the appropriate use of shielding, clinicians will be able to adhere to the 'as low as reasonably achievable (ALARA)' principle. PMID:21630110

Small, Gary R; Kazmi, Mustapha; Dekemp, Robert A; Chow, Benjamin J W

2011-08-01

186

Sudden cardiac death  

Microsoft Academic Search

The rate of cardiac deaths that are sudden is approximately 50%, and decreases with age. The causes of sudden cardiac death are diverse, and are a function of age. In children and adolescents, coronary anomalies, hypertrophic cardiomyopathy and myocarditis are frequent substrates for lethal arrhythmias; in adults, coronary atherosclerosis and acquired forms of cardiomyopathy are the most common findings at

Renu Virmani; Allen P Burke; Andrew Farb

2001-01-01

187

Hybrid Pediatric Cardiac Surgery  

Microsoft Academic Search

Minimally invasive strategies can be expanded by combining standard surgical and interventional techniques. We performed a longitudinal prospective study of all pediatric patients who have undergone hybrid cardiac surgery at the University of Chicago Children's Hospital. Hybrid cardiac surgery was defined as combined catheter-based and surgical interventions in either one setting or in a planned sequential fashion within 24 hours.

E. A. Bacha; Z. M. Hijazi; Q. L. Cao; R. Abdulla; J. P. Starr; J. Quinones; P. Koenig; B. Agarwala

2005-01-01

188

Micromolded gelatin hydrogels for extended culture of engineered cardiac tissues  

E-print Network

Ltd. All rights reserved. 1. Introduction Cardiotoxicity is a leading cause of market withdrawal- diotoxicity is usually identified in animal models, such as mice [5,6] or dogs [7], that are exposed of cardiac output. Furthermore, studies with animals and animal cells are not always relevant to humans due

189

Functional cardiac tissue engineering  

PubMed Central

Heart attack remains the leading cause of death in both men and women worldwide. Stem cell-based therapies, including the use of engineered cardiac tissues, have the potential to treat the massive cell loss and pathological remodeling resulting from heart attack. Specifically, embryonic and induced pluripotent stem cells are a promising source for generation of therapeutically relevant numbers of functional cardiomyocytes and engineering of cardiac tissues in vitro. This review will describe methodologies for successful differentiation of pluripotent stem cells towards the cardiovascular cell lineages as they pertain to the field of cardiac tissue engineering. The emphasis will be placed on comparing the functional maturation in engineered cardiac tissues and developing heart and on methods to quantify cardiac electrical and mechanical function at different spatial scales. PMID:22397609

Liau, Brian; Zhang, Donghui; Bursac, Nenad

2013-01-01

190

Radiation Propulsion For Maintaining Orbits  

NASA Technical Reports Server (NTRS)

Brief report proposes radiative propulsion systems for maintaining precise orbits of spacecraft. Radiation from electrical heaters directed outward by paraboloidal reflectors to produce small forces to oppose uncontrolled drag and solar-radiative forces perturbing orbits. Minimizes or eliminates need to fire rocket thrusters to correct orbits.

Richter, Robert

1995-01-01

191

Maintaining Digital Clocks In Step  

Microsoft Academic Search

We design a stabilizing system of simultaneously triggered clocks: if the clock values ever differ, then the system is guaranteed to converge to a state where all clock values are identical, and are subsequently maintained to be identical. Our design of an N-clock system uses N registers of 2 log N bits each and is guaranteed to converge to identical

Anish Arora; Shlomi Dolev; Mohamed G. Gouda

1991-01-01

192

Maintaining Discipline in Classroom Instruction.  

ERIC Educational Resources Information Center

This document focuses on classroom discipline and how the teacher can maintain an environment that will optimize appropriate learning. Part 1 defines classroom discipline. Part 2 discusses classroom misbehavior and describes a number of classroom management techniques. Part 3 offers suggestions for control techniques. Part 4 discusses techniques…

Gnagey, William J.

193

Maintaining Sustainability for Green Schools  

ERIC Educational Resources Information Center

The promise of sustainably designed school facilities is that they will operate more efficiently and last longer than buildings constructed in more traditional ways. But that promise comes with a big if. The payoff is delivered only if the facility managers operate and maintain the buildings in ways that adhere to sustainable strategies called for…

Kennedy, Mike

2011-01-01

194

A case series of real-time hemodynamic assessment of high output heart failure as a complication of arteriovenous access in dialysis patients.  

PubMed

Congestive heart failure (CHF) is an important source of morbidity and mortality in end-stage renal disease patients. Although CHF is commonly associated with low cardiac output (CO), it may also occur in high CO states. Multiple conditions are associated with increased CO including congenital or acquired arteriovenous fistulae or arteriovenous grafts. Increased CO resulting from permanent AV access in dialysis patients has been shown to induce structural and functional cardiac changes, including the development of eccentric left ventricle hypertrophy. Often, the diagnosis of high output heart failure requires invasive right heart monitoring in the acute care setting such as a medical or cardiac intensive care unit. The diagnosis of an arteriovenous access causing high output heart failure is usually confirmed after the access is ligated surgically. We present for the first time, a case for real-time hemodynamic assessment of high output heart failure due to AV access by interventional nephrology in the cardiac catheterization suite. PMID:24673654

Singh, Sarguni; Elramah, Mohsen; Allana, Salman S; Babcock, Michael; Keevil, Jon G; Johnson, Maryl R; Yevzlin, Alexander S; Chan, Micah R

2014-11-01

195

Output optics for laser velocimeters  

NASA Technical Reports Server (NTRS)

Space savings are effected in the optical output system of a laser velocimeter. The output system is comprised of pairs of optical fibers having output ends from which a beam of laser light emerges, a transfer lens for each light beam, and at least one final (LV) lens for receiving the light passing through the transfer lenses and for focussing that light at a common crossing point or area. In order to closely couple the transfer lenses to the final lens, each transfer lens is positioned relative to the final lens receiving light therefrom such that the output waist of the corresponding beam received by the final lens from the transfer lens is a virtual waist located before the transfer lens.

Lynch, Dana H. (inventor); Gunter, William D. (inventor); Mcalister, Kenneth W. (inventor)

1993-01-01

196

World Input-Output Network  

E-print Network

Economic systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD) is one of the first efforts to construct the multi-regional input-output (MRIO) tables at the global level. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we study the network properties of the so-called world input-output network (WION) and document its evolution over time. We are able to quantify not only some global network properties such as assortativity, clustering coefficient, and degree and strength distributions, but also its subgraph structure and dynamics by using community detection techniques. Over time, we detect a marked increase in cross-country connectivity of the production system, only temporarily interrupted by the 2008-2009 crisis. Moreover...

Cerina, Federica; Chessa, Alessandro; Riccaboni, Massimo

2014-01-01

197

Maximum output at minimum cost  

E-print Network

at generator output terminals, on low voltage side before transformer input terminals. Rotor Blades Tubular converters and PWM (Pulse Width Modulation) electronic control. Benefits: ®® Active and reactive power

Firestone, Jeremy

198

Output collapses and productivity destruction  

Microsoft Academic Search

In this paper we analyze the long-run relationship between output collapses—defined as GDP falling substantially below trend—and\\u000a total factor productivity (TFP). We use a panel of 76 developed and developing countries during the period 1960–2004 to identify\\u000a episodes of output collapse and estimate counterfactual post-collapse TFP trends. Collapses are concentrated in developing\\u000a countries, especially Africa and Latin America, and were

Juan S. Blyde; Christian Daude; Eduardo Fernández-Arias

2010-01-01

199

Chronic fatigue syndrome: comments on deconditioning, blood volume and resulting cardiac function  

PubMed Central

Cardiovascular and autonomic dysfunction have been suggested to underlie the symptoms accompanying CFS (chronic fatigue syndrome). In the present issue of Clinical Science, Hurwitz and co-workers have investigated whether deficits were present in cardiac output and blood volume in a cohort of patients with CFS and if these were linked to illness severity and sedentary lifestyle. The results clearly demonstrate reduced cardiac stroke volume and cardiac output in more severely afflicted patients with CFS, which is primarily attributable to a measurable reduction in blood volume. Similar findings are observed in microgravity and bed rest deconditioning, in forms of orthostatic intolerance and, to a lesser extent, in sedentary people. The circulatory consequences of reduced cardiac output may help to account for many of the findings of the syndrome. PMID:19534728

STEWART, Julian M.

2014-01-01

200

Modeling inherited cardiac disorders.  

PubMed

Advances in the understanding and treatment of cardiac disorders have been thwarted by the inability to study beating human cardiac cells in vitro. Induced pluripotent stem cells (iPSCs) bypass this hurdle by enabling the creation of patient-specific iPSC-derived cardiomyocytes (iPSC-CMs). These cells provide a unique platform to study cardiac diseases in vitro, especially hereditary cardiac conditions. To date, iPSC-CMs have been used to successfully model arrhythmic disorders, showing excellent recapitulation of cardiac channel function and electrophysiologic features of long QT syndrome types 1, 2, 3, and 8, and catecholaminergic polymorphic ventricular tachycardia (CPVT). Similarly, iPSC-CM models of dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) have shown robust correlation of predicted morphologic, contractile, and electrical phenotypes. In addition, iPSC-CMs have shown some features of the respective phenotypes for arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), LEOPARD syndrome, Pompe's disease, and Friedriech's ataxia. In this review, we examine the progress of utilizing iPSC-CMs as a model for cardiac conditions and analyze the potential for the platform in furthering the biology and treatment of cardiac disorders.?? PMID:24632794

Sallam, Karim; Kodo, Kazuki; Wu, Joseph C

2014-01-01

201

Cardiac involvement in leptospirosis.  

PubMed

Leptospirosis is a neglected global disease with significant morbidity and mortality. Cardiac complications such as chest pain, arrhythmias, pulmonary oedema and refractory shock have been reported in patients with severe disease. However, the frequency and extent of cardiac involvement in leptospirosis, are under-reported and poorly understood. Multiple factors may contribute to clinical manifestations that suggest cardiac involvement, causing diagnostic confusion. A variety of electrocardiographic changes occur in leptospirosis, with atrial fibrillation, atrioventricular conduction blocks and non-specific ventricular repolarization abnormalities being the most common. Electrolyte abnormalities are likely to contribute to electrocardiographic changes; direct effects on Na(+)-K(+)-Cl(-) transporters in the renal tubules have been postulated. Echocardiographic evidence of myocardial dysfunction has not been adequately demonstrated. The diagnostic value of cardiac biomarkers is unknown. Histopathological changes in the myocardium have been clearly shown, with myocardial inflammation and vasculitis present in postmortem studies. Nonetheless, the pathophysiology of cardiac involvement in leptospirosis is poorly understood. Cardiac involvement, demonstrated electrocardiographically or clinically, tends to predict poor outcome. No specific therapies are available to prevent or treat cardiac involvement in leptospirosis; current management is based on correction of deranged homeostasis and supportive therapy. Evidence suggests that direct myocardial damage occurs in patients with severe leptospirosis, and further studies are recommended to elucidate its pathophysiology, clinical features and contribution to overall prognosis, and to identify appropriate diagnostic investigations and specific therapies. PMID:22818758

Navinan, Mitrakrishnan Rayno; Rajapakse, Senaka

2012-09-01

202

Indonesian drilling maintains steady pace  

SciTech Connect

Offshore drilling activity in Indonesia increased nominally the first quarter of 1985 to an average 29 rigs. Barring any further problems with oil prices and markets, operators are expected to maintain essentially the current general level of appraisal/development work for the rest of this year. There are still a number of prospective regions to be explored in Southeast Asia. Regional developments are described for the South China Sea area, the Java Sea, South Sumatra, Kalimantan, Irian Jaya and the Malacca Strait.

Not Available

1985-05-01

203

NITROGEN OUTPUTS OF SMALL MAMMALS FROM FECAL AND URINE DEPOSITION: IMPLICATIONS FOR NITROGEN CYCLING  

EPA Science Inventory

The contribution of small mammals in nitrogen cycling is poorly understood and could have reverberations back to the producer community by maintaining or even magnifying increased nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) ...

204

High output power widely tunable laser module  

NASA Astrophysics Data System (ADS)

We have developed highly reliable widely tunable module, whose performances were comparable with fixed-wavelength DFB laser module. To realize wide tunability, 12 l/4-shifted DFB laser array, S-bend waveguides, MMI coupler and an SOA were integrated on a chip. We could achieve 37nm tunability by controlling each chip temperature in the range of 5 to 45°C. High output fiber coupled power of 30mW and very uniform L-I curves out of 12 DFB lasers were achieved even at 50°C. Good quality of lasing spectrum was obtained. Side mode suppression ratio (SMSR) > 45dB. The well-suppressed reflection at chip front facet contributed to the lower noise characteristics, such as RIN < -140dB/Hz and linewidth < 4MHz. The shift of locked frequency was less than 0.4GHz as the case temperature varied from -5 to 75°C. Very small frequency shift was realized by controlling the temperature of locker part, independently. By optimizing TEC design, we could achieve low TEC power consumption less than 4W under Tcase=75°C and the end of life condition of SOA current. The new function by incorporating SOA was VOA. By changing the operating SOA current, we could vary output power from 1mW to 20mW, maintaining SMSR > 40dB, RIN < -135dB/Hz, linewidth < 4MHz. We also performed optical blocking > 40dB, when SOA current was turned off. We examined modules reliability under high temperature storage of 85°C. The change of output power was < +/- 10%, and the shift of locked frequency was < +/- 5pm after 2000 hours.

Mukaihara, Toshikazu; Kurobe, Tatsuro; Kimoto, Tatsuya; Shinagawa, Tatsuyuki; Nishita, Masayoshi; Kasukawa, Akihiko

2004-10-01

205

Cardiac muscle cells  

NSDL National Science Digital Library

Cardiac muscles are found only in the heart. They work together to bring deoxygenated blood in and push oxygenated blood out into the body. Essentially, they keep your heart pumping and your body alive.

Nathanael Reveal (None;)

2007-07-02

206

Cardiac ablation procedures  

MedlinePLUS

... 4(6):816-61. Miller JM, Zipes DP. Therapy for cardiac arrhythmias. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . 8th ed. Philadelphia, ...

207

Integrative Cardiac Health Project.  

National Technical Information Service (NTIS)

The Integrative Cardiac Health Project (ICHP) aims to lead the way in Cardiovascular Disease (CVD) Prevention by conducting novel research utilizing a Systems Biology / personalized medicine design to discover and develop practical, effective and preempti...

A. H. Nixon, M. N. Vernalis

2013-01-01

208

Integrative Cardiac Health Project.  

National Technical Information Service (NTIS)

The Integrative Cardiac Health Project (ICHP) aims to lead the way in Cardiovascular Disease (CVD) Prevention by conducting novel research utilizing a Systems Biology / personalized medicine design to discover and develop practical, effective and preempti...

A. H. NIxon, M. N. Vernalis

2011-01-01

209

Integrative Cardiac Health Project.  

National Technical Information Service (NTIS)

The Integrative Cardiac Health Project (ICHP) aims to lead the way in Cardiovascular Disease (CVD) Prevention by conducting novel research utilizing a Systems Biology / personalized medicine design to discover and develop practical, effective and preempti...

A. H. Nixon, M. N. Vernalis

2012-01-01

210

Functional cardiac MR imaging  

NASA Astrophysics Data System (ADS)

Undersampled projection reconstruction acquisitions are investigated for use in functional cardiac MR imaging. 256×256 resolution is obtainable using only 64 projections, with acceptable artifact level. Reduced FOV techniques decrease artifact. Variable angular sampling using projection reconstruction is investigated.

Peters, Dana C.; Epstein, Frederick H.; McVeigh, Elliot R.

2000-10-01

211

Cardiac arrest during pregnancy.  

PubMed

Cardiac arrest is a rare event during pregnancy. The pregnant population represents a unique subset of cardiac arrest victims. Not only are there unique causes of circulatory collapse during the pregnant state, but the physiological modifications to the maternal physiology during pregnancy require specific modifications to the standard management of the arrest. Lastly, the pregnant victim presents herself with the challenges of a second patient who needs to be considered in the decision-making process. PMID:25314090

Montufar-Rueda, Carlos; Gei, Alfredo

2014-12-01

212

Impairment of cardiac function and energetics in experimental renal failure.  

PubMed Central

Cardiac function and energetics in experimental renal failure in the rat (5/6 nephrectomy) have been investigated by means of an isolated perfused working heart preparation and an isometric Langendorff preparation using 31P nuclear magnetic resonance (31P NMR). 4 wk after nephrectomy cardiac output of isolated hearts perfused with Krebs-Henseleit buffer was significantly lower (P < 0.0001) at all levels of preload and afterload in the renal failure groups than in the pair-fed sham operated control group. In control hearts, cardiac output increased with increases in perfusate calcium from 0.73 to 5.61 mmol/liter whereas uremic hearts failed in high calcium perfusate. Collection of 31P NMR spectra from hearts of renal failure and control animals during 30 min normoxic Langendorff perfusion showed that basal phosphocreatine was reduced by 32% to 4.7 mumol/g wet wt (P < 0.01) and the phosphocreatine to ATP ratio was reduced by 32% (P < 0.01) in uremic hearts. During low flow ischemia, there was a substantial decrease in phosphocreatine in the uremic hearts and an accompanying marked increase in release of inosine into the coronary effluent (14.9 vs 6.1 microM, P < 0.01). We conclude that cardiac function is impaired in experimental renal failure, in association with abnormal cardiac energetics and increased susceptibility to ischemic damage. Disordered myocardial calcium utilization may contribute to these derangements. PMID:8254048

Raine, A E; Seymour, A M; Roberts, A F; Radda, G K; Ledingham, J G

1993-01-01

213

Multi-Output Battery Cells  

E-print Network

+ + + _ _ _ Fig.2 Multi-output SC (MoSC) based power management system. Intermediate bus Battery cells LDO loads power management system. A LOW-VOLUME POWER MANAGEMENT MODULE FOR PORTABLE APPLICATIONS BASED ON A MULTI,prodic}@ele.utoronto.ca Abstract-- This paper introduces a 2-stage power management architecture for battery powered portable

Prodiæ, Aleksandar

214

Viewing Output With IRIS Explorer  

E-print Network

combination of components may be displayed together. The user may view the output from any angle or distance pages or help files for use on other machines. After reading this overview, you may wish to run through via anonymous ftp from: bishop.stanford.edu in the directory /pub/p3dexplorer These tools may

Cooke, Michele

215

Output prediction of cone crushers  

Microsoft Academic Search

The output prediction of cone crushers has been focused on both by the aggregate producing industry and the mining industry as the demands for higher quality and lower costs increase. In this paper a method for prediction of cone crusher performance is presented By using the method both product size distributions and total capacity can be predicted. By combining these

C. M. Evertsson

1998-01-01

216

Abnormal Cardiac Autonomic Regulation in Mice Lacking ASIC3  

PubMed Central

Integration of sympathetic and parasympathetic outflow is essential in maintaining normal cardiac autonomic function. Recent studies demonstrate that acid-sensing ion channel 3 (ASIC3) is a sensitive acid sensor for cardiac ischemia and prolonged mild acidification can open ASIC3 and evoke a sustained inward current that fires action potentials in cardiac sensory neurons. However, the physiological role of ASIC3 in cardiac autonomic regulation is not known. In this study, we elucidate the role of ASIC3 in cardiac autonomic function using Asic3?/? mice. Asic3?/? mice showed normal baseline heart rate and lower blood pressure as compared with their wild-type littermates. Heart rate variability analyses revealed imbalanced autonomic regulation, with decreased sympathetic function. Furthermore, Asic3?/? mice demonstrated a blunted response to isoproterenol-induced cardiac tachycardia and prolonged duration to recover to baseline heart rate. Moreover, quantitative RT-PCR analysis of gene expression in sensory ganglia and heart revealed that no gene compensation for muscarinic acetylcholines receptors and beta-adrenalin receptors were found in Asic3?/? mice. In summary, we unraveled an important role of ASIC3 in regulating cardiac autonomic function, whereby loss of ASIC3 alters the normal physiological response to ischemic stimuli, which reveals new implications for therapy in autonomic nervous system-related cardiovascular diseases. PMID:24804235

Cheng, Ching-Feng; Kuo, Terry B. J.; Chen, Wei-Nan

2014-01-01

217

Increasing atrial pressure during cardiac tamponade does not elevate plasma levels of the peptide ANP in conscious dogs.  

PubMed Central

1. Factors influencing the release of atrial natriuretic peptide (ANP) are not well understood. We chose a conscious euvolaemic canine model of cardiac tamponade to investigate the roles played by atrial blood pressure, transmural atrial pressure, atrial size, and arginine vasopressin (AVP) on ANP release since during cardiac tamponade the atrial transmural pressure and size decrease as atrial pressure increases. The haemodynamic response to acute cardiac tamponade in conscious dogs differs from that in anaesthetized or convalescent animals. 2. Eighteen mongrel dogs were prepared for the chronic measurement of: ascending aortic blood flow (electromagnetic flowmeter); intrapericardial, right atrial and aortic blood pressures, and the evaluation of right atrial size (two-dimensional echocardiography). After the animals had recovered from surgery, data were collected during progressive cardiac tamponade induced by intrapericardial infusion of warmed saline (20 ml/min) to the point of haemodynamic decompensation. Decompensated cardiac tamponade (DCT) was defined as a decline in mean aortic blood pressure to 70% of the level present when the pericardial space was drained of fluid (baseline) and was produced in all animals within 25 min. Plasma ANP and AVP levels were measured at selected intervals. 3. Cardiac output decreased progressively as intrapericardial pressure, right atrial blood pressure and heart rate increased. Mean aortic blood pressure was well maintained until late in tamponade when it declined rapidly, while atrial transmural pressure and atrial size decreased continuously. These haemodynamic changes were associated with stable ANP plasma levels. There was no significant change in AVP plasma levels from the baseline level of 2.5 +/- 0.4 pg/ml until the point of DCT when they abruptly increased to 117 +/- 36.4 pg/ml. 4. The ability to increase ANP plasma levels was confirmed in a subgroup of animals by noting the response to AVP injection. Although the animals were able to increase plasma ANP levels in response to AVP injection (when intrapericardial pressure was normal) and the plasma AVP level was markedly increased late in tamponade, the time course of plasma AVP elevation could not explain why plasma ANP levels did not decrease as atrial transmural pressure and atrial size declined. 5. Thus, although atrial distention and not simply atrial blood pressure must play a dominant role in stimulating ANP release from the atria, decreased atrial size does not result in lowering of plasma ANP levels below baseline levels in this conscious euvolaemic canine model. PMID:2140860

Klopfenstein, H S; Mathias, D W; Bernath, G A; Cogswell, T L

1990-01-01

218

Explicit feedback maintains implicit knowledge.  

PubMed

The role of feedback was investigated with respect to conscious and unconscious knowledge acquired during artificial grammar learning (AGL). After incidental learning of training sequences, participants classified further sequences in terms of grammaticality and reported their decision strategy with or without explicit veridical feedback. Sequences that disobeyed the learning structure conformed to an alternative structure. Feedback led to an increase in the amount of reported conscious knowledge of structure (derived rules and recollections) but did not increase its accuracy. Conversely, feedback maintained the accuracy of unconscious knowledge of structure (intuition or familiarity-based responses) which otherwise degraded. Results support a dual-process account of AGL. They suggest that implicit learning of the to-be-rejected structure at test contaminates familiarity-based classifications whereas feedback allows competing familiarity signals to be contextualised, which is incompatible with theories that consider familiarity context-insensitive. PMID:23770696

Mealor, Andy D; Dienes, Zoltan

2013-09-01

219

Adolescents and headaches: maintaining control.  

PubMed

Migraine headaches, much like a chronic illness, are reported to negatively affect adolescents physically, mentally, and socially, further disturbing this already turbulent time of development. Prior migraine research is limited in adolescents, and no qualitative studies have examined the lived experience of adolescents with migraines. This interpretive phenomenological study explored the experience of living with migraines in six adolescents ranging in age from 12 to 17 years. After coding data and grouping into clusters, three themes emerged: 1) maintaining control by either pressing on and enduring the burden, or by disengaging and isolating self; 2) mind overload; and 3) unsettling manifestations. Adolescents approach migraine episodes by either continuing with their life as "normal," or by removing themselves physically and/or emotionally. By understanding the potentially unique physical and psychological disruptions that adolescents with migraines experience, nurses can offer education, provide nonpharmacologic interventions, and conduct further research that will improve health outcomes. PMID:23540101

Helvig, Ashley W; Minick, Ptlene

2013-01-01

220

Vasoplegia during cardiac surgery: current concepts and management.  

PubMed

Vasoplegic syndrome (VS) is a recognized and relatively common complication of cardiopulmonary bypass (CPB), appearing with an incidence ranging between 5% and 25%. It is characterized by significant hypotension, high or normal cardiac outputs and low systemic vascular resistance (SVR), and increased requirements for fluids and vasopressors during or after CPB. Patients developing VS are at increased risk for death and other major complications following cardiac surgery. This review will focus on the pathophysiology and contemporary strategies of treating VS encountered after CPB. PMID:21092891

Fischer, Gregory W; Levin, Mathew A

2010-01-01

221

Berberine attenuates cardiac dysfunction in hyperglycemic and hypercholesterolemic rats.  

PubMed

The positive effects of berberine (30 mg/kg/day, i.g. for 6 weeks) on cardiac dysfunction were evaluated in the rat model of hyperglycemia and hypercholesterolemia. Hyperglycemia and hypercholesterolemia were induced by feeding high-sucrose/fat diet (HSFD) consisting of 20% sucrose, 10% lard, 2.5% cholesterol, 1% bile salt for 12 weeks and streptozotocin (30 mg/kg, i.p.). The plasma sugar, total cholesterol, and triglyceride levels were significantly increased (422, 194 and 82%, respectively) in the HSFD/streptozotocin-treated rats, when compared with control animals receiving normal diet and vehicle. Berberine treatment reduced the plasma sugar and lipid levels by 24-69% in the rat model of hyperglycemia and hypercholesterolemia. Cardiac functions signed as values of cardiac output, left ventricular systolic pressure, the maximum rate of myocardial contraction (+dp/dtmax), left ventricular end diastolic pressure and the maximum rate of myocardial diastole (-dp/dtmax) were injured by 16-55% in the hyperglycemic/hypercholesterolemic rats. Berberine increased cardiac output, left ventricular systolic pressure and +dp/dtmax by 64, 16 and 79%, but decreased left ventricular end diastolic pressure and -dp/dtmax by 121 and 61% in the rats receiving HSFD/streptozotocin, respectively, when compared with the drug-untreated rats of hyperglycemia and hypercholesterolemia. Berberine caused significant increase in cardiac fatty acid transport protein-1 (159%), fatty acid transport proteins (56%), fatty acid beta-oxidase (52%), as well as glucose transporter-4 and peroxisome proliferator-activated receptor-? (PPAR?), but decrease in PPAR? mRNA and protein expression in hyperglycemic/hypercholesterolemic rats. These results indicated that berberine exerted protective effects on cardiac dysfunction induced by hyperglycemia/hypercholesterolemia through alleviating cardiac lipid accumulation and promoting glucose transport. PMID:21458442

Dong, Shi-Fen; Hong, Ying; Liu, Ming; Hao, Ying-Zhi; Yu, Hai-Shi; Liu, Yang; Sun, Jian-Ning

2011-06-25

222

Standardized multiple output power supply  

NASA Technical Reports Server (NTRS)

A comprehensive program to develop a prototype model of a standardized multiple output power supply for use in space flight applications is described. The prototype unit was tested and evaluated to assure that the design would provide near optimum performance for the planned application. The prototype design used a dc-to-dc converter incorporating reqenerative current feedback with a time-ratio controlled duty cycle to achieve high efficiency over a wide variation of input voltage and output loads. The packaging concept uses a mainframe capable of accommodating up to four inverter/regulator modules with one common input filter and housekeeping module. Each inverter/regulator module provides a maximum of 100 watts or 10 amperes. Each module is adaptable to operate at any voltage between 4.0 volts and 108 volts. The prototype unit contains +5, + or - 15 and +28 volt modules.

Ragusa, E. V.

1975-01-01

223

Microgyroscope with closed loop output  

NASA Technical Reports Server (NTRS)

A micro-gyroscope (10) having closed loop operation by a control voltage (V.sub.TY), that is demodulated by an output signal of the sense electrodes (S1, S2), providing Coriolis torque rebalance to prevent displacement of the micro-gyroscope (10) on the output axis (y-axis). The present invention provides wide-band, closed-loop operation for a micro-gyroscope (10) and allows the drive frequency to be closely tuned to a high Q sense axis resonance. A differential sense signal (S1-S2) is compensated and fed back by differentially changing the voltage on the drive electrodes to rebalance Coriolis torque. The feedback signal is demodulated in phase with the drive axis signal (K.sub..omega..crclbar..sub.x) to produce a measure of the Coriolis force.

Challoner, A. Dorian (Inventor); Gutierrez, Roman C. (Inventor); Tang, Tony K. (Inventor); Cargille, Donald R. (Inventor)

2002-01-01

224

Thymic output, ageing and zinc  

Microsoft Academic Search

The role of the thymus is vital for orchestration of T-cell development and maturation. With increasing age the thymus undergoes a process of involution which results in a reduction in thymic size, function and output. Until relatively recent it was not feasible to accurately measure the magnitude of age-related loss of thymic function. With the discovery of T-cell receptor excision

Wayne A Mitchell; Irene Meng; Stuart A Nicholson; Richard Aspinall

2006-01-01

225

Minimal output sets for identifiability.  

PubMed

Ordinary differential equation models in biology often contain a large number of parameters that must be determined from measurements by parameter estimation. For a parameter estimation procedure to be successful, there must be a unique set of parameters that can have produced the measured data. This is not the case if a model is not uniquely structurally identifiable with the given set of outputs selected as measurements. In designing an experiment for the purpose of parameter estimation, given a set of feasible but resource-consuming measurements, it is useful to know which ones must be included in order to obtain an identifiable system, or whether the system is unidentifiable from the feasible measurement set. We have developed an algorithm that, from a user-provided set of variables and parameters or functions of them assumed to be measurable or known, determines all subsets that when used as outputs give a locally structurally identifiable system and are such that any output set for which the system is structurally identifiable must contain at least one of the calculated subsets. The algorithm has been implemented in Mathematica and shown to be feasible and efficient. We have successfully applied it in the analysis of large signalling pathway models from the literature. PMID:22609467

Anguelova, Milena; Karlsson, Johan; Jirstrand, Mats

2012-09-01

226

Pediatric sudden cardiac arrest.  

PubMed

Pediatric sudden cardiac arrest (SCA), which can cause sudden cardiac death if not treated within minutes, has a profound effect on everyone: children, parents, family members, communities, and health care providers. Preventing the tragedy of pediatric SCA, defined as the abrupt and unexpected loss of heart function, remains a concern to all. The goal of this statement is to increase the knowledge of pediatricians (including primary care providers and specialists) of the incidence of pediatric SCA, the spectrum of causes of pediatric SCA, disease-specific presentations, the role of patient and family screening, the rapidly evolving role of genetic testing, and finally, important aspects of secondary SCA prevention. This statement is not intended to address sudden infant death syndrome or sudden unexplained death syndrome, nor will specific treatment of individual cardiac conditions be discussed. This statement has been endorsed by the American College of Cardiology, the American Heart Association, and the Heart Rhythm Society. PMID:22451713

2012-04-01

227

Constraints for Input\\/Output Logics  

Microsoft Academic Search

In a previous paper we developed a general theory of input\\/output logics. These are operations resembling inference, but where inputs need not be included among outputs, and outputs need not be reusable as inputs. In the present paper we study what happens when they are constrained to render output consistent with input. This is of interest for deontic logic, where

David Makinson; Leendert van der Torre

2001-01-01

228

Polarization-maintaining picosecond oscillator based on quantum dot SESAM  

NASA Astrophysics Data System (ADS)

We report a simple, environmentally-stable, passively mode-locked Yb-based fiber oscillator operating at 1035 nm with pulse duration of ~5 ps. Mode-locking was achieved using a saturable absorber mirror. The output of the laser exhibited a polarization extinction ratio >20 dB with the implementation a polarization maintaining fiber cavity and a polarization sensitive fiber coupler. The laser outputted near transform-limited pulses at 25-100 MHz at a pump threshold of 20-30 mW. We have tested operation of the laser using two different saturable absorber mirror structures: multiple quantum wells and quantum-dots at 1035 nm. Pulse properties and laser performance were comparable using quantum-dots and multiple quantum wells as the saturable absorber.

Crittenden, Paul; Starodumov, Andrei; Reed, Murray

2006-02-01

229

Dynamic Control of Cardiac Alternans  

NASA Astrophysics Data System (ADS)

A dynamic control technique was used to suppress a cardiac arrhythmia called an alternans rhythm in a piece of dissected rabbit heart. Our control algorithm adapted to drifting system parameters, making it well suited for the control of physiological rhythms. Control of cardiac alternans rhythms may have important clinical implications since they often precede serious cardiac arrhythmias and are a harbinger of sudden cardiac death.

Hall, Kevin; Christini, David J.; Tremblay, Maurice; Collins, James J.; Glass, Leon; Billette, Jacques

1997-06-01

230

Penetrating Cardiac Injury: A Review  

PubMed Central

Cardiac injury presents a great challenge to the emergency resident because these injuries require urgent intervention to prevent death. Sometimes serious cardiac injury may manifest only subtle or occult symptoms or signs. As there is an epidemic of cardiac injuries in Kashmir valley due to problems of law and order, we herein present a review on management of such injuries. PMID:24829887

Lateef Wani, Mohd; Ahangar, Ab Gani; Wani, Shadab Nabi; Irshad, Ifat; Ul-Hassan, Nayeem

2012-01-01

231

Cardiac Response and Personality Organization  

ERIC Educational Resources Information Center

This study examines the level and variability of cardiac response during complex problem-solving and interposed rest periods and their differing relationships to estimates of personality integration on the Rorschach. Findings suggest cardiac variability may be a more differentiated measure than level of cardiac response. (Author)

Blatt, Sidney J.; Feirstein, Alan

1977-01-01

232

Management of the pediatric patient after cardiac surgery.  

PubMed Central

The medical management of the child with congenital cardiac disease prior to and following cardiac surgery has made a substantial contribution to the improved morbidity and mortality attributed to surgical advances. This paper provides a framework for understanding the problems that arise in the perioperative period and a systematic approach, by organ system, to monitoring and management of these problems. The discussion is intended to be of general application, focusing on initial stabilization following surgery and the cardiorespiratory, renal, metabolic, hematologic, and neurologic alterations that result from surgery with cardiopulmonary bypass. An approach for the management of the low output state is also provided. Little attempt has been made to focus on problems unique to a specific type of cardiac disease or certain operative approaches. Rather, it is the contention that an understanding of general principles and an appreciation of the common problems will provide adequate preparation for those responsible for the care of the child. PMID:6375165

Lister, G.

1984-01-01

233

Impact of obesity and weight loss on cardiac performance and morphology in adults.  

PubMed

Obesity, particularly severe obesity is capable of producing hemodynamic alterations that predispose to changes in cardiac morphology and ventricular function. These include increased cardiac output, left ventricular hypertrophy and diastolic and systolic dysfunction of both ventricles. Facilitated by co-morbidities such as hypertension, the sleep apnea/obesity hypoventilation syndrome, and possibly certain neurohormonal and metabolic alterations, these abnormalities may predispose to left and right heart failure, a disorder known as obesity cardiomyopathy. PMID:24438730

Alpert, Martin A; Omran, Jad; Mehra, Ankit; Ardhanari, Sivakumar

2014-01-01

234

Effects of Chronic Aluminum Exposure on Swimming and Cardiac Performance in Rainbow Trout, Oncorhynchus mykiss  

Microsoft Academic Search

Rainbow trout were exposed to 0–80 ?g l?1 aluminum (Al) at pH 5.2 in synthetic soft water, for up to 8 weeks. Trout were submitted to an incremental swimming test to quantify their aerobic swimming capacity (Ucrit). After a simple, non-invasive cardiac surgery to install Doppler flow probes, their heart rate, cardiac output and stroke volume were measured while swimming at increasing water velocities.

È. B Dussault; R. C Playle; D. G Dixon; R. S McKinley

2004-01-01

235

Advanced Cardiac Life Support.  

ERIC Educational Resources Information Center

This document contains materials for an advanced college course in cardiac life support developed for the State of Iowa. The course syllabus lists the course title, hours, number, description, prerequisites, learning activities, instructional units, required text, six references, evaluation criteria, course objectives by units, course…

Kirkwood Community Coll., Cedar Rapids, IA.

236

Nonexercise cardiac stress testing  

SciTech Connect

Many patients who require evaluation for coronary artery disease are unable to undergo exercise stress testing because of physiologic or psychological limitations. Drs Vacek and Baldwin describe three alternative methods for assessment of cardiac function in these patients, all of which have high levels of diagnostic sensitivity and specificity. 23 references.

Vacek, J.L.; Baldwin, T. (Univ. of Kansas Medical Center, Kansas City (USA))

1989-09-15

237

Cardiac disease in pregnancy.  

PubMed

Cardiac disease complicates approximately 1% to 3% of pregnancies and is responsible for 10% to 15% of maternal mortality. The number of women of childbearing age with congenital disease is increasing as advances in diagnosis and treatment improve survival rates and overall health, allowing successful pregnancy. Pregnant women with severe cardiac disease or women who experience a cardiac event during pregnancy will require admission and stabilization in an adult critical care unit. This group of patients can prove challenging for the obstetrical staff and the critical care staff because they require blending of the knowledge and skills of 2 highly specialized areas of healthcare. The key component to a comprehensive and organized approach to management that ensures the best possible outcome for the woman is a multidisciplinary team that devises a plan on the basis of the most current information, communicates with each other and the patient effectively, and assumes responsibility for implementation of the plan. The purpose of this article is to review management of the woman with cardiac disease throughout pregnancy. PMID:16456361

Arafeh, Julie M R; Baird, Suzanne McMurtry

2006-01-01

238

Cardiac and Pulmonary Injury  

Microsoft Academic Search

Cardiac and pulmonary injuries present major chal- lenges in diagnosis and treatment. Distinct differences between penetrating and blunt trauma of these or- gans exist. Outcomes for severe injuries are still grave. Organized trauma systems can provide optimal care by minimizing prehospital time, allowing easy access to imaging modalities, and offering state-of-the-art treatment strategies. A multidisciplinary approach, including surgeons, intensivists, and

George C. Velmahos; Muhammad U. Butt

2008-01-01

239

The cardiac malpositions.  

PubMed

Dextrocardia was known in the 17th century and was 1 of the first congenital malformations of the heart to be recognized. Fifty years elapsed before Matthew Baillie published his account of complete transposition in a human of the thoracic and abdominal viscera to the opposite side from what is natural. In 1858, Thomas Peacock stated that "the heart may be congenitally misplaced in various ways, occupying either an unusual position within the thorax, or being situated external to that cavity." In 1915, Maude Abbott described ectopia cordis, and Richard Paltauf's remarkable illustrations distinguished the various types of dextrocardia. In 1928, the first useful classification of the cardiac malpositions was proposed, and in 1966, Elliott et al's radiologic classification set the stage for clinical recognition. The first section of this review deals with the 3 basic cardiac malpositions in the presence of bilateral asymmetry. The second section deals with cardiac malpositions in the presence of bilateral left-sidedness or right-sidedness. Previous publications on cardiac malpositions are replete with an arcane vocabulary that confounds rather than clarifies. Even if the terms themselves are understood, inherent complexity weighs against clarity. This review was designed as a guided tour of an unfamiliar subject. PMID:21861958

Perloff, Joseph K

2011-11-01

240

Biomechanics of Early Cardiac Development  

PubMed Central

Biomechanics affect early cardiac development, from looping to the development of chambers and valves. Hemodynamic forces are essential for proper cardiac development, and their disruption leads to congenital heart defects. A wealth of information already exists on early cardiac adaptations to hemodynamic loading, and new technologies, including high resolution imaging modalities and computational modeling, are enabling a more thorough understanding of relationships between hemodynamics and cardiac development. Imaging and modeling approaches, used in combination with biological data on cell behavior and adaptation, are paving the road for new discoveries on links between biomechanics and biology and their effect on cardiac development and fetal programming. PMID:22760547

Goenezen, Sevan; Rennie, Monique Y.

2012-01-01

241

Ethical Issues in Cardiac Surgery  

PubMed Central

While ethical behavior has always been part of cardiac surgical practice, ethical deliberation has only recently become an important component of cardiac surgical practice. Issues such as informed consent, conflict of interest, and professional self-regulation, among many others, have increasingly attracted the attention of cardiac surgeons. This review covers several broad topics of interest to cardiac surgeons and cardiologists, and treats several other topics more briefly. There is much uncertainty about what the future holds for cardiac surgical practice, research, and culture, and we discuss the background of ethical issues to serve as a platform for envisioning what is to come. PMID:22642634

Kavarana, Minoo N.; Sade, Robert M.

2012-01-01

242

Cardiac surgery outcomes.  

PubMed

Accrediting organizations and payers are demanding valid and reliable data that demonstrate the value of services. Federal agencies, healthcare industry groups, and healthcare watchdog groups are increasing the demand for public access to outcomes data. A new and growing outcomes dynamic is the information requested by prospective patients in an increasingly consumer-oriented business. Patients demand outcomes, and resources are developing to meet these demands. Physicians are increasingly confronted with requests for information about their mortality and morbidity rates, malpractice suits, and disciplinary actions received. For example, in Virginia, prospective patients have access to data provided by the nonprofit group Virginia Health Information. After numerous resolutions by the Virginia Senate since 1999, the prospective Virginia medical consumer now has access to several annual publications: Virginia Hospitals: A Consumer's Guide, 1999 Annual Report and Strategic Plan Update, and the 1999 Industry Report: Virginia Hospitals and Nursing Facilities. Consumers have access to cardiac outcomes data stratified by hospital, gender, and cardiac service line (cardiac surgery, noninvasive cardiology, and invasive cardiology). This is particularly relevant to IHI because Virginia Health Information specifically targets cardiac care. IHI has a sizable investment in cardiovascular outcomes and has found outcomes measurement and research are key to providing quality care. IHI's goal is to move from an outcomes management model to a disease management model. The hope is to incorporate all aspects of the patient's continuum of care, from preoperative and diagnostic services through cardiac interventions to postoperative rehabilitation. Furthermore, every step along the way will be supported with functional status and quality of life assessments. Although these goals are ambitious and expensive, the return on investment is high. PMID:14618772

Halpin, Linda S; Barnett, Scott D; Beachy, Jim

2003-01-01

243

Building and Maintaining Successful Relationships between  

E-print Network

Building and Maintaining Successful Relationships between Reservation and University Programs Vogt Building and maintaining successful relationships between Indian reservations and University activity (Demmert 2001). When young people were no longer learning from tribal elders and other adults

Blanchette, Robert A.

244

Regulation of the cardiac Na(+) pump by palmitoylation of its catalytic and regulatory subunits.  

PubMed

The Na+/K+-ATPase (Na+ pump) is the principal consumer of ATP in multicellular organisms. In the heart, the Na+ gradient established by the pump is essential for all aspects of cardiac function, and appropriate regulation of the cardiac Na+ pump is therefore crucial to match cardiac output to the physiological requirements of an organism. The cardiac pump is a multi-subunit enzyme, consisting of a catalytic ?-subunit and regulatory ?- and FXYD subunits. All three subunits may become palmitoylated, although the functional outcome of these palmitoylation events is incompletely characterized to date. Interestingly, both ?- and FXYD subunits may be palmitoylated or glutathionylated at the same cysteine residues. These competing chemically distinct post-translational modifications may mediate functionally different effects on the cardiac pump. In the present article, we review the cellular events that control the balance between these modifications, and discuss the likely functional effects of pump subunit palmitoylation. PMID:23356265

Howie, Jacqueline; Tulloch, Lindsay B; Shattock, Michael J; Fuller, William

2013-02-01

245

[Relation between cardiac function and the pulse condition, sphygmogram in patients with hemopathy].  

PubMed

The authors determined the impedance plethysmogram, differentiator (dz/dt), carotid arterial pulse wave, apexcardiogram, electrocardiogram and radial sphygmogram of 106 cases with hemopathy by using a RM-6000 polygraph systems. The results showed that the cardiac function of the patients with hemopathy had obviously been injured. The time of ejecting blood was shortened markedly in the left ventricle. The heart rate increased, total peripheral resistance and cardiac output decreased. These led to the formation of rapid slippery and thready pulse. The formation of string-like pulse is related to the injury of cardiac function and decrease of the arterial compliance. PMID:1504532

Chen, S Y

1992-03-01

246

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

247

[Cardiac glycosides: From ancient history through Withering's foxglove to endogeneous cardiac glycosides].  

PubMed

For centuries, drugs that increase the power of contraction of the failing heart have been used for the treatment of congestive heart failure (dropsy). The cardiac effect is due to the content of cardiac glycosides. Squill or sea onion, Urginea (Scilla) maritima, a seashore plant, was known by the ancient Romans and Syrians and possibly also by the ancient Egyptians. Squills were used erratically, but some prescriptions indicate that they may have been used for the treatment of oedematous states. The toxic effect of strophanthus species was known from poisoned arrows used by the natives in Africa. Digitalis, derived form the foxglove plant, Digitalis purpurea, is mentioned in writings as early as 1250; a Welsh family, known as the Physicians of Myddvai, collected different herbs and digitalis was included in their prescriptions. However, the druge was used erratically until the 18th century, when William Withering, an English physician and botanist, published a monograph describing the clinical effects of an extract of the foxglove plant. Later, in 1785, the indication and the toxicity of digitalis were reported in his book, "An account of the Foxglove and some of its medical uses with practical remarks on dropsy, and other diseases". In Denmark, the leaves of Digitalis purpurea or Digitalis lanata were tested for cardiac glycoside activity. The standardized digitalis powder was used in tinctures, infusions, and tablets. The preparations were included in successive editions of the Danish pharmacopoeia, some of the tinctures already in 1828, i.e. before the standardization of the drug. Isolation of cardiac glycosides from digitalis, strophanthus and squill and determination of their chemical structures initiated biochemical and pharmacological studies. The scientific advances led to an understanding of cardiac muscle contractility and the Na,K pump as the cellular receptor for the inotropic action of digitalis. Examination of putative endogenous ligands to the receptor revealed some endogenous cardiac glycosides of similar or identical structures as those found in digitalis, strophanthus and squill. Increased concentrations of these glycosides are found in patients with heart failure. Further investigations are needed to determine whether the secretion of glycosides might be a physiologic response to a diminished cardiac output. PMID:15685783

Norn, Svend; Kruse, Poul R

2004-01-01

248

The Network Structure of Economic Output  

E-print Network

Much of the analysis of economic growth has focused on the study of aggregate output. Here, we deviate from this tradition and look instead at the structure of output embodied in the network connecting countries to the ...

Hidalgo, Cesar A.

249

Cardiac nuclear medicine  

SciTech Connect

The book begins with a review of the radionuclide methods available for evaluating cardiac perfusion and function. The authors discuss planar and tomographic thallium myocardial imaging, first-pass and equilibrium radionuclide angiography, and imaging with infarct-avid tracers. Several common but more specialized procedures are then reviewed: nonogemetric measurement of left ventricular volume, phase (Fourier) analysis, stroke volume ratio, right ventricular function, and diastolic function. A separate chapter is devoted to drug interventions and in particular the use of radionuclide ventriculography to monitor doxorubicin toxicity and therapy of congestive heart failure. The subsequent chapters provide a comprehensive guide to test selection, accuracy, and results in acute myocardial infarction, in postmyocardial infarction, in chronic coronary artery disease, before and after medical or surgical revascularization, in valvular heart disease, in cardiomyopathies, and in cardiac trauma.

Gerson, M.C.

1987-01-01

250

Cardiac assist device infections  

Microsoft Academic Search

Cardiac assist devices have emerged as an increasingly important option for circulatory support in patients with advanced\\u000a congestive heart failure. Infection has been the leading cause of death with use of ventricular assist devices for the past\\u000a 25 years, and continues to be a major cause of morbidity and mortality in this population. Infections may involve the internal\\u000a (blood-containing) components,

Shmuel Shoham; Leslie W. Miller

2009-01-01

251

Oxytocin in cardiac ontogeny  

PubMed Central

Previous studies demonstrated the presence of oxytocin (OT) and oxytocin receptors (OTRs) in the heart. The present work provides results supporting a potential role of OT in cardiomyogenesis. Here, we show a maximal OT and OTR protein level in the developing rat heart at day 21 of gestation and postnatal days 1-4, when cardiac myocytes are at a stage of intense hyperplasia. Between postnatal days 1 and 66, OT decreased linearly in all heart chambers (4.1- to 6.6-fold). Correspondingly, immunocytochemistry demonstrated that OTRs, which were eminent in postnatal cardiomyocytes, declined with age to low levels in adults. Interestingly, in coronary vasculature, OTRs developed in endothelial cells at postnatal days 12 and 22 and achieved a plateau in adult rats. These findings suggest that OT can be involved in developmental formation of the coronary vessels. In vivo, the OT/OTR system in the fetal heart was sensitive to the actions of retinoic acid (RA), recognized as a major cardiac morphogen. RA treatment produced a significant increase (2- to 3-fold) both in the OT concentration and in the OT mRNA levels. Ex vivo, an OT antagonist inhibited RA-mediated cardiomyocyte differentiation of P19 embryonic stem cells. The decline of cardiac OT expression from infancy to adulthood of the rat and changes in cell types expressing OTR indicate a dynamic regulation of the OT system in the heart rather than constitutive expression. The results support the hypothesis that RA induces cardiomyogenesis by activation of the cardiac OT system. PMID:15316117

Jankowski, Marek; Danalache, Bogdan; Wang, Donghao; Bhat, Pangala; Hajjar, Fadi; Marcinkiewicz, Mieczyslaw; Paquin, Joanne; McCann, Samuel M.; Gutkowska, Jolanta

2004-01-01

252

Oxytocin in cardiac ontogeny.  

PubMed

Previous studies demonstrated the presence of oxytocin (OT) and oxytocin receptors (OTRs) in the heart. The present work provides results supporting a potential role of OT in cardiomyogenesis. Here, we show a maximal OT and OTR protein level in the developing rat heart at day 21 of gestation and postnatal days 1-4, when cardiac myocytes are at a stage of intense hyperplasia. Between postnatal days 1 and 66, OT decreased linearly in all heart chambers (4.1- to 6.6-fold). Correspondingly, immunocytochemistry demonstrated that OTRs, which were eminent in postnatal cardiomyocytes, declined with age to low levels in adults. Interestingly, in coronary vasculature, OTRs developed in endothelial cells at postnatal days 12 and 22 and achieved a plateau in adult rats. These findings suggest that OT can be involved in developmental formation of the coronary vessels. In vivo, the OT/OTR system in the fetal heart was sensitive to the actions of retinoic acid (RA), recognized as a major cardiac morphogen. RA treatment produced a significant increase (2- to 3-fold) both in the OT concentration and in the OT mRNA levels. Ex vivo, an OT antagonist inhibited RA-mediated cardiomyocyte differentiation of P19 embryonic stem cells. The decline of cardiac OT expression from infancy to adulthood of the rat and changes in cell types expressing OTR indicate a dynamic regulation of the OT system in the heart rather than constitutive expression. The results support the hypothesis that RA induces cardiomyogenesis by activation of the cardiac OT system. PMID:15316117

Jankowski, Marek; Danalache, Bogdan; Wang, Donghao; Bhat, Pangala; Hajjar, Fadi; Marcinkiewicz, Mieczyslaw; Paquin, Joanne; McCann, Samuel M; Gutkowska, Jolanta

2004-08-31

253

Cardiac hybrid imaging.  

PubMed

Hybrid cardiac single photon emission computed tomography (SPECT)/CT imaging allows combined assessment of anatomical and functional aspects of cardiac disease. In coronary artery disease (CAD), hybrid SPECT/CT imaging allows detection of coronary artery stenosis and myocardial perfusion abnormalities. The clinical value of hybrid imaging has been documented in several subsets of patients. In selected groups of patients, hybrid imaging improves the diagnostic accuracy to detect CAD compared to the single imaging techniques. Additionally, this approach facilitates functional interrogation of coronary stenoses and guidance with regard to revascularization procedures. Moreover, the anatomical information obtained from CT coronary angiography or coronary artery calcium scores (CACS) adds prognostic information over perfusion data from SPECT. The use of cardiac hybrid imaging has been favoured by the dissemination of dedicated hybrid systems and the release of dedicated image fusion software, which allow simple patient throughput for hybrid SPECT/CT studies. Further technological improvements such as more efficient detector technology to allow for low-radiation protocols, ultra-fast image acquisition and improved low-noise image reconstruction algorithms will be instrumental to further promote hybrid SPECT/CT in research and clinical practice. PMID:24658682

Gaemperli, Oliver; Kaufmann, Philipp A; Alkadhi, Hatem

2014-05-01

254

Cardiac Signatures of Personality  

PubMed Central

Background There are well-established relations between personality and the heart, as evidenced by associations between negative emotions on the one hand, and coronary heart disease or chronic heart failure on the other. However, there are substantial gaps in our knowledge about relations between the heart and personality in healthy individuals. Here, we investigated whether amplitude patterns of the electrocardiogram (ECG) correlate with neurotisicm, extraversion, agreeableness, warmth, positive emotion, and tender-mindedness as measured with the Neuroticism-Extraversion-Openness (NEO) personality inventory. Specifically, we investigated (a) whether a cardiac amplitude measure that was previously reported to be related to flattened affectivity (referred to as values) would explain variance of NEO scores, and (b) whether correlations can be found between NEO scores and amplitudes of the ECG. Methodology/Principal Findings NEO scores and rest ECGs were obtained from 425 healthy individuals. Neuroticism and positive emotion significantly differed between individuals with high and low values. In addition, stepwise cross-validated regressions indicated correlations between ECG amplitudes and (a) agreeableness, as well as (b) positive emotion. Conclusions/Significance These results are the first to demonstrate that ECG amplitude patterns provide information about the personality of an individual as measured with NEO personality scales and facets. These findings open new perspectives for a more efficient personality assessment using cardiac measures, as well as for more efficient risk-stratification and pre-clinical diagnosis of individuals at risk for cardiac, affective and psychosomatic disorders. PMID:22363649

Koelsch, Stefan; Enge, Juliane; Jentschke, Sebastian

2012-01-01

255

Cardiac outflow tract anomalies  

PubMed Central

The mature outflow tract (OFT) is, in basic terms, a short conduit. It is a simple, although vital, connection situated between contracting muscular heart chambers and a vast embryonic vascular network. Unfortunately, it is also a focal point underlying many multifactorial congenital heart defects (CHDs). Through the use of various animal models combined with human genetic investigations, we are beginning to comprehend the molecular and cellular framework that controls OFT morphogenesis. Clear roles of neural crest cells (NCC) and second heart field (SHF) derivatives have been established during OFT formation and remodeling. The challenge now is to determine how the SHF and cardiac NCC interact, the complex reciprocal signaling that appears to be occurring at various stages of OFT morphogenesis, and finally how endocardial progenitors and primary heart field (PHF) communicate with both these colonizing extra-cardiac lineages. Although we are beginning to understand that this dance of progenitor populations is wonderfully intricate, the underlying pathogenesis and the spatiotemporal cell lineage interactions remain to be fully elucidated. What is now clear is that OFT alignment and septation are independent processes, invested via separate SHF and cardiac neural crest (CNC) lineages. This review will focus on our current understanding of the respective contributions of the SHF and CNC lineage during OFT development and pathogenesis. PMID:24014420

Neeb, Zachary; Lajiness, Jacquelyn D.; Bolanis, Esther; Conway, Simon J

2014-01-01

256

PULMONARY HEPATIC FLOW DISTRIBUTION IN TOTAL CAVOPULMONARY CONNECTIONS: EXTRA CARDIAC VS INTRA CARDIAC  

PubMed Central

Background Pulmonary arteriovenous malformations (PAVMs) can occur after the Fontan and are believed to be associated with disproportionate pulmonary distribution of hepatic venous effluent. We studied the impact of total cavo-pulmonary connection (TCPC) geometry and the effect of increased cardiac output (CO) on distribution of inferior vena caval (IVC) return to the lungs. Methods 10 Fontan patients – 5 with extra-cardiac (EC) and 5 with intra-cardiac (IC) configurations of the TCPC previously analyzed for power loss were processed for calculating the distribution of inferior vena caval return to the lungs (2nd order accuracy). One idealized TCPC was similarly analyzed under parametric variation of IVC offset and CO flow split Results Streaming of the IVC return in the idealized TCPC model was dependent on both IVC offset magnitude and CO flow split ratio. For patient-specific TCPCs, preferential streaming of the IVC return was directly proportional to CO flow split ratio in the IC type TCPCs (p < 0.0001). Preferential streaming in EC TCPCs correlated to the IVC offset (p<0.05) and did not correlate to CO flow split. Enhanced mixing in IC is speculated to explain the contrasting results. Exercising tends to reduce streaming towards LPA in IC, while for EC, exercising tends to equalize the streaming. Conclusions EC and IC TCPCs have inherently different streaming characteristics due to contrasting mixing characteristics owing to their geometric differences. PA diameters and IVC offsets may together determine hepatic flow streaming. PMID:20621314

Dasi, Lakshmi P.; Whitehead, Kevin; Pekkan, Kerem; de Zelicourt, Diane; Sundareswaran, Kartik; Kanter, Kirk; Fogel, Mark A.; Yoganathan, Ajit P.

2010-01-01

257

Sudden cardiac death – Historical perspectives  

PubMed Central

Sudden cardiac death (SCD) is an unexpected death due to cardiac causes that occurs in a short time period (generally within 1 h of symptom onset) in a person with known or unknown cardiac disease. It is believed to be involved in nearly a quarter of human deaths, with ventricular fibrillation being the most common mechanism. It is estimated that more than 7 million lives per year are lost to SCD worldwide. Historical perspectives of SCD are analyzed with a brief description on how the developments in the management of sudden cardiac arrest evolved over time. PMID:24568828

Abhilash, S.P.; Namboodiri, Narayanan

2014-01-01

258

Maternal hyperglycemia leads to fetal cardiac hyperplasia and dysfunction in a rat model.  

PubMed

Accelerated fetal myocardial growth with altered cardiac function is a well-documented complication of human diabetic pregnancy, but its pathophysiology is still largely unknown. Our aim was to explore the mechanisms of fetal cardiac remodeling and cardiovascular hemodynamics in a rat model of maternal pregestational streptozotocin-induced hyperglycemia. The hyperglycemic group comprised 107 fetuses (10 dams) and the control group 219 fetuses (20 dams). Fetal cardiac function was assessed serially by Doppler ultrasonography. Fetal cardiac to thoracic area ratio, newborn heart weight, myocardial cell proliferative and apoptotic activities, and cardiac gene expression patterns were determined. Maternal hyperglycemia was associated with increased cardiac size, proliferative, apoptotic and mitotic activities, upregulation of genes encoding A- and B-type natriuretic peptides, myosin heavy chain types 2 and 3, uncoupling proteins 2 and 3, and the angiogenetic tumor necrosis factor receptor superfamily member 12A. The genes encoding Kv channel-interacting protein 2, a regulator of electrical cardiac phenotype, and the insulin-regulated glucose transporter 4 were downregulated. The heart rate was lower in fetuses of hyperglycemic dams. At 13-14 gestational days, 98% of fetuses of hyperglycemic dams had holosystolic atrioventricular valve regurgitation and decreased outflow mean velocity, indicating diminished cardiac output. Maternal hyperglycemia may lead to accelerated fetal myocardial growth by cardiomyocyte hyperplasia. In fetuses of hyperglycemic dams, expression of key genes that control and regulate cardiomyocyte electrophysiological properties, contractility, and metabolism are altered and may lead to major functional and clinical implications on the fetal heart. PMID:23839525

Lehtoranta, Lara; Vuolteenaho, Olli; Laine, V Jukka; Koskinen, Anna; Soukka, Hanna; Kytö, Ville; Määttä, Jorma; Haapsamo, Mervi; Ekholm, Eeva; Räsänen, Juha

2013-09-01

259

Cardiac electrophysiology and the susceptibility to sustained ventricular tachycardia in intact, conscious mice.  

PubMed

Cardiac electrophysiological dysfunction is a major cause of death in humans. Accordingly, electrophysiological testing is routinely performed in intact, conscious, humans to evaluate arrhythmias and disorders of cardiac conduction. However, to date, in vivo electrophysiological studies in mice are limited to anesthetized open-chest or closed-chest preparations. However, cardiac electrophysiology in anesthetized mice or mice with surgical trauma may not adequately represent what occurs in conscious mice. Accordingly, an intact, conscious murine model of cardiac electrophysiology has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of cardiac electrophysiology. The conscious mouse model permits measurements of atrioventricular interval, sinus cycle length, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, Wenckebach cycle length, the ventricular effective refractory period (VERP) and the electrical stimulation threshold to induce sustained ventricular tachyarrhythmias in an intact, complex model free of the confounding influences of anesthetics and surgical trauma. This is an important consideration because anesthesia and surgical trauma markedly reduced cardiac output and heart rate as well as altered cardiac electrophysiology parameters. Most importantly, anesthesia and surgical trauma significantly increased the VERP and virtually eliminated the ability to induce sustained ventricular tachyarrhythmias. Accordingly, the methodology allows for the accurate documentation of cardiac electrophysiology in complex, conscious mice and may be adopted for advancing the concepts and ideas that drive cardiovascular research. PMID:24561859

Lujan, Heidi L; DiCarlo, Stephen E

2014-04-15

260

Space Maintainers in Dentistry: Past to Present  

PubMed Central

Early orthodontic interventions are often initiated in the developing dentition to promote favourable developmental changes. Interceptive orthodontic can eliminate or reduce the severity of a developing malocclusion, the complexity of orthodontic treatment, overall treatment time and cost. The safest way to prevent future malocclusions from tooth loss is to place a space maintainer that is effective and durable. An appropriate use of space maintainer is advocated to hold the space until the eruption of permanent teeth. This case report describes the various changing trends in use of space maintainers: conventional band and loop, prefabricated band with custom made loop and glass fibre reinforced composite resins as space maintainers. PMID:24298544

Setia, Vikas; Pandit, Inder Kumar; Srivastava, Nikhil; Gugnani, Neeraj; Sekhon, Harveen Kaur

2013-01-01

261

Designing for Maintainability and System Availability  

NASA Technical Reports Server (NTRS)

The final goal for a delivered system (whether a car, aircraft, avionics box or computer) should be its availability to operate and perform its intended function over its expected design life. Hence, in designing a system, we cannot think in terms of delivering the system and just walking away. The system supplier needs to provide support throughout the operating life of the product. Here, supportability requires an effective combination of reliability, maintainability, logistics and operations engineering (as well as safety engineering) to have a system that is available for its intended use throughout its designated mission lifetime. Maintainability is a key driving element in the effective support and upkeep of the system as well as providing the ability to modify and upgrade the system throughout its lifetime. This paper then, will concentrate on maintainability and its integration into the system engineering and design process. The topics to be covered include elements of maintainability, the total cost of ownership, how system availability, maintenance and logistics costs and spare parts cost effect the overall program costs. System analysis and maintainability will show how maintainability fits into the overall systems approach to project development. Maintainability processes and documents will focus on how maintainability is to be performed and what documents are typically generated for a large scale program. Maintainability analysis shows how trade-offs can be performed for various alternative components. The conclusions summarize the paper and are followed by specific problems for hands-on training.

Lalli, Vincent R.; Packard, Michael H.

1997-01-01

262

Maintaining and Enhancing a College or University Image. AIR Forum 1982 Paper.  

ERIC Educational Resources Information Center

The use of marketing concepts to maintain and enhance the image of a university is considered. Over all, what is needed is a system for image assessment to provide a basis for image development. Without this system and its information outputs, misconceptions can enter the policy-making process at critical junctures, and the life of the institution…

Fram, Eugene H.

263

Automatic UAV Landing with Ground Target Maintained in the Field of View  

E-print Network

Automatic UAV Landing with Ground Target Maintained in the Field of View Laurent Burlion and Henry de Plinval Abstract In this paper, a key feature for UAV visual servoing in automatic land- ing. First, a control law for UAV automatic landing is proposed. Then, the output con- straint method

264

Segmentation and visualization for cardiac ablation procedures  

E-print Network

In this thesis, we present novel medical image analysis methods to improve planning and outcome evaluation of cardiac ablation procedures. Cardiac ablation is a common medical procedure that consists of burning cardiac ...

Depa, Michal

2011-01-01

265

Extracorporeal life support in pediatric cardiac dysfunction  

PubMed Central

Background Low cardiac output (LCO) after corrective surgery remains a serious complication in pediatric congenital heart diseases (CHD). In the case of refractory LCO, extra corporeal life support (ECLS) extra corporeal membrane oxygenation (ECMO) or ventricle assist devices (VAD) is the final therapeutic option. In the present study we have reviewed the outcomes of pediatric patients after corrective surgery necessitating ECLS and compared outcomes with pediatric patients necessitating ECLS because of dilatated cardiomyopathy (DCM). Methods A retrospective single-centre cohort study was evaluated in pediatric patients, between 1991 and 2008, that required ECLS. A total of 48 patients received ECLS, of which 23 were male and 25 female. The indications for ECLS included CHD in 32 patients and DCM in 16 patients. Results The mean age was 1.2 ± 3.9 years for CHD patients and 10.4 ± 5.8 years for DCM patients. Twenty-six patients received ECMO and 22 patients received VAD. A total of 15 patients out of 48 survived, 8 were discharged after myocardial recovery and 7 were discharged after successful heart transplantation. The overall mortality in patients with extracorporeal life support was 68%. Conclusion Although the use of ECLS shows a significantly high mortality rate it remains the ultimate chance for children. For better results, ECLS should be initiated in the operating room or shortly thereafter. Bridge to heart transplantation should be considered if there is no improvement in cardiac function to avoid irreversible multiorgan failure (MFO). PMID:21083896

2010-01-01

266

Angular dependence of the output of a kilovoltage X-ray therapy unit.  

PubMed

During the recommissioning of a Philips RT-250 kilovoltage X-ray unit, unexpected output variations with tube head rotation (cross-plane) and tube head tilt (in-plane) were observed. The measured output showed an increase of up to 7.3% relative to the neutral position (0? in-plane and 0? cross-plane) over the possible range of angles of in-plane rotation for 75 kVp (half-value layer, HVL = 1.84 mm Al). A less pronounced but noticeable output change (with respect to the neutral position) was observed for cross-plane rotation reaching 2% for the 225 kVp beam (HVL = 0.90 mm Cu). This output variation was observed while manually adjusting the current to maintain constancy according to the current meter gauge. In order to address the observed output dependence with head orientation, the dose rate monitor chamber of the kilovoltage unit was calibrated to monitor the beam output in real time. The dose rate was manually adjusted to maintain a constant dose rate (in r/min) as displayed on the r/min gauge. This approach resulted in maintaining beam output for the 75 kVp and the 225 kVp beams within +/- 2% for the in-plane angle variation and +/- 0.5% for the cross-plane angle variation. A daily output check that includes ion chamber-based measurements at the neutral position and an in-plane angle of 45? has been implemented using the constant dose rate approach to monitor the stability of the X-ray beams. As a result of the output variations with in/cross-plane rotation, the quality control (QC) procedures that are typically used for clinical setup have been modified to test the stability of the beams under the non-neutral positioning of the X-ray tube. PMID:20717089

Goharian, Mehran; Nygren, Ian; Tambasco, Mauro; Villarreal Barajas, Jose Eduardo

2010-01-01

267

Capillary force lithography for cardiac tissue engineering.  

PubMed

Cardiovascular disease remains the leading cause of death worldwide(1). Cardiac tissue engineering holds much promise to deliver groundbreaking medical discoveries with the aims of developing functional tissues for cardiac regeneration as well as in vitro screening assays. However, the ability to create high-fidelity models of heart tissue has proven difficult. The heart's extracellular matrix (ECM) is a complex structure consisting of both biochemical and biomechanical signals ranging from the micro- to the nanometer scale(2). Local mechanical loading conditions and cell-ECM interactions have recently been recognized as vital components in cardiac tissue engineering(3-5). A large portion of the cardiac ECM is composed of aligned collagen fibers with nano-scale diameters that significantly influences tissue architecture and electromechanical coupling(2). Unfortunately, few methods have been able to mimic the organization of ECM fibers down to the nanometer scale. Recent advancements in nanofabrication techniques, however, have enabled the design and fabrication of scalable scaffolds that mimic the in vivo structural and substrate stiffness cues of the ECM in the heart(6-9). Here we present the development of two reproducible, cost-effective, and scalable nanopatterning processes for the functional alignment of cardiac cells using the biocompatible polymer poly(lactide-co-glycolide) (PLGA)(8) and a polyurethane (PU) based polymer. These anisotropically nanofabricated substrata (ANFS) mimic the underlying ECM of well-organized, aligned tissues and can be used to investigate the role of nanotopography on cell morphology and function(10-14). Using a nanopatterned (NP) silicon master as a template, a polyurethane acrylate (PUA) mold is fabricated. This PUA mold is then used to pattern the PU or PLGA hydrogel via UV-assisted or solvent-mediated capillary force lithography (CFL), respectively(15,16). Briefly, PU or PLGA pre-polymer is drop dispensed onto a glass coverslip and the PUA mold is placed on top. For UV-assisted CFL, the PU is then exposed to UV radiation (? = 250-400 nm) for curing. For solvent-mediated CFL, the PLGA is embossed using heat (120 °C) and pressure (100 kPa). After curing, the PUA mold is peeled off, leaving behind an ANFS for cell culture. Primary cells, such as neonatal rat ventricular myocytes, as well as human pluripotent stem cell-derived cardiomyocytes, can be maintained on the ANFS(2). PMID:24962161

Macadangdang, Jesse; Lee, Hyun Jung; Carson, Daniel; Jiao, Alex; Fugate, James; Pabon, Lil; Regnier, Michael; Murry, Charles; Kim, Deok-Ho

2014-01-01

268

Cardiac toxicity of clonidine.  

PubMed

A 22-year-old woman with systemic lupus erythematosus complicated by mild renal insufficiency and severe systemic hypertension inadvertently received an excessive amount of clonidine hydrochloride. In association with a presumed toxic level of clonidine in the serum, the patient developed abnormalities of cardiac conduction, including 2:1 atrioventricular block, complete heart block, 3:2 Wenckebach block, and first-degree atrioventricular block. The transient nature of these abnormalities, with the return of normal conduction upon the cessation of therapy with clonidine, implicates this drug as being capable of producing high-grade atrioventricular block at toxic levels. PMID:923317

Williams, P L; Krafcik, J M; Potter, B B; Hooper, J H; Hearne, M J

1977-12-01

269

Ghrelin maintains the cardiovascular stability in severe sepsis  

PubMed Central

Background Cardiovascular dysfunction, characterized by reduced cardiac contractility and depressed endothelium-dependent vascular relaxation, is common in severe sepsis. Although it is known that ghrelin produces beneficial effects following various adverse circulatory conditions, it remains unknown whether ghrelin increases cardiac contractility and improves vascular responsiveness to vasoactive agents in severe sepsis. Methods Male adult rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 h after CLP, a bolus intravenous injection of 2 nmol ghrelin was followed by a continuous infusion of 12 nmol ghrelin via a primed mini-pump over 15 h. At 20 h after CLP (i.e., severe sepsis), the maximal rates of ventricular pressure increase (+dP/dtmax) and decrease (?dP/dtmax) were determined in vivo. In additional groups of animals, the thoracic aortae were isolated at 20 h after CLP. The aortae were cut into rings, and placed in organ chambers. Norepinephrine (NE) was used to induce vascular contraction. Dose responses for an endothelium-dependent vasodilator, acetylcholine (ACh), and an endothelium-independent vasodilator, nitroglycerine (NTG) were carried out. Results +dP/dtmax and ?dP/dtmax decreased significantly at 20 h after CLP. Treatment with ghrelin significantly increased +dP/dtmax and ?dP/dtmax by 36% (P<0.05) and 35% (P<0.05), respectively. Moreover, NE-induced vascular contraction and endothelium-dependent (ACh-induced) vascular relaxation decreased significantly at 20 h after CLP. Administration of ghrelin, however, increased NE-induced vascular contraction and ACh-induced vascular relaxation. In contrast, no significant reduction in NTG-induced vascular relaxation was seen in rats with severe sepsis irrespective of ghrelin treatment. Conclusions Ghrelin may be further developed as a useful agent for maintaining cardiovascular stability in severe sepsis. PMID:22459289

Wu, Rongqian; Chaung, Wayne W.; Dong, Weifeng; Ji, Youxin; Barrera, Rafael; Nicastro, Jeffrey; Molmenti, Ernesto P.; Coppa, Gene F.; Wang, Ping

2011-01-01

270

Metrics for assessing a software system's maintainability  

Microsoft Academic Search

It is noted that the factors of software that determine or influence maintainability can be organized into a hierarchical structure of measurable attributes. For each of these attributes the authors show a metric definition consistent with the published definitions of the software characteristic being measured. The result is a tree structure of maintainability metrics which can be used for purposes

Paul Oman; Jack Hagemeister

1992-01-01

271

Constructing and testing software maintainability assessment models  

Microsoft Academic Search

Software metrics are used to quantitatively characterize the essential features of software. The paper investigates the use of metrics in assessing software maintainability by presenting and comparing seven software maintainability assessment models. Eight software systems were used for initial construction and calibrating the automated assessment models, and an additional six software systems were used for testing the results. A comparison

Fang Zhuo; Bruce Lowther; Paul Oman; Jack Hagemeister

1993-01-01

272

Health Enhancing Behavior Maintaining a Healthy Diet  

E-print Network

day Unhealthy eating contributes to 300,000+ deaths per year Dietary change is critical for those Will reducing calories increase the life span? Animal studies support this hypothesis. #12;Maintaining a Healthy;Maintaining a Healthy Diet: Resistance to Modifying Diet Stress has a direct effect on eating Especially true

Meagher, Mary

273

Encapsulation method for maintaining biodecontamination activity  

DOEpatents

A method for maintaining the viability and subsequent activity of microorganisms utilized in a variety of environments to promote biodecontamination of surfaces. One application involves the decontamination of concrete surfaces. Encapsulation of microbial influenced degradation (MID) microorganisms has shown that MID activity is effectively maintained under passive conditions, that is, without manual addition of moisture or nutrients, for an extended period of time.

Rogers, Robert D. (Idaho Falls, ID); Hamilton, Melinda A. (Idaho Falls, ID); Nelson, Lee O. (Idaho Falls, ID); Benson, Jennifer (Cockermouth, GB); Green, Martin J. (Wooton, GB); Milner, Timothy N. (Centerville, VA)

2002-01-01

274

X-ray source assembly having enhanced output stability, and fluid stream analysis applications thereof  

DOEpatents

An x-ray source assembly and method of operation are provided having enhanced output stability. The assembly includes an anode having a source spot upon which electrons impinge and a control system for controlling position of the anode source spot relative to an output structure. The control system can maintain the anode source spot location relative to the output structure notwithstanding a change in one or more operating conditions of the x-ray source assembly. One aspect of the disclosed invention is most amenable to the analysis of sulfur in petroleum-based fuels.

Radley, Ian (Glenmont, NY); Bievenue, Thomas J. (Delmar, NY); Burdett, John H. (Charlton, NY); Gallagher, Brian W. (Guilderland, NY); Shakshober, Stuart M. (Hudson, NY); Chen, Zewu (Schenectady, NY); Moore, Michael D. (Alplaus, NY)

2008-06-08

275

Low temperature cardiac response to exhaustive exercise in fish with different levels of winter quiescence.  

PubMed

We examined the cardiac responses of different fish species to anaerobic exercise at low temperatures (3 degrees C). Three species of sympatric warmwater fish with perceived differences in winter activity were used for this comparative study: the winter-quiescent largemouth bass (Micropterus salmoides); the winter-active white bass (Morone chrysops); and the intermediately winter-active black crappie (Pomoxis nigromaculatus). Perceived differences in winter activity were reflected in cardiac responses; e.g. basal cardiac values were lowest for largemouth bass, highest for white bass, and intermediate for black crappie. In addition, cardiac recovery was most rapid for white bass, slowest for largemouth bass and intermediate for black crappie. When disturbed at low temperatures, largemouth bass and black crappie elevated cardiac output principally through increases in heart rate despite substantial decreases in stroke volume. Conversely, white bass principally used stroke volume modulation to change cardiac output. The results of this study indicate that different species respond differently to exercise at low temperatures. Management strategies should recognize that such variation exists and ensure that management decisions are based upon an understanding of the low temperature exercise physiology and winter biology of the species of interest. PMID:12507619

Cooke, Steven J; Grant, Emily C; Schreer, Jason F; Philipp, David P; Devries, Arthur L

2003-01-01

276

Current perspectives on cardiac amyloidosis  

PubMed Central

Amyloidosis represents a group of diseases in which proteins undergo misfolding to form insoluble fibrils with subsequent tissue deposition. While almost all deposited amyloid fibers share a common nonbranched morphology, the affected end organs, clinical presentation, treatment strategies, and prognosis vary greatly among this group of diseases and are largely dependent on the specific amyloid precursor protein. To date, at least 27 precursor proteins have been identified to result in either local tissue or systemic amyloidosis, with nine of them manifesting in cardiac deposition and resulting in a syndrome termed “cardiac amyloidosis” or “amyloid cardiomyopathy.” Although cardiac amyloidosis has been traditionally considered to be a rare disorder, as clinical appreciation and understanding continues to grow, so too has the prevalence, suggesting that this disease may be greatly underdiagnosed. The most common form of cardiac amyloidosis is associated with circulating amyloidogenic monoclonal immunoglobulin light chain proteins. Other major cardiac amyloidoses result from a misfolding of products of mutated or wild-type transthyretin protein. While the various cardiac amyloidoses share a common functional consequence, namely, an infiltrative cardiomyopathy with restrictive pathophysiology leading to progressive heart failure, the underlying pathophysiology and clinical syndrome varies with each precursor protein. Herein, we aim to provide an up-to-date overview of cardiac amyloidosis from nomenclature to molecular mechanisms and treatment options, with a particular focus on amyloidogenic immunoglobulin light chain protein cardiac amyloidosis. PMID:22058156

Guan, Jian; Mishra, Shikha; Falk, Rodney H.

2012-01-01

277

Cardiac echinococcosis with multivisceral involvement  

Microsoft Academic Search

Cardiac hydatid cyst is an uncommon lesion. The infection, often acquired by children during play with infected dogs, is most\\u000a common in sheep-raising areas of the world. We report our clinical and surgical experience in the treatment of one of the\\u000a youngest reported cardiac hydatidosis patients with multivisceral involvement.

A. Uysalel; A. Aral; S. Atalay; H. Akalin

1996-01-01

278

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

279

Challenges in Cardiac Tissue Engineering  

PubMed Central

Cardiac tissue engineering aims to create functional tissue constructs that can reestablish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell—the actual “tissue engineer”—is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure. PMID:19698068

Tandon, Nina; Godier, Amandine; Maidhof, Robert; Marsano, Anna; Martens, Timothy P.; Radisic, Milica

2010-01-01

280

Cardiac Hemangioma: A Case Report  

PubMed Central

Hemangioma of the heart, presenting as a primary cardiac tumor is extremely rare; it accounts for approximately 2% of all primary resected heart tumors. In our patient, the tumor was located in the orifice of the right lower pulmonary vein. Few cases of cardiac hemangiomas have been reported to arise from the left atrial (LA) wall. Left atrial hemangiomas, especially those attached to the LA wall, may be erroneously diagnosed as myxomas. Cardiac hemangioma is a rare disease; furthermore, a tumor arising from the LA wall and misconceived as a myxoma is extremely rare. We removed a mass misdiagnosed as a myxoma; it was pathologically confirmed to be a cardiac capillary hemangioma. Therefore, we report a rare case of a cardiac hemangioma misconceived as a myxoma; the tumor was removed successfully. PMID:24782967

Hong, Sung-Yong; Park, Kyung-Taek; Lee, Yang-Haeng; Cho, Kwang-Hyun; Seo, Jeong-Sook

2014-01-01

281

Cointegration of output, capital, labor, and energy  

NASA Astrophysics Data System (ADS)

Cointegration analysis is applied to the linear combinations of the time series of (the logarithms of) output, capital, labor, and energy for Germany, Japan, and the USA since 1960. The computed cointegration vectors represent the output elasticities of the aggregate energy-dependent Cobb-Douglas function. The output elasticities give the economic weights of the production factors capital, labor, and energy. We find that they are for labor much smaller and for energy much larger than the cost shares of these factors. In standard economic theory output elasticities equal cost shares. Our heterodox findings support results obtained with LINEX production functions.

Stresing, R.; Lindenberger, D.; Kã¼mmel, R.

2008-11-01

282

Dilated cardiomyopathy and impaired cardiac hypertrophic response to angiotensin II in mice lacking FGF-2  

PubMed Central

FGF-2 has been implicated in the cardiac response to hypertrophic stimuli. Angiotensin II (Ang II) contributes to maintain elevated blood pressure in hypertensive individuals and exerts direct trophic effects on cardiac cells. However, the role of FGF-2 in Ang II–induced cardiac hypertrophy has not been established. Therefore, mice deficient in FGF-2 expression were studied using a model of Ang II–dependent hypertension and cardiac hypertrophy. Echocardiographic measurements show the presence of dilated cardiomyopathy in normotensive mice lacking FGF-2. Moreover, hypertensive mice without FGF-2 developed no compensatory cardiac hypertrophy. In wild-type mice, hypertrophy was associated with a stimulation of the c-Jun N-terminal kinase, the extracellular signal regulated kinase, and the p38 kinase pathways. In contrast, mitogen-activated protein kinase (MAPK) activation was markedly attenuated in FGF-2–deficient mice. In vitro, FGF-2 of fibroblast origin was demonstrated to be essential in the paracrine stimulation of MAPK activation in cardiomyocytes. Indeed, fibroblasts lacking FGF-2 expression have a defective capacity for releasing growth factors to induce hypertrophic responses in cardiomyocytes. Therefore, these results identify the cardiac fibroblast population as a primary integrator of hypertrophic stimuli in the heart, and suggest that FGF-2 is a crucial mediator of cardiac hypertrophy via autocrine/paracrine actions on cardiac cells. PMID:11748268

Pellieux, Corinne; Foletti, Alessandro; Peduto, Giovanni; Aubert, Jean-Francois; Nussberger, Jurg; Beermann, Friedrich; Brunner, Hans-R.; Pedrazzini, Thierry

2001-01-01

283

Phrenic nerve stimulation in cardiac resynchronization therapy.  

PubMed

In cardiac resynchronization therapy (CRT), the electrical impulse delivered by the left ventricular (LV) lead may incidentally cause phrenic nerve stimulation (PNS). The purpose of this state-of-the-art review is to describe the frequency, risk factors, and clinical consequences of PNS and to present the most recent options to successfully manage PNS. PNS occurs in 2 to 37 % of implanted patients and is not always detected in the supine position during implantation. Lateral and posterior veins are at higher risk of PNS than anterior veins, and apical positions are at higher risk of PNS than basal positions. The management of PNS discovered during implantation may include mapping the course of the target vein in order to find a PNS-free site, targeting another vein if available, and pacing with alternative configurations before changing the lead location. Non-invasive options for management of post-operative PNS depend on the difference between PNS and LV stimulation thresholds and include reducing the LV pacing output, automatic determination of LV stimulation threshold and minimal output delivery by the device, increasing the pulse duration, and electronic repositioning. New quadripolar leads allow to pace from different cathodes, and the multiple pacing configurations available have proved superior to bipolar leads in mitigating PNS. This electronic repositioning addresses almost all of the clinically relevant PNS and should markedly reduce the need for invasive lead repositioning or CRT abandon, which is actually the last option for 2 % of patients. PMID:24934757

Moubarak, Ghassan; Bouzeman, Abdeslam; Ollitrault, Jacky; Anselme, Frederic; Cazeau, Serge

2014-10-01

284

Functional evolution of cardiac microRNAs in heart development and functions.  

PubMed

MicroRNAs (miRNAs) are a class of endogenous small noncoding RNAs that regulate gene expression either by degrading target mRNAs or by suppressing protein translation. miRNAs have been found to be involved in many biological processes, such as development, differentiation, and growth. However, the evolution of miRNA regulatory functions and networks has not been well studied. In this study, we conducted a cross-species analysis to study the evolution of cardiac miRNAs and their regulatory functions and networks. We found that conserved cardiac miRNA target genes have maintained highly conserved cardiac functions. Additionally, most of cardiac miRNA target genes in human with annotations of cardiac functions evolved from the corresponding homologous targets, which are also involved in heart development-related functions. On the basis of these results, we investigated the functional evolution of cardiac miRNAs and presented a functional evolutionary map. From this map, we identified the evolutionary time at which the cardiac miRNAs became involved in heart development or function and found that the biological processes of heart development evolved earlier than those of heart functions, for example, heart contraction/relaxation or cardiac hypertrophy. Our study of the evolution of the cardiac miRNA regulatory networks revealed the emergence of new regulatory functional branches during evolution. Furthermore, we discovered that early evolved cardiac miRNA target genes tend to participate in the early stages of heart development. This study sheds light on the evolution of developmental features of genes regulated by cardiac miRNAs. PMID:25063441

Lin, Chen-Ching; Chang, Yao-Ming; Pan, Cheng-Tsung; Chen, Chien-Chang; Ling, Li; Tsao, Ku-Chi; Yang, Ruey-Bing; Li, Wen-Hsiung

2014-10-01

285

A Modular Approach to Cardiac Tissue Engineering  

PubMed Central

Functional cardiac tissue was prepared using a modular tissue engineering approach with the goal of creating vascularized tissue. Rat aortic endothelial cells (RAEC) were seeded onto submillimeter-sized modules made of type I bovine collagen supplemented with Matrigel™ (25% v/v) embedded with cardiomyocyte (CM)-enriched neonatal rat heart cells and assembled into a contractile, macroporous, sheet-like construct. Modules (without RAEC) cultured in 10% bovine serum (BS) were more contractile and responsive to external stimulus (lower excitation threshold, higher maximum capture rate, and greater en face fractional area changes) than modules cultured in 10% fetal BS. Incorporating 25% Matrigel in the matrix reduced the excitation threshold and increased the fractional area change relative to collagen only modules (without RAEC). A coculture medium, containing 10% BS, low Mg2+ (0.814?mM), and normal glucose (5.5?mM), was used to maintain RAEC junction morphology (VE-cadherin) and CM contractility, although the responsiveness of CM was attenuated with RAEC on the modules. Macroporous, sheet-like module constructs were assembled by partially immobilizing a layer of modules in alginate gel until day 8, with or without RAEC. RAEC/CM module sheets were electrically responsive; however, like modules with RAEC this responsiveness was attenuated relative to CM-only sheets. Muscle bundles coexpressing cardiac troponin I and connexin-43 were evident near the perimeter of modules and at intermodule junctions. These results suggest the potential of the modular approach as a platform for building vascularized cardiac tissue. PMID:20504074

Leung, Brendan M.

2010-01-01

286

Modelling of an Oesophageal Electrode for Cardiac Function Tomography  

PubMed Central

There is a need in critical care units for continuous cardiopulmonary monitoring techniques. ECG gated electrical impedance tomography is able to localize the impedance variations occurring during the cardiac cycle. This method is a safe, inexpensive and potentially fast technique for cardiac output imaging but the spatial resolution is presently low, particularly for central locations such as the heart. Many parameters including noise deteriorate the reconstruction result. One of the main obstacles in cardiac imaging at the heart location is the high impedance of lungs and muscles on the dorsal and posterior side of body. In this study we are investigating improvements of the measurement and initial conductivity estimation of the internal electrode by modelling an internal electrode inside the esophagus. We consider 16 electrodes connected around a cylindrical mesh. With the random noise level set near 0.05% of the signal we evaluated the Graz consensus reconstruction algorithm for electrical impedance tomography. The modelling and simulation results showed that the quality of the target in reconstructed images was improved by up to 5 times for amplitude response, position error, resolution, shape deformation and ringing effects with perturbations located in cardiac related positions when using an internal electrode. PMID:22481975

Tehrani, J. Nasehi; Jin, C.; McEwan, A. L.

2012-01-01

287

Cooling after successful resuscitation in cardiac surgery patients  

PubMed Central

Background Despite many years of intensive research sudden cardiac death is one of the most common causes of death all over the world. The European Resuscitation Council (ERC) recommends the use of moderate therapeutic hypothermia for 12–24 hours to improve neurological outcome. However, the beneficial effect of this therapy on outcomes for cardiac surgery patients with In- Hospital- Resuscitation (IHR) has not been well studied. The purpose of this single center analysis was to investigate our first experience in a non – selected IHR population, where hypothermia was induced independent from initial heart rhythm disturbance. Method A total of 20 resuscitated patients who were treated in our institution between January 2010 and December 2011 formed the study cohort. Results In all patients post- resuscitation course was significantly prolonged with severe low cardiac output syndrome in six patients (30%). Overall four patients (20%) sustained septicemia with the need for high dose inotropic support. The 30 day mortality was 30% (six of twenty). However, stroke with severe neurological impairment appeared in only four patients (20%) after resuscitation with subsequent therapeutic hypothermia. Conclusion With our observation study we could demonstrate the benefits for neurological outcome due to therapeutic hypothermia in cardiac surgery patients after successful resuscitation. However post- resuscitation treatment should focus on sufficient therapeutic strategies to avoid the distinctive short term morbidity and mortality. PMID:24053475

2013-01-01

288

Cardiac adipose tissue: a new frontier for cardiac regeneration?  

PubMed

The human heart has limited regenerative capacity. We focused on cardiac adipose tissue as a source of progenitor cells and biological matrix material for salvaging injured myocardium. First, a population of human adult mesenchymal-like progenitors derived from cardiac adipose tissue, with inherent cardiac and endothelial cell potential, was identified and characterized. Next, a salvage strategy was tested, where a pericardial-derived, vascularized, adipose flap was used to cover oxygen-deprived myocardium in a porcine model. The fat flap reduced the myocardial scar size, in both acute and chronic infarcts. A human clinical trial to examine this novel intervention is currently underway. PMID:22709728

Bayes-Genis, Antoni; Gálvez-Montón, Carolina; Prat-Vidal, Cristina; Soler-Botija, Carolina

2013-07-15

289

Multithreaded cardiac CT  

SciTech Connect

Phase-correlated CT, as it is used for cardiac imaging, is the most popular and the most important but also the most demanding special CT application in the clinical routine, today. Basically, it fulfills the four-dimensional imaging task of depicting a quasiperiodically moving object at any desired motion phase with significantly reduced motion artifacts. Although image quality with phase-correlated reconstruction is far better than with standard reconstruction, there are motion artifacts remaining and improvements of temporal resolution are required. As a well-known alternative to simply decreasing rotation time, we consider a spiral cone-beam CT scanner that has G x-ray guns and detectors mounted. We call this a multisource or a multithreaded CT scanner. Aiming for improved temporal resolution the relative temporal resolution {tau}, which measures the fraction of a motion period that enters the image, is studied as a function of the motion rate (heart rate) and the degree of scan overlap (pitch value) for various configurations. The parameters to optimize are the number of threads G and the interthread parameters {delta}{alpha} and {delta}z, which are the angular and the longitudinal separation between adjacent threads, respectively. To demonstrate the improvements approximate image reconstruction of multithreaded raw data is performed by using a generalization of the extended parallel back projection cone-beam reconstruction algorithm [Med. Phys. 31(6), 1623-1641 (2004)] to the case of multithreaded CT. Reconstructions of a simulated cardiac motion phantom and of simulated semi-antropomorphic phantoms are presented for two and three threads and compared to the single-threaded case to demonstrate the potential of multithreaded cardiac CT. Patient data were acquired using a clinical double-threaded CT scanner to validate the theoretical results. The optimum angle {delta}{alpha} between the tubes is 90 deg.for a double-threaded system, and for triple-threaded scanners it is 60 deg.or 120 deg.. In all cases, {delta}z=0 results as an optimum, which means that the threads should be mounted in the same transversal plane. However, the dependency of the temporal resolution on {delta}z is very weak and a longitudinal separation {delta}z{ne}0 would not deteriorate image quality. The mean temporal resolution achievable with an optimized multithreaded CT scanner is a factor of G better than the mean temporal resolution obtained with a single-threaded scanner. The standard reconstructions showed decreased cone-beam artifacts with multithreaded CT compared to the single-threaded case. Our phase-correlated reconstructions demonstrate that temporal resolution is significantly improved with multithreaded CT. The clinical patient data confirm our results.

Kachelriess, Marc; Knaup, Michael; Kalender, Willi A. [Institute of Medical Physics, University of Erlangen, Nuernberg (Germany)

2006-07-15

290

Registration-based segmentation of murine 4D cardiac micro-CT data using symmetric normalization  

NASA Astrophysics Data System (ADS)

Micro-CT can play an important role in preclinical studies of cardiovascular disease because of its high spatial and temporal resolution. Quantitative analysis of 4D cardiac images requires segmentation of the cardiac chambers at each time point, an extremely time consuming process if done manually. To improve throughput this study proposes a pipeline for registration-based segmentation and functional analysis of 4D cardiac micro-CT data in the mouse. Following optimization and validation using simulations, the pipeline was applied to in vivo cardiac micro-CT data corresponding to ten cardiac phases acquired in C57BL/6 mice (n = 5). After edge-preserving smoothing with a novel adaptation of 4D bilateral filtration, one phase within each cardiac sequence was manually segmented. Deformable registration was used to propagate these labels to all other cardiac phases for segmentation. The volumes of each cardiac chamber were calculated and used to derive stroke volume, ejection fraction, cardiac output, and cardiac index. Dice coefficients and volume accuracies were used to compare manual segmentations of two additional phases with their corresponding propagated labels. Both measures were, on average, >0.90 for the left ventricle and >0.80 for the myocardium, the right ventricle, and the right atrium, consistent with trends in inter- and intra-segmenter variability. Segmentation of the left atrium was less reliable. On average, the functional metrics of interest were underestimated by 6.76% or more due to systematic label propagation errors around atrioventricular valves; however, execution of the pipeline was 80% faster than performing analogous manual segmentation of each phase.

Clark, Darin; Badea, Alexandra; Liu, Yilin; Johnson, G. Allan; Badea, Cristian T.

2012-10-01

291

Relating Noninvasive Cardiac Output and Total Peripheral Resistance Estimates to Physical Activity in an Ambulatory Setting  

E-print Network

The prevalence and cost of heart disease indicate the need for better methods of detecting, diagnosing and treating this pervasive problem. Appropriate monitoring outside of the hospital can potentially lead to earlier ...

Haslam, Bryan Todd

292

The cardiac output response and the oxygen cost of increased work of breathing  

E-print Network

OF THE WORK OF BREATHING 17 19 22 27 29 29 32 37 43 45 50 TABLE OF CONTENTS (Continued) APPENDIX B ? INFORMED CONSENT FORM VITA Page 65 70 LIST OF FIGURES Figure Inspiratory threshold loading valve C02 rebreathing tracing showing the Fet...CO2 determination Page 12 18 C02 rebreathing tracing showing the FeqCO2 determination 18 Work of breathing measurement of a single breath at rest . 20 Work of breathing measurement from a twenty second collection period Loaded breathing...

Krause, Kevin Michael

2012-06-07

293

The measurement of cardiac output and related cardiovascular parameters in the Javelina (Tayassu tajacu)  

E-print Network

by the end of the Doppler flowprobe nearest the heart. A fibrous capsule which had formed around the probe and aorta evidently prevented the animals from bleeding to death, The aorta of A46 was not affected by the flowprobe. The liver, spleen, lymph nodes... by the end of the Doppler flowprobe nearest the heart. A fibrous capsule which had formed around the probe and aorta evidently prevented the animals from bleeding to death, The aorta of A46 was not affected by the flowprobe. The liver, spleen, lymph nodes...

Schilling, Paul Wesley

2012-06-07

294

7 CFR 1430.508 - Maintaining records.  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this program...

2012-01-01

295

7 CFR 1430.508 - Maintaining records.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this program...

2010-01-01

296

7 CFR 1430.508 - Maintaining records.  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this program...

2011-01-01

297

7 CFR 1430.508 - Maintaining records.  

...DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS DAIRY PRODUCTS Dairy Market Loss Assistance Program § 1430.508 Maintaining records. Dairy operations making application for benefits under this program...

2014-01-01

298

Space Maintainers for Premature Tooth Loss  

MedlinePLUS

... space maintainer. For example, children with a congenital disease called ectodermal dysplasia often are missing multiple primary teeth. There are no permanent teeth to replace them. A child with this ...

299

Agent Program Planning Information Maintain No Gain  

E-print Network

no more than two pounds during the holiday season. Motivation for participants to maintain their weight weekly exercise and fruit and vegetable consumption. Using with Community-Based Groups, Support Groups

300

Keys to Maintaining a Good Banking Relationship.  

ERIC Educational Resources Information Center

Suggests strategies for finding an appropriate bank for a day care center, maintaining a good relationship with a bank once one has been selected, and obtaining and repaying a day care center loan. (SKC)

Stephens, Keith

1988-01-01

301

Pitx2-Mediated Cardiac Outflow Tract Remodeling  

PubMed Central

Background Heart morphogenesis involves sequential anatomical changes from a linear tube of a single channel peristaltic pump to a four-chamber structure with two channels controlled by one-way valves. The developing heart undergoes continuous remodeling, including septation. Results Pitx2-null mice are characterized by cardiac septational defects of the atria, ventricles, and outflow tract. Pitx2-null mice also exhibited a short outflow tract, including unseptated conus and deformed endocardial cushions. Cushions were characterized with a jelly-like structure, rather than the distinct membrane-looking leaflets, indicating that endothelial mesenchymal transition was impaired in Pitx2?/? embryos. Mesoderm cells from the branchial arches and neural crest cells from the otic region contribute to the development of the endocardial cushions, and both were reduced in number. Members of the Fgf and Bmp families exhibited altered expression levels in the mutants. Conclusion We suggest that Pitx2 is involved in the cardiac outflow tract septation by promoting and/or maintaining the number and the remodeling process of the mesoderm progenitor cells. Pitx2 influences the expression of transcription factors and signaling molecules involved in the differentiation of the cushion mesenchyme during heart development. PMID:23361844

Ma, Hsiao-Yen; Xu, Jun; Eng, Diana; Gross, Michael K.; Kioussi, Chrissa

2013-01-01

302

[Benefits of cardiac rehabilitation--a controversy].  

PubMed

Cardiac rehabilitation is a comprehensive process of continuing care which takes place at different levels. Individual office-based care, out-patient group activities and in-patient programmes in specialized centres may be complementary or alternatively used according to the needs of individual patients. In Switzerland organized cardiac rehabilitation is available for 6000 patients per year. Formal rehabilitation programmes exert their beneficial effects mainly through exercise training, instruction in relaxation techniques as well as dietary and occupational counseling. These benefits are documented as an overall reduction of cardiovascular mortality by 20%, a slowing of disease progression, an improvement of physical work capacity, the modification of serum lipid fractions, and possibly improved psychosocial adjustment. Patients should be helped to accept coronary disease as a chronic disease, to maintain lifestyle changes in order to halt progression and to avoid complications while enjoying a meaningful life. Future improvements in Switzerland will include the careful selection of patients for the different forms and phases of rehabilitation, more extensive psychosocial counseling, continuity of care and the involvement of family members. PMID:8446863

Hoffmann, A

1993-02-20

303

Multi-output programmable quantum processor  

E-print Network

By combining telecloning and programmable quantum gate array presented by Nielsen and Chuang [Phys.Rev.Lett. 79 :321(1997)], we propose a programmable quantum processor which can be programmed to implement restricted set of operations with several identical data outputs. The outputs are approximately-transformed versions of input data. The processor successes with certain probability.

Yafei Yu; Jian Feng; Mingsheng Zhan

2002-09-10

304

Laser wavelength selector and output coupler  

NASA Technical Reports Server (NTRS)

Optical system eliminates displacement occurring when wavelengths are selected in multiple wavelength laser utilizing intracavity wavelength selection by first-order Littrow reflection of plane grating. Output coupling varies direction of output beam as different wavelengths are selected by grating rotation.

Hard, T. M.

1970-01-01

305

Test Generation with Inputs, Outputs, and Quiescence  

Microsoft Academic Search

This paper studies testing based on labelled transition systems, using the assumption that implementations communicate with their environment via inputs and outputs. Such implementations are formalized by restricting the class of transition systems to those systems that can always accept input actions, as in input\\/output automata. Implementation relations, formalizing the notion of conformance of these implementations with respect to labelled

Jan Tretmans

1996-01-01

306

Multi-output programmable quantum processor  

NASA Astrophysics Data System (ADS)

By combining telecloning and the programmable quantum gate array presented by Nielsen and Chuang [Phys. Rev. Lett. 79, 321 (1997)], we propose a programmable quantum processor which can be programmed to implement a restricted set of operations with several identical data outputs. The outputs are approximately transformed versions of input data. The processor successes with certain probability.

Yu, Yafei; Feng, Jian; Zhan, Mingsheng

2002-11-01

307

Computer Output Microfilm and Library Catalogs.  

ERIC Educational Resources Information Center

Early computers dealt with mathematical and scientific problems requiring very little input and not much output, therefore high speed printing devices were not required. Today with increased variety of use, high speed printing is necessary and Computer Output Microfilm (COM) devices have been created to meet this need. This indirect process can…

Meyer, Richard W.

308

Output characteristics of Stirling thermoacoustic engine  

Microsoft Academic Search

A thermoacoustic engine (TE), which converts thermal energy into acoustic power by the thermoacoustic effect, shows several advantages due to the absence of moving parts, such as high reliability and long lifetime associated with reduced manufacturing costs. Power output and efficiency are important criteria of the performance of a TE. In order to increase the acoustic power output and thermal

Daming Sun; Limin Qiu; Bo Wang; Yong Xiao; Liang Zhao

2008-01-01

309

Maintaining Financial Stability in a Global Economy  

NSDL National Science Digital Library

The Federal Reserve Bank of Kansas City has made available the papers presented at the "Maintaining Financial Stability in a Global Economy" symposium. The aim of the symposium is to explore "options for public authorities in adapting policies to keep financial systems safe and efficient, and to discuss response mechanisms to financial crises." The papers presented here look at the causes of financial instability, why policymakers should be concerned about financial instability, lessons from recent financial crises, and policies for maintaining financial stability.

1997-01-01

310

Maintaining competency for float nursing staff.  

PubMed

Orienting staff to multiple areas is challenging, as is maintaining multiple competencies, which might be used infrequently. Creating a strategy to regularly assess needed competencies to maintain a highly skilled pool of nurses, prepared to float to multiple areas, is critical to supporting flexible staffing. A plan for how to achieve this complex analysis is described and can be translated to other complex environments. PMID:25036084

Overman, Kimberly; Hauver, Jeni; McKay, Jennifer; Aucoin, Julia

2014-01-01

311

Trends in Cardiac Pacemaker Batteries  

PubMed Central

Batteries used in Implantable cardiac pacemakers-present unique challenges to their developers and manufacturers in terms of high levels of safety and reliability. In addition, the batteries must have longevity to avoid frequent replacements. Technological advances in leads/electrodes have reduced energy requirements by two orders of magnitude. Micro-electronics advances sharply reduce internal current drain concurrently decreasing size and increasing functionality, reliability, and longevity. It is reported that about 600,000 pacemakers are implanted each year worldwide and the total number of people with various types of implanted pacemaker has already crossed 3 million. A cardiac pacemaker uses half of its battery power for cardiac stimulation and the other half for housekeeping tasks such as monitoring and data logging. The first implanted cardiac pacemaker used nickel-cadmium rechargeable battery, later on zinc-mercury battery was developed and used which lasted for over 2 years. Lithium iodine battery invented and used by Wilson Greatbatch and his team in 1972 made the real impact to implantable cardiac pacemakers. This battery lasts for about 10 years and even today is the power source for many manufacturers of cardiac pacemakers. This paper briefly reviews various developments of battery technologies since the inception of cardiac pacemaker and presents the alternative to lithium iodine battery for the near future. PMID:16943934

Mallela, Venkateswara Sarma; Ilankumaran, V; Rao, N.Srinivasa

2004-01-01

312

Maintainability program requirements for space systems  

NASA Technical Reports Server (NTRS)

This document is established to provide common general requirements for all NASA programs to: design maintainability into all systems where maintenance is a factor in system operation and mission success; and ensure that maintainability characteristics are developed through the systems engineering process. These requirements are not new. Design for ease of maintenance and minimization of repair time have always been fundamental requirements of the systems engineering process. However, new or reusable orbital manned and in-flight maintainable unmanned space systems demand special emphasis on maintainability, and this document has been prepared to meet that need. Maintainability requirements on many NASA programs differ in phasing and task emphasis from requirements promulgated by other Government agencies. This difference is due to the research and development nature of NASA programs where quantities produced are generally small; therefore, the depth of logistics support typical of many programs is generally not warranted. The cost of excessive maintenance is very high due to the logistics problems associated with the space environment. The ability to provide timely maintenance often involves safety considerations for manned space flight applications. This document represents a basic set of requirements that will achieve a design for maintenance. These requirements are directed primarily at manned and unmanned orbital space systems. To be effective, maintainability requirements should be tailored to meet specific NASA program and project needs and constraints. NASA activities shall invoke the requirements of this document consistent with program planning in procurements or on inhouse development efforts.

1987-01-01

313

Nonlinearities in Magnetostrictive Transducer Dynamic Output  

NASA Astrophysics Data System (ADS)

We have designed a magnetostrictive transducer for use in characterizing material properties of 11.5 cm long by 1.27 cm diameter cylindrical samples of the magnetostrictive material Terfenol-D. The material studied is a commercially available Terfenol-D, made using a modified Brigman manufacturing process. Output displacements in the stiffness controlled portion of the transducer's dynamic range (as loaded, up to 1000 Hz) were measured using a LVDT. Trends in output were observed as controlled changes in operating conditions were made. Excitation frequency, amplitude of magnetic excitation, and prestress were varied independently as other operating conditions (including temperature, mass load, and magnetic bias) were held fixed. Data are presented demonstrating distinct nonlinearities associated with a monotonic decrease in output with increased excitation frequency, a monotonic increase in output with increased excitation amplitude, and an initial increase followed by a decrease in output with increased prestress.

Flatau, Alison; Faidley, L. E.; Calkins, F. T.; Dapino, M. J.

1997-03-01

314

Peripartum cardiac failure  

PubMed Central

Peripartum cardiac failure (PPCF) is common in Zaria, in northern Nigeria, but has not been described elsewhere in Nigeria except in Ibadan. The geographic origin of a series of 224 patients with PPCF was studied in Zaria, and a survey of the syndrome as seen in hospitals and by physicians in the northern states of Nigeria was carried out; information was also gathered from medical and nursing students from various tribal groups in the same area. It was found that PPCF is only common in the areas of Hausa majority, mostly around Zaria and Malumfashi, where the postpartum practices of taking hot baths, lying on a hot bed, and taking large amounts of kanwa (a lake-salt rich in sodium) are pursued with great vigour. These customs may impose a critical load on a vulnerable myocardium, and it seems that tribe and tradition could well explain the high incidence of PPCF around Zaria. PMID:4549486

Davidson, N. McD.; Trevitt, Lorna; Parry, E. H. O.

1974-01-01

315

Aprotinin in cardiac surgery.  

PubMed

Aprotinin is a naturally occurring serine protease inhibitor that is being used with increasing frequency in cardiac surgery and beyond to reduce blood loss and the need for perioperative blood transfusion. Through inhibition of serine proteases such as plasmin, aprotinin significantly reduces fibrinolysis, thereby aiding hemostasis during surgical procedures. In addition, aprotinin interacts with other factors in the coagulation and fibrinolytic cascade, creating a hemostatic balance, without increasing the risk of thrombosis. These proven benefits are supplemented by the anti-inflammatory properties of aprotinin, which may help curb some of the deleterious effects of cardiopulmonary bypass. This article will review the discovery of aprotinin, its mechanism of action, dosing and adverse effects, and highlight the major recent trials demonstrating its efficacy. PMID:16509811

Sodha, Neel R; Boodhwani, Munir; Bianchi, Cesario; Ramlawi, Basel; Sellke, Frank W

2006-03-01

316

Cardiac cone-beam CT  

SciTech Connect

This doctoral thesis addresses imaging of the heart with retrospectively gated helical cone-beam computed tomography (CT). A thorough review of the CT reconstruction literature is presented in combination with a historic overview of cardiac CT imaging and a brief introduction to other cardiac imaging modalities. The thesis includes a comprehensive chapter about the theory of CT reconstruction, familiarizing the reader with the problem of cone-beam reconstruction. The anatomic and dynamic properties of the heart are outlined and techniques to derive the gating information are reviewed. With the extended cardiac reconstruction (ECR) framework, a new approach is presented for the heart-rate-adaptive gated helical cardiac cone-beam CT reconstruction. Reconstruction assessment criteria such as the temporal resolution, the homogeneity in terms of the cardiac phase, and the smoothness at cycle-to-cycle transitions are developed. Several reconstruction optimization approaches are described: An approach for the heart-rate-adaptive optimization of the temporal resolution is presented. Streak artifacts at cycle-to-cycle transitions can be minimized by using an improved cardiac weighting scheme. The optimal quiescent cardiac phase for the reconstruction can be determined automatically with the motion map technique. Results for all optimization procedures applied to ECR are presented and discussed based on patient and phantom data. The ECR algorithm is analyzed for larger detector arrays of future cone-beam systems throughout an extensive simulation study based on a four-dimensional cardiac CT phantom. The results of the scientific work are summarized and an outlook proposing future directions is given. The presented thesis is available for public download at www.cardiac-ct.net.

Manzke, Robert [University of London (King's College) (United Kingdom)]. E-mail: robert.manzke@philips.com

2005-10-15

317

Metoclopramide-induced cardiac arrest  

PubMed Central

The authors report a case of cardiac arrest in a patient receiving intravenous (IV) metoclopramide and review the pertinent literature. A 62-year-old morbidly obese female admitted for a gastric sleeve procedure, developed cardiac arrest within one minute of receiving metoclopramide 10 mg via slow intravenous (IV) injection. Bradycardia at 4 beats/min immediately appeared, progressing rapidly to asystole. Chest compressions restored vital function. Electrocardiogram (ECG) revealed ST depression indicative of myocardial injury. Following intubation, the patient was transferred to the intensive care unit. Various cardiac dysrrhythmias including supraventricular tachycardia (SVT) associated with hypertension and atrial fibrillation occurred. Following IV esmolol and metoprolol, the patient reverted to normal sinus rhythm. Repeat ECGs revealed ST depression resolution without pre-admission changes. Metoclopramide is a non-specific dopamine receptor antagonist. Seven cases of cardiac arrest and one of sinus arrest with metoclopramide were found in the literature. The metoclopramide prescribing information does not list precautions or adverse drug reactions (ADRs) related to cardiac arrest. The reaction is not dose related but may relate to the IV administration route. Coronary artery disease was the sole risk factor identified. According to Naranjo, the association was possible. Other reports of cardiac arrest, severe bradycardia, and SVT were reviewed. In one case, five separate IV doses of 10 mg metoclopramide were immediately followed by asystole repeatedly. The mechanism(s) underlying metoclopramide's cardiac arrest-inducing effects is unknown. Structural similarities to procainamide may play a role. In view of eight previous cases of cardiac arrest from metoclopramide having been reported, further elucidation of this ADR and patient monitoring is needed. Our report should alert clinicians to monitor patients and remain diligent in surveillance and reporting of bradydysrrhythmias and cardiac arrest in patients receiving metoclopramide. PMID:24765383

Rumore, Martha M.; Lee, Spencer Evan; Wang, Steven; Farmer, Brenna

2011-01-01

318

[Optimal timing of pediatric surgery to prevent deleterious effects on associated cardiac defects].  

PubMed

Although cardiac defects are thought to have deleterious effects on the outcome of general pediatric surgery due to low cardiac output syndrome and hypoxemia, both pediatric surgery and cardiac surgery can be performed at the optimal timing with good results. However, some conditions requiring pediatric surgery may have deleterious effects on the outcome of cardiac surgery. Airway obstructive diseases sometimes require concomitant repair of the associated cardiac defects. In particular, tracheal stenosis may be repaired in cooperation with not only general pediatric and cardiac surgeons but also with pediatric thoracic surgeons who work in other healthcare institutions. Low birth-weight infants with symptomatic patent ductal artery are at risk of poor outcome. For patients with right isomerism, midgut malrotation or sliding hernia should be diagnosed early and repaired at the optimal timing to prevent urgent surgical intervention. Pediatric surgery should be performed at the optimal timing to prevent any deleterious effects on cardiac defects. Moreover, respiratory infection and neurologic disease should be treated to reduce late deaths. PMID:21819010

Kawata, Hiroaki

2011-07-01

319

How Is Sudden Cardiac Arrest Treated?  

MedlinePLUS

... from the NHLBI on Twitter. How Is Sudden Cardiac Arrest Treated? Emergency Treatment Sudden cardiac arrest (SCA) is an emergency. A person having SCA ... go to "How Can Death Due to Sudden Cardiac Arrest Be Prevented?" ) Rate This Content: Sudden Cardiac Arrest ...

320

The non-cardiac use and significance of cardiac troponins.  

PubMed

Cardiac Troponins are blood markers of myocardial damage and are widely utilised across all acute medical departments. However, with a massive rise in requests for this test, the interpretation of raised serum levels in the absence of cardiac sounding clinical features can become a clinical conundrum. This is especially true if the numerous causes of positive test results are not fully appreciated. A thorough understanding of the strengths and weaknesses of this blood test in light of a patient population living longer, increasing in comorbidities and possible causes of false test results can provide invaluable support in establishing an accurate diagnosis and instigating effective management. This article will describe the history of cardiac markers along with a discussion of the various causes of elevated cardiac troponins outside acute coronary syndrome. It will elaborate on the applications and significance of this blood test and the potential uses of positive results with elevated serum Troponin levels. PMID:24934496

Mannu, Gurdeep Singh

2014-08-01

321

Videoscope-assisted cardiac surgery  

PubMed Central

Videoscope-assisted cardiac surgery (VACS) offers a minimally invasive platform for most cardiac operations such as coronary and valve procedures. It includes robotic and thoracoscopic approaches and each has strengths and weaknesses. The success depends on appropriate hardware setup, staff training, and troubleshooting efficiency. In our institution, we often use VACS for robotic left-internal-mammary-artery takedown, mitral valve repair, and various intra-cardiac operations such as tricuspid valve repair, combined Maze procedure, atrial septal defect repair, ventricular septal defect repair, etc. Hands-on reminders and updated references are provided for reader’s further understanding of the topic. PMID:24455172

Chen, Robert Jeen-Chen

2014-01-01

322

The Role of Cardiac Computed Tomography in Cardiac Surgery  

Microsoft Academic Search

Electrocardiogram-synchronized multidetector computed tomography (MDCT) allows for a comprehensive assessment of the heart\\u000a that facilitates planning and performing surgical procedures. MDCT permits for a high-resolution three-dimensional visualization\\u000a of cardiac structures along with a simultaneous evaluation of cardiac function. Used for the preoperative work-up MDCT enables\\u000a the non-invasive evaluation of the coronary arteries. With its high negative predictive value MDCT can

Alexander Lembcke

323

Predicting cardiac complications in patients undergoing non-cardiac surgery  

Microsoft Academic Search

The authors prospectively studied 455 consecutive patients referred to the general medical consultation service for cardiac\\u000a risk assessment prior to non-cardiac surgery, in order to validate a previously derived multifactorial index in their clinical\\u000a setting. They also tested a version of the index that they had modified to reflect factors they believed to be important.\\u000a For patients undergoing major surgery,

Allan S. Detsky; Howard B. Abrams; John R. McLaughlin; Daniel J. Drucker; Zion Sasson; Nancy Johnston; J. Gerald Scott; Nicholas Forbath; Joseph R. Hilliard

1986-01-01

324

Normal cardiac function in mice with supraphysiological cardiac creatine levels.  

PubMed

Creatine and phosphocreatine levels are decreased in heart failure, and reductions in myocellular phosphocreatine levels predict the severity of the disease and portend adverse outcomes. Previous studies of transgenic mouse models with increased creatine content higher than two times baseline showed the development of heart failure and shortened lifespan. Given phosphocreatine's role in buffering ATP content, we tested the hypothesis whether elevated cardiac creatine content would alter cardiac function under normal physiological conditions. Here, we report the creation of transgenic mice that overexpress the human creatine transporter (CrT) in cardiac muscle under the control of the ?-myosin heavy chain promoter. Cardiac transgene expression was quantified by qRT-PCR, and human CrT protein expression was documented on Western blots and immunohistochemistry using a specific anti-CrT antibody. High-energy phosphate metabolites and cardiac function were measured in transgenic animals and compared with age-matched, wild-type controls. Adult transgenic animals showed increases of 5.7- and 4.7-fold in the content of creatine and free ADP, respectively. Phosphocreatine and ATP levels were two times as high in young transgenic animals but declined to control levels by the time the animals reached 8 wk of age. Transgenic mice appeared to be healthy and had normal life spans. Cardiac morphometry, conscious echocardiography, and pressure-volume loop studies demonstrated mild hypertrophy but normal function. Based on our characterization of the human CrT protein expression, creatine and phosphocreatine content, and cardiac morphometry and function, these transgenic mice provide an in vivo model for examining the therapeutic value of elevated creatine content for cardiac pathologies. PMID:24271489

Santacruz, Lucia; Hernandez, Alejandro; Nienaber, Jeffrey; Mishra, Rajashree; Pinilla, Miguel; Burchette, James; Mao, Lan; Rockman, Howard A; Jacobs, Danny O

2014-02-01

325

NITROGEN OUTPUTS FROM FECAL AND URINE DEPOSITION OF SMALL MAMMALS: IMPLICATIONS FOR NITROGEN CYCLING  

EPA Science Inventory

The contribution of small mammals to nitrogen cycling is poorly understood, but it could have reverberations back to the producer community by maintaining or perhaps magnifying nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) of ...

326

Airway management in cardiac arrest—comparison of the laryngeal tube, tracheal intubation and bag-valve mask ventilation in emergency medical training  

Microsoft Academic Search

Tracheal intubation (ETI) is considered the method of choice for securing the airway and for providing effective ventilation during cardiac arrest. However, ETI requires skills which are difficult to maintain especially if practised infrequently. The laryngeal tube (LT) has been successfully tested and used in anaesthesia and in simulated cardiac arrest in manikins. To compare the initiation and success of

J. Kurola; H. Harve; T. Kettunen; J.-P. Laakso; J. Gorski; H. Paakkonen; T. Silfvast

2004-01-01

327

Cardiac performance correlates of relative heart ventricle mass in amphibians.  

PubMed

This study used an in situ heart preparation to analyze the power output and stroke work of spontaneously beating hearts of four anurans (Rhinella marina, Lithobates catesbeianus, Xenopus laevis, Pyxicephalus edulis) and three urodeles (Necturus maculosus, Ambystoma tigrinum, Amphiuma tridactylum) that span a representative range of relative ventricle mass (RVM) found in amphibians. Previous research has documented that RVM correlates with dehydration tolerance and maximal aerobic capacity in amphibians. The power output (mW g(-1) ventricle mass) and stroke work (mJ g(-1) ventricle muscle mass) were independent of RVM and were indistinguishable from previously published results for fish and reptiles. RVM was significantly correlated with maximum power output (P max, mW kg(-1) body mass), stroke volume, cardiac output, afterload pressure (P O) at P max, and preload pressure (P I) at P max. P I at P max and P O at P max also correlated very closely with each other. The increases in both P I and P O at maximal power outputs in large hearts suggest that concomitant increases in blood volume and/or increased modulation of vascular compliance either anatomically or via sympathetic tone on the venous vasculature would be necessary to achieve P max in vivo. Hypotheses for variation in RVM and its concomitant increased P max in amphibians are developed. PMID:23619575

Kluthe, Gregory J; Hillman, Stanley S

2013-08-01

328

Aggregate Input Output Models of Neuronal Populations  

PubMed Central

An extraordinary amount of electrophysiological data has been collected from various brain nuclei to help us understand how neural activity in one region influences another region. In this paper, we exploit the point process modeling (PPM) framework and describe a method for constructing aggregate input-output (IO) stochastic models that predict spiking activity of a population of neurons in the “output” region as a function of the spiking activity of a population of neurons in the “input” region. We first build PPMs of each output neuron as a function of all input neurons, and then cluster the output neurons using the model parameters. Output neurons that lie within the same cluster have the same functional dependence on the input neurons. We first applied our method to simulated data, and successfully uncovered the predetermined relationship between the two regions. We then applied our method to experimental data to understand the input-output relationship between motor cortical neurons and (i) somatosensory and (ii) premotor cortical neurons during a behavioral task. Our aggregate IO models highlighted interesting physiological dependencies including relative effects of inhibition/excitation from input neurons and extrinsic factors on output neurons. PMID:22552544

Saxena, Shreya; Schieber, Marc H.; Thakor, Nitish V.; Sarma, Sridevi V.

2014-01-01

329

Therapeutic hypothermia after cardiac arrest.  

PubMed

Prognosis following out-of-hospital cardiac arrest is generally poor, which is mostly due to the severity of neuronal damage. Recently, the use of therapeutic hypothermia has gradually occupied an important role in managing neuronal injuries in some cases of cardiac arrests. Some of the clinical trials conducted in comatose post-resuscitation cardiac arrest patients within the last decade have shown induced hypothermia to be effective in facilitating neuronal function recovery. This method has since been adopted in a number of guidelines and protocols as the standard method of treatment in carefully selected patient groups. Patient inclusion criteria ensure that hypothermia-associated complications are kept to a minimum while at the same time maximizing the treatment benefits. In the present work, we have examined different aspects in the use of therapeutic hypothermia as a means of managing comatose patients following cardiac arrest. PMID:25281626

Alshimemeri, Abdullah

2014-01-01

330

Integrative Cardiac Health Project (ICHP).  

National Technical Information Service (NTIS)

The Integrative Cardiac Health Project (ICHP) aims to lead the way in Cardiovascular Disease (CVD) Prevention by conducting novel research utilizing a Systems Biology / personalized medicine design to discover and develop practical, effective and preempti...

A. H. Nixon, M. Vernalis

2012-01-01

331

Image guidance in cardiac electrophysiology  

E-print Network

Cardiac arrhythmias are characterized by a disruption or abnormal conduction of electrical signals within the heart. Treatment of arrhythmias has dramatically evolved over the past half-century, and today, minimally-invasive ...

Malchano, Zachary John

2006-01-01

332

Radiation from Cardiac Imaging Tests  

MedlinePLUS

... Key Words: cardiac imaging techniques computed tomography imaging nuclear medicine radiation Next Section Introduction Many patients are referred by ... by heart disease, appropriate use criteria classify a nuclear stress test as ... radiation exposure. The appropriate use criteria cover dozens of ...

333

Generalization ability of perceptrons with continuous outputs  

NASA Astrophysics Data System (ADS)

In this paper we examine the influence of different input-output relations on the generalization ability of a single-layer perceptron. The input-output relations can be linear, binary, or sigmoid. With this choice we take into account most of the cases which are of present interest. The generalization problem will be realizable or unrealizable if the input-output relations for teacher and student are identical or not. We show that sometimes it can have a positive effect on the generalization ability, if one learns with errors.

Bös, S.; Kinzel, W.; Opper, M.

1993-02-01

334

Design of hydraulic output Stirling engine  

NASA Technical Reports Server (NTRS)

A hydraulic output system for the RE-1000 free piston stirling engine (FPSE) was designed. The hydraulic output system can be readily integrated with the existing hot section of RE-1000 FPSE. The system has two simply supported diaphragms which separate the engine gas from the hydraulic fluid, a dynamic balance mechanism, and a novel, null center band hydraulic pump. The diaphragms are designed to endure more than 10 billion cycles, and to withstand the differential pressure load as high as 14 MPa. The projected thermodynamic performance of the hydraulic output version of RE-1000 FPSE is 1.87 kW at 29/7 percent brake efficiency.

Toscano, W. M.; Harvey, A. C.; Lee, K.

1983-01-01

335

Cardiac Transplantation in Friedreich Ataxia  

PubMed Central

In this paper, we describe a 14-year-old boy with a confirmed diagnosis of Friedreich ataxia who underwent cardiac transplantation for left ventricular failure secondary to dilated cardiomyopathy with restrictive physiology. His neurological status prior to transplantation reflected early signs of neurologic disease, with evidence of dysarthria, weakness, mild gait impairment, and limb ataxia. We review the ethical issues considered during the process leading to the decision to offer cardiac transplantation. PMID:22752490

Yoon, Grace; Soman, Teesta; Wilson, Judith; George, Kristen; Mital, Seema; Dipchand, Anne I.; McCabe, Jane; Logan, William; Kantor, Paul

2013-01-01

336

Cardiac Involvement in Hereditary Ataxias  

PubMed Central

Although much attention has been focused on the neurological sequelae of the hereditary ataxias, patients with these conditions also may develop cardiac complications that represent a significant cause of disability and even death. In this paper, we describe the hereditary ataxias with known cardiac involvement, discuss underlying causes, and review guidelines for screening and treatment. Continued progress will require coordinated clinical trial networks, interdisciplinary care teams, and team science. PMID:22764180

Moore, Sean; Raman, Subha V.

2013-01-01

337

Sudden cardiac death in Athletes  

Microsoft Academic Search

The impact of sudden cardiac death (SCD) in athletes has been highlighted by increasing media coverage, as well as medical\\u000a and lay awareness of the entities associated with SCD. Common etiologies include cardiac abnormalities such as hypertrophic\\u000a cardiomyopathy (HCM), arrhythmogenic right ventricular dysplasia\\/cardiomyopathy (ARVD), and coronary artery anomalies, each\\u000a with varying geographic incidence. New recommendations regarding noninvasive preparticipation screening have

Olaf Hedrich; Mark Estes; Mark S. Link

2006-01-01

338

Cardiac manifestations in systemic sclerosis  

PubMed Central

Primary cardiac involvement, which develops as a direct consequence of systemic sclerosis (SSc), may manifest as myocardial damage, fibrosis of the conduction system, pericardial and, less frequently, as valvular disease. In addition, cardiac complications in SSc may develop as a secondary phenomenon due to pulmonary arterial hypertension and kidney pathology. The prevalence of primary cardiac involvement in SSc is variable and difficult to determine because of the diversity of cardiac manifestations, the presence of subclinical periods, the type of diagnostic tools applied, and the diversity of patient populations. When clinically manifested, cardiac involvement is thought to be an important prognostic factor. Profound microvascular disease is a pathognomonic feature of SSc, as both vasospasm and structural alterations are present. Such alterations are thought to predict macrovascular atherosclerosis over time. There are contradictory reports regarding the prevalence of atherosclerosis in SSc. According to some authors, the prevalence of atherosclerosis of the large epicardial coronary arteries is similar to that of the general population, in contrast with other rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus. However, the level of inflammation in SSc is inferior. Thus, the atherosclerotic process may not be as aggressive and not easily detectable in smaller studies. Echocardiography (especially tissue Doppler imaging), single-photon emission computed tomography, magnetic resonance imaging and cardiac computed tomography are sensitive techniques for earlier detection of both structural and functional scleroderma-related cardiac pathologies. Screening for subclinical cardiac involvement via modern, sensitive tools provides an opportunity for early diagnosis and treatment, which is of crucial importance for a positive outcome.

Lambova, Sevdalina

2014-01-01

339

Cardiac Metabolism in Heart Failure - Implications beyond ATP production  

PubMed Central

The heart has a high rate of ATP production and turnover which is required to maintain its continuous mechanical work. Perturbations in ATP generating processes may therefore affect contractile function directly. Characterizing cardiac metabolism in heart failure revealed several metabolic alterations termed metabolic remodeling, ranging from changes in substrate utilization to mitochondrial dysfunction, ultimately resulting in ATP deficiency and impaired contractility. However, ATP depletion is not the only relevant consequence of metabolic remodeling during heart failure. By providing cellular building blocks and signaling molecules, metabolic pathways control essential processes such as cell growth and regeneration. Thus, alterations in cardiac metabolism may also affect the progression to heart failure by mechanisms beyond ATP supply. Our aim is therefore to highlight that metabolic remodeling in heart failure not only results in impaired cardiac energetics, but also induces other processes implicated in the development of heart failure such as structural remodeling and oxidative stress. Accordingly, modulating cardiac metabolism in heart failure may have significant therapeutic relevance that goes beyond the energetic aspect. PMID:23989714

Doenst, Torsten; Nguyen, T. Dung; Abel, E. Dale

2013-01-01

340

Cardiac intercellular communication: are myocytes and fibroblasts fair-weather friends?  

PubMed

The cardiac fibroblast (CF) has historically been thought of as a quiescent cell of the heart, passively maintaining the extracellular environment for the cardiomyocytes (CM), the functional cardiac cell type. The increasingly appreciated role of the CF, however, extends well beyond matrix production, governing many aspects of cardiac function including cardiac electrophysiology and contractility. Importantly, its contributions to cardiac pathophysiology and pathologic remodeling have created a shift in the field's focus from the CM to the CF as a therapeutic target in the treatment of cardiac diseases. In response to cardiac injury, the CF undergoes a pathologic phenotypic transition into a myofibroblast, characterized by contractile smooth muscle proteins and upregulation of collagens, matrix proteins, and adhesion molecules. Further, the myofibroblast upregulates expression and secretion of a variety of pro-inflammatory, profibrotic mediators, including cytokines, chemokines, and growth factors. These mediators act in both an autocrine fashion to further activate CFs, as well as in a paracrine manner on both CMs and circulating inflammatory cells to induce myocyte dysfunction and chronic inflammation, respectively. Together, cell-specific cytokine-induced effects exacerbate pathologic remodeling and progression to HF. A better understanding of this dynamic intercellular communication will lead to novel targets for the attenuation of cardiac remodeling. Current strategies aimed at targeting cytokines have been largely unsuccessful in clinical trials, lending insights into ways that such intercellular cross talk can be more effectively attenuated. This review will summarize the current knowledge regarding CF functions in the heart and will discuss the regulation and signaling behind CF-mediated cytokine production and function. We will then highlight clinical trials that have exploited cytokine cross talk in the treatment of heart failure and provide novel strategies currently under investigation that may more effectively target pathologic CF-CM communication for the treatment of cardiac disease. This review explores novel mechanisms to directly attenuate heart failure progression through inhibition of signaling downstream of pro-inflammatory cytokines that are elevated after cardiac injury. PMID:23015462

Martin, Melissa L; Blaxall, Burns C

2012-12-01

341

Investigation following resuscitated cardiac arrest.  

PubMed

Roughly two thirds of resuscitated cardiac arrests in children and youth are due to inherited heart diseases. The most commonly implicated are the cardiac ion channelopathies long QT syndrome, CPVT (catecholaminergic polymorphic ventricular tachycardia) and Brugada syndrome. Diagnosis is pivotal to further management of the child if he/she survives, and also to other family members who may be at risk. Thorough investigation of the cardiac arrest survivor is essential to either identify or exclude inherited heart disease. If standard cardiac investigation does not reveal a diagnosis, pharmacological provocation tests are needed to unmask electrocardiographic signs of disease, even if, due to severe brain injury, it is planned ultimately to allow a natural death. Examples are the ajmaline/flecainide challenge for Brugada syndrome and epinephrine for CPVT. A supportive, informative and sympathetic approach to the family is essential. An arrhythmia specialist and a cardiac genetic service should be involved early, with storage of DNA and cardiac/genetic investigation of the family. This review proposes a diagnostic algorithm-based approach to the investigation of this increasingly common clinical scenario. PMID:23060598

Skinner, Jonathan R

2013-01-01

342

Drosophila Models of Cardiac Disease  

PubMed Central

The fruit fly Drosophila melanogaster has emerged as a useful model for cardiac diseases, both developmental abnormalities and adult functional impairment. Using the tools of both classical and molecular genetics, the study of the developing fly heart has been instrumental in identifying the major signaling events of cardiac field formation, cardiomyocyte specification, and the formation of the functioning heart tube. The larval stage of fly cardiac development has become an important model system for testing isolated preparations of living hearts for the effects of biological and pharmacological compounds on cardiac activity. Meanwhile, the recent development of effective techniques to study adult cardiac performance in the fly has opened new uses for the Drosophila model system. The fly system is now being used to study long-term alterations in adult performance caused by factors such as diet, exercise, and normal aging. The fly is a unique and valuable system for the study of such complex, long-term interactions, as it is the only invertebrate genetic model system with a working heart developmentally homologous to the vertebrate heart. Thus, the fly model combines the advantages of invertebrate genetics (such as large populations, facile molecular genetic techniques, and short lifespan) with physiological measurement techniques that allow meaningful comparisons with data from vertebrate model systems. As such, the fly model is well situated to make important contributions to the understanding of complicated interactions between environmental factors and genetics in the long-term regulation of cardiac performance. PMID:21377627

Piazza, Nicole; Wessells, R.J.

2013-01-01

343

Magnetocardiography and cardiac risk.  

PubMed

Risk evaluation is a challenging problem in clinical cardiology. Recently, the development of new therapeutic strategies for malignant cardiac arrhythmias and ischemia has urged the need for more accurate screening methods of risk patients The purpose of this review is to summarize the current scientific evidence on the applicability of a new method, high-resolution magnetocardiography (HR-MCG), in identification of cardiac patients at risk of malignant ventricular arrhythmias and ischemic episodes. In recent years different methods for recognizing the electromagnetic abnormalities indicating the increased risk have been used with promising results. At present, the following conclusions can be made: 1) MCG can reliably identify patients prone to malignant ventricular arrhythmias after myocardial infarction as well as in cardiomyopathy, in long QT syndrome, and in operated congenital heart disease. 2) Several analysis methods seem to work: high-pass filtering, relative smoothness score and magnetic field map trajectory plots. 3) Detection and localization of acute and chronic ischemia seems technically feasible and may be one of the most important new clinical applications of the method. 4) Larger clinical series are needed to optimize these techniques and to evaluate their feasibility in the clinics. 5) Prognostic studies should also be started as soon as possible. There are already many multichannel MCG measurement systems available in hospitals to enable clinical studies.ZUSAMMENFASSUNG: Die Risikoabschätzung stellt in der klinischen Kardiologie ein schwieriges Problem dar. Kürzlich hat die Entwicklung neuer Strategien bei malignen kardialen Arrhythmien und der Ischämie die, Notwendigkeit an exakteren Untersuchungsmethoden bei Risikopatienten unterstrichen. Diese Ubersicht soll dem Zweck dienen, die derzeitige wissenschaftliche Anwendbarkeit einer neuen Methode, der hochauflösenden Magnetokardiographie (HR-MCG) bei Herzpatienten nachzuweisen, bei denen ein Risiko des Auftretens maligner Kammerarrhythmien und ischämischen Episoden beseht. Im Verlauf der letzten Jahre sind mit vielversprechenden Resultaten verschiedene Methoden zum Nachweis elektromagnetischer Störungen entwickelt worden, die auf ein erhöhtes Risiko hinweisen. Momentan können daraus die folgenden Schlussfolgerungen gezogen werden: 1) Die MCG kann das erhöhte Risiko bei den Patienten zuverlässig aufzeigen, die einen Herzinfarkt durchgemacht haben oder an einer Kardiomyopathie, einem langen QT-Syndrom oder einer operierten, kongenitalen Herzerkrankung leiden. 2) Es scheinen verschiedene Auswertungsmethoden zu funktionieren: Hochpassfiltrierung, Relative Smoothness Score und Magnetkarten-Trajektaufzeichnungen. 3) Nachweis und Lokalisation der akuten und chronischen Ischämie erscheinen technisch möglich zu sein und können eine der wichtigsten neuen klinischen Untersuchungsmethoden darstellen. 4) Umfangreichere klinische Studien sind erforderlich, um die Optimierung dieser Methoden zu erreichen und ihre Eignung unter klinischen Bedingungen aufzuzeigen. 5) So bald als möglich sollten ausserdem prognostische Studien eingeleitet werden. Es existieren in Krankenhäusern bereits einige Multikanal-MCG-Messgeräte, die sich zur Durchführung klinischer Studien eignen. PMID:19484514

Mäkijärvi, M

1997-09-01

344

Automated Methods to Maintain Aircraft Separation  

NASA Technical Reports Server (NTRS)

The air traffic control system in the United States has a great track-record for safety. As more aircraft enter the system at a given time, the situation becomes more complex though. Researchers at NASA are attempting to leverage advances in many fields including optimization, data mining, and numerical modeling of systems to improve the air-transportation system maintaining safety while increasing throughput and reducing delays. This talk will give a brief overview of the research at NASA towards modernizing the air-transportation system. It will then focus on the specific area of automation tools for maintaining physical separation between aircraft known as Separation Assurance.

Lauderdale, Todd

2011-01-01

345

Coupling output of multichannel high power microwaves  

SciTech Connect

The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

Li Guolin; Shu Ting; Yuan Chengwei; Zhang Jun; Yang Jianhua; Jin Zhenxing; Yin Yi; Wu Dapeng; Zhu Jun; Ren Heming; Yang Jie [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2010-12-15

346

Output Tube Emission Characteristics of Operational Radars.  

National Technical Information Service (NTIS)

This report contains the emission spectra of 19 different types of radars, selected to show the different emission spectrum characteristics produced by a variety of radar output tube technologies. The radars include examples of ground-based search, airpor...

R. J. Matheson, J. D. Smilley, G. D. Falcon, V. S. Lawrence

1982-01-01

347

Memory-based parallel data output controller  

NASA Technical Reports Server (NTRS)

A memory-based parallel data output controller employs associative memories and memory mapping to decommutate multiple channels of telemetry data. The output controller contains a random access memory (RAM) which has at least as many address locations as there are channels. A word counter addresses the RAM which provides as it outputs an encoded peripheral device number and a MSB/LSB-first flag. The encoded device number and a bit counter address a second RAM which contains START and STOP flags to pick out the required bits from the specified word number. The LSB/MSB, START and STOP flags, along with the serial input digital data go to a control block which selectively fills a shift register used to drive the parallel data output bus.

Stattel, R. J.; Niswander, J. K. (inventors)

1984-01-01

348

Mapping Circadian Output Pathways in Neurospora crassa  

E-print Network

. Our lab has focused on identifying output pathways from the clock, using the model organism Neurospora crassa. We have previously demonstrated the circadian regulation of the conserved Mitogen Activated Protein Kinase (MAPK) OS-2 pathway, a homolog...

Bennett, Lindsay Danielle

2013-12-09

349

297 W continuous-wave output power  

Microsoft Academic Search

We have demonstrated a high-power and high-efficiency erbium:ytterbium (Er:Yb) co-doped fiber laser that produces 297 W of continuous-wave output at 1567 nm. The slope efficiency with respect to the launched pump power changed from 40% to 19% at higher output power due to the onset of Yb co-lasing at 1067 nm. However, the Yb co-lasing was essential for the suppression

Y. Jeong; S. Yoo; C. A. Codemard; J. Nilsson; J. K. Sahu; D. N. Payne; R. Horley; P. W. Turner; Louise Hickey; Andrew Harker; Mike Lovelady

350

Elevated miR-499 Levels Blunt the Cardiac Stress Response  

PubMed Central

Background The heart responds to myriad stresses by well-described transcriptional responses that involve long-term changes in gene expression as well as more immediate, transient adaptations. MicroRNAs quantitatively regulate mRNAs and thus may affect the cardiac transcriptional output and cardiac function. Here we investigate miR-499, a microRNA embedded within a ventricular-specific myosin heavy chain gene, which is expressed in heart and skeletal muscle. Methodology/Principal Findings We assessed miR-499 expression in human tissue to confirm its potential relevance to human cardiac gene regulation. Using a transgenic mouse model, we found that elevated miR-499 levels caused cellular hypertrophy and cardiac dysfunction in a dose-dependent manner. Global gene expression profiling revealed altered levels of the immediate early stress response genes (Egr1, Egr2 and Fos), ß-myosin heavy chain (Myh7), and skeletal muscle actin (Acta1). We verified the effect of miR-499 on the immediate early response genes by miR-499 gain- and loss-of-function in vitro. Consistent with a role for miR-499 in blunting the response to cardiac stress, asymptomatic miR-499-expressing mice had an impaired response to pressure overload and accentuated cardiac dysfunction. Conclusions Elevated miR-499 levels affect cardiac gene expression and predispose to cardiac stress-induced dysfunction. miR-499 may titrate the cardiac response to stress in part by regulating the immediate early gene response. PMID:21573063

Shieh, Joseph T. C.; Huang, Yu; Gilmore, Jacqueline; Srivastava, Deepak

2011-01-01

351

Generalized Hash Chain Traversal with Selective Output  

NASA Astrophysics Data System (ADS)

A hash chain H for a one-way hash function h(·) is a sequence of hash values < v0, v1, . . . , vn >, where v0 is a public value, vn a secret value, and vi =h(vi+1). A hash chain traversal algorithm T computes and outputs the hash chain H, returning vi in time period (called round) i for 1 ? i ? n. While previous hash chain traversal algorithms were designed to output all hash values vi (1 ? i ? n) in order, there are applications where every m-th hash value (i.e., vm, v2m, v3m, . . .) is required to be output. We introduce a hash chain traversal algorithm that selectively outputs every m-th hash value efficiently. The main technique is a transformation from a hash chain traversal algorithm outputting every hash value into that outputting every m-th hash value. Compared with the direct use of previous hash chain traversal algorithms, our proposed method requires less memory storages and computational costs.

Yum, Dae Hyun; Seo, Jae Woo; Cho, Kookrae; Lee, Pil Joong

352

Unstable resonator with reduced output coupling.  

PubMed

The properties of a laser beam coupled out of a standard unstable laser resonator are heavily dependent on the chosen resonator magnification. A higher magnification results in a higher output coupling and a better beam quality. But in some configurations, an unstable resonator with a low output coupling in combination with a good beam quality is desirable. In order to reduce the output coupling for a particular resonator, magnification fractions of the outcoupled radiation are reflected back into the cavity. In the confocal case, the output mirror consists of a spherical inner section with a high reflectivity and a flat outer section with a partial reflectivity coating. With the application of the unstable resonator with reduced output coupling (URROC), magnification and output coupling can be adjusted independently from each other and it is possible to get a good beam quality and a high power extraction for lasers with a large low gain medium. The feasibility of this resonator design is examined numerically and experimentally with the help of a chemical oxygen iodine laser. PMID:22722301

Pargmann, Carsten; Hall, Thomas; Duschek, Frank; Grünewald, Karin Maria; Handke, Jürgen

2012-06-20

353

An atypical course of pancreatic neuroendocrine tumour manifesting as cardiac metastasis - a clinical case.  

PubMed

This paper presents a ten-year course of the disease in a patient with pancreatic neuroendocrine tumour NEN G1, and with confirmed single, asymptomatic metastasis to the left cardiac ventricle. Initially, the cardiac metastasis was visible only on a positron emission tomography (PET) scan using gallium-68-labelled somatostatin analogue; the sensitivity of an echocardiography scan was lower. Despite the advanced stage of the disease, surgical excision of the cardiac metastasis was performed. The patient underwent a total of eight operations, and received chemotherapy, radiotherapy and somatostatin analogues. Currently, he is on a targeted therapy with everolimus. As a result of the treatment, the patient remains in a good general condition. This is the second described case of cardiac metastasis of PNEN. Using different methods of treatment in the case of generalised pancreatic neuroendocrine tumour with low proliferative potential, patients are offered the chance to prolong their survival and maintain a good quality of life. PMID:24971925

Boratyn-Nowicka, Agnieszka; Blicharz-Dorniak, Jolanta; Wachu?a, Ewa; Kunikowska, Jolanta; Kos-Kud?a, Beata

2014-01-01

354

Maintaining Information Awareness in a Dynamic Environment  

E-print Network

Mechanism A Thesis Presented to The Academic Faculty by D. Scott McCrickard In Partial Ful llment 2000 Copyright c 2000 by D. Scott McCrickard #12;Maintaining Information Awareness in a Dynamic to keep a positive attitude while doing so. Special thanks to Joan Morton for constantly coming to my

McCrickard, Scott

355

Reliability and maintainability seminar: summary of proceedings  

SciTech Connect

The following are described briefly: Overview of the Federal Reliability and Maintainability Program Plan, Summary of Proceedngs, Overview of Southern Solar Energy Center Programs, and Solar Domestic Hot Water Design Guidelines Handbook. Also included are the Seminar Agenda and the list of Seminar Attendees. (MHR)

Beek, C.R.

1981-04-01

356

Can punishment maintain sex? Daniel J. Rankin  

E-print Network

male harassment punish asexual females? Male behaviour can have both negative and positive effectsCan punishment maintain sex? Daniel J. Rankin D. J. Rankin (daniel.rankin@esh.unibe.ch), Div. Here I discuss this idea, and further ask whether punishment of asexual females by sexual females could

Rankin, Daniel

357

Improving Avionics Fiber Optic Network Reliability & Maintainability  

Microsoft Academic Search

Work is ongoing at NAVAIR to understand how avionics fiber optic BIT technology can help reduce military aviation platform fiber optic network life cycle and total ownership cost. Operational availability enhancements via comprehensive supportability programs combined with keen attentiveness to reliability and maintainability metrics are driving the avionics fiber optic BIT value proposition. Avionics fiber optic BIT technology is expected

Mark W. Beranek; Anthony R. Avak

2007-01-01

358

Stoichiometric analysis of self-maintaining metabolisms  

Microsoft Academic Search

This paper presents an extension of stoichiometric analysis in systems where the catalytic compounds (enzymes) are also intermediates of the metabolic network (dual property), so they are produced and degraded by the reaction network itself. To take this property into account, we introduce the definition of enzyme-maintaining mode, a set of reactions that produces its own catalyst and can operate

Francisco Montero; Juan Carlos Nuño; Enrique Meléndez-Hevia; Felix Olasagasti; Sara Vázquez; Federico Morán

2008-01-01

359

How Clones are Maintained: An Empirical Study  

Microsoft Academic Search

Abstract Despite the conventional wisdom,concerning,the risks related to the use of source code cloning as a software de- velopment strategy, several studies appeared in literature indicated that this is not true. In most cases clones are prop- erly maintained and, when this does not happen, is because cloned code evolves independently. Stemming from previous works, this paper combines clone detection

Lerina Aversano; Luigi Cerulo; Massimiliano Di Penta

2007-01-01

360

Maintaining Academic Integrity in Online Education  

Microsoft Academic Search

Online education has come under a great deal of scrutiny over the issue of academic integrity. It is assumed that cheating and plagiarism are a greater problem online than in a traditional class. In reality, maintaining academic integrity is equally a challenge in both delivery modes. However, by the very nature of online education, a case can be made that

Michael Heberling

361

Maintaining Effective Classroom Control in Vocational Education.  

ERIC Educational Resources Information Center

This handbook is designed to assist vocational teachers in maintaining effective classroom and laboratory control. Following an introduction to the topic, the importance of effective control and teacher attitude are overviewed. The third section offers definitions of discipline and "in loco parentis", a perspective on discipline, and reasons for…

Bowen, Blannie E., Ed.; McCracken, J. David

362

WEB Maintainers Meetup Web Branding Committee  

E-print Network

WEB Maintainers Meetup UF/IFAS DEPARTMENT #12; Web Branding Committee Introduction and TERMINALFOUR (T4) recap Preparation Page layouts Questions #12;WEB BRANDING COMMITTEE what we heard #12;Some) is the new UF Web Content Management System (WCMS) chosen for the next five years. T4 allows non

Florida, University of

363

[Methylene blue in the therapy of vasoplegic syndrome after cardiac surgery procedure].  

PubMed

Vasoplegic syndrome after cardiac surgery with cardiopulmonary bypass is severe complication with high morbidity and mortality. Without appropriate therapy the syndrome advances to the shock state with subsequent multiorgan failure. Basic haemodynamic parameters of vasoplegic syndrome include low systemic vascular resistance with severe hypotension, tachycardia, and normal or increased cardiac output and low filling pressures. In therapy norepinephrine and vasopressin or its analogues are used. Methylene blue is other therapeutic option. The case of successful application of methylene blue for the treatment of vasoplegic syndrome is presented. PMID:16639934

Ríha, H; Ríhová, L; Pind'ák, M; Brezina, A; Pirk, J

2006-01-01

364

Standardized Preoperative Corticosteroid Treatment in Neonates Undergoing Cardiac Surgery- Results From a Randomized Trial  

PubMed Central

Objective A heightened inflammatory response occurs following cardiac surgery. The perioperative use of glucocorticoids has been advocated as a method to improve postoperative outcomes. Randomized prospective studies to quantify the effect of methylprednisolone on perioperative outcomes in neonatal cardiac surgery have not been performed. We sought to determine whether pre-operative methylprednisolone would improve postoperative recovery in neonates requiring cardiac surgery. Methods Neonates scheduled for cardiac surgery were randomly assigned to receive either Two Dose (8 hours preoperatively and operatively; n=39) or Single Dose (operatively; n=37) methylprednisolone (30 mg/kg/dose) in a double-blind, placebo-controlled trial. The primary outcome was the incidence of low cardiac output syndrome (standardized score) or death 36 hours postoperatively. Secondary outcomes were death at 30 days, interlukin-6 levels, inotropic score, fluid balance, serum creatinine, and ICU and hospital stay. Results Preoperative plasma levels of the inflammatory cytokine interlukin-6 were reduced by 2-fold (p<0.001) in the Two Dose methylprednisolone group, consistent with the anti-inflammatory effects of methylprednisolone. However, the incidence of low cardiac output syndrome was 46% (17/37) in the Single Dose and 38% (15/39) in the Two Dose methylprednisolone groups (p=0.51). Two Dose methylprednisolone was associated with a higher serum creatinine (0.61±0.18 vs. 0.53±0.12 mg/dL, p=0.03), and poorer postoperative diuresis (?96±49 mL, p=0.05). Inotropic requirement, duration of mechanical ventilation, ICU, and hospital stay did not differ between the 2 groups. Conclusions Combined preoperative and intraoperative use of glucocorticoids in neonatal cardiac surgery does not favorably affect early clinical outcomes, and may exacerbate perioperative renal dysfunction. PMID:21600592

Graham, Eric M.; Atz, Andrew M.; Butts, Ryan J.; Baker, Nathaniel L.; Zyblewski, Sinai C.; Deardorff, Rachael L.; DeSantis, Stacia M.; Reeves, Scott T.; Bradley, Scott M.; Spinale, Francis G.

2011-01-01

365

Catecholamine and Volume Therapy for Cardiac Surgery in Germany - Results from a Postal Survey  

PubMed Central

Background Management of cardiac surgery patients is a very standardized procedure in respective local institutions. Yet only very limited evidence exists concerning optimal indication, safety and efficacy of hemodynamic monitoring catecholamine and fluid therapy. Methods Between April and May 2013, all 81 German anaesthesia departments involved in cardiac surgery care were asked to participate in a questionnaire addressing the institutional specific current practice in hemodynamic monitoring, catecholamine and volume therapy. Results 51 (63%) questionnaires were completed and returned. All participating centers used basic hemodynamic monitoring (i.e. invasive arterial blood pressure and central venous pressure), supplemented by transesophageal echocardiography. Pulmonary arterial catheter and calibrated trend monitoring devices were also routinely available. In contrast, non-calibrated trend monitoring and esophageal doppler ultrasound devices were not commonly in use. Cerebral oximetry is increasingly emerging, but lacks clear indications. The majority of patients undergoing cardiac surgery, especially in university hospitals, required catecholamines during perioperative care, In case of low cardiac output syndrome, dobutamine (32%), epinephrine (30%) or phosphodiesterase inhibitors (8%) were first choice. In case of hypotension following vasoplegia, norepinephrine (96%) represented the most common catecholamine. 88% of the participating centers reported regular use of colloid fluids, with hydroxyethyl starches (HES) being first choice (64%). Conclusions Choice of hemodynamic monitoring is homogenous throughout German centers treating cardiac surgery patients. Norepinephrine is the first line catecholamine in cases of decrease in peripheral vascular resistance. However, catecholamine choice for low cardiac output syndrome varies considerably. HES was the primary colloid used for fluid resuscitation. After conduct of this survey, HES use was restricted by European regulatory authorities in critically ill patients and should only be considered as second-line fluid in surgical patients without renal impairment or severe coagulopathy. Large clinical studies addressing catecholamine and fluid therapy in cardiac surgery patients are lacking. PMID:25084362

Reinhart, Konrad; Schirmer, Uwe; Stehr, Sebastian N.

2014-01-01

366

[Anaesthetic treatment in the removal of a cardiac hydatid cyst].  

PubMed

Echinococcosis is an endemic infection in hot countries. Cardiac involvement is rare, but serious. The risk of anaphylactic shock during surgery requires a rapid intra-operative diagnosis and immediate treatment. We present the case of a 35 year-old male in whom a cardiac hydatid cyst was detected that required surgery. He was given preliminary treatment with oral albendazole for one month and prescribed anti-H1, anti-H2 and corticosteroids prior to the removal of the cyst using bypass surgery. During the operation he was also given a bolus of hydrocortisone and dexchlorpheniramine and the surgical area was protected by gauzes soaked in hypertonic saline. The patient required an infusion of noradrenaline to maintain haemodynamic stability. He progressed with no more complications, and was discharged at 14 days. PMID:22789614

Martínez Rodríguez, R; Campello Ros, D; Sopena García, R

2012-01-01

367

Neuronal Inputs and Outputs of Aging and Longevity  

PubMed Central

An animal’s survival strongly depends on its ability to maintain homeostasis in response to the changing quality of its external and internal environment. This is achieved through intracellular and intercellular communication within and among different tissues. One of the organ systems that plays a major role in this communication and the maintenance of homeostasis is the nervous system. Here we highlight different aspects of the neuronal inputs and outputs of pathways that affect aging and longevity. Accordingly, we discuss how sensory inputs influence homeostasis and lifespan through the modulation of different types of neuronal signals, which reflects the complexity of the environmental cues that affect physiology. We also describe feedback, compensatory, and feed-forward mechanisms in these longevity-modulating pathways that are necessary for homeostasis. Finally, we consider the temporal requirements for these neuronal processes and the potential role of natural genetic variation in shaping the neurobiology of aging. PMID:23653632

Alcedo, Joy; Flatt, Thomas; Pasyukova, Elena G.

2013-01-01

368

Phosphorylation of the ryanodine receptor mediates the cardiac fight or flight response in mice.  

PubMed

During the classic "fight-or-flight" stress response, sympathetic nervous system activation leads to catecholamine release, which increases heart rate and contractility, resulting in enhanced cardiac output. Catecholamines bind to ?-adrenergic receptors, causing cAMP generation and activation of PKA, which phosphorylates multiple targets in cardiac muscle, including the cardiac ryanodine receptor/calcium release channel (RyR2) required for muscle contraction. PKA phosphorylation of RyR2 enhances channel activity by sensitizing the channel to cytosolic calcium (Ca²+). Here, we found that mice harboring RyR2 channels that cannot be PKA phosphorylated (referred to herein as RyR2-S2808A+/+ mice) exhibited blunted heart rate and cardiac contractile responses to catecholamines (isoproterenol). The isoproterenol-induced enhancement of ventricular myocyte Ca²+ transients and fractional shortening (contraction) and the spontaneous beating rate of sinoatrial nodal cells were all blunted in RyR2-S2808A+/+ mice. The blunted cardiac response to catecholamines in RyR2-S2808A+/+ mice resulted in impaired exercise capacity. RyR2-S2808A+/+ mice were protected against chronic catecholaminergic-induced cardiac dysfunction. These studies identify what we believe to be new roles for PKA phosphorylation of RyR2 in both the heart rate and contractile responses to acute catecholaminergic stimulation. PMID:21099118

Shan, Jian; Kushnir, Alexander; Betzenhauser, Matthew J; Reiken, Steven; Li, Jingdong; Lehnart, Stephan E; Lindegger, Nicolas; Mongillo, Marco; Mohler, Peter J; Marks, Andrew R

2010-12-01

369

Animal-to-animal variability in the phasing of the crustacean cardiac motor pattern: an experimental and computational analysis.  

PubMed

The cardiac ganglion (CG) of Homarus americanus is a central pattern generator that consists of two oscillatory groups of neurons: "small cells" (SCs) and "large cells" (LCs). We have shown that SCs and LCs begin their bursts nearly simultaneously but end their bursts at variable phases. This variability contrasts with many other central pattern generator systems in which phase is well maintained. To determine both the consequences of this variability and how CG phasing is controlled, we modeled the CG as a pair of Morris-Lecar oscillators coupled by electrical and excitatory synapses and constructed a database of 15,000 simulated networks using random parameter sets. These simulations, like our experimental results, displayed variable phase relationships, with the bursts beginning together but ending at variable phases. The model suggests that the variable phasing of the pattern has important implications for the functional role of the excitatory synapses. In networks in which the two oscillators had similar duty cycles, the excitatory coupling functioned to increase cycle frequency. In networks with disparate duty cycles, it functioned to decrease network frequency. Overall, we suggest that the phasing of the CG may vary without compromising appropriate motor output and that this variability may critically determine how the network behaves in response to manipulations. PMID:23446690

Williams, Alex H; Kwiatkowski, Molly A; Mortimer, Adam L; Marder, Eve; Zeeman, Mary Lou; Dickinson, Patsy S

2013-05-01

370

Deriving Production Rules for Constraint Maintainance  

Microsoft Academic Search

Abstract. Traditionally, integrity constraints in database systems,are,maintained,either,by,rolling,back,any,transac- tion,that,produces,an,inconsistent,state,or,by,disallowing or modifying,operations,that,may,produce,an,inconsistent state. An alternative,approach,is to provide,automatic,“re- pair” of inconsistent,states,using,production,rules. For each constraint, a production rule is used to detect constraint violation,and,to initiate,database,operations,that,restore consistency. We describe,an,SQL-based language,for defining,integrity constraints,and,a framewcrk,for translating,these,constraints into constraint-maintaining,production,rules. Some parts of the,translation,are automatic,while,other,parts,require,user intervention.,Based,on the semantics,of our set-oriented,pro- duction rules language and under certain assumptions, we prove,that,at

Stefano Ceri; Jennifer Widom

1990-01-01

371

Arginylation regulates myofibrils to maintain heart function and prevent dilated cardiomyopathy  

PubMed Central

Protein arginylation mediated by arginyltransferase (ATE1) is essential for heart formation during embryogenesis, however its cell-autonomous role in cardiomyocytes and the differentiated heart muscle has never been investigated. To address this question, we generated cardiac muscle-specific Ate1 knockout mice, in which Ate1 deletion was driven by ?-myosin heavy chain promoter (?MHC-Ate1 mouse). These mice were initially viable, but developed severe cardiac contractility defects, dilated cardiomyopathy, and thrombosis over time, resulting in high rates of lethality after 6 months of age. These symptoms were accompanied by severe ultrastructural defects in cardiac myofibrils, seen in the newborns and far preceding the onset of cardiomyopathy, suggesting that these defects were primary and likely underlay the development of the future heart defects. Several major sarcomeric proteins were arginylated in vivo. Moreover, Ate1 deletion in the hearts resulted in a significant reduction of active and passive myofibril forces, suggesting that arginylation is critical for both myofibril structural integrity and contractility. Thus, arginylation is essential for maintaining the heart function by regulation of the major myofibril proteins and myofibril forces, and its absence in the heart muscle leads to progressive heart failure through cardiomyocyte-specific defects. PMID:22626847

Kurosaka, Satoshi; Leu, N. Adrian; Pavlov, Ivan; Han, Xuemei; Ribeiro, Paula Aver Bretanha; Xu, Tao; Bunte, Ralph; Saha, Sougata; Wang, Junling; Cornachione, Anabelle; Mai, Wilfried; Yates, John R; Rassier, Dilson E.; Kashina, Anna

2012-01-01

372

Molecular candidates for cardiac stretch-activated ion channels  

PubMed Central

The heart is a mechanically-active organ that dynamically senses its own mechanical environment. This environment is constantly changing, on a beat-by-beat basis, with additional modulation by respiratory activity and changes in posture or physical activity, and further overlaid with more slowly occurring physiological (e.g. pregnancy, endurance training) or pathological challenges (e.g. pressure or volume overload). Far from being a simple pump, the heart detects changes in mechanical demand and adjusts its performance accordingly, both via heart rate and stroke volume alteration. Many of the underlying regulatory processes are encoded intracardially, and are thus maintained even in heart transplant recipients. Over the last three decades, molecular substrates of cardiac mechanosensitivity have gained increasing recognition in the scientific and clinical communities. Nonetheless, the processes underlying this phenomenon are still poorly understood. Stretch-activated ion channels (SAC) have been identified as one contributor to mechanosensitive autoregulation of the heartbeat. They also appear to play important roles in the development of cardiac pathologies – most notably stretch-induced arrhythmias. As recently discovered, some established cardiac drugs act, in part at least, via mechanotransduction pathways suggesting SAC as potential therapeutic targets. Clearly, identification of the molecular substrate of cardiac SAC is of clinical importance and a number of candidate proteins have been identified. At the same time, experimental studies have revealed variable–and at times contrasting–results regarding their function. Further complication arises from the fact that many ion channels that are not classically defined as SAC, including voltage and ligand-gated ion channels, can respond to mechanical stimulation. Here, we summarise what is known about the molecular substrate of the main candidates for cardiac SAC, before identifying potential further developments in this area of translational research.

Reed, Alistair; Kohl, Peter; Peyronnet, Remi

2014-01-01

373

Maintaining MultiModality through Mixture Tracking  

Microsoft Academic Search

In recent years particle filters have become a tremen- dously popular tool to perform tracking for non-linear and\\/or non-Gaussian models. This is due to their simplic- ity, generality and success over a wide range of challeng- ing applications. Particle filters, and Monte Carlo methods in general, are however poor at consistently maintaining the multi-modality of the target distributions that may

Jaco Vermaak; Arnaud Doucet; Patrick Pérez

2003-01-01

374

Issues in Purchasing and Maintaining Intrinsic Standards  

SciTech Connect

Intrinsic standards are widely used in the metrology community because they realize the best level uncertainty for many metrology parameters. For some intrinsic standards, recommended practices have been developed to assist metrologists in the selection of equipment and the development of appropriate procedures in order to realize the intrinsic standard. As with the addition of any new standard, the metrology laboratory should consider the pros and cons relative to their needs before purchasing the standard so that the laboratory obtains the maximum benefit from setting up and maintaining these standards. While the specific issues that need to be addressed depend upon the specific intrinsic standard and the level of realization, general issues that should be considered include ensuring that the intrinsic standard is compatible with the laboratory environment, that the standard is compatible with the current and future workload, and whether additional support standards will be required in order to properly maintain the intrinsic standard. When intrinsic standards are used to realize the best level of uncertainty for a specific metrology parameter, they usually require critical and important maintenance activities. These activities can including training of staff in the system operation, as well as safety procedures; performing periodic characterization measurements to ensure proper system operation; carrying out periodic intercomparisons with similar intrinsic standards so that proper operation is demonstrated; and maintaining control or trend charts of system performance. This paper has summarized many of these important issues and therefore should be beneficial to any laboratory that is considering the purchase of an intrinsic standard.

PETTIT,RICHARD B.; JAEGER,KLAUS; EHRLICH,CHARLES D.

2000-09-12

375

Prenatal exposure to maternal undernutrition induces adult cardiac dysfunction.  

PubMed

An adverse environmental experience of the growing fetus may lead to permanent changes in the structure and function of organs that may predispose the individual to chronic diseases in later life; however, nothing is known about the occurrence and mechanisms of heart failure. We employed a rat model in which pregnant dams were fed diets containing either 180 g (normal) or 90 g (low) casein/kg for 2 weeks before mating and throughout pregnancy. The ejection fraction (EF) of the pups exposed to the low-protein (LP) diet was severely depressed in the first 2 weeks of life and was associated with an increase in cardiomyocyte apoptosis. This early depressed cardiac function was followed by progressive recovery and normalization of the EF of the offspring in the LP group. The left ventricular (LV) internal diameters were increased between 24 h and 84 d (12 weeks) of age in the LP-exposed group. Although between 3 d and 2 weeks of age the LV wall of the heart in the LP group was thinner, a progressive increase in LV wall thickness was seen. At 40 weeks of age, although the EF was normal, a two-fold elevation in LV end-diastolic pressure, reduced cardiac output, decreased maximum rates of contraction and relaxation, and reduced mean arterial pressure were observed. Our findings demonstrate that exposure of the developing fetus to a maternal LP diet programs cardiac dysfunction in the offspring in later life. PMID:15946408

Cheema, Kuljeet K; Dent, Melissa R; Saini, Harjot K; Aroutiounova, Nina; Tappia, Paramjit S

2005-04-01

376

Exact-Output Tracking Theory for Systems with Parameter Jumps  

NASA Technical Reports Server (NTRS)

In this paper we consider the exact output tracking problem for systems with parameter jumps. Necessary and sufficient conditions are derived for the elimination of switching-introduced output transient. Previous works have studied this problem by developing a regulator that maintains exact tracking through parameter jumps (switches). Such techniques are, however, only applicable to minimum-phase systems. In contrast, our approach is applicable to nonminimum-phase systems and obtains bounded but possibly non-causal solutions. If the reference trajectories are generated by an exo-system, then we develop an exact-tracking controller in a feedback form. As in standard regulator theory, we obtain a linear map from the states of the exo-system to the desired system state which is defined via a matrix differential equation. The constant solution of this differential equation provides asymptotic tracking, and coincides with the feedback law used in standard regulator theory. The obtained results are applied to a simple flexible manipulator with jumps in the pay-load mass.

Devasia, Santosh; Paden, Brad; Rossi, Carlo

1996-01-01

377

PV output smoothing with energy storage.  

SciTech Connect

This report describes an algorithm, implemented in Matlab/Simulink, designed to reduce the variability of photovoltaic (PV) power output by using a battery. The purpose of the battery is to add power to the PV output (or subtract) to smooth out the high frequency components of the PV power that that occur during periods with transient cloud shadows on the PV array. The control system is challenged with the task of reducing short-term PV output variability while avoiding overworking the battery both in terms of capacity and ramp capability. The algorithm proposed by Sandia is purposely very simple to facilitate implementation in a real-time controller. The control structure has two additional inputs to which the battery can respond. For example, the battery could respond to PV variability, load variability or area control error (ACE) or a combination of the three.

Ellis, Abraham; Schoenwald, David Alan

2012-03-01

378

Caffeine, maximal power output and fatigue.  

PubMed Central

The purpose of this investigation was to determine the effects of caffeine ingestion on maximal power output and fatigue during short term, high intensity exercise. Nine adult males performed 15 s maximal exercise bouts 60 min after ingestion of caffeine (7 mg.kg-1) or placebo. Exercise bouts were carried out on a modified cycle ergometer which allowed power output to be computed for each one-half pedal stroke via microcomputer. Peak power output under caffeine conditions was not significantly different from that obtained following placebo ingestion. Similarly, time to peak power, total work, power fatigue index and power fatigue rate did not differ significantly between caffeine and placebo conditions. These results suggest that caffeine ingestion does not increase one's maximal ability to generate power. Further, caffeine does not alter the rate or magnitude of fatigue during high intensity, dynamic exercise. PMID:3228680

Williams, J H; Signorile, J F; Barnes, W S; Henrich, T W

1988-01-01

379

Output radiation from a degenerate parametric oscillator  

E-print Network

We study the squeezing as well as the statistical properties of the output radiation from a degenerate parametric oscillator coupled to a squeezed vacuum reservoir employing the stochastic differential equations associated with the normal ordering. It is found that the degree of squeezing of the output radiation is less than the corresponding cavity radiation. However, for output radiation the correlation of the quadrature operators evaluated at different times also exhibits squeezing, which is the reason for quenching of the overall noise in one of the quadrature components of the squeezing spectrum even when the oscillator is coupled to a vacuum reservoir. Moreover, coupling the oscillator to the squeezed vacuum reservoir enhances the squeezing exponentially and it also increases the mean photon number.

Sintayehu Tesfa

2007-02-12

380

Mechanical Regulation of Cardiac Development  

NASA Astrophysics Data System (ADS)

Mechanical forces are an essential contributor to and unavoidable component of cardiac formation, both inducing and orchestrating local and global molecular and cellular changes. Experimental animal studies have contributed substantially to understanding the mechanobiology of heart development. More recent integration of high-resolution imaging modalities with computational modeling has greatly improved our quantitative understanding of hemodynamic flow in heart development. Merging these latest experimental technologies with molecular and genetic signaling analysis will accelerate our understanding of the relationships integrating mechanical and biological signaling for proper cardiac formation. These advances will likely be essential for clinically translatable guidance for targeted interventions to rescue malforming hearts and/or reconfigure malformed circulations for optimal performance. This review summarizes our current understanding on the levels of mechanical signaling in the heart and their roles in orchestrating cardiac development.

Lindsey, Stephanie; Butcher, Jonathan; Yalcin, Huseyin

2014-08-01

381

Evaluation of conventional Doppler fetal cardiac function parameters: E/A ratios, outflow tracts, and myocardial performance index.  

PubMed

Structural evaluation of the fetal heart is well established. Functional evaluation using pulsed-wave Doppler may also be performed. E/A ratios express the relationship between the maximal velocities of the E and A waveforms of ventricular filling. In normal fetuses, E/A ratios are usually <1 but show a constant increment during gestation, mainly related to the increment of the E wave. In intrauterine growth restriction (IUGR) fetuses, E/A ratios are lower compared to values in normally grown fetuses at the same gestational age. Cardiac outflows provide information on the time-velocity integral that, combined with the vessel area, allows calculation of the left and right cardiac outputs. In normal fetuses there is a predominance of the right ventricle (55-60%) in contributing to the combined cardiac output. In IUGR fetuses this predominance shifts to the left ventricle in order to increase the flow to the upper part of the fetal body and brain. The myocardial performance index (MPI) also provides information on systolic and diastolic cardiac function. The MPI is an early and consistent marker of cardiac dysfunction which becomes altered in early stages of chronic hypoxia or in cases with cardiac overload such as in twin-to-twin transfusion syndrome. PMID:22677618

Hernandez-Andrade, Edgar; Benavides-Serralde, Jesus Andres; Cruz-Martinez, Rogelio; Welsh, Alec; Mancilla-Ramirez, Javier

2012-01-01

382

Exceptional CO? tolerance in white sturgeon (Acipenser transmontanus) is associated with protection of maximum cardiac performance during hypercapnia in situ.  

PubMed

White sturgeon rank among the most CO?-tolerant fish species examined to date. We investigated whether this exceptional CO? tolerance extended to the heart, an organ generally viewed as acidosis intolerant. Maximum cardiac output (Q(max)) and maximum cardiac power output (PO(max)) were assessed using a working, perfused, in situ heart preparation. Exposure to a Pco? of 3 kPa for 20 min had no significant effect on maximum cardiac performance, while exposure to 6-kPa Pco? reduced heart rate, Q(max), PO(max), and rate of ventricular force generation (F(O)) by 23%, 28%, 26%, and 18%, respectively; however, full recovery was observed in all these parameters upon return to control conditions. These modest impairments during exposure to 6-kPa Pco? were associated with partially compensated intracellular ventricular acidosis. Maximum adrenergic stimulation (500 nmol L?¹ adrenaline) during 6-kPa Pco? protected maximum cardiac performance via increased inotropy (force of contraction) without affecting heart rate. Exposure to higher CO? levels associated with morbidity in vivo (i.e., 8-kPa Pco?) induced arrhythmia and a reduction in stroke volume during power assessment. Clearly, white sturgeon hearts are able to increase cardiac performance during severe hypercapnia that is lethal to other fishes. Future work focusing on atypical aspects of sturgeon cardiac function, including the lack of chronotropic response to adrenergic stimulation during hypercapnia, is warranted. PMID:21527814

Baker, Daniel W; Hanson, Linda M; Farrell, Anthony P; Brauner, Colin J

2011-01-01

383

From Cardiac Cells to Genetic Regulatory Networks  

E-print Network

such a disorder arise? To answer to this question, we develop a multiaffine hybrid automaton (MHA) cardiac the MHA model accurately reproduces the disorder. The MHA model is obtained from the minimal cardiac model

Grosu, Radu

384

Cardiac Metastasis from Invasive Thymoma Via the Superior Vena Cava: Cardiac MRI Findings  

SciTech Connect

Cardiac tumors are rare, and metastatic deposits are more common than primary cardiac tumors. We present cardiac magnetic resonance imaging (MRI) findings of a 50-year-old woman with invasive thymoma. Cardiac MRI revealed a heterogeneous, lobulated anterior mediastinal mass invading the superior vena cava and extending to the right atrium. In cine images there was no invasion to the right atrial wall.

Dursun, Memduh, E-mail: memduhdursun@yahoo.com; Sarvar, Sadik; Cekrezi, Bledi [Istanbul University, Istanbul Faculty of Medicine, Department of Radiology (Turkey); Kaba, Erkan [Istanbul University, Istanbul Faculty of Medicine, Department of Thoracic Surgery (Turkey); Bakir, Baris [Istanbul University, Istanbul Faculty of Medicine, Department of Radiology (Turkey); Toker, Alper [Istanbul University, Istanbul Faculty of Medicine, Department of Thoracic Surgery (Turkey)

2008-07-15

385

Input/Output Subroutine Library Program  

NASA Technical Reports Server (NTRS)

Efficient, easy-to-use program moved easily to different computers. Purpose of NAVIO, Input/Output Subroutine Library, provides input/output package of software for FORTRAN programs that is portable, efficient, and easy to use. Implemented as hierarchy of libraries. At bottom is very small library containing only non-portable routines called "I/O Kernel." Design makes NAVIO easy to move from one computer to another, by simply changing kernel. NAVIO appropriate for software system of almost any size wherein different programs communicate through files.

Collier, James B.

1988-01-01

386

Cardiac and vascular adaptation to 0g with and without thigh cuffs (Antares 14 and Altair 21 day Mir spaceflights)  

Microsoft Academic Search

Cardiovascular Actaptation was evaluated on 2 astronauts: one wearing thigh cuffs from flight day 1 to 8 (14d flight), the second without cuffs (21d flight). Ultrasound investigations were performed at rest and during LBNP. Results: Without thigh cuffs the cardiovascular Actaptation consists in (1) the development of a hypovolemia with an increase of the heart rate and the cardiac output,

Ph. Arbeille; G. Fomina; F. Achaibou; J. Pottier; A. Kotovskaya

1995-01-01

387

Cardiac Syndrome X: update 2014.  

PubMed

Cardiac Syndrome X (CSX), characterized by angina-like chest discomfort, ST segment depression during exercise, and normal epicardial coronary arteries at angiography, is highly prevalent in women. CSX is not benign, and linked to adverse cardiovascular outcomes and a poor quality of life. Coronary microvascular and endothelial dysfunction and abnormal cardiac nociception have been implicated in the pathogenesis of CSX. Treatment includes life-style modification, anti-anginal, anti-atherosclerotic, and anti-ischemic medications. Non-pharmacological options include cognitive behavioral therapy, enhanced external counterpulsation, neurostimulation, and stellate ganglionectomy. Studies have shown the efficacy of individual treatments but guidelines outlining the best course of therapy are lacking. PMID:25091971

Agrawal, Shilpa; Mehta, Puja K; Bairey Merz, C Noel

2014-08-01

388

An integrated platform for image-guided cardiac resynchronization therapy  

NASA Astrophysics Data System (ADS)

Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information, derived from cardiac magnetic resonance imaging (MRI), may improve outcome by guiding the physician for optimal LV lead positioning. Whole heart MR data can be processed to yield detailed anatomical models including the coronary veins. Cine MR data can be used to measure the motion of the LV to determine which regions are late-activating. Finally, delayed Gadolinium enhancement imaging can be used to detect regions of scarring. This paper presents a complete platform for the guidance of CRT using pre-procedural MR data combined with live x-ray fluoroscopy. The platform was used for 21 patients undergoing CRT in a standard catheterization laboratory. The patients underwent cardiac MRI prior to their procedure. For each patient, a MRI-derived cardiac model, showing the LV lead targets, was registered to x-ray fluoroscopy using multiple views of a catheter looped in the right atrium. Registration was maintained throughout the procedure by a combination of C-arm/x-ray table tracking and respiratory motion compensation. Validation of the registration between the three-dimensional (3D) roadmap and the 2D x-ray images was performed using balloon occlusion coronary venograms. A 2D registration error of 1.2 ± 0.7 mm was achieved. In addition, a novel navigation technique was developed, called Cardiac Unfold, where an entire cardiac chamber is unfolded from 3D to 2D along with all relevant anatomical and functional information and coupled to real-time device detection. This allowed more intuitive navigation as the entire 3D scene was displayed simultaneously on a 2D plot. The accuracy of the unfold navigation was assessed off-line using 13 patient data sets by computing the registration error of the LV pacing lead electrodes which was found to be 2.2 ± 0.9 mm. Furthermore, the use of Unfold Navigation was demonstrated in real-time for four clinical cases.

Ma, Ying Liang; Shetty, Anoop K.; Duckett, Simon; Etyngier, Patrick; Gijsbers, Geert; Bullens, Roland; Schaeffter, Tobias; Razavi, Reza; Rinaldi, Christopher A.; Rhode, Kawal S.

2012-05-01

389

Cardiac Angiosarcoma-Associated Membranoproliferative Glomerulonephropathy  

PubMed Central

Primary cardiac angiosarcoma is a rare cardiac tumor. The initial clinical course is often asymptomatic, and metastatic disease is present in a majority of affected patients at diagnosis. We present a patient who presented with a hemorrhagic pericardial effusion. No malignant cells were evident on cytological examination. He subsequently developed membranoproliferative glomerulonephritis requiring hemodialysis. Metastatic cardiac angiosarcoma was diagnosed 5 months later. To our knowledge, this is the first reported case of paraneoplastic membranoproliferative glomerulopathy associated with cardiac angiosarcoma. PMID:21629818

Shahani, Lokesh; Beckmann, Michael; Vallurupalli, Srikanth

2011-01-01

390

d-Propranolol protects against oxidative stress and progressive cardiac dysfunction in iron overloaded rats.  

PubMed

d-Propranolol (d-Pro: 2-8 mg·(kg body mass)(-1)·day(-1)) protected against cardiac dysfunction and oxidative stress during 3-5 weeks of iron overload (2 mg Fe-dextran·(g body mass)(-1)·week(-1)) in Sprague-Dawley rats. At 3 weeks, hearts were perfused in working mode to obtain baseline function; red blood cell glutathione, plasma 8-isoprostane, neutrophil basal superoxide production, lysosomal-derived plasma N-acetyl-?-galactosaminidase (NAGA) activity, ventricular iron content, and cardiac iron deposition were assessed. Hearts from the Fe-treated group of rats exhibited lower cardiac work (26%) and output (CO, 24%); end-diastolic pressure rose 1.8-fold. Further, glutathione levels increased 2-fold, isoprostane levels increased 2.5-fold, neutrophil superoxide increased 3-fold, NAGA increased 4-fold, ventricular Fe increased 4.9-fold; and substantial atrial and ventricular Fe-deposition occurred. d-Pro (8 mg) restored heart function to the control levels, protected against oxidative stress, and decreased cardiac Fe levels. After 5 weeks of Fe treatment, echocardiography revealed that the following were depressed: percent fractional shortening (%FS, 31% lower); left ventricular (LV) ejection fraction (LVEF, 17%), CO (25%); and aortic pressure maximum (P(max), 24%). Mitral valve E/A declined by 18%, indicating diastolic dysfunction. Cardiac CD11b+ infiltrates were elevated. Low d-Pro (2 mg) provided modest protection, whereas 4-8 mg greatly improved LVEF (54%-75%), %FS (51%-81%), CO (43%-78%), P(max) (56%-100%), and E/A >100%; 8 mg decreased cardiac inflammation. Since d-Pro is an antioxidant and reduces cardiac Fe uptake as well as inflammation, these properties may preserve cardiac function during Fe overload. PMID:22913465

Kramer, Jay H; Spurney, Christopher F; Iantorno, Micaela; Tziros, Constantine; Chmielinska, Joanna J; Mak, I Tong; Weglicki, William B

2012-09-01

391

Brain natriuretic factor: regional plasma concentrations and correlations with haemodynamic state in cardiac disease.  

PubMed Central

OBJECTIVE--To document regional plasma concentrations of brain natriuretic factor (BNF) and their relations to concurrent concentrations of atrial natriuretic factor, cyclic guanosine monophosphate, and haemodynamic state. DESIGN--Regional blood sampling from a systemic artery and vein, renal vein, and coronary sinus together with concurrent haemodynamic indices in patients coming forward for left and right cardiac catheterisation. SETTING--Tertiary referral centre. PATIENTS--22 consecutive unselected patients coming forward for left and right cardiac catheterisation or electrophysiological studies in the course of standard diagnosis for a range of cardiac disorders. MAIN OUTCOME MEASURES--Significant arteriovenous gradients for plasma BNF concentration were found across the lower limb, the kidney, and the heart. These were less than concurrent arteriovenous gradients in plasma atrial natriuretic factor (ANF). Arterial concentrations of plasma BNF were positively related to concurrent concentrations of ANF (r = 0.72, p < 0.01) and cyclic guanosine monophosphate (r = 0.52, p < 0.05). Arterial plasma concentrations of BNF showed a significant positive correlation with right atrial pressure and pulmonary artery wedge pressure and an inverse relation to cardiac output. CONCLUSIONS--Regional plasma concentrations of BNF indicate cardiac secretion of this peptide and clearance in a number of tissues. Renal clearance is proportionally greater than that found across the limb. Absolute and proportional arteriovenous gradients of this peptide are considerably less than for concomitant concentrations of ANF suggesting slower metabolic clearance of BNF. Plasma BNF concentrations rise with increasing cardiac impairment and are related to indices of cardiac function. These findings are consistent with a role for BNF in the neurohumoral response to cardiac impairment. PMID:8390847

Richards, A M; Crozier, I G; Yandle, T G; Espiner, E A; Ikram, H; Nicholls, M G

1993-01-01

392

REAL TIME ESTIMATION OF POTENTIAL OUTPUT AND OUTPUT GAP FOR THE EURO-AREA : COMPARING PRODUCTION FUNCTION WITH  

E-print Network

REAL TIME ESTIMATION OF POTENTIAL OUTPUT AND OUTPUT GAP FOR THE EURO-AREA : COMPARING PRODUCTION2014 #12;1 Real time estimation of potential output and output gap for the euro- area : comparing) approach usually used for estimating the output gap of the euro area. Our version does not call for any

Paris-Sud XI, Université de

393

Absence of tolerance and toxicity to high-dose continuous intravenous furosemide in haemodynamically unstable infants after cardiac surgery  

PubMed Central

What is already known about this subject Continous i.v. infusion of furosemide is superior to intermittent administrations, especially in haemodynamically unstable infants, because it results in a more controlled diuresis (although doses are generally chosen rather low). What this study adds High-dose continuous furosemide infusion is an effective treatment for volume overload in haemodynamically unstable infants. Development of tolerance to furosemide was not observed despite high doses and prolonged exposure. Maximum serum furosemide concentrations remained well below the presumed toxic concentration. Aim To evaluate a high-dose continuous furosemide regimen in infants after cardiac surgery. Methods Fifteen haemodynamically unstable infants with volume overload admitted to a paediatric intensive care unit were treated with an aggressive furosemide regimen consisting of a loading bolus (1–2 mg kg?1) followed by a continuous infusion at 0.2 mg kg?1 h?1 which was adjusted according to a target urine output of 4 ml kg?1 h?1. Frequent sampling for furosemide concentrations in blood and urine was done for 3 days with simultaneous assessment of sodium excretion and urine output. Results The mean furosemide dose was 0.22 (± 0.06), 0.25 (± 0.10) and 0.22 (± 0.11) mg kg?1 h?1 on the first, second and third day, respectively. Median urine production was 3.0 (0.6–5.3), 4.2 (1.7–6.6) and 3.9 (2.0–8.5) ml kg?1 h?1, respectively, on the first, second and third day of the study. The target urine production was reached at a median time of 24 (6–60) h and this was maintained during the study period. The regimen did not result in toxic serum concentrations and was haemodynamically well tolerated. Conclusion High-dose continuous furosemide infusion for 72 h in haemodynamically unstable infants after cardiac surgery appears to be a safe and effective treatment for volume overload. Development of tolerance against the effects of furosemide and ototoxic furosemide concentrations were not observed. PMID:17441933

van der Vorst, Maria M J; Kist-van Holthe, Joana E; den Hartigh, Jan; van der Heijden, Albert J; Cohen, Adam F; Burggraaf, Jacobus

2007-01-01

394

Comparison of cardiac, hepatic, and renal effects of arginine vasopressin and noradrenaline during porcine fecal peritonitis: a randomized controlled trial  

PubMed Central

Introduction Infusing arginine vasopressin (AVP) in vasodilatory shock usually decreases cardiac output and thus systemic oxygen transport. It is still a matter of debate whether this vasoconstriction impedes visceral organ blood flow and thereby causes organ dysfunction and injury. Therefore, we tested the hypothesis whether low-dose AVP is safe with respect to liver, kidney, and heart function and organ injury during resuscitated septic shock. Methods After intraperitoneal inoculation of autologous feces, 24 anesthetized, mechanically ventilated, and instrumented pigs were randomly assigned to noradrenaline alone (increments of 0.05 ?g/kg/min until maximal heart rate of 160 beats/min; n = 12) or AVP (1 to 5 ng/kg/min; supplemented by noradrenaline if the maximal AVP dosage failed to maintain mean blood pressure; n = 12) to treat sepsis-associated hypotension. Parameters of systemic and regional hemodynamics (ultrasound flow probes on the portal vein and hepatic artery), oxygen transport, metabolism (endogenous glucose production and whole body glucose oxidation derived from blood glucose isotope and expiratory 13CO2/12CO2 enrichment during 1,2,3,4,5,6-13C6-glucose infusion), visceral organ function (blood transaminase activities, bilirubin and creatinine concentrations, creatinine clearance, fractional Na+ excretion), nitric oxide (exhaled NO and blood nitrate + nitrite levels) and cytokine production (interleukin-6 and tumor necrosis factor-? blood levels), and myocardial function (left ventricular dp/dtmax and dp/dtmin) and injury (troponin I blood levels) were measured before and 12, 18, and 24 hours after peritonitis induction. Immediate post mortem liver and kidney biopsies were analysed for histomorphology (hematoxylin eosin staining) and apoptosis (TUNEL staining). Results AVP decreased heart rate and cardiac output without otherwise affecting heart function and significantly decreased troponin I blood levels. AVP increased the rate of direct, aerobic glucose oxidation and reduced hyperlactatemia, which coincided with less severe kidney dysfunction and liver injury, attenuated systemic inflammation, and decreased kidney tubular apoptosis. Conclusions During well-resuscitated septic shock low-dose AVP appears to be safe with respect to myocardial function and heart injury and reduces kidney and liver damage. It remains to be elucidated whether this is due to the treatment per se and/or to the decreased exogenous catecholamine requirements. PMID:19591694

2009-01-01

395

Hybrid procedures in pediatric cardiac surgery  

Microsoft Academic Search

Hybrid pediatric cardiac surgery is an emerging field that combines skills and techniques used by pediatric cardiac surgeons and interventional pediatric cardiologists. This article describes the emerging indications and techniques in hybrid pediatric cardiac surgery and discusses potential future applications. It focuses on peratrial and perventricular septal defect closure, intraoperative stenting, hybrid stage I palliation for hypoplastic left heart syndrome,

Emile A. M. Bacha; Ziyad M. Hijazi

2005-01-01

396

Advanced Imaging Applications to Cardiac Resynchronization Therapy  

E-print Network

of Medicine and Radiology Director of Advanced CV Imaging Dartmouth 4pm, Wed, Jan. 31, 2007 AuditoriumAdvanced Imaging Applications to Cardiac Resynchronization Therapy Justin D. Pearlman Professor of the Center for Imaging Science For Cardiac Resynchronization Therapy the goal is to identify where cardiac

Zanibbi, Richard

397

Software Enhanced Learning of Cardiac Auscultation  

Microsoft Academic Search

Listening to heart sounds during physical exams can offer useful clues to the presence of cardiac disease. Cardiac auscultation is non-invasive, inexpensive and fast. It is also highly unreliable, and requires good hearing and considerable expertise. In this paper, we describe an audio-visual tool designed to help people learn to be better at cardiac auscultation. The use of digital signal

Zeeshan Syed; Dorothy Curtis; John Guttag; Francesca Nesta; Robert A. Levine

2006-01-01

398

Analysis of output capacitor parasitic effects to output voltage ripple on power converter  

Microsoft Academic Search

This paper provides analysis of output capacitor parasitic effects to output ripple on power converter and verification is made by experiments, thereby giving suggestions to persons skilled in the related art. Generally, a capacitor roughly consists of a nominal capacitance, an equivalent series resistance (ESR) and an equivalent series inductance (ESL) where ESR and ESL are called the parasitic elements.

Sheng-Yuan Ou; Huei-Fa Su; Cheng-Yu Tang

2011-01-01

399

The digital cardiac network: today and the future.  

PubMed

Cine replacement or cineless angiography is now a serious consideration for any new cardiac catheterization laboratory installation. Standards have been set by the Dicom committee, and CD's are rapidly appearing instead of angiogram film. Core labs. are geared to perform CD interpretation as well as film during this transition phase. Attempts are made to network multiple labs. and maintain the same kind of flow encountered in an analog lab. Labour and material costs seem to be cheaper for cineless labs. The future will see faster and deeper storage and commercially available means to network hospitals. This technology may be the forerunner of the digital patient record. PMID:10091083

Katz, S

1998-01-01

400

Identifying Crucial Parameter Correlations Maintaining Bursting Activity  

PubMed Central

Recent experimental and computational studies suggest that linearly correlated sets of parameters (intrinsic and synaptic properties of neurons) allow central pattern-generating networks to produce and maintain their rhythmic activity regardless of changing internal and external conditions. To determine the role of correlated conductances in the robust maintenance of functional bursting activity, we used our existing database of half-center oscillator (HCO) model instances of the leech heartbeat CPG. From the database, we identified functional activity groups of burster (isolated neuron) and half-center oscillator model instances and realistic subgroups of each that showed burst characteristics (principally period and spike frequency) similar to the animal. To find linear correlations among the conductance parameters maintaining functional leech bursting activity, we applied Principal Component Analysis (PCA) to each of these four groups. PCA identified a set of three maximal conductances (leak current, Leak; a persistent K current, K2; and of a persistent Na+ current, P) that correlate linearly for the two groups of burster instances but not for the HCO groups. Visualizations of HCO instances in a reduced space suggested that there might be non-linear relationships between these parameters for these instances. Experimental studies have shown that period is a key attribute influenced by modulatory inputs and temperature variations in heart interneurons. Thus, we explored the sensitivity of period to changes in maximal conductances of Leak, K2, and P, and we found that for our realistic bursters the effect of these parameters on period could not be assessed because when varied individually bursting activity was not maintained. PMID:24945358

Doloc-Mihu, Anca; Calabrese, Ronald L.

2014-01-01

401

Practical circular-polarization-maintaining optical fiber.  

PubMed

The author describes a new idea for making circular-polarization-maintaining optical fiber with an existing fabrication technique. The method simply requires one to spin at a constant rate a special preform consisting of only one off-axis stress-applying element in addition to the on-axis core. Measurements taken with such a fiber specimen verify the existence of circular eigenmodes, the ease of joining or splicing two fiber segments, the tolerance to macrobending with a small radius, etc. Good agreement exists between the experimental data and the theoretical analysis. Prospective applications are discussed. PMID:18259569

Huang, H C

1997-09-20

402

Computational Mechanics: Linear Functional Outputs and  

E-print Network

Computational Mechanics: Linear Functional Outputs and Certificates J. Peraire Massachusetts scale and leaving nothing but a pile of debris at a depth of 220m · Sinking traced to a failure registering 3.0 on the Richter scale and leaving nothing but a pile of debris at a depth of 220m · Sinking

Peraire, Jaime

403

Solar cell system having alternating current output  

NASA Technical Reports Server (NTRS)

A monolithic multijunction solar cell was modified by fabricating an integrated circuit inverter on the back of the cell to produce a device capable of generating an alternating current output. In another embodiment, integrated curcuit power conditioning electronics was incorporated in a module containing a solar cell power supply.

Evans, J. C., Jr. (inventor)

1980-01-01

404

Static output feedback—A survey  

Microsoft Academic Search

This paper reviews the static output feedback problem in the control of linear, time-invariant (LTI) systems. It includes analytical and computational methods and presents in a unified fashion the knowledge gained in the decades of research into this important open problem. The paper shows that although many approaches and techniques exist to approach different versions of the problem, no efficient

V. L. Syrmos; C. T. Abdallah; P. Dorato; K. Grigoriadis

1997-01-01

405

Adjoint Error Correction for Integral Outputs  

E-print Network

.1 Output functionals Why do engineers perform CFD calculations? In the case of a transport air- craft at cruise conditions, a calculation might be performed to investigate whether there is an adverse pressure engineer, the lift and drag on the aircraft. The quality of the CFD calculation is judged, #12;rst

Pierce, Niles A.

406

Police officer salaries and agency performance outputs  

Microsoft Academic Search

Spending on law enforcement services, including police officer salaries, is an important public policy issue. What is unclear is whether raising officer salaries results in an increase in the services police officer provide. This pilot test involves a partial, macro-level test to determine if, after controlling for community contextual values, higher officer salaries are associated with law enforcement agency outputs.

Richard R. Johnson

2012-01-01

407

Clutchless multiple drive source for output shaft  

NASA Technical Reports Server (NTRS)

A first shaft is connected to a source of rotational power and has a gear fixedly mounted on the shaft. A second gear is fixedly mounted on a gear shaft that is parallel to the first shaft. A third gear, also fixedly mounted on gear shaft, meshes with a fourth gear fixedly mounted on the output shaft. The first input shaft and output shaft are rotatably mounted through a housing that is itself rotatable with respect to a support. Both shafts are coaxial and in end-to-end relationship. A second input shaft is connected to a second source of rotational power. A fifth gear, fixedly mounted on second input shaft, meshes with a sixth gear, which is fixedly mounted on rotatable housing and in coaxial relationship with first input shaft. In operation, the first drive source and gear train provide rotational power in a first direction to drive the output shaft in a given direction of rotation. The second source of rotational power may be operated either to decrease the rate of rotation imparted to the output shaft by the first source of rotational power, or to increase that rate of rotation, depending on which direction the housing is rotated by the second source of rotational power.

Webster, L. D. (inventor)

1982-01-01

408

RAM-Based parallel-output controller  

NASA Technical Reports Server (NTRS)

Selected bit strings in serial-data link are extracted for processing. Controller is programmable interface between serial-data link and peripherals that accept parallel data. It can be used to drive displays, printers, plotters, digital-to-analog converters, and parallel-output ports.

Niswander, J. K.; Stattel, R. J.

1980-01-01

409

Title Slide "The broadband acoustic output of  

E-print Network

, Landro, Laws, Vaage, Ziolkowski Treatment of very close clustering and high- frequency output by Hatton next Overview #12;The current position Conventional data (0-500Hz) Most gun types measured under laboratory conditions for depths 3-30m Extended data (0-1500Hz) Some gun types in restricted conditions IFRC

Hatton, Les

410

Micropower CMOS temperature sensor with digital output  

Microsoft Academic Search

A CMOS smart temperature sensor with digital output is presented. It consumes only 7 ?W. To achieve this extremely low-power consumption, the system is equipped with a facility that switches off the supply power after each sample. The circuit uses substrate bipolars as a temperature sensor. Conversion to the digital domain is done by a sigma-delta converter which makes the

Anton Bakker; J. H. Huijsing

1996-01-01

411

Multiple Output Channels in the Basal Ganglia  

Microsoft Academic Search

The neural circuits that link the basal ganglia with the cerebral cortex are critically involved in the generation and control of voluntary movement. Retrograde transneuronal transport or herpes simplex virus type 1 was used to examine the organization of connections in the cebus monkey between an output nucleus of the basal ganglia, the internal segment of the globus pallidus (GPi),

John E. Hoover; Peter L. Strick

1993-01-01

412

Multiple Output Sensory Trainer (MOST). Final Report.  

ERIC Educational Resources Information Center

This final report describes the design, development, and testing of the Multiple Output Sensory Trainer (MOST), a computer-based system which enables the evaluation of students with visual impairments to determine the optimal combination of sensory adaptive aids to meet their needs. The system uses multimedia devices in conjunction with customized…

Automated Functions, Inc., Arlington, VA.

413

Debugging by asking questions about program output  

Microsoft Academic Search

One reason debugging is the most time-consuming part of software development is because developers struggle to map their questions about a program's behavior onto debugging tools' limited support for analyzing code. Interrogative debugging is a new debugging paradigm that allows developers to ask questions directly about their programs' output, helping them to more efficiently and accurately determine what parts of

Andrew Jensen Ko

2006-01-01

414

Better sensors = better imagery = better outputs  

NASA Astrophysics Data System (ADS)

The photogrammetric workflow has traditionally relied upon the use of high quality metric cameras that enable the acquisition of good quality imagery, from which outputs with a well constrained geometry can be obtained. However with the proliferation of low altitude aerial photography from a range of platforms, the quality of sensor itself has largely become of secondary importance in order to reduce weight and minimise cost. These instruments are often "off-the-shelf" consumer digital cameras, not designed for either aerial photography or photogrammetry. This imposes limitations upon the quality of imagery that can be collected and outputs subsequently produced. Photogrammetric techniques such as a self-calibrating bundle adjustment or Structure from Motion allow the use of "less stable" imagery. Yet at the simplest level, the better the sensor, the better the imagery, the better the output. Where analysis and the validity of scientific conclusions are dependent upon the quality of outputs it is critical that consideration is given to the choice of sensor - the wide availability and application of UAVs across disciplines means that users may not be aware of such choices and their implications. This presentation is designed to stimulate discussion around the use of consumer cameras with a focus upon the exposure triangle of ISO-aperture-shutter speed and how this is related to dynamic range and the signal-to-noise ratio. A further important factor is understanding the ground resolution element in terms of resolution, focal length, sensor size (crop factor) and height.

Smith, Michael

2014-05-01

415

Porous radiant burners having increased radiant output  

DOEpatents

Means and methods for enhancing the output of radiant energy from a porous radiant burner by minimizing the scattering and increasing the adsorption, and thus emission of such energy by the use of randomly dispersed ceramic fibers of sub-micron diameter in the fabrication of ceramic fiber matrix burners and for use therein.

Tong, Timothy W. (Tempe, AZ); Sathe, Sanjeev B. (Tempe, AZ); Peck, Robert E. (Tempe, AZ)

1990-01-01

416

Continuously adjusting CRT therapy: clinical impact of adaptive cardiac resynchronization therapy.  

PubMed

Cardiac resynchronization therapy (CRT) is a well-established therapy to reduce morbidity and mortality in patients with moderate and severe symptomatic congestive heart failure. Left ventricular (LV) pacing that fuses with intrinsic right ventricular (RV) conduction results in similar or even better cardiac performance compared to biventricular (Biv) pacing. Optimal programming of the atrio-ventricular (AV) and inter-ventricular (VV) delays is crucial to improve LV performance since suboptimal programming of AV and VV delays affect LV filling as well as cardiac output. CRT optimization using echocardiogram is resource-dependent and time consuming. Adaptive CRT (aCRT) algorithm provides a dynamic, automatic, ambulatory adjustment of CRT pacing configuration (Biv or LV pacing) and optimization of AV and VV delays. aCRT algorithm is safe and efficacious for CRT-indicated patients without permanent atrial fibrillation. It has been shown to improve CRT response and reduce morbidity and mortality for patients with normal AV conduction. PMID:24678730

Houmsse, Mahmoud; Abraham, William T

2014-05-01

417

Temperature-dependent development of cardiac activity in unrestrained larvae of the minnow Phoxinus phoxinus.  

PubMed

The minnow (Phoxinus phoxinus) was raised up to the stage of swim bladder inflation at temperatures between 10 degrees C and 25 degrees C, and the time of development significantly decreased at higher temperatures. Accordingly, initiation of cardiac activity was observed at day 2 in 25 degrees C animals and at day 4 in 12.5 degrees C animals. Only a minor increase in body mass was observed during the incubation period, and, at the end of the incubation period, animals raised at 25 degrees C did not have a significantly lower body mass compared with animals raised at 15 degrees C. Metabolic activity, determined as the rate of oxygen consumption of a larva, increased from 3.3 to 19.5 nmol/h during development at 15 degrees C and from 5.6 to 47.6 nmol/h during development at 25 degrees C. Heart rate showed a clear correlation to developmental stage as well as to developmental temperature, but at the onset of cardiac activity, diastolic ventricular volume and also stroke volume were higher at the lower temperatures. Furthermore, stroke volume increased with development, except for the group incubated at 12.5 degrees C, in which stroke volume decreased with development. Initial cardiac output showed no correlation to incubation temperature. Although metabolic activity increased severalfold during development from egg to the stage of swim bladder inflation at 15 degrees C and at 25 degrees C, weight-specific cardiac output increased only by approximately 40% with proceeding development. At 12.5 degrees C, cardiac output remained almost constant until opening of the swim bladder. The data support the notion that oxygen transport is not the major function of the circulatory system at this stage of development. The changes in heart rate with temperature appear to be due to the intrinsic properties of the pacemaker; there was no indication for a regulated response. PMID:11049845

Schönweger, G; Schwerte, T; Pelster, B

2000-11-01

418

To Grow, Nurture, and Maintain: Soil  

NASA Astrophysics Data System (ADS)

The importance and difficulties encountered in a sustainable urban farm can be witnessed at the Stanford Earth Systems Educational Garden, in the growth, maintenance, and nurturing of the soil. Techniques and chemicals developed in the mid to late 1900's have infiltrated the traditional farming techniques that allowed humans to continuously farm for hundreds of years. The sudden spur of interest in sustainability has lead many, including Stanford Earth Systems, to reincorporate traditional methods in conjunction with modern technology. To override the damage made by chemicals and industrial farming, we had to recognize that healthy crops originated from healthy soil; thus we began investigating how to nourish soil. We began to research the ideal composition and structure of soil and methods to create and maintain fertile soil. Secondly, we prioritized the importance of nurturing plants and fed the plants with a plethora of natural fertilizers. We also created a compost pile so that the soil could rehabilitate and refill with nutrients with help provided by bacteria. Lastly, we had to maintain the soil to keep the soil viable for future crops. To do this, we had to acknowledge the chemical composition of the soil and plant cover crops to ensure that the nutrients are replenished. Our experiences enabled us to understand the time and effort required to manage suitable crops, animals, and structures for an urban farm.

Joshi, I.; Lam, K.; Hennelly, L. O.; Archie, J. P.

2012-12-01

419

Cardiac Arrhythmias in the Elderly  

Microsoft Academic Search

Cardiac arrhythmias are frequent in the elderly population, perhaps secondary to an increased prevalence of hypertension (HT) and coronary artery disease (CAD) as well as aging related changes resulting in loss of pacemaker cells and degenerative change of the conduction system. Management is especially challenging in view of significant associated morbidity and mortality, an increased risk of side effects with

Anoop K. Gupta; Alok Maheshwari; Donald D. Tresch; Ranjan K. Thakur

2002-01-01

420

Phenomics of Cardiac Chloride Channels  

PubMed Central

Forward genetic studies have identified several chloride (Cl?) channel genes, including CFTR, ClC-2, ClC-3, CLCA, Bestrophin, and Ano1, in the heart. Recent reverse genetic studies using gene targeting and transgenic techniques to delineate the functional role of cardiac Cl? channels have shown that Cl? channels may contribute to cardiac arrhythmogenesis, myocardial hypertrophy and heart failure, and cardioprotection against ischemia reperfusion. The study of physiological or pathophysiological phenotypes of cardiac Cl? channels, however, is complicated by the compensatory changes in the animals in response to the targeted genetic manipulation. Alternatively, tissue-specific conditional or inducible knockout or knockin animal models may be more valuable in the phenotypic studies of specific Cl? channels by limiting the effect of compensation on the phenotype. The integrated function of Cl? channels may involve multiprotein complexes of the Cl? channel subproteome. Similar phenotypes can be attained from alternative protein pathways within cellular networks, which are influenced by genetic and environmental factors. The phenomics approach, which characterizes phenotypes as a whole phenome and systematically studies the molecular changes that give rise to particular phenotypes achieved by modifying the genotype under the scope of genome/proteome/phenome, may provide more complete understanding of the integrated function of each cardiac Cl? channel in the context of health and disease. PMID:23720326

Duan, Dayue Darrel

2014-01-01

421

Cardiac arrest during dipyridamole imaging  

SciTech Connect

A case of cardiac arrest and subsequent acute myocardial infarction occurring during thallium-201 imaging with oral dipyridamole augmentation is presented. Previous reports emphasizing the safety of this procedure are briefly reviewed and a recommendation for close hemodynamic and arrhythmia monitoring during the study is made. Large doses of oral dipyridamole may be contraindicated in patients with unstable angina.

Blumenthal, M.S.; McCauley, C.S.

1988-05-01

422

Cardiac Catheterization Objectives: Vascular Access  

E-print Network

states. · Aortic Insufficiency · Aortic Stenosis · Gorlin Equation · Hypertrophic Cardiomyopathy · Mitral Insufficiency · Mitral Stenosis · Gorlin Equation · Cardiomyopathy · Constrictive physiology · Cardiac Tamponade Artery Disease · Mitral Insufficiency · Hypertrophic Cardiomyopathy · Estimation of Ejection Fraction #12

Ford, James

423

Bifurcation theory and cardiac arrhythmias  

PubMed Central

In this paper we review two types of dynamic behaviors defined by the bifurcation theory that are found to be particularly useful in describing two forms of cardiac electrical instabilities that are of considerable importance in cardiac arrhythmogenesis. The first is action potential duration (APD) alternans with an underlying dynamics consistent with the period doubling bifurcation theory. This form of electrical instability could lead to spatially discordant APD alternans leading to wavebreak and reentrant form of tachyarrhythmias. Factors that modulate the APD alternans are discussed. The second form of bifurcation of importance to cardiac arrhythmogenesis is the Hopf-homoclinic bifurcation that adequately describes the dynamics of the onset of early afterdepolarization (EAD)-mediated triggered activity (Hopf) that may cause ventricular tachycardia and ventricular fibrillation (VT/VF respectively). The self-termination of the triggered activity is compatible with the homoclinic bifurcation. Ionic and intracellular calcium dynamics underlying these dynamics are discussed using available experimental and simulation data. The dynamic analysis provides novel insights into the mechanisms of VT/VF, a major cause of sudden cardiac death in the US. PMID:23459417

Karagueuzian, Hrayr S; Stepanyan, Hayk; Mandel, William J

2013-01-01

424

Sudden Cardiac Death in Athletes  

Microsoft Academic Search

Sudden cardiac death in athletes, although relatively uncommon, is a well-recognized condition generally associated with some congenital abnormalities. It, however, continues to be of vast interest to the public as athletes are seen as a distinct group of individuals who are especially able to tolerate more intense physical activities than the general population. Obviously, intense activities predispose susceptible athletes to

Peem Lorvidhaya; Shoei K. Stephen Huang

2003-01-01

425

Regulation of cloned cardiac channels  

E-print Network

cardiac calcium channels. In HEK cells transfected with a1c, ??2a and a2-d1 subunits alone, currents increased 1.8 ?? 2.0 fold on application of a5??1 antibody. The potentiation was almost completely abolished on the application of PKI, a highly specific...

Balasubramanian, Bharathi

2005-11-01

426

Robotic Assistance in Cardiac Surgery  

Microsoft Academic Search

Da Vinci robotic assistance has taken minimally invasive cardiac surgery to a new frontier. Many of the surgical pro- cedures can be performed through ports resulting in less trauma and pain, reduced use of blood products, reduced hospital stay, fast functional recovery and superior cosmet- ic results. The attributes of the da Vinci robotic system, i.e., 3-dimensional vision with up

Sudhir Srivastava; Reyna Barrera; Shaune Quismundo

427

Cardiac Arrhythmias in Hemodialysis Patients  

Microsoft Academic Search

Cardiac arrhythmias were evaluated in 100 patients undergoing regular maintenance hemodialysis for chronic renal failure by Holier ECG monitoring a 72-hour period beginning on the day of hemodialysis. Clinically significant ventricular arrhythmias (more than 700 beats\\/24 h) were found in 18 patients (the frequent group) in whom premature ventricular contractions (PVCs) were recorded frequently during and for 4 h after

Ken-ichi Kimura; Kaoru Tabei; Yasushi Asano; Saichi Hosoda

1989-01-01

428

47 CFR 1.20004 - Maintaining secure and accurate records.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Maintaining secure and accurate records. 1.20004...Enforcement Act § 1.20004 Maintaining secure and accurate records. (a) A telecommunications carrier shall maintain a secure and accurate record of each...

2010-10-01

429

33 CFR 150.555 - How must cranes be maintained?  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false How must cranes be maintained? 150.555 Section 150.555...Miscellaneous Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in...

2011-07-01

430

33 CFR 150.555 - How must cranes be maintained?  

...2014-07-01 2014-07-01 false How must cranes be maintained? 150.555 Section 150.555...Miscellaneous Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in...

2014-07-01

431

33 CFR 150.555 - How must cranes be maintained?  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false How must cranes be maintained? 150.555 Section 150.555...Miscellaneous Operations § 150.555 How must cranes be maintained? Cranes must be operated, maintained, and tested in...