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1

Understanding cardiac output  

PubMed Central

Cardiac output is the amount of blood the heart pumps in 1 minute, and it is dependent on the heart rate, contractility, preload, and afterload. Understanding of the applicability and practical relevance of each of these four components is important when interpreting cardiac output values. In the present article, we use a simple analogy comparing cardiac output with the speed of a bicycle to help appreciate better the effects of various disease processes and interventions on cardiac output and its four components.

Vincent, Jean-Louis

2008-01-01

2

[Noninvasive cardiac output determinations].  

PubMed

The thermodilution determination of cardiac output (CO) by pulmonary arterial catheterization is considered to be the gold standard. However, a diversity of complications associated with the insertion and use of a catheter has made for the design of CO-measuring devices in a mini- or noninvasive mode. This prospective controlled study has been conducted to compare various CO determination techniques by the shape of the arterial curve (ART), as shown by the use of a transesophageal Doppler ultrasonic sensor (TEDUS) determining the blood flow velocity in the descending thoracic aorta by the Fick's backward equation with partial CO2 recirculation, by measuring thoracic bioimpedance (Tbio) by bolus thermodilution as the reference method (CO BT). In all the study examined, the mean CO values are lower than those in the reference method. In addition, there was a wide scatter of the CO values calculated by alternative methods. The mean difference and its standard deviation are 1.27 +/- 2.26 (ART); 0.87 +/- 1.57 (TEDUS); 1.01 +/- 1.46 (Fick); and 1.46 +/- 1.70 (Tbio). The errors of the methods, as compared to CO BT have the following values: APT, 27% (24-31% conference interval (CI)); TEDUS, 19% (17-21% CI); Fick, 20% (19-22%); Tbio, 25% (22-27%). By taking into account the findings, it should be stated that there is not any accurate mini- or noninvasive CO determination method that could completely substitute for the classical thermodilution technique. PMID:18051495

Subbotin, V V; Sitnikov, A V; Il'in, S A; Ovezov, A M; Chernogaeva, N V

2007-01-01

3

Predictors of low cardiac output syndrome after coronary artery bypass  

Microsoft Academic Search

The purpose of this study was to identify patients at risk for the development of low cardiac output syndrome after coronary artery bypass. Low cardiac output syndrome was defined as the need for postoperative intraaortic balloon pump or inotropic support for longer than 30 minutes in the intensive care unit to maintain the systolic blood pressure greater than 90 mm

Vivek Rao; Joan Ivanov; Richard D. Weisel; John S. Ikonomidis; George T. Christakis; Tirone E. David

1996-01-01

4

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

5

Role of cardiac output in mediating arterial blood pressure oscillations.  

PubMed

The objective of this study was to determine the role of cardiac output in mediating spontaneous fluctuations in mean arterial pressure (MAP) conscious dogs. Dogs were chronically instrumented to monitor MAP and cardiac output. Atrioventricular (AV) block was induced, and left ventricular and right atrial electrodes were implanted. After recovery, MAP was observed for 5 min under two conditions: 1) normal variation in heart rate and cardiac output via triggering the ventricular stimulator with each atrial depolarization (effectively reversing the AV block, AV-linked stimulation) and 2) computer control of ventricular rate to maintain cardiac output constant on a by-beat basis at the same level as observed during normal variations in heart rate and cardiac output. When cardiac output was held constant, large-amplitude, low-frequency oscillations in MAP were readily apparent. Spectral analysis by fast Fourier transform revealed that during constant cardiac output the power observed at low frequencies in the MAP spectrum represented 95.0 +/- 2.7% of the total power compared with 75.5 +/- 4.6% during normal variations in heart rate and cardiac output (P < 0.05). In addition, when cardiac output was held constant, the power observed at higher frequencies markedly decreased from 24.5 +/- 4.6% of total power during AV-linked stimulation to only 5.0 +/- 2.7% of total power during constant cardiac output (P < 0.05). We conclude that low-frequency oscillations in MAP are due to changes in peripheral resistance, whereas a significant amount of high-frequency changes in MAP stems from spontaneous changes in cardiac output. PMID:8853386

O'Leary, D S; Woodbury, D J

1996-09-01

6

Cardiac output: a view from Buffalo  

Microsoft Academic Search

Cardiac output ( Q?) is a primary determinant of blood pressure and O 2 delivery and is critical in the maintenance of homeostasis, particularly during environmental stress. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine Q?. Historically, measurements during a breathhold, prolonged expiration and

A. J. Olszowka; B. E. Shykoff; D. R. Pendergast; C. E. G. Lundgren; L. E. Farhi

2003-01-01

7

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

8

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

9

A Computer Learning Technique for Determining Cardiac Output.  

National Technical Information Service (NTIS)

The paper describes an automatic error-correcting algorithm for determining cardiac output from indicator-dilution curves. The importance of this technique, as opposed to existing methods, is that the use of error correction (also referred to as relaxatio...

R. Roy S. R. Powers

1970-01-01

10

Use of Dichromatic Earpiece Densitometry for Determination of Cardiac Output.  

National Technical Information Service (NTIS)

Dye-dilution curves were recorded simultaneously by a monochromatic earpiece densitometer, a dichromatic earpiece densitometer and a cuvette densitometer through which blood was sampled continuously from a radial artery. Comparison of cardiac output value...

J. H. Reed E. H. Wood

1964-01-01

11

Continuous cardiac output monitoring by peripheral blood pressure waveform analysis  

Microsoft Academic Search

We introduce a novel technique for continuously monitoring changes in cardiac output (CO) by mathematical analysis of a single peripheral arterial blood pressure (ABP) waveform. In contrast to all previous techniques, our technique analyzes ABP variations over time scales greater than a cardiac cycle in which wave reflections are attenuated. To validate the technique, we performed six swine experiments in

R. Mukkamala; A. T. Reisner; H. M. Hojman; Roger G. Mark; Richard J. Cohen

2003-01-01

12

Evaluation of heavy water for indicator dilution cardiac output measurement  

SciTech Connect

We evaluated deuterium oxide (D2O) as a tracer for cardiac output measurements. Cardiac output measurements made by thermodilution were compared with those made by indicator dilution with D2O and indocyanine green as tracers. Five triplicate measurements for each method were made at intervals of 30 minutes in each of 9 anesthetized, mechanically ventilated goats. Cardiac output ranged between 0.68 and 3.79 L/min. The 45 data points yielded a correlation coefficient of 0.948 for the comparison of D2O indicator dilution cardiac output measurements with thermodilution measurements and a linear regression slope of 1.046. D2O indicator dilution measurements were biased by -0.11 +/- 0.22 L/min compared with thermodilution measurements and had a standard deviation of +/- 0.12 L/min for triplicate measurements. Hematocrits ranging between 20 and 50 vol% had no effect on optical density for D2O. D2O is more stable than indocyanine green and approximately one-tenth the price (40 cents per injection compared with $4). The basic instrumentation cost of approximately $9,000 is an additional initial expense, but provides the ability to perform pulmonary extravascular water measurements with a double-indicator dilution technique. D2O has potential as a tracer for the clinical determination of indicator dilution cardiac output measurements and pulmonary extravascular water measurements.

Schreiner, M.S.; Leksell, L.G.; Neufeld, G.R. (Univ. of Pennsylvania School of Medicine, Philadelphia (USA))

1989-10-01

13

The thermal-dye method of lung water measurement is reliable at a low cardiac output.  

PubMed

The measurement of lung water by the thermal-dye double indicator dilution technique was evaluated in dogs with normal and edematous lungs during a state of reduced cardiac output. The technique used cold indocyanine green dye to measure extravascular thermal volume (EVTV) as an estimate of extravascular lung water (EVLW). Anesthesia was maintained with pentobarbital. In 15 of 21 animals, pulmonary edema was first induced with oleic acid (0.75 to 0.18 ml/kg). Cardiac output (CO) was then decreased by a combination of propranolol and slow exsanguination (mean CO reduction to 36% of baseline). Extravascular lung water produced in this model ranged from 1.4 to 30.2 ml/kg. Predetermination measurements of EVTV correlated closely with EVLW as determined by gravimetric analysis (EVTV = 1.1 EVLW + 4.7 ml/kg, n = 21, r = 0.93, P less than 0.001). Thermodilution cardiac output measured in the abdominal aorta (used in the calculation of the EVTV) correlated well with simultaneous measurements of cardiac output by both indocyanine green dye dilution and pulmonary artery thermodilution (r = 0.86 and r = 0.88, respectively, pretermination). The thermal-dye technique appears to provide an accurate reflection of lung water in normal and edematous lungs, even in the presence of a low cardiac output. PMID:3762135

Calcagni, D E; Mihm, F G; Feeley, T W; Halperin, B D; Rosenthal, M H

1986-09-01

14

Model for Non-invasive Cardiac Output Measurement  

Microsoft Academic Search

Aim of the presented work has been the development of an algorithm for a non-invasive, portable, easy to use, and affordable device for measuring systemic cardiovascular parameters like cardiac output and peripheral resistance. The data acquisition is based on a common oscillometric measurement using an occlusive blood pressure cuff and no additional calibration is necessary. The introduced novel algorithm combines

Siegfried Wassertheurer; Felix Breitenecker

2007-01-01

15

Continuous negative extrathoracic pressure and cardiac output —a pilot study  

Microsoft Academic Search

Continuous negative extrathoracic pressure (CNEP) has been recently reintroduced as therapy for respiratory failure. To determine its effects on cardiac output a pilot study was performed in ten patients aged 2 months-3 years (meadian 4 months). All had chronic respiratory failure (seven with bronchopulmonary dysplasia). Five were breathing spontaneously and five were intubated and undergoing intermittent positive pressure ventilation. Transcutaneous

J. Raine; A. N. Redington; A. Benatar; M. P. Samuels; D. P. Southall

1993-01-01

16

Continuous cardiac output monitoring by peripheral blood pressure waveform analysis  

Microsoft Academic Search

A clinical method for monitoring cardiac output (CO) should be continuous, minimally invasive, and accurate. However, none of the conventional CO measurement methods possess all of these characteristics. On the other hand, peripheral arterial blood pressure (ABP) may be measured reliably and continuously with little or no invasiveness. We have developed a novel technique for continuously monitoring changes in CO

Ramakrishna Mukkamala; Andrew T. Reisner; Horacio M. Hojman; Roger G. Mark; Richard J. Cohen

2006-01-01

17

Evaluation of noninvasive cardiac output methods during exercise  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

18

Comparison of cardiac output determined by an ultrasound velocity dilution cardiac output method and by the lithium dilution cardiac output method in juvenile horses with experimentally induced hypovolemia.  

PubMed

Objective-To assess the accuracy of an ultrasound velocity dilution cardiac output (UDCO) method, compared with that of the lithium dilution cardiac output (LiDCO) method, for determination of cardiac output (CO) in juvenile horses with experimentally induced hypovolemia. Animals-12 anesthetized 2- to 6-month-old horses. Procedures-For each anesthetized horse, CO was determined by the LiDCO and UDCO methods prior to any intervention (baseline state), after withdrawal of approximately 40% of the horse's blood volume (low CO state), after maintenance of hypovolemia and infusion of norepinephrine until mean arterial blood pressure was equal to baseline value (high CO state), and after further infusion of norepinephrine and back-transfusion of withdrawn blood (posttransfusion state). For each of the 4 hemodynamic situations, CO and calculated cardiac index (CI) values were obtained by each method in duplicate (8 pairs of measurements/horse); mean values for each horse and overall mean values across all horses were calculated. Agreement between CI determined by each method (96 paired values) was assessed by Bland-Altman analysis. Results-For the UDCO method-derived CI measurements among the 12 horses, mean ± SD bias was -4 ± 11.3 mL/kg/min (95% limits of agreement, -26.1 to 18.2 mL/kg/min) and mean relative bias was -10.4 ± 21.5% (95% limits of agreement, -52.6% to 31.8%). Conclusions and Clinical Relevance-Results indicated that, compared with the LiDCO method, the UDCO method has acceptable clinical usefulness for determination of CO in foals. PMID:24866512

Shih, Andre C; Queiroz, Patricia; Vigani, Alessio; Da Cunha, Anderson; Pariaut, Romain; Ricco, Carolina; Bornkamp, Jennifer; Garcia-Pereira, Fernando; Bandt, Carsten

2014-06-01

19

Comparison of uncalibrated arterial waveform analysis in cardiac surgery patients with thermodilution cardiac output measurements  

Microsoft Academic Search

INTRODUCTION: Cardiac output (CO) monitoring is indicated only in selected patients. In cardiac surgical patients, perioperative haemodynamic management is often guided by CO measurement by pulmonary artery catheterisation (COPAC). Alternative strategies of CO determination have become increasingly accepted in clinical practice because the benefit of guiding therapy by data derived from the PAC remains to be proven and less invasive

Michael Sander; Claudia D Spies; Herko Grubitzsch; Achim Foer; Marcus Müller; Christian von Heymann

2006-01-01

20

Cardiac output and sympathetic vasoconstrictor responses during upright tilt to presyncope in healthy humans.  

PubMed

Syncope is a common clinical condition occurring even in healthy people without manifest cardiovascular disease. The purpose of this study was to determine the role of cardiac output and sympathetic vasoconstriction in neurally mediated (pre)syncope. Twenty-five subjects (age 15–51) with no history of recurrent syncope but who had presyncope during 60 deg upright tilt were studied; 10 matched controls who completed 45 min tilting were analysed retrospectively. Beat-to-beat haemodynamics (Modelflow), muscle sympathetic nerve activity (MSNA) and sympathetic baroreflex sensitivity (MSNA–diastolic pressure relation) were measured. MSNA, haemodynamic responses and baroreflex sensitivity during early tilting were not different between presyncopal subjects and controls. Hypotension was mediated by a drop in cardiac output in all presyncopal subjects, accompanied by a decrease in total peripheral resistance in 16 of them (64%, group A). In the other 9 subjects, total peripheral resistance was well maintained even at presyncope (36%, group B). Cardiac output was smaller (3.26 ± 0.34 (SEM) vs. 5.02 ± 0.40 l min(?1), P = 0.01), while total peripheral resistance was greater (1327 ± 117 vs. 903 ± 80 dyn s cm(?5), P < 0.01) in group B than group A at presyncope. The steeper fall in cardiac output in group B was due to a drop in heart rate. MSNA decreased rapidly at presyncope after the onset of hypotension. Thus, a moderate fall in cardiac output with coincident vasodilatation or a marked fall in cardiac output with no changes in peripheral vascular resistance may contribute to (pre)syncope. However, an intrinsic impairment of vasomotor responsiveness and sympathetic baroreflex function is not the cause of neurally mediated (pre)syncope in this population. PMID:22331415

Fu, Qi; Verheyden, Bart; Wieling, Wouter; Levine, Benjamin D

2012-04-15

21

Cardiac output and sympathetic vasoconstrictor responses during upright tilt to presyncope in healthy humans  

PubMed Central

Syncope is a common clinical condition occurring even in healthy people without manifest cardiovascular disease. The purpose of this study was to determine the role of cardiac output and sympathetic vasoconstriction in neurally mediated (pre)syncope. Twenty-five subjects (age 15–51) with no history of recurrent syncope but who had presyncope during 60 deg upright tilt were studied; 10 matched controls who completed 45 min tilting were analysed retrospectively. Beat-to-beat haemodynamics (Modelflow), muscle sympathetic nerve activity (MSNA) and sympathetic baroreflex sensitivity (MSNA–diastolic pressure relation) were measured. MSNA, haemodynamic responses and baroreflex sensitivity during early tilting were not different between presyncopal subjects and controls. Hypotension was mediated by a drop in cardiac output in all presyncopal subjects, accompanied by a decrease in total peripheral resistance in 16 of them (64%, group A). In the other 9 subjects, total peripheral resistance was well maintained even at presyncope (36%, group B). Cardiac output was smaller (3.26 ± 0.34 (SEM) vs. 5.02 ± 0.40 l min?1, P= 0.01), while total peripheral resistance was greater (1327 ± 117 vs. 903 ± 80 dyn s cm?5, P < 0.01) in group B than group A at presyncope. The steeper fall in cardiac output in group B was due to a drop in heart rate. MSNA decreased rapidly at presyncope after the onset of hypotension. Thus, a moderate fall in cardiac output with coincident vasodilatation or a marked fall in cardiac output with no changes in peripheral vascular resistance may contribute to (pre)syncope. However, an intrinsic impairment of vasomotor responsiveness and sympathetic baroreflex function is not the cause of neurally mediated (pre)syncope in this population.

Fu, Qi; Verheyden, Bart; Wieling, Wouter; Levine, Benjamin D

2012-01-01

22

[Continuous measurement of cardiac output with pulse contour analysis].  

PubMed

Pulse contour cardiac output (PCCO) is an easily applicable method for continuous measurement of cardiac output in critically ill patients. Calculation of stroke volume is possible by analysing the area under the systolic part of the arterial pulse pressure waveform together with an individual calibration factor (Zao) to account for the individually variable vascular impedance. Since vascular impedance is potentially affected by altered vascular tone, it was the aim of the present study to examine the validity of PCCO in ICU patients receiving various dosages of a variety of vasoactive drugs. PATIENTS AND METHODS. Continuous cardiac output was measured in 20 ICU patients for a total of 110 h using the pulse contour method. The precision of PCCO was determined in comparison with its calibration reference, the thermodilution method (TDCO): (1) during administration of vasoactive drugs at a constant rate and (2) during conditions with altered vascular tone and haemodynamics elicited by changes in vasoactive drug dosage. For this purpose, the patients received varying dosages of vasoactive drugs (dopamine, dobutamine, epinephrine, norepinephrine, nitroglycerin, prostacyclin and urapidil). RESULTS. A total of 165 data sets was obtained, each consisting of the average of four capnometrically triggered TDCO measurements and the corresponding PCCO values. The relative difference between methods (+/- 2 SD) was +/- 23.9% (SD 0.85 l.min-1; r = 0.93) if a single calibration at the beginning of measurement series was performed (Fig. 2). The bias of the mean cardiac output values of both methods was -0.09 l.min-1. The precision of PCCO improved to +/- 15.7% by additional calibrations (SD 0.56.min-1; r = 0.96; bias 0.003 l.min-1). Data of two patients showed that recalibration may be necessary after extreme haemodynamic changes due to septic shock or cooling. Alteration of vascular tone by clinically used dosage of vasoactive drugs, however, had no destabilizing effect on the pulse contour method. CONCLUSIONS. It could be demonstrated that PCCO provides a valuable method for continuous cardiac output measurement in the intensive care setting with a precision comparable to that of thermodilution. PMID:7661336

Irlbeck, M; Forst, H; Briegel, J; Haller, M; Peter, K

1995-07-01

23

Determination of Cardiac Output by the Fick Method, Thermodilution, and Acetylene Rebreathing in Pulmonary Hypertension  

Microsoft Academic Search

Assessment of cardiac output is an important part of the management of patients with pulmonary hypertension. The accuracy of the thermodilution technique in patients with low cardiac output or severe tricuspid regurgitation has been questioned. To address this issue, we simultaneously com- pared 105 cardiac output measurements by the Fick method and thermodilution in 35 patients with pulmonary hypertension. Moreover,

MARIUS M. HOEPER; ROMAN MAIER; JOERN TONGERS; JOST NIEDERMEYER; JENS M. HOHLFELD; MICHAEL HAMM; HELMUT FABEL

1999-01-01

24

Non-Invasive Measurement of Cardiac Output during Atrial Fibrillation: Comparison between Cardiac Magnetic Resonance Imaging and Inert Gas Rebreathing  

Microsoft Academic Search

Objectives: Atrial fibrillation (AF) is one of the most frequent heart rhythm disorders. It potentially influences cardiac function and its measurement. Cardiac magnetic resonance imaging (CMR) has become the new gold standard for non-invasive assessment of cardiac output (CO). A novel inert gas rebreathing (IGR) device based on the Fick Principle also proved promising in patients in sinus rhythm (SR).

J. Saur; F. Trinkmann; C. Doesch; J. Weissmann; K. Hamm; S. O. Schoenberg; M. Borggrefe; D. Haghi; J. J. Kaden

2010-01-01

25

Regional blood flow distribution in dog during induced hypotension and low cardiac output. Spontaneous breathing versus artificial ventilation.  

PubMed Central

Respiratory muscle blood flow and organ blood flow was studied in two groups of dogs with radioactively labeled microspheres to assess the influence of the working respiratory muscles on the regional distribution of blood flow when arterial pressure and cardiac output were lowered by pericardial tamponade. In one group (n = 6), the dogs were paralyzed and mechanically ventilated (Mv), while in the other (n = 6), they were left to breathe spontaneously (Sb). Cardiac output fell to 30% of control values during tamponade in both groups and was maintained constant. None of the dogs was hypoxic. Ventilation in the Sb group peaked after 50 min of hypotension, but remained unchanged in the Mv group. Duplicate measurements of blood flow were made during a control period and after 50 min of tamponade (corresponding to the peak ventilation in Sb). Blood flow to the respiratory muscles increased significantly (P less than 0.001) during tamponade in Sb (diaphragmatic flow increased to 361% of control values), while it decreased in Mv. Although the arterial blood pressure and cardiac output were comparable in the two groups, blood flow distribution during tamponade was different. In Sb, the respiratory muscles received 21% of the cardiac output, compared with only 3% in the Mv group. Thus, by muscle paralysis and Mv, a large fraction of the cardiac output used by the working respiratory muscles can be made available for perfusion of other organs during low cardiac output state: blood flows to the liver, brain, and quadriceps muscles were significantly higher during tamponade in the Mv group compared with the Sb group. Similarly, blood lactate at all times after the induction of low cardiac output and hypotension was significantly lower in the Mv animals (P less than 0.005).

Viires, N; Sillye, G; Aubier, M; Rassidakis, A; Roussos, C

1983-01-01

26

Cardiac Output Assessed by Invasive and Minimally Invasive Techniques  

PubMed Central

Cardiac output (CO) measurement has long been considered essential to the assessment and guidance of therapeutic decisions in critically ill patients and for patients undergoing certain high-risk surgeries. Despite controversies, complications and inherent errors in measurement, pulmonary artery catheter (PAC) continuous and intermittent bolus techniques of CO measurement continue to be the gold standard. Newer techniques provide less invasive alternatives; however, currently available monitors are unable to provide central circulation pressures or true mixed venous saturations. Esophageal Doppler and pulse contour monitors can predict fluid responsiveness and have been shown to decrease postoperative morbidity. Many minimally invasive techniques continue to suffer from decreased accuracy and reliability under periods of hemodynamic instability, and so few have reached the level of interchangeability with the PAC.

Lee, Allison J.; Cohn, Jennifer Hochman; Ranasinghe, J. Sudharma

2011-01-01

27

Arteriovenous fistula-associated high-output cardiac failure: a review of mechanisms  

Microsoft Academic Search

High-output cardiac failure can be a rare complication of high-output arterioveous fistula. The authors present a case in which a hemodialysis patient with a high-flow arteriovenous fistula has cardiac failure that improves with fistula closure. The hemodynamic effects of a fistula are reviewed, and the hemodialysis literature regarding high-output cardiac failure is summarized. To gain insight into the problem of

Jennifer M MacRae; Sanjay Pandeya; Dennis P Humen; Nikolai Krivitski; Robert M Lindsay

2004-01-01

28

Partial CO2 Rebreathing Indirect Fick Technique for Non-Invasive Measurement of Cardiac Output  

Microsoft Academic Search

Objective.Evaluation in animals of a non-invasive and continuous cardiac output monitoring system based on partial carbon-dioxide (CO2) rebreathing indirect Fick technique. Methods.We have developed a non-invasive cardiac output (NICO) monitoring system, based on the partial rebreathing method. The partial\\u000a rebreathing technique employs a differential form of the Fick equation for calculating cardiac output (QT) using non-invasive measurements. Changes in CO2

Dinesh G. Haryadi; Joseph A. Orr; Kai Kuck; Scott McJames; Dwayne R. Westenskow

2000-01-01

29

Comparison of methods to calculate cardiac output using the CO 2 rebreathing method  

Microsoft Academic Search

Summary  A comparison was made of methods used to calculate cardiac output by the indirect (CO2) Fick procedure (equilibrium method). Alternative methods for calculation of arterialPCO2, mixed venousPCO2, and conversion of gas tension to content were tested. Cardiac output values determined with a “corrected” equilibriumPCO2, to approximate mixed venousPCO2, were observed to be closest to cardiac output values determined on similar

Donald H. Paterson; David A. Cunningham

1976-01-01

30

Cardiac output estimation using pulmonary mechanics in mechanically ventilated patients.  

PubMed

The application of positive end expiratory pressure (PEEP) in mechanically ventilated (MV) patients with acute respiratory distress syndrome (ARDS) decreases cardiac output (CO). Accurate measurement of CO is highly invasive and is not ideal for all MV critically ill patients. However, the link between the PEEP used in MV, and CO provides an opportunity to assess CO via MV therapy and other existing measurements, creating a CO measure without further invasiveness.This paper examines combining models of diffusion resistance and lung mechanics, to help predict CO changes due to PEEP. The CO estimator uses an initial measurement of pulmonary shunt, and estimations of shunt changes due to PEEP to predict CO at different levels of PEEP. Inputs to the cardiac model are the PV loops from the ventilator, as well as the oxygen saturation values using known respiratory inspired oxygen content. The outputs are estimates of pulmonary shunt and CO changes due to changes in applied PEEP. Data from two published studies are used to assess and initially validate this model.The model shows the effect on oxygenation due to decreased CO and decreased shunt, resulting from increased PEEP. It concludes that there is a trade off on oxygenation parameters. More clinically importantly, the model also examines how the rate of CO drop with increased PEEP can be used as a method to determine optimal PEEP, which may be used to optimise MV therapy with respect to the gas exchange achieved, as well as accounting for the impact on the cardiovascular system and its management. PMID:21108836

Sundaresan, Ashwath; Chase, J Geoffrey; Hann, Christopher E; Shaw, Geoffrey M

2010-01-01

31

Continuous cardiac output monitoring by peripheral blood pressure waveform analysis.  

PubMed

A clinical method for monitoring cardiac output (CO) should be continuous, minimally invasive, and accurate. However, none of the conventional CO measurement methods possess all of these characteristics. On the other hand, peripheral arterial blood pressure (ABP) may be measured reliably and continuously with little or no invasiveness. We have developed a novel technique for continuously monitoring changes in CO by mathematical analysis of a peripheral ABP waveform. In contrast to the previous techniques, our technique analyzes the ABP waveform over time scales greater than a cardiac cycle in which the confounding effects of complex wave reflections are attenuated. The technique specifically analyzes 6-min intervals of ABP to estimate the pure exponential pressure decay that would eventually result if pulsatile activity abruptly ceased (i.e., after the high frequency wave reflections vanish). The technique then determines the time constant of this exponential decay, which equals the product of the total peripheral resistance and the nearly constant arterial compliance, and computes proportional CO via Ohm's law. To validate the technique, we performed six acute swine experiments in which peripheral ABP waveforms and aortic flow probe CO were simultaneously measured over a wide physiologic range. We report an overall CO error of 14.6%. PMID:16532772

Mukkamala, Ramakrishna; Reisner, Andrew T; Hojman, Horacio M; Mark, Roger G; Cohen, Richard J

2006-03-01

32

Relation of QRS Shortening to Cardiac Output During Temporary Resynchronization Therapy after Cardiac Surgery  

PubMed Central

Cardiac resynchronization therapy (CRT) can improve cardiac function in heart failure without increasing myocardial oxygen consumption. However, CRT optimization based on hemodynamics or echocardiography is difficult. QRS duration (QRSd) is a possible alternative optimization parameter. Accordingly, we assessed QRSd optimization of CRT during cardiac surgery. We hypothesized that QRSd shortening during changes in interventricular pacing delay (VVD) would increase cardiac output (CO). Seven patients undergoing coronary artery bypass, aortic or mitral valve surgery with LV ejection fraction ? 40% and QRSd ? 100 msec were studied. CRT was implemented at epicardial pacing sites in the left and right ventricle and right atrium during VVD variation after cardiopulmonary bypass. QRSd was correlated with CO from an electromagnetic aortic flow probe. Both positive and negative correlations were observed. Correlation coefficients ranged from 0.70 to ?0.74 during VVD testing. Clear minima in QRSd were observed in four patients and were within 40 msec of maximum CO in two. We conclude that QRSd is not useful for routine optimization of VVD after cardiac surgery but may be useful in selected patients. Decreasing QRSd is associated with decreasing CO in some patients, suggesting that CRT can affect determinants of QRSd and ventricular function independently.

Spotnitz, Matthew E.; Richmond, Marc E.; Quinn, T. Alexander; Cabreriza, Santos E.; Wang, Daniel Y.; Albright, Catherine M.; Weinberg, Alan D.; Dizon, Jose M.; Spotnitz, Henry M.

2011-01-01

33

Non-invasive cardiac output monitoring during catheter interventions in patients with cavopulmonary circulations.  

PubMed

Introduction: Functionally univentricular hearts palliated with superior or total cavopulmonary connection result in circulations in series. The absence of a pre-pulmonary pump means that cardiac output is more difficult to adjust and control. Continuous monitoring of cardiac output is crucial during cardiac catheter interventions and can provide new insights into the complex physiology of these lesions. Materials and methods: The Icon® cardiac output monitor was used to study the changes in cardiac output during catheter interventions in 15 patients (median age: 6.1 years, range: 4.8-15.3 years; median weight: 18.5 kg, range: 15-63 kg) with cavopulmonary circulations. A total of 19 interventions were undertaken in these patients and the observed changes in cardiac output were recorded and analysed. Results: Cardiac output was increased with creation of stent fenestrations after total cavopulmonary connection (median increase of 22.2, range: 6.7%-28.6%) and also with drainage of significant pleural effusions (16.7% increase). Cardiac output was decreased with complete or partial occlusion of fenestrations (median decrease of 10.6, range: 7.1%-13.4%). There was a consistent increase in cardiac output with stenting of obstructive left pulmonary artery lesions (median increase of 7.7, range: 5%-14.3%, p = 0.007). Conclusions: Icon® provides a novel technique for the continuous, non-invasive monitoring of cardiac output. It provides a further adjunct for monitoring of physiologically complex patients during catheter interventions. These results are consistent with previously reported series involving manipulation of fenestrations. This is the first report identifying an increase in cardiac output with stenting of obstructive pulmonary arterial lesions. PMID:23680531

Noonan, Patrick Michael Emmet; Viswanathan, Sangeetha; Chambers, Amy; Stumper, Oliver

2014-06-01

34

Continuous cardiac output measurement: pulse contour analysis vs thermodilution technique in cardiac surgical patients.  

PubMed

We have analysed the clinical agreement between two methods of continuous cardiac output measurement pulse contour analysis (PCCO) and a continuous thermodilution technique (CCO), were both compared with the intermittent bolus thermodilution technique (BCO). Measurements were performed in 26 cardiac surgical patients (groups 1 and 2, 13 patients each, with an ejection fraction > 45% and < 45%, respectively) at 12 selected times. During operation, mean differences (bias) between PCCO-BCO and CCO-BCO did not differ in either group. However, phenylephrine-induced increases in systemic vascular resistance (SVR) by approximately 60% resulted in significant differences. Significantly higher absolute bias values of PCCO-BCO compared with CCO-BCO were also found early after operation in the ICU. Thus PCCO and CCO provided comparable measurements during coronary bypass surgery. After marked changes in SVR, further calibration of the PCCO device is necessary. PMID:10472216

Rödig, G; Prasser, C; Keyl, C; Liebold, A; Hobbhahn, J

1999-04-01

35

Continuous wave doppler cardiac output: Use in pediatric patients receiving inotropic support  

Microsoft Academic Search

Summary Doppler estimates of cardiac output have been shown to correlate closely with invasive measurement of cardiac output in hemodynamically stable adults and children. However, this method has not been validated in hemodynamically unstable pediatric patients. To assess the accuracy of continuous wave Doppler echocardiography in pediatric patients with unstable hemodynamics, we performed 27 simultaneous Doppler and thermodilution comparisons in

William R. Morrow; Daniel J. Murphy; David J. Fisher; James C. Huhta; Larry S. Jefferson; E. O'Brian Smith

1988-01-01

36

Thermodynamics of the heart: Relation between cardiac output and oxygen consumption  

NASA Astrophysics Data System (ADS)

A thermodynamic approach is used to derive a relation between cardiac output and rate of oxygen consumption. As an example, the relation is used to calculate the cardiac output of a young woman exercising on a treadmill. The results can be understood by undergraduates without any previous knowledge of human physiology.

Uehara, Mituo; Sakane, Kumiko K.; Bertolotti, Simone A.

2008-06-01

37

An experimental, simplified method for intradialytic cardiac output measurement.  

PubMed

Hypotension during hemodialysis (HD) is a frequent and troublesome treatment complication. A decrease in the cardiac output (CO) due to an imbalance in the rates of fluid ultrafiltration vs. tissue reabsorption is a major cause of such episodes; thus, routine repeated measurements of CO during HD sessions could be of use in preventing its occurrence. We tested an experimental method (EXP) for measuring CO during HD using hardware already supplied with current Gambro dialysis machines. In 12 HD patients, CO was measured twice during dialysis by injecting a small (2?mL) bolus of highly concentrated saline into the patient's bloodstream and measuring the subsequent increase in dialysate conductivity using the Diascan technology. CO was calculated with the Stewart-Hamilton method using the area under the conductivity curve, measured dialysate flow rate, and dialyzer clearance. Compared with ultrasound hemodilution measurements, the EXP showed no bias and limits of agreement of ±34.6%. The intradialytic trend correlated well between the two methods (r(2) ?=?0.63, concordance rate 100%). We propose that with further development and refining, reliable measurements of CO could be performed easily during routine HD treatment using this new methodology. PMID:22188038

Cordtz, Joakim; Sternby, Jan

2012-03-01

38

Cardiac output by arterial pulse contour: reliability under hemodynamic derangements.  

PubMed

Pulse contour methods (PCM) for the measurements of cardiac output (CO) are gaining popularity in intensive care settings but their reliability during hemodynamic instability has been questioned. Pressure-recording-analytical-method (PRAM) is a newly developed uncalibrated hemodynamic monitor and its capability in measuring CO during hemodynamic instability is still under investigation. Dobutamine (2.5 and 5 microg/kg/min), vasoconstriction (arginine-vasopressin 4, 8 and 16 IU/h), hemorrhage (-10%, -20%, -35%, and -50% of the theoretical volemia), and volume resuscitation were induced in eight swine. CO by means of thermodilution (CO(ThD)), transesophageal echocardiography (CO(TEE)) and PRAM (CO(PRAM)) were contemporarily registered. R(2), bias, and percentage error were used to compare the methods. Comparison between CO(PRAM) and CO(ThD) resulted in: r(2)=0.87; bias=-0.006 l/min; precision=+/-0.87 l/min; percentage error=22.8%. Comparison between CO(PRAM) and CO(TEE) resulted in: r(2)=0.85; bias=-0.007 l/min; precision=+/-0.86 l/min; percentage error=22%. Sub-group analysis revealed disagreement between methods only during the last two steps of hemorrhage: CO(PRAM) vs. CO(ThD): r(2)=0.67, bias=-0.37 l/min, precision=+/-1.04 l/min, limits of agreement=-1.39+0.66 l/min, and percentage error=45%; CO(PRAM) vs. CO(TEE): r(2)=0.38, bias=0.4 l/min, precision=+/-1.42 l/min, limits of agreement=-0.99+1.79 l/min, and percentage error=62%. PRAM resulted to be accurate in measuring CO during hemodynamic stability, tachycardia, and vasoconstriction. When volemia was reduced by >35%, disagreement between methods was observed. PMID:19299422

Romagnoli, Stefano; Romano, Salvatore Mario; Bevilacqua, Sergio; Ciappi, Francesco; Lazzeri, Chiara; Peris, Adriano; Dini, Daniele; Gelsomino, Sandro

2009-06-01

39

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

PubMed

An area integrator for the thermodilution curve in cardiac output measurement is described. A new temperature sensor is used, a diode with some advantages over the thermistor normally used. The main advantages are: easy calibration and replacement, and broad range of linearity. The cardiac output values obtained in dog with the integrator follow a linear relationship with those of the flowmeter. In simultaneous measurements the correlation is R = 0.96. Using a diode as temperature sensor a modification of the Steward Hamilton equation (used for thermistor) is necessary. With this new equation a monogram is performed to calculate the cardiac output from the area given by the numerical integrator. PMID:550124

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

1979-01-01

40

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

PubMed Central

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.

Kang, Dongyel; Huang, Qiaojian; Li, Youzhi

2014-01-01

41

Application of ultrasound dilution technology for cardiac output measurement: Cerebral and systemic hemodynamic consequences in a juvenile animal model  

Microsoft Academic Search

OBJECTIVE: Analysis of cerebral and systemic hemodynamic consequences of ultrasound dilution cardiac output measurements. DESIGN: : Prospective, experimental piglet study. SETTING: Animal laboratory. SUBJECTS: Nine piglets. INTERVENTIONS: Ultrasound dilution cardiac output measurements were performed in ventilated, anesthetized piglets. Interventions that are required for ultrasound dilution cardiac output measurement were evaluated for its effect on cerebral and systemic circulation and oxygenation.

W. P. de Boode; A. F. J. van Heijst; J. C. W. Hopman; R. B. Tanke; J. G. van der Hoeven; K. D. Liem

2010-01-01

42

Health Technology Assessment Reports, 1989. Number 3. Cardiac Output by Electrical Bioimpedance.  

National Technical Information Service (NTIS)

Electrical bioimpedance is a method used to determine stroke volume and cardiac output from thoracic tissue resistance to an imposed alternating electric current. The tissue resistance is inversely related to the thoracic blood content. When thoracic bloo...

H. Handelsman

1989-01-01

43

Comparison of dye dilution method to radionuclide techniques for cardiac output determination in dogs  

SciTech Connect

A study was undertaken to identify the most accurate /sup 99m/Tc-labeled radiopharmaceutical and to determine the accuracy of a noninvasive radionuclide technique or cardiac output determinations. Phase I employed sodium pertechnetate, stannous pyrophosphate with sodium pertechnetate, /sup 99m/Tc red blood cells, and /sup 99m/Tc human serum albumin as radionuclide tracers. Cardiac output was determined by the dye dilution method and then by the invasive radionuclide technique. A pairied t test and regression analysis indicated that /sup 99m/Tc human serum albumin was the most accurate radiopharmaceutical for cardiac output determinations, and the results compared favorably to those obtained by the dye dilution method. In Phase II, /sup 99m/Tc human serum albumin was used as the radionuclide tracer for cardiac output determinations with the noninvasive technique. The results compared favorably to those obtained by the dye dilution method.

Eng, S.S.; Robayo, J.R.; Porter, W.; Smith, R.E.

1980-05-01

44

Pulse contour cardiac output derived from non-invasive arterial pressure in cardiovascular disease.  

PubMed

Pulse contour methods determine cardiac output semi-invasively using standard arterial access. This study assessed whether cardiac output can be determined non-invasively by replacing the intra-arterial pressure input with a non-invasive finger arterial pressure input in two methods, Nexfin CO-trek and Modelflow , in 25 awake patients after coronary artery bypass surgery. Pulmonary artery thermodilution cardiac output served as a reference. In the supine position, the mean (SD) differences between thermodilution cardiac output and Nexfin CO-trek were 0.22 (0.77) and 0.44 (0.81) l.min(-1) , for intra-arterial and non-invasive pressures, respectively. For Modelflow, these differences were 0.70 (1.08) and 1.80 (1.59) l.min(-1) , respectively. Similarly, in the sitting position, differences between thermodilution cardiac output and Nexfin CO-trek were 0.16 (0.78) and 0.34 (0.83), for intra-arterial and non-invasive arterial pressure, respectively. For Modelflow, these differences were 0.58 (1.11) and 1.52 (1.54) l.min(-1) , respectively. Thus, Nexfin CO-trek readings were not different from thermodilution cardiac output, for both invasive and non-invasive inputs. However, Modelflow readings differed greatly from thermodilution when using non-invasive arterial pressure input. PMID:20860647

Bogert, L W J; Wesseling, K H; Schraa, O; Van Lieshout, E J; de Mol, B A J M; van Goudoever, J; Westerhof, B E; van Lieshout, J J

2010-11-01

45

Cardiac Output Derived from Arterial Pressure Waveform Analysis in Patients Undergoing Cardiac Surgery: Validity of a Second Generation Device  

Microsoft Academic Search

BACKGROUND: The performance of a recently introduced, arterial waveform-based device for measuring cardiac output (CO) without the need of invasive calibration (FloTrac\\/Vigileo™) has been controversial. We designed the present study to assess the validity of an improved version of this monitoring technique compared with intermittent thermodilution CO measurement using a pulmonary artery catheter in patients undergoing cardiac surgery. METHODS: Forty

Jochen Mayer; Joachim Boldt; Michael W. Wolf; Johannes Lang; Stefan Suttner

2008-01-01

46

Expiratory Loading Improves Cardiac Output During Exercise In Heart Failure  

PubMed Central

Purpose To investigate the effect of changes in expiratory intrathoracic pressure (ITP) on stroke volume (SV) at rest and during moderate exercise in patients with heart failure vs. healthy individuals. Methods SV was obtained by echocardiography during spontaneous breathing and during expiratory loads of 5 and 10 cm H2O produced by a ventilator in 11 patients with heart failure (61±9 years, EF: 32±4%, NYHA class I-II) and 11 age-matched healthy individuals at rest and during exercise at 60% of aerobic capacity on a semi-recumbent cycle ergometer. Results At rest, expiratory loading did not change heart rate, SV index (SVI) or cardiac index (CI) in either group. During moderate exercise, expiratory loading increased SVI and CI in patients with heart failure, but decreased SVI and CI in healthy individuals. There was a negative correlation between changes in gastric pressure and SVI (r=?0.51, p<0.05) in healthy individuals, while there was a positive correlation between changes in gastric pressure accompanying expiratory loading and CI (r=0.83, p<0.01) in patients with heart failure. Conclusion Expiratory loading during moderate exercise elicited increases in SVI and CI in patients with heart failure but decreased SVI and CI in healthy individuals. Improvements in cardiac function during submaximal exercise in patients with heart failure may be caused by a beneficial reduction in LV preload.

Lalande, Sophie; Luoma, Charles E.; Miller, Andrew D.; Johnson, Bruce D.

2012-01-01

47

Peak Cardiac Power Output, Measured Noninvasively, Is a Powerful Predictor of Outcome in Chronic Heart Failure  

Microsoft Academic Search

Background—The cardiac output (CO) response to exercise and other invasively derived hemodynamic variables has been variably described to provide better prognostication than peak VO2 in patients with chronic heart failure. Using noninvasive measurements of CO during exercise, we compared the prognostic value of peak CO and cardiac power to peak VO2 in chronic heart failure patients. Method and Results—One hundred

Chim C. Lang; Paula Karlin; Jennifer Haythe; Tiong K. Lim; Donna M. Mancini

2010-01-01

48

Decreased cardiac output, venous congestion and the association with renal impairment in patients with cardiac dysfunction  

Microsoft Academic Search

Background: Renalfailureinheartfailureisrelatedtodecreasedcardiacoutput.However,littleisknownaboutitsassociationwithvenouscongestion. Aims: To investigate the relationship between venous congestion and glomerular filtration rate (GFR) in patients with cardiac dysfunction. Methods and results: Right atrial pressure (RAP) and cardiac index (CI) were determined by right heart catheterisation in 51 patients with cardiac dysfunction, secondary to pulmonary hypertension. GFR and renal blood flow (RBF) were measured as 125I-Iothalamate and 131I- Hippuran

Kevin Damman; Gerjan Navis; Tom D. J. Smilde; Adriaan A. Voors; Wim van der Bij; Dirk J. van Veldhuisen; Hans L. Hillege

2007-01-01

49

Evaluation of a noninvasive method for cardiac output measurement in critical care patients  

Microsoft Academic Search

Objective. Thermodilution (TD) is the gold standard to monitor cardiac output (CO) in critical care. However, there is concern about the safety of right-ventricular catheterization. The CO2 rebreathing technique allows noninvasive CO determination by means of the indirect Fick principle. Our objectives were: (a) to assess the accuracy of a new system of CO measurement using the CO2 partial rebreathing

Gastón E. Murias; Ana Villagrá; Sara Vatua; Maria del Mar Fernandez; Héctor Solar; Ana Ochagavía; Rafael Fernández; Josefina Aguilar; Pablo V. Romero; Lluis Blanch

2002-01-01

50

Reproducibility of noninvasive cardiac output during arm exercise in spinal cord injury  

Microsoft Academic Search

The carbon dioxide (CO 2 ) rebreathing method is a noninvasive technique to estimate cardiac output during exer- cise, but few data are available on the validity and reliability of this measure in individuals with spinal cord injury (SCI). Six- teen male subjects with SCI (mean age 45 +\\/? 9, seven paraple- gic and nine tetraplegic) underwent three submaximal steady

Jonathan Myers; Heather Brown; Susan Smith; Inder Perkash; B. Jenny Kiratli

2007-01-01

51

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

52

Circulation Time in Man from Lung to Periphery as an Indirect Index of Cardiac Output  

Microsoft Academic Search

Circulation time (Ct) between lung and periphery may be a surrogate for cardiac output, estimated here, for the most part, as the time between taking a breath of nitrogen and peripheral detection of a desaturation pulse. Use of pulse oximetry involves an internal, instrument delay; however, using the ear, we found shortening with exercise (12.1 ± 0.37 sec, at rest;

Chris B. Wolff; Sophie K. Checkley; Georgina Bhageerutty; Himanshu Bhatt; Atholl Johnston; David Collier; Ilias Tachtsidis; N. Garvie; M. Rosenberg; Nigel Benjamin

53

Effect of Hemorrhage on Cardiac Output, PVP, Alodosterone and Diuresis during Immersion in Men  

NASA Technical Reports Server (NTRS)

The purpose of this study was to test the hypothesis that a reduction in blood volume would attenuate or eliminate immersion-induced increases in cardiac output (Q (sup dot) sub co)) and urine excretion, and to investigate accompanying vasoactive and fluid-electrolyte hormonal responses.

Simanonok, K.; Greenleaf, John E.; Bernauer, E. M.; Wade, C. E.; Keil, L. C.

1990-01-01

54

PI3Ks Maintain the Structural Integrity of T-Tubules in Cardiac Myocytes  

PubMed Central

Background Phosphoinositide 3-kinases (PI3Ks) regulate numerous physiological processes including some aspects of cardiac function. Although regulation of cardiac contraction by individual PI3K isoforms has been studied, little is known about the cardiac consequences of downregulating multiple PI3Ks concurrently. Methods and Results Genetic ablation of both p110? and p110? in cardiac myocytes throughout development or in adult mice caused heart failure and death. Ventricular myocytes from double knockout animals showed transverse tubule (T-tubule) loss and disorganization, misalignment of L-type Ca2+ channels in the T-tubules with ryanodine receptors in the sarcoplasmic reticulum, and reduced Ca2+ transients and contractility. Junctophilin-2, which is thought to tether T-tubules to the sarcoplasmic reticulum, was mislocalized in the double PI3K-null myocytes without a change in expression level. Conclusions PI3K p110? and p110? are required to maintain the organized network of T-tubules that is vital for efficient Ca2+-induced Ca2+ release and ventricular contraction. PI3Ks maintain T-tubule organization by regulating junctophilin-2 localization. These results could have important medical implications because several PI3K inhibitors that target both isoforms are being used to treat cancer patients in clinical trials.

Wu, Chia-Yen C.; Jia, Zhiheng; Wang, Wei; Ballou, Lisa M.; Jiang, Ya-Ping; Chen, Biyi; Mathias, Richard T.; Cohen, Ira S.; Song, Long-Sheng; Entcheva, Emilia; Lin, Richard Z.

2011-01-01

55

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

56

Investigations concerning the application of the cross-correlation method in cardiac output measurements  

PubMed Central

Background In spite of numerous non-invasive examinations the “gold clinical standard” of cardiac output measurements is the invasive pulmonary artery catheterization by means of the Swan-Ganz catheter and the application of the thermodilution method to estimate the blood flow. The results obtained by means of thermodilution are sensitive to many physical and biological disturbances. The unreliability of this method amounts to 20-45% and depends on the given variant of the method. Therefore some other method, more accurate and resistant to disturbances, was looked for. This paper presents a new approach to cardiac output measurements, based on cross-correlation signal analysis. The goal of investigations was to verify experimentally the application of the cross-correlation method of cardiac output measurements. Results In 99.2% of the examined cases the extreme of the cross-correlation function was easy to be estimated by numerical algorithms. In 0,8% of the remaining cases (with a plateau region adjacent to the maximum point) numerical detection of the extreme was inaccurate. The typical unreliability of the investigated method amounted o 5.1% (9.8% in the worst case). Investigations performed on a physical model revealed that the unreliability of cardiac output measurements by means of the cross-correlation method is 3–5 times better than in the case of thermodilution. Conclusions The performed investigations and theoretical analysis have shown, that the cross-correlation method may be applied in cardiac output measurements. This kind of measurements seems to be more accurate and disturbance-resistant than clinically applied thermodilution.

2012-01-01

57

Drug detection in breath: effects of pulmonary blood flow and cardiac output on propofol exhalation.  

PubMed

Breath analysis could offer a non-invasive means of intravenous drug monitoring if robust correlations between drug concentrations in breath and blood can be established. In this study, propofol blood and breath concentrations were determined in an animal model under varying physiological conditions. Propofol concentrations in breath were determined by means of two independently calibrated analytical methods: continuous, real-time proton transfer reaction mass spectrometry (PTR-MS) and discontinuous solid-phase micro-extraction coupled with gas chromatography mass spectrometry (SPME-GC-MS). Blood concentrations were determined by means of SPME-GC-MS. Effects of changes in pulmonary blood flow resulting in a decreased cardiac output (CO) and effects of dobutamine administration resulting in an increased CO on propofol breath concentrations and on the correlation between propofol blood and breath concentrations were investigated in seven acutely instrumented pigs. Discontinuous propofol determination in breath by means of alveolar sampling and SPME-GC-MS showed good agreement (R(2)=0.959) with continuous alveolar real-time measurement by means of PTR-MS. In all investigated animals, increasing cardiac output led to a deterioration of the relationship between breath and blood propofol concentrations (R(2)=0.783 for gas chromatography-mass spectrometry and R(2)=0.795 for PTR-MS). Decreasing pulmonary blood flow and cardiac output through banding of the pulmonary artery did not significantly affect the relationship between propofol breath and blood concentrations (R(2)>0.90). Estimation of propofol blood concentrations from exhaled alveolar concentrations seems possible by means of different analytical methods even when cardiac output is decreased. Increases in cardiac output preclude prediction of blood propofol concentration from exhaled concentrations. PMID:21643859

Kamysek, Svend; Fuchs, Patricia; Schwoebel, Henny; Roesner, Jan P; Kischkel, Sabine; Wolter, Kathi; Loeseken, Christian; Schubert, Jochen K; Miekisch, Wolfram

2011-10-01

58

Prediction of the Changes in Cardiac Output in Association with Preload Reduction Therapy in Patients with Hypertensive Heart Failure  

Microsoft Academic Search

In treating patients with acute hypertensive heart failure we often try preload-reduction therapy using diuretics or vasodilators, but this may frequently produce a considerable decrease in cardiac output, particularly in hypertensive patients with diastolic dysfunction. Therefore, it is important from the clinical standpoint to predict the change in cardiac output following preload-reduction therapy. The objective of this study was to

Reiko Nagano; Tohru Masuyama; Jung-Myung Lee; Kazuhiro Yamamoto; Johji Naito; Toshiaki Mano; Hiroya Kondo; Masatsugu Hori; Michitoshi Inoue; Takenobu Kamada

1997-01-01

59

Cardiac output, coronary blood flow, and blood gases during open-chest standard and compression-active-decompression cardiopulmonary resuscitation  

Microsoft Academic Search

Objective: To determine whether open-chest compression-active-decompression (CAD) could improve cardiac output, coronary blood flow, blood gases, and resuscitation compared to open-chest manual compression in a porcine model of cardiac arrest. Design: Prospective, randomized laboratory investigation for measurement of cardiac output, coronary blood flow, arterial and mixed venous blood gases and potassium levels, and return of spontaneous circulation. Subjects: Ten pigs

Milo Engoren; Fred Severyn; Nancy Fenn-Buderer; Michael DeFrank

2002-01-01

60

Comparison of dynamic measurements of pulse contour with pulsed heat continuous cardiac output in postoperative cardiac surgical patients.  

PubMed

Cardiac output (CO) can be measured using bolus thermodilution via a pulmonary artery catheter (PAC) and as continuous cardiac output (CCO), using pulsed heat thermoditution. Pulse contour cardiac output (PCCO) measures continuous CO by analysis of the arterial waveform after calibration with thermodilution CO. The Pulsion Medical Systems (PiCCO system) achieves this by transpulmonary aortic thermodilution (TDtpa). There is uncertainty regarding the agreement between TDtpa, CCO, and PCCO CO measurements in situations of rapid haemodynamic changes. We studied the agreement of the measures by comparing digital recordings of cardiac index (CI) determined by PCCO and CCO (PCCI and CCI, respectively) made during periods of haemodynamic instability. After ethics committee approval we studied four post-coronary artery bypass graft patients, in the immediate postoperative period. Each patient had a 7.5F CCO catheter (Edwards Lifesciences) and a 5F, 20cm PCCO femoral artery catheter. Digital recordings were obtained for the first 12-18 postoperative hours. Six epochs of instability were identified in the first two to three postoperative hours, and at the commencement of inotropic or vasoactive drugs. Notable features, despite frequent PCCO calibrations, were the marked difference of PCCI compared to CCI. In contradistinction, they tracked very closely during a period of stability. Limitations of both methods were noted. Whilst PCCO responded to rapid change, it developed significant error during haemodynmamic instability and requires frequent recalibration. CCO on the other hand has a considerable time lag in responding to changes in CO. The way a monitor measures CO must be taken into account when using the data in clinical management. PMID:17424793

Boyle, Martin; Lawrence, John; Belessis, Andrew; Murgo, Margherita; Shehabi, Yahya

2007-02-01

61

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

62

Beta-adrenergic stimulation maintains cardiac function in Serca2 knockout mice.  

PubMed

Previous studies on Serca2 knockout (KO) mice showed that cardiac function is sustained in vivo for several weeks after knockout, whereas SERCA protein levels decrease and calcium dynamics are significantly impaired. In this study, we reconcile observed cellular and organ level contractile function using a cardiac multiscale model. We identified and quantified the changes in cellular function that are both consistent with observations and able to compensate for the decrease in SERCA. Calcium transients were used as input for multiscale computational simulations to predict whole-organ response. Although this response matched experimental pressure-volume (PV) measurements in healthy mice, the reduced magnitude calcium transients observed in KO cells were insufficient to trigger ventricular ejection. To replicate the effects of elevated catecholamine levels observed in vivo, cells were treated with isoproterenol. Incorporation of the resulting measured ?-adrenergically stimulated calcium transients into the model resulted in a close match with experimental PV loops. Changes in myofilament properties, when considered in isolation, were not able to increase tension development to levels consistent with measurements, further confirming the necessity of a high ?-adrenergic state. Modeling additionally indicated that increased venous return observed in the KO mice helps maintain a high ejection fraction via the Frank-Starling effect. Our study shows that increased ?-adrenergic stimulation is a potentially highly significant compensatory mechanism by which cardiac function is maintained in Serca2 KO mice, producing the increases in both systolic and diastolic calcium, consistent with the observed contractile function observed in experimental PV measurements. PMID:23528094

Land, Sander; Louch, William E; Niederer, Steven A; Aronsen, Jan Magnus; Christensen, Geir; Sjaastad, Ivar; Sejersted, Ole M; Smith, Nicolas P

2013-03-19

63

Beta-Adrenergic Stimulation Maintains Cardiac Function in Serca2 Knockout Mice  

PubMed Central

Previous studies on Serca2 knockout (KO) mice showed that cardiac function is sustained in vivo for several weeks after knockout, whereas SERCA protein levels decrease and calcium dynamics are significantly impaired. In this study, we reconcile observed cellular and organ level contractile function using a cardiac multiscale model. We identified and quantified the changes in cellular function that are both consistent with observations and able to compensate for the decrease in SERCA. Calcium transients were used as input for multiscale computational simulations to predict whole-organ response. Although this response matched experimental pressure-volume (PV) measurements in healthy mice, the reduced magnitude calcium transients observed in KO cells were insufficient to trigger ventricular ejection. To replicate the effects of elevated catecholamine levels observed in vivo, cells were treated with isoproterenol. Incorporation of the resulting measured ?-adrenergically stimulated calcium transients into the model resulted in a close match with experimental PV loops. Changes in myofilament properties, when considered in isolation, were not able to increase tension development to levels consistent with measurements, further confirming the necessity of a high ?-adrenergic state. Modeling additionally indicated that increased venous return observed in the KO mice helps maintain a high ejection fraction via the Frank-Starling effect. Our study shows that increased ?-adrenergic stimulation is a potentially highly significant compensatory mechanism by which cardiac function is maintained in Serca2 KO mice, producing the increases in both systolic and diastolic calcium, consistent with the observed contractile function observed in experimental PV measurements.

Land, Sander; Louch, William E.; Niederer, Steven A.; Aronsen, Jan Magnus; Christensen, Geir; Sjaastad, Ivar; Sejersted, Ole M.; Smith, Nicolas P.

2013-01-01

64

Extracorporeal life support with an integrated left ventricular vent in children with a low cardiac output.  

PubMed

Background: The aim of this study was to evaluate our experience in central extracorporeal life support with an integrated left ventricular vent in children with cardiac failure. Methods: Eight children acquired extracorporeal life support with a left ventricular vent, either after cardiac surgery (n = 4) or during an acute cardiac illness (n = 4). The ascending aorta and right atrium were cannulated. The left ventricular vent was inserted through the right superior pulmonary vein and connected to the venous line on the extracorporeal life support such that active left heart decompression was achieved. Results: No patient died while on support, seven patients were successfully weaned from it and one patient was transitioned to a biventricular assist device. The median length of support was 6 days (range 5-10 days). One patient died while in the hospital, despite successful weaning from extracorporeal life support. No intra-cardiac thrombus or embolic stroke was observed. No patient developed relevant intracranial bleeding resulting in neurological dysfunction during and after extracorporeal life support. Conclusions: In case of a low cardiac output and an insufficient inter-atrial shunt, additional left ventricular decompression via a vent could help avoid left heart distension and might promote myocardial recovery. In pulmonary dysfunction, separate blood gas analyses from the venous cannula and the left ventricular vent help detect possible coronary hypoxia when the left ventricle begins to recover. We recommend the use of central extracorporeal life support with an integrated left ventricular vent in children with intractable cardiac failure. PMID:23919969

Sandrio, Stany; Springer, Wolfgang; Karck, Matthias; Gorenflo, Matthias; Weymann, Alexander; Ruhparwar, Arjang; Loukanov, Tsvetomir

2014-08-01

65

Automated non-invasive measurement of cardiac output by the carbon dioxide rebreathing method: comparisons with dye dilution and thermodilution.  

PubMed Central

The accuracy and reproducibility of indirect measurement of cardiac output at rest by the carbon dioxide rebreathing (indirect Fick) method with an automated respiratory analysis system (Gould 9000IV) were compared with simultaneous measurements made in duplicate by dye dilution and thermodilution in 25 patients having cardiac catheterisation studies. Measurements of cardiac output by the carbon dioxide rebreathing method were not significantly different from those obtained with dye dilution (mean difference -0.3 l/min, SD 0.76, 95% confidence interval -0.7 to 0.1). Thermodilution significantly over-estimated cardiac output by a mean of 2.2 l/min or 39% (SD 1.5, 95% confidence interval 1.6 to 2.8) compared with the carbon dioxide rebreathing method and significantly overestimated cardiac output by 1.9 l/min or 31% (SD 1.2, 95% confidence interval 1.2 to 2.5) compared with dye dilution. The reproducibility of measurements of cardiac output in individual patients was satisfactory with the dye dilution method but was poor with carbon dioxide rebreathing and thermodilution. Indirect measurement of resting cardiac output by the Gould 9000IV automated carbon dioxide rebreathing method is more accurate but the variability inherent with this method requires that multiple measurements be taken for each determination. Measurement of cardiac output by the thermodilution method by a commercially available cardiac output computer was not satisfactory because not only was there considerable variability between repeat measurements but the method also consistently overestimated cardiac output compared with the dye dilution method.

Russell, A E; Smith, S A; West, M J; Aylward, P E; McRitchie, R J; Hassam, R M; Minson, R B; Wing, L M; Chalmers, J P

1990-01-01

66

[Non-invasive cardiac output measurement with USCOM in air rescue operation].  

PubMed

In cardiac emergency events (NACA score = 3.4), a non-invasive cardiac output test involving transaortalic blood flow velocity measurement was used in the air rescue of 30 patients. An average velocity integral (Vti) of 21.9 +/- 9.9 cm was determined in the short examination time (t = 120 +/- 30 sec). Related to the middle body surface (BSA = 2.0 +/- 0.3 m (2)), the calculated cardiac index (CI) was 2.6 +/- 1.1 l/min/m (2). The CI was under 2.2 l/min/m (2) in 12 examinations (40 %). 5 patients in this group subsequently received catecholamine therapy. Thrombolysis therapy increased by 17 % in the myocardial infarction group with CI

Schedler, O; Handschak, H; Hensel, M

2008-12-01

67

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

NASA Astrophysics Data System (ADS)

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

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

68

Cardiac output in single-lead VDD pacing versus rate-matched VVIR pacing.  

PubMed

The importance of atrioventricular synchronous pacing compared with single-chamber rate-responsive pacing is still under discussion, especially for low-intensity workload representing daily life activities. We evaluated hemodynamics in single-lead VDD pacing versus VVIR pacing in 11 patients (8 men and 3 women, aged 58.6 +/- 13.8 years) with normal left ventricular function and a previously implanted single-lead VDDR pacemaker. A low-intensity steady-state treadmill test at 1 to 2.5 mph with a gradient of 2% to 4% was performed. Cardiac output was determined using a standard carbon dioxide rebreathing technique. Initially, the VDD mode was programmed, and after 5 minutes of exercise, cardiac output was measured in steady-state conditions. The pacemaker was then reprogrammed to the VVI mode at a rate 5 to 10 beats above the maximal atrial tracking rate to simulate rate-matched VVIR pacing (VVIRm). After 5 additional minutes of steady-state exercise, cardiac output was measured again. The maximal atrial rate in the VDD mode was 119 +/- 19 beats/min versus a programmed rate of 129 +/- 18 beats/min in the VVIRm mode. VDD pacing resulted in a significantly higher cardiac output than VVIRm pacing (10.6 +/- 1.9 vs 9.2 +/- 1.4 L/min; p < 0.002), with a mean difference of 1.6 +/- 1.2 L/min between the 2 modes. In the VDD mode, stroke volume (90.7 +/- 20.1 vs 71.6 +/- 13.0 ml; p < 0.001) and maximal oxygen uptake (1,183 +/- 264 vs 1,076 +/- 289 ml/min, p < 0.01) were also higher than in VVIRm.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7732998

Nowak, B; Voigtländer, T; Himmrich, E; Liebrich, A; Poschmann, G; Epperlein, S; Treese, N; Meyer, J

1995-05-01

69

Noninvasive Cardiac Output Determination for Children by the Inert Gas-Rebreathing Method  

Microsoft Academic Search

Standard methods for determination of cardiac output (CO) are either invasive or technically demanding. Measurement of CO\\u000a by the inert gas–rebreathing (IGR) method, applied successfully in adults, uses a low-concentration mixture of an inert and\\u000a a blood-soluble gas, respectively. This study tested the feasibility of this method for determining CO during exercise for\\u000a pediatric patients with complete congenital atrioventricular block

Gesa Wiegand; Gunter Kerst; Winfried Baden; Michael Hofbeck

2010-01-01

70

Dynamic vs. fixed bag filling: Impact on cardiac output rebreathing protocol  

Microsoft Academic Search

A main purpose of this study was to compare the repeatability (2.77 multiplied by the within-subject SD) between two different rebreathing protocols on cardiac output (Q?), pulmonary diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO), and pulmonary capillary blood volume (Vc). This study compared two bag volume conditions [Fixed Bag Volume (FBV)=BV fixed at 60% of forced vital

Gerald S. Zavorsky; Kenneth C. Beck; Lauren M. Cass; Raul Artal; Peter D. Wagner

2010-01-01

71

A comparison of the Nexfin® and transcardiopulmonary thermodilution to estimate cardiac output during coronary artery surgery.  

PubMed

The newly introduced Nexfin(®) device allows analysis of the blood pressure trace produced by a non-invasive finger cuff. We compared the cardiac output derived from the Nexfin and PiCCO, using transcardiopulmonary thermodilution, during cardiac surgery. Forty patients with preserved left ventricular function undergoing elective coronary artery bypass graft surgery were studied after induction of general anaesthesia and until discharge to the intensive care unit. There was a significant correlation between Nexfin and PiCCO before (r(2) = 0.81, p < 0.001) and after (r(2) = 0.56, p < 0.001) cardiopulmonary bypass. Bland-Altman analysis demonstrated the mean bias of Nexfin to be -0.1 (95% limits of agreement -0.6 to +0.5, percentage error 23%) and -0.1 (-0.8 to +0.6, 26%) l.min(-1).m(-2), before and after cardiopulmonary bypass, respectively. After a passive leg-raise was performed, there was also good correlation between the two methods, both before (r(2) = 0.72, p < 0.001) and after (r(2) = 0.76, p < 0.001) cardiopulmonary bypass. We conclude that the Nexfin is a reliable method of measuring cardiac output during and after cardiac surgery. PMID:22324797

Broch, O; Renner, J; Gruenewald, M; Meybohm, P; Schöttler, J; Caliebe, A; Steinfath, M; Malbrain, M; Bein, B

2012-04-01

72

Validation and application of single breath cardiac output determinations in man  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

73

Monitoring cardiac output trends with end-tidal carbon dioxide pressures in off-pump coronary bypass.  

PubMed

The optimum method of intraoperative monitoring in patients undergoing off-pump coronary bypass remains debatable. Using capnography and end-tidal carbon dioxide pressure may be a helpful method of monitoring cardiac output trends, especially when grafting posterior and lateral vessels. After repositioning the heart, End-tidal carbon dioxide pressures that continue to trend down usually indicate decreased cardiac output and precede hemodynamic and electrical instability. The advantages of this method include simplicity, universal availability, and a short response time to changes in cardiac output. PMID:21524440

Saleh, Hesham Z; Pullan, D Mark

2011-05-01

74

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.

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

2012-01-01

75

[Effects of cardiac output on PETCO2 and PaCO2 during combined inhalational-epidural anesthesia].  

PubMed

We investigated the effects of cardiac output on PETCO2 in anesthetized patients. We studied 8 adult patients undergoing long-lasting lower abdominal surgery. Anesthesia was maintained with epidural combined with inhalational anesthesia. The minute ventilation volume was kept constant at 10 ml.kg-1 x 10 cycles.min-1. PETCO2, PaCO2, and cardiac index, (CI) by thermodilution method were measured simultaneously. PaCO2 was corrected for body temperature for comparison with PETCO2. Approximate value of alveolar dead space to tidal volume ratio was calculated as VD/ VTalv = (PaCO2-PETCO2)/PaCO2. The measurements were repeated every 10 to 20 minutes under the steady body temperature. One hundred and six sets of data were obtained from these patients. PETCO2 as well as PaCO2 correlated positively with CI, while VD/VTalv did not correlate with CI. PETCO2 correlated positively with PaCO2, while it did not correlate with VD/VTa1v. When examined in individual patients, PETCO2 correlated positively with CI in 7 patients. PaCO2 correlated positively with CI in 6 patients, while VD/VTa1v correlated negatively with CI only in 2 patients, in whom CI showed a large fluctuation. PaCO2 correlated positively with PETCO2 in 8 patient, while VD/VTa1v correlated negatively with PETCO2 only in 1 patient. By multiple regression analysis, VD/VTa1v change accounted for only 20.0 +/- 15.3% of PETCO2 change, while PACO2 or PaCO2 change accounted for 79.3 +/- 16.7%. Decreased CI was associated with a decrease in oxygen uptake (VO2), and PaCO2 correlated positively with VO2. Decreased CI was also associated with an increase in VA/Q, and PaCO2 correlated negatively with VA/Q. Thus, PETCO2 decreased with decreasing cardiac output. A decrease in PACO2 explained the decrease in PETCO2 better than an increase in VD/VT did. Decreased cardiac output caused hypocapnia through decreased CO2 production and/or increased ventilation to perfusion ratio i.e. relative hyperventilation. PMID:9369041

Hayashida, M; Orii, R; Komatsu, K; Chinzei, M; Nakagawa, Y; Nishiyama, T; Suwa, K; Hanaoka, K

1997-10-01

76

Effect of atrioventricular synchronous pacing on cardiac output determined by CO 2 rebreathing at constant submaximal exercise  

Microsoft Academic Search

This study compared cardiac output assessed by a noninvasive CO2 rebreathing method at identical submaximal exercise and heart rate response in patients undergoing DDD or VVI pacing. Our results did not show any hemodynamic superiority of AV synchronous pacing.

Herve´ Douard; Catherine Blaquiere-Roche; Vincent Tourtoulou; Philippe Bordier; Jean Paul Broustet

1995-01-01

77

Recurrent gastrointestinal bleeding and high output cardiac failure caused by hereditary hemorrhagic telangiectasia.  

PubMed

Hereditary hemorrhagic telangiectasia, commonly known as Osler-Weber-Rendu disease, is a systemic autosomal dominant inherited disorder, that occurs in Caucasian populations. We report the case of a 56-year-old housewife who was admitted to the gastrointestinal and cardiovascular ward because she had suffered from recurrent gastrointestinal bleeding and heart failure from 1994 to 1997. Panendoscopy showed vascular ectasia scattered over the tongue, larynx, esophagus, and posterior wall of the gastric body. Colonoscopy showed clusters of telangiectasia over the cecum and ascending colon. Arteriovenous malformations (AVMs) were found in the liver and lungs on computerized tomography. Recurrent gastrointestinal bleeding was controlled by estrogen treatment during the follow-up period. In July 1997, the patient was readmitted to our cardiovascular section due to aggravated dyspnea, orthopnea and bilateral lower leg edema. Cardiac catheterization showed a large fistula from the left pulmonary artery to the left atrium and left ventricle, pulmonary arterial pressure of 37/13 mmHg and cardiac output of 9.61/minute. Other studies excluded the possibility of sepsis, and high-output cardiac failure was suspected. The patient was discharged in a stable condition and scheduled for AVM embolization management. Unfortunately, she died of a suspected heart attack at home two weeks following discharge. PMID:10820915

Lin, C P; Cheng, J S; Lai, K H; Lo, G H; Pan, H B

2000-04-01

78

Clinical validation of a real-time data processing system for cardiac output and arterial pressure measurement during intraoperative biventricular pacing optimization.  

PubMed

Biventricular pacing (BiVP) improves cardiac output (CO) and mean arterial pressure (MAP) after cardiopulmonary bypass (CPB) in selected patients at risk for acute left heart failure after cardiac surgery. Optimization of atrioventricular delay (AVD) and interventricular delay (VVD) to maximize the hemodynamic effect of pacing requires rapid and accurate data processing. Conventional post hoc data processing (PP) is accurate but time-consuming, and infeasible in the intraoperative setting. We created a customized, real-time data processing (RTP) system to improve data processing efficiency, while maintaining accuracy. Biventricular pacing optimization was performed within 1 hour of the conclusion of CPB in 10 patients enrolled in the Biventricular Pacing After Cardiac Surgery trial. Cardiac output, measured by an electromagnetic flow meter, and arterial pressure were recorded as AVD was randomly varied across seven settings and VVD across nine settings. Post hoc data processing values calculated by two observers were compared to RTP-generated outputs for CO and MAP. Interexaminer reliability coefficients were generated to access the dependability of RTP. Interexaminer reliability coefficient values ranged from 0.997 to 0.999, indicating RTP is as reliable as PP for optimization. Real-time data processing is instantaneous and therefore is more practical in a clinical setting than the PP method. Real-time data processing is useful for guiding intraoperative BiVP optimization and merits further development. PMID:22395120

Johnson, Christopher K; Cabreriza, Santos E; Sahar, Rana L; Rusanov, Alexander; Wang, Daniel Y; Cheng, Bin; Gendy, Mira S; Quinn, T Alexander; Spotnitz, Henry Michael

2012-01-01

79

Noninvasive Determination of Cardiac Output by the Inert-Gas-Rebreathing Method – Comparison with Cardiovascular Magnetic Resonance Imaging  

Microsoft Academic Search

Background: An easy, noninvasive and accurate technique for measuring cardiac output (CO) would be desirable for the diagnosis and therapy of cardiac diseases. Innocor, a novel inert-gas-rebreathing (IGR) system, has shown promising results in smaller studies. An extensive evaluation in a larger, less homogeneous patient collective is lacking. Methods: We prospectively assessed the accuracy and reproducibility of CO measurements obtained

Joachim Saur; Stephan Fluechter; Frederik Trinkmann; Theano Papavassiliu; Stefan Schoenberg; Joerg Weissmann; Dariusch Haghi; Martin Borggrefe; Jens J. Kaden

2009-01-01

80

Cardiac output measurement in critically ill patients: comparison of continuous and conventional thermodilution techniques.  

PubMed

The purpose of the study was to compare cardiac output (CO) measurement by continuous (CTD) with that by conventional thermodilution (TD) in critically ill patients. In 19 of 20 critically ill patients requiring a pulmonary artery catheterism, 105 paired CO measurements were performed by both CTD and TD. Regression analysis showed that: CTD CO = 1.18 TD CO - 0.47. Correlation coefficient was 0.96. Bias and limit of agreement were -0.8 and 2.4 L.min-1, respectively. When a Bland and Altman diagram was constructed according to cardiac index ranges, biases were -0.2 and -0.3 and -0.8 L.min-1.m-2 and limits of agreement were 0.3, 0.7 and 1.6 L.min-1.m-2 for low (< 2.5 L.min-1.m-2), normal (between 2.5 and 4.5 L.min-1.m-2) and high (> 4.5 L.min-1.m-2) cardiac indexes, respectively. It is concluded that CTD, compared with TD, is a reliable method of measuring CO, especially when cardiac index is < or = 4.5 L.min-1.m-2. PMID:8590506

Lefrant, J Y; Bruelle, P; Ripart, J; Ibanez, F; Aya, G; Peray, P; Saïssi, G; de La Coussaye, J E; Eledjam, J J

1995-11-01

81

The clinical application of pulse contour cardiac output and intrathoracic volume measurements in critically ill patients.  

PubMed

Cardiac output (CO) determination by pulmonary artery (PA) catheter has increasingly been criticised within the literature due to its invasive nature and poor correlation between the pressure measurements and intravascular volume status in mechanically ventilated patients. Consequently, alternative less invasive technologies to PA catheterisation are emerging within intensive care. One such novel technology are pulse contour CO (PCCO) systems. They establish comprehensive and continuous haemodynamic monitoring utilising a central venous catheter (CVC) and an arterial line. Furthermore, a key feature of this technology is its ability to produce intrathoracic volume measurements which may provide a better estimation of cardiac preload as well as indicate the presence and severity of pulmonary oedema. This article aims to discuss the theoretical basis and clinical application of PCCO systems, how PCCO systems differ from PA catheters and how the intrathoracic volume measurements are derived. Understanding these advanced concepts will ensure that clinicians are able to employ this innovative monitoring technology more effectively. PMID:16933635

Hewitt, Nicky A; Braaf, Sandra C

2006-08-01

82

Effect of hemorrhage on cardiac output, vasopressin, aldosterone, and diuresis during immersion in men  

NASA Technical Reports Server (NTRS)

The purpose of this research was to test the hypotesis that a reduction in blood volume would attenuate or eliminate immersion-induced increases in cardiac output (Q(sub co)) and urine excretion, and to investigate accompanying vasoactive and fluid-electrolyte hormonal responses. Eight men (19-23 yr) were supine during a 2-hr control period in air, and then sat for 5-hr test periods in air at 20 C (dry control, DC); water at 34.5 C (wet control, WC); and water (34.5 C) after hemorrhage (WH) of 14.8 plus or minus 0.3 percent of their blood volume. Blood volume was -11.6 plus or minus 0.6 percent at immersion (time 0). Mean (bar-X hrs 1-5) Q(sub co) was unchanged in WC (5.3 plus or minus 0.01 l/min) and in WH (4.5 plus or minus 0.1 l/min), but decreased (P less than 0.05) in DC to 3.6 plus or minus 0.1 l/min. Mean urine excretion rates were 1.0 plus or minus 0.2 ml/min for DC and 1.1 plus or minus 0.2 ml/min for WH; both were lower (P less than 0.05) than that for WC of 2.0 plus or minus 0.4 ml/min. Plasma (Na+) and (Osm) were unchanged in all experiments. Mean plasma vasopressin (PVP) (bar-X hrs 1-5) was 1.1 plus or minus 0.1 pg/ml in WC, and higher (P less than 0.05) in DC (2.1 plus or minus 0.2 pg/ml)and WH (2.1 plus or minus 0.1 pg/ml); it was unchanged during air and water test periods. Thus, hemorrhage attenuated the immersion-induced increase in Q(sub co), eliminated the WC diuresis, maintained plasma renin activity and PVP at DC levels and did not change immersion-induced aldosterone suppression; the osmotic diuresis during control immersion is apparently not due to either aldosterone suppression or vasopressin suppression.

Greenleaf, J. E.; Simanonok, K.; Bernauer, E. M.; Wade, C. E.; Keil, L. C.

1992-01-01

83

The consistency of cardiac output measurement (CO 2 rebreathe) in children during exercise  

Microsoft Academic Search

Summary  Exercise cardiac output (\\u000a$$\\\\dot Q$$\\u000a) was determined using the CO2 rebreathing equilibrium method. Five repeat tests in 12 boys and two tests over a 4 month interval in 47 boys were performed. Regression equations to predict \\u000a$$\\\\dot Q$$\\u000a from \\u000a$$\\\\dot V$$\\u000aO2 were in close agreement with dye dilution studies in boys (Eriksson and Koch 1973). Group mean

D. H. Paterson; D. A. Cunningham; M. J. Plyley; C. J. R. Blimkie; A. P. Donner

1982-01-01

84

Improved Accuracy Of Cardiac Output Estimation By The Partial CO 2 Rebreathing Method  

Microsoft Academic Search

Objective  This study investigated the accuracy of the NICO monitor equipped with the newer software. Additionally, the effects of the\\u000a increased dead space produced by the NICO monitor on ventilatory settings were investi-\\u0009gated.\\u000a \\u000a \\u000a \\u000a Methods  Forty-two patients undergoing elective aortic reconstruction participated in this prospective, obser-\\u0009vational study at a\\u000a university hospital. Cardiac output was continuously monitored using both the NICO monitor

Yoshifumi Kotake; Takashige Yamada; Hiromasa Nagata; Takeshi Suzuki; Ryohei Serita; Nobuyuki Katori; Junzo Takeda; Hideyuki Shimizu

2009-01-01

85

Cardiac Output Derived From Left Ventricular Pressure During Conductance Catheter Evaluations: An Extended Modelflow Method  

Microsoft Academic Search

Objective  The Modelflow method computes cardiac output (CO) from arterial pressure (CO-MFao) by simulating a non-linear three-element\\u000a Windkessel model of aortic input impedance. We present a novel technique to apply the Modelflow method to the left ventricular\\u000a pressure (Plv) signal, to obtain an estimation of CO (CO-MFlv).\\u000a \\u000a \\u000a \\u000a Methods  We extended the model by simulating the aortic valve as a resistance placed in

Sergio Valsecchi; Giovanni B. Perego; Jan J. Schreuder; Federica Censi; Jos R. C. Jansen

2007-01-01

86

Maintaining low BCR-ABL signaling output to restrict CML progression and enable persistence.  

PubMed

Deregulated BCR-ABL oncogenic activity leads to transformation, oncogene addiction and drives disease progression in chronic myeloid leukemia (CML). Inhibition of BCR-ABL using Abl-specific kinase inhibitors (TKI) such as imatinib induces remarkable clinical responses. However, approximately only less than 15 % of all chronic-phase CML patients will remain relapse-free after discontinuation of imatinib in deep molecular remission. It is not well understood why persisting CML cells survive under TKI therapy without developing clonal evolution and frank TKI resistance. BCR-ABL expression level may be critically involved. Whereas higher BCR-ABL expression has been described as a pre-requisite for malignant CML stem cell transformation and CML progression to blast crisis, recent evidence suggests that during persistence TKI select for CML precursors with low BCR-ABL expression. Genetic, translational and clinical evidence is discussed to suggest that TKI-induced maintenance of low BCR-ABL signaling output may be potently tumor suppressive, because it abrogates oncogenic addiction. PMID:24500518

Burchert, Andreas

2014-03-01

87

Effect of aging on power output properties in rat skinned cardiac myocytes.  

PubMed

Aging is generally associated with a decline in several indices of cardiac function. The cellular mechanisms for this decline are not completely understood. The ability of the myocardium to perform external work (power output) is a critical aspect of ventricular function. The purpose of this study was to determine the effect of aging on loaded shortening and power output properties. We measured force-velocity properties in permeabilized (skinned) myocytes from the hearts of 9-, 24-, and 33-month-old male Fisher 344 × Brown Norway F1 hybrid rats (F344BN) during loaded contractions using a force-clamp technique. Power output was calculated by multiplying force and shortening velocity values. We found that peak power output normalized to maximal force was significantly decreased by 18% and 31% in myocytes from 24- and 33-month-old group, respectively, compared with 9-month group (p < .05). These results suggest that aging is associated with a significant decrease in the ability of the myocardium to do work. PMID:21896503

Chung, Eunhee; Diffee, Gary M

2011-12-01

88

Measurement of cardiac output by the thermodilution method in rats. II. Simultaneous measurement of cardiac output and blood pressure in conscious rats.  

PubMed

A method is described for the simultaneous measurement of cardiac output (CO), using the thermodilution method, and arterial blood pressure in conscious unrestrained rats. For the injection of the indicator solution (ice-cold, 0.9% saline) and for the measurement of systolic and diastolic blood pressure, chronically-implanted polyethylene cathethers were used, while CO was measured transpulmonarily with a commercially available CO computer and an acutely-implanted (via caudal artery) arterial thermistor catheter. The following were observed in 10 rats at rest: a CO of 40.2 +/- 1.9 ml/min/100 g, a mean arterial blood pressure of 106 +/- 5 mmHg, a heart rate of 417 +/- 20 beats/min and a peripheral vascular resistance of 2.68 +/- 0.13 mmHG/(ml/min/100 g). After injection of the beta-adrenergic agonist isoprenaline, there was a rise in CO and heart rate, while peripheral resistance and blood pressure were lowered. Injection of the beta-receptor-blocked propranolol caused decreases in CO and heart rate, while peripheral resistance and blood pressure rose. It is concluded, that the method described here for the simultaneous measurement of CO and arterial blood pressure is suitable for the investigation of drug-induced cardiovascular effects in conscious rats. PMID:7265984

Müller, B; Mannesmann, G

1981-01-01

89

Comparison of cardiac output measurements in critically ill patients: FloTrac/Vigileo vs transthoracic Doppler echocardiography.  

PubMed

Measurement of cardiac output is an integral part of patient management in the intensive care unit. FloTrac/Vigileo is a continuous cardiac output monitoring device that does not need re-calibration. However its reliability has been questioned in some studies, especially involving surgical patients. In this study, we evaluated the comparability of FloTrac/Vigileo and transthoracic Doppler echocardiography in 53 critically ill patients requiring continuous cardiac output monitoring. Most of these patients had septic or cardiogenic shock. Cardiac output was measured by both FloTrac/Vigileo and transthoracic Doppler echocardiography. The bias and precision (mean and SD) between the two devices was 0.35 +/- 1.35 l/minute. The limits of agreement were -2.3 to 3.0 l/minute (%error = 49.3%). When patients with irregular heart rhythms and aortic stenosis were excluded, the bias and precision was 0.02 +/- 0.80 l/minute (n = 42). The limits of agreement were -1.55 to 1.59 l/minute (%error = 29.5%). Patient demographics (body surface area, gender and age) did not affect the bias, but there was a mild tendency for FloTrac/ Vigileo to register a higher cardiac output at high heart rates. Changes in cardiac output for two consecutive days correlated well between the two methods (r = 0.86; P < 0.001). In summary, with the exceptions of patients with irregular heart rhythms and significant aortic stenosis, FloTrac/Vigileo is clinically comparable to transthoracic Doppler echocardiography in cardiac output measurements in critically ill patients. PMID:21823375

McLean, A S; Huang, S J; Kot, M; Rajamani, A; Hoyling, L

2011-07-01

90

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

91

Effect of norepinephrine dosage and calibration frequency on accuracy of pulse contour-derived cardiac output  

PubMed Central

Introduction Continuous cardiac output monitoring is used for early detection of hemodynamic instability and guidance of therapy in critically ill patients. Recently, the accuracy of pulse contour-derived cardiac output (PCCO) has been questioned in different clinical situations. In this study, we examined agreement between PCCO and transcardiopulmonary thermodilution cardiac output (COTCP) in critically ill patients, with special emphasis on norepinephrine (NE) administration and the time interval between calibrations. Methods This prospective, observational study was performed with a sample of 73 patients (mean age, 63 ± 13 years) requiring invasive hemodynamic monitoring on a non-cardiac surgery intensive care unit. PCCO was recorded immediately before calibration by COTCP. Bland-Altman analysis was performed on data subsets comparing agreement between PCCO and COTCP according to NE dosage and the time interval between calibrations up to 24 hours. Further, central artery stiffness was calculated on the basis of the pulse pressure to stroke volume relationship. Results A total of 330 data pairs were analyzed. For all data pairs, the mean COTCP (±SD) was 8.2 ± 2.0 L/min. PCCO had a mean bias of 0.16 L/min with limits of agreement of -2.81 to 3.15 L/min (percentage error, 38%) when compared to COTCP. Whereas the bias between PCCO and COTCP was not significantly different between NE dosage categories or categories of time elapsed between calibrations, interchangeability (percentage error <30%) between methods was present only in the high NE dosage subgroup (?0.1 ?g/kg/min), as the percentage errors were 40%, 47% and 28% in the no NE, NE < 0.1 and NE ? 0.1 ?g/kg/min subgroups, respectively. PCCO was not interchangeable with COTCP in subgroups of different calibration intervals. The high NE dosage group showed significantly increased central artery stiffness. Conclusions This study shows that NE dosage, but not the time interval between calibrations, has an impact on the agreement between PCCO and COTCP. Only in the measurements with high NE dosage (representing the minority of measurements) was PCCO interchangeable with COTCP.

2011-01-01

92

Clinical evaluation of the flotrac/vigileo(TM) system for continuous cardiac output monitoring in patients undergoing regional anesthesia for elective cesarean section: a pilot study  

PubMed Central

BACKGROUND: Spinal anesthesia for cesarean delivery may cause severe maternal hypotension and a decrease in cardiac output. Compared to assessment of cardiac output via a pulmonary artery catheter, the FloTrac/Vigileo™ system may offer a less invasive technique. The aim of this study was to evaluate cardiac output and other hemodynamic measurements made using the FloTrac/Vigileo™ system in patients undergoing spinal anesthesia for elective cesarean section. METHODS: A prospective study enrolling 10 healthy pregnant women was performed. Hemodynamic parameters were continuously obtained at 15 main points: admission to surgery (two baseline measurements), after preload, after spinal anesthesia administration and 4 time points thereafter (4, 6, 8 and 10 min after anesthesia), at skin and uterine incision, newborn and placental delivery, oxytocin administration, end of surgery, and recovery from anesthesia. Hemodynamic therapy was guided by mean arterial pressure, and vasopressors were used as appropriate to maintain baseline values. A repeated measures ANOVA was used for data analysis. RESULTS: There was a significant increase in heart rate and a decrease of stroke volume and stroke volume index up to 10 min after spinal anesthesia (P < 0.01). Importantly, stroke volume variation increased immediately after newborn delivery (P < 0.001) and returned to basal values at the end of surgery. Further hemodynamic parameters showed no significant changes over time. DISCUSSION AND CONCLUSIONS: No significant hemodynamic effects, except for heart rate and stroke volume changes, were observed in pregnant women managed with preload and vasopressors when undergoing elective cesarean section and spinal anesthesia.

Auler, Jose Otavio C.; Torres, Marcelo L. A.; Cardoso, Monica M.; Tebaldi, Thais C.; Schmidt, Andre P.; Kondo, Mario M.; Zugaib, Marcelo

2010-01-01

93

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

PubMed Central

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 subjects. Cardiac output values obtained with impedance cardiography were significantly correlated with those measured by the indirect Fick method, although there was a wide scatter with over 73% of the readings lying outside the limits defined by the line of identity +/- 20%. This correlation was greatly reduced when stroke volume index was used instead of cardiac output. Indirect Fick results were linearly related to oxygen uptake both at rest and on exercise, while impedance cardiography results did not correlate with oxygen uptake. Impedance cardiography gave consistently lower results for cardiac output than indirect Fick at all levels of exercise. Both machines were easy to use and produced acceptable mean (SE) coefficients of variation (BoMed NCCOM3 7.7 (1.0)%, Gould 9000 IV 10.6 (1.4)%). Further validation is required before either of these machines can be recommended as an alternative to invasive monitoring in clinical practice.

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

1988-01-01

94

Rapamycin Attenuated Cardiac Hypertrophy Induced by Isoproterenol and Maintained Energy Homeostasis via Inhibiting NF-?B Activation  

PubMed Central

Rapamycin, also known as sirolimus, is an immunosuppressant drug used to prevent rejection organ (especially kidney) transplantation. However, little is known about the role of Rapa in cardiac hypertrophy induced by isoproterenol and its underlying mechanism. In this study, Rapa was administrated intraperitoneally for one week after the rat model of cardiac hypertrophy induced by isoproterenol established. Rapa was demonstrated to attenuate isoproterenol-induced cardiac hypertrophy, maintain the structure integrity and functional performance of mitochondria, and upregulate genes related to fatty acid metabolism in hypertrophied hearts. To further study the implication of NF-?B in the protective role of Rapa, cardiomyocytes were pretreated with TNF-? or transfected with siRNA against NF-?B/p65 subunit. It was revealed that the upregulation of extracellular circulating proinflammatory cytokines induced by isoproterenol was able to be reversed by Rapa, which was dependent on NF-?B pathway. Furthermore, the regression of cardiac hypertrophy and maintaining energy homeostasis by Rapa in cardiomyocytes may be attributed to the inactivation of NF-?B. Our results shed new light on mechanisms underlying the protective role of Rapa against cardiac hypertrophy induced by isoproterenol, suggesting that blocking proinflammatory response by Rapa might contribute to the maintenance of energy homeostasis during the progression of cardiac hypertrophy.

Chen, Xi; Zeng, Siyu; Zou, Jian; Chen, Yanfang; Yue, Zhongbao; Gao, Ying; Zhang, Luankun; Cao, Weiwei; Liu, Peiqing

2014-01-01

95

Validation of the use of foreign gas rebreathing method for non-invasive determination of cardiac output in heart disease patients  

Microsoft Academic Search

Objective: To compare a new device (Innocor) for non-invasive measurement of cardiac output (CO) by foreign gas rebreathing\\u000a method with conventional techniques used in the measurements of cardiac function. Methods: Cardiac outputs measured by Innocor\\u000a (CORB) were compared with CO obtained by echocardiography (COEC), Swan-Ganz thermodilution (COTD), and left ventricle radiography (COLVR) in 34 patients subjected to cardiac catheterization. Values

Liang Dong; Jian-an Wang; Chen-yang Jiang

2005-01-01

96

Reference values for total blood volume and cardiac output in humans  

SciTech Connect

Much research has been devoted to measurement of total blood volume (TBV) and cardiac output (CO) in humans but not enough effort has been devoted to collection and reduction of results for the purpose of deriving typical or {open_quotes}reference{close_quotes} values. Identification of normal values for TBV and CO is needed not only for clinical evaluations but also for the development of biokinetic models for ultra-short-lived radionuclides used in nuclear medicine (Leggett and Williams 1989). The purpose of this report is to offer reference values for TBV and CO, along with estimates of the associated uncertainties that arise from intra- and inter-subject variation, errors in measurement techniques, and other sources. Reference values are derived for basal supine CO and TBV in reference adult humans, and differences associated with age, sex, body size, body position, exercise, and other circumstances are discussed.

Williams, L.R. [Indiana Univ., South Bend, IN (United States). Division of Liberal Arts and Sciences] [Indiana Univ., South Bend, IN (United States). Division of Liberal Arts and Sciences

1994-09-01

97

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.

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

2014-01-01

98

Cardiac output distribution in response to hypoxia in the chick embryo in the second half of the incubation time.  

PubMed

1. The fetus develops cardiovascular adaptations to protect vital organs in situations such as hypoxia and asphyxia. These include bradycardia, increased systemic blood pressure and redistribution of the cardiac output. The extent to which they involve maternal or placenta influences is not known. The objective of the present work was to study the cardiac output distribution in response to hypoxia in the chick embryo, which is independent of the mother. 2. Fertilized eggs were studied at three incubation times (10-13 days, 14-16 days and 17-19 days of a normal incubation time of 21 days). Eggs were placed in a Plexiglass box in which the oxygen concentration could be changed. Eggs were opened at the air cell and a chorioallantoic vein was catheterized. Cardiac output distribution was measured with 15 micron fluorescent microspheres injected during normoxia, during the last minute of a 5 min period of hypoxia and after 5 min of subsequent reoxygenation. 3. Hypoxia caused a redistribution of the cardiac output in favour of heart (+17 to +160 % of baseline) and brain (+21 to +57 % of baseline) at the expense of liver (-3 to -65 % of baseline), yolk-sac (-46 to -77 % of baseline) and carcass (-6 to -33 % of baseline). 4. The magnitude of the changes in cardiac output distribution to the heart, brain, liver and carcass in response to hypoxia increased with advancing incubation time. 5. The data demonstrate the development of a protective redistribution of the cardiac output in response to hypoxia in the chick embryo from day 10 of incubation. PMID:9490852

Mulder, A L; van Golde, J C; Prinzen, F W; Blanco, C E

1998-04-01

99

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

100

Pulse contour cardiac output system use in pediatric orthotopic liver transplantation: preliminary report of nine patients.  

PubMed

Anesthetic management of orthotopic liver transplantation (OLT) in pediatric patients is challenging in terms of intraoperative bleeding, fluid management, and hemodynamic monitoring. The pulse contour cardiac output (PiCCO) system, a relatively new device based on the single-indicator transaortic thermodilution technique, may be useful for intraoperative hemodynamic monitoring in pediatric patients. This is a preliminary report of PiCCO use in nine children (aged 9.8 +/- 4.7 years) undergoing OLT. Hemodynamic volumetric parameters monitored by the PiCCO system were mean arterial pressure (MAP), cardiac index (CI), intrathoracic blood volume index (ITBVI), extravascular lung water index (EVLWI), systemic vascular resistance index (SVRI), and stroke volume variability (SVV). All parameters were recorded at anesthesia induction (T0), at the end of the anhepatic phase (Tanhepatic), and at the end of operation (Tend). The PiCCO system revealed similar MAP, CI, EVLWI, SVV, and SVRI values at all measurement intervals. Despite similar central venous pressure measurements, ITBVI values indicated significantly lower values at Tanhepatic than at T0 (627 +/- 160 mL/m2 and 751 +/- 151 mL/m2, respectively, P = .013). There were no PiCCO catheter-related complications in any patient. These findings demonstrate that the PiCCO system is a safe, continuous, multiparameter invasive monitoring device for use in pediatric patients undergoing OLT. This system may provide valuable data during pediatric OLT and appears to be a promising monitoring tool in these patients. PMID:16213339

Torgay, A; Pirat, A; Akpek, E; Zeyneloglu, P; Arslan, G; Haberal, M

2005-09-01

101

Estimation of cardiac output in patients with congestive heart failure by analysis of right ventricular pressure waveforms  

Microsoft Academic Search

Background  Cardiac output (CO) is an important determinant of the hemodynamic state in patients with congestive heart failure (CHF).\\u000a We tested the hypothesis that CO can be estimated from the right ventricular (RV) pressure waveform in CHF patients using\\u000a a pulse contour cardiac output algorithm that considers constant but patient specific RV outflow tract characteristic impedance.\\u000a \\u000a \\u000a \\u000a \\u000a Method  In 12 patients with CHF,

Mustafa Karamanoglu; Tom Bennett; Marcus Ståhlberg; Vincent Splett; Barbro Kjellström; Cecilia Linde; Frieder Braunschweig

2011-01-01

102

In vivo validation of cardiac output assessment in non-standard 3D echocardiographic images  

NASA Astrophysics Data System (ADS)

Automatic segmentation of the endocardial surface in three-dimensional (3D) echocardiographic images is an important tool to assess left ventricular (LV) geometry and cardiac output (CO). The presence of speckle noise as well as the nonisotropic characteristics of the myocardium impose strong demands on the segmentation algorithm. In the analysis of normal heart geometries of standardized (apical) views, it is advantageous to incorporate a priori knowledge about the shape and appearance of the heart. In contrast, when analyzing abnormal heart geometries, for example in children with congenital malformations, this a priori knowledge about the shape and anatomy of the LV might induce erroneous segmentation results. This study describes a fully automated segmentation method for the analysis of non-standard echocardiographic images, without making strong assumptions on the shape and appearance of the heart. The method was validated in vivo in a piglet model. Real-time 3D echocardiographic image sequences of five piglets were acquired in radiofrequency (rf) format. These ECG-gated full volume images were acquired intra-operatively in a non-standard view. Cardiac blood flow was measured simultaneously by an ultrasound transit time flow probe positioned around the common pulmonary artery. Three-dimensional adaptive filtering using the characteristics of speckle was performed on the demodulated rf data to reduce the influence of speckle noise and to optimize the distinction between blood and myocardium. A gradient-based 3D deformable simplex mesh was then used to segment the endocardial surface. A gradient and a speed force were included as external forces of the model. To balance data fitting and mesh regularity, one fixed set of weighting parameters of internal, gradient and speed forces was used for all data sets. End-diastolic and end-systolic volumes were computed from the segmented endocardial surface. The cardiac output derived from this automatic segmentation was validated quantitatively by comparing it with the CO values measured from the volume flow in the pulmonary artery. Relative bias varied between 0 and -17%, where the nominal accuracy of the flow meter is in the order of 10%. Assuming the CO measurements from the flow probe as a gold standard, excellent correlation (r = 0.99) was observed with the CO estimates obtained from image segmentation.

Nillesen, M. M.; Lopata, R. G. P.; de Boode, W. P.; Gerrits, I. H.; Huisman, H. J.; Thijssen, J. M.; Kapusta, L.; de Korte, C. L.

2009-04-01

103

In vivo validation of cardiac output assessment in non-standard 3D echocardiographic images.  

PubMed

Automatic segmentation of the endocardial surface in three-dimensional (3D) echocardiographic images is an important tool to assess left ventricular (LV) geometry and cardiac output (CO). The presence of speckle noise as well as the nonisotropic characteristics of the myocardium impose strong demands on the segmentation algorithm. In the analysis of normal heart geometries of standardized (apical) views, it is advantageous to incorporate a priori knowledge about the shape and appearance of the heart. In contrast, when analyzing abnormal heart geometries, for example in children with congenital malformations, this a priori knowledge about the shape and anatomy of the LV might induce erroneous segmentation results. This study describes a fully automated segmentation method for the analysis of non-standard echocardiographic images, without making strong assumptions on the shape and appearance of the heart. The method was validated in vivo in a piglet model. Real-time 3D echocardiographic image sequences of five piglets were acquired in radiofrequency (rf) format. These ECG-gated full volume images were acquired intra-operatively in a non-standard view. Cardiac blood flow was measured simultaneously by an ultrasound transit time flow probe positioned around the common pulmonary artery. Three-dimensional adaptive filtering using the characteristics of speckle was performed on the demodulated rf data to reduce the influence of speckle noise and to optimize the distinction between blood and myocardium. A gradient-based 3D deformable simplex mesh was then used to segment the endocardial surface. A gradient and a speed force were included as external forces of the model. To balance data fitting and mesh regularity, one fixed set of weighting parameters of internal, gradient and speed forces was used for all data sets. End-diastolic and end-systolic volumes were computed from the segmented endocardial surface. The cardiac output derived from this automatic segmentation was validated quantitatively by comparing it with the CO values measured from the volume flow in the pulmonary artery. Relative bias varied between 0 and -17%, where the nominal accuracy of the flow meter is in the order of 10%. Assuming the CO measurements from the flow probe as a gold standard, excellent correlation (r = 0.99) was observed with the CO estimates obtained from image segmentation. PMID:19265202

Nillesen, M M; Lopata, R G P; de Boode, W P; Gerrits, I H; Huisman, H J; Thijssen, J M; Kapusta, L; de Korte, C L

2009-04-01

104

Evaluation of coronary blood flow velocity during cardiac arrest with circulation maintained through mechanical chest compressions in a porcine model  

PubMed Central

Background Mechanical chest compressions (CCs) have been shown capable of maintaining circulation in humans suffering cardiac arrest for extensive periods of time. Reports have documented a visually normalized coronary blood flow during angiography in such cases (TIMI III flow), but it has never been actually measured. Only indirect measurements of the coronary circulation during cardiac arrest with on-going mechanical CCs have been performed previously through measurement of the coronary perfusion pressure (CPP). In this study our aim was to correlate average peak coronary flow velocity (APV) to CPP during mechanical CCs. Methods In a closed chest porcine model, cardiac arrest was established through electrically induced ventricular fibrillation (VF) in eleven pigs. After one minute, mechanical chest compressions were initiated and then maintained for 10 minutes upon which the pigs were defibrillated. Measurements of coronary blood flow in the left anterior descending artery were made at baseline and during VF with a catheter based Doppler flow fire measuring APV. Furthermore measurements of central (thoracic) venous and arterial pressures were also made in order to calculate the theoretical CPP. Results Average peak coronary flow velocity was significantly higher compared to baseline during mechanical chests compressions and this was observed during the entire period of mechanical chest compressions (12 - 39% above baseline). The APV slowly declined during the 10 min period of mechanical chest compressions, but was still higher than baseline at the end of mechanical chest compressions. CPP was simultaneously maintained at > 20 mmHg during the 10 minute episode of cardiac arrest. Conclusion Our study showed good correlation between CPP and APV which was highly significant, during cardiac arrest with on-going mechanical CCs in a closed chest porcine model. In addition APV was even higher during mechanical CCs compared to baseline. Mechanical CCs can, at minimum, re-establish coronary blood flow in non-diseased coronary arteries during cardiac arrest.

2011-01-01

105

Role of cardiac output versus peripheral vasoconstriction in mediating muscle metaboreflex pressor responses: dynamic exercise versus postexercise muscle ischemia  

PubMed Central

Muscle metaboreflex activation (MMA) during submaximal dynamic exercise in normal individuals increases mean arterial pressure (MAP) via increases in cardiac output (CO) with little peripheral vasoconstriction. The rise in CO occurs primarily via increases in heart rate (HR) with maintained or slightly increased stroke volume. When the reflex is sustained during recovery (postexercise muscle ischemia, PEMI), HR declines yet MAP remains elevated. The role of CO in mediating the pressor response during PEMI is controversial. In seven chronically instrumented canines, steady-state values with MMA during mild exercise (3.2 km/h) were observed by reducing hindlimb blood flow by ?60% for 3–5 min. MMA during exercise was followed by 60 s of PEMI. Control experiments consisted of normal exercise and recovery. MMA during exercise increased MAP, HR, and CO by 55.3 ± 4.9 mmHg, 42.5 ± 6.9 beats/min, and 2.5 ± 0.4 l/min, respectively. During sustained MMA via PEMI, MAP remained elevated and CO remained well above the normal recovery levels. Neither MMA during dynamic exercise nor during PEMI significantly affected peripheral vascular conductance. We conclude that the sustained increase in MAP during PEMI is driven by a sustained increase in CO not peripheral vasoconstriction.

Spranger, Marty D.; Sala-Mercado, Javier A.; Coutsos, Matthew; Kaur, Jasdeep; Stayer, Doug; Augustyniak, Robert A.

2013-01-01

106

Comparison of Doppler flow Tei-indexes with pulmonary artery thermodilution measurement of cardiac output in an experimental porcine model.  

PubMed

The objective of our study was to compare Doppler echocardiography imaging with pulmonary artery thermodilution measurement during mechanical ventilation. Total 78 piglets (6 weeks old, average weight 24 kg, under general anesthesia) were divided into 4 groups under different cardiac loading conditions (at rest, with increased left ventricular afterload, with increased right ventricular preload, and with increased afterload of both heart ventricles). At 60 and 120 min the animals were examined by echocardiography and simultaneously pulmonary artery thermodilution was used to measure cardiac output. Tei-indexes data were compared with invasively monitored hemodynamic data and cardiac output values together with calculated vascular resistance indices. A total of 224 parallel measurements were obtained. Correlation was found between values of right Tei-index of myocardial performance and changes in right ventricular preload (p<0.05) and afterload (p<0.01). Significant correlation was also found between left index values and changes of left ventricular preload (p<0.001), afterload (p<0.001), stroke volume (p<0.01), and cardiac output (p<0.01). In conclusion, echocardiographic examination and determination of the global performance selectively for the right and left ventricle can be recommended as a suitable non-invasive supplement to the whole set of methods used for monitoring of circulation and cardiac performance. PMID:21401299

Kobr, J; T?eška, V; Molá?ek, J; Kuntscher, V; Liška, V; Slavík, Z

2011-01-01

107

Reduced peripheral arterial blood flow with preserved cardiac output during submaximal bicycle exercise in elderly heart failure  

Microsoft Academic Search

BACKGROUND: Older heart failure (HF) patients exhibit exercise intolerance during activities of daily living. We hypothesized that reduced lower extremity blood flow (LBF) due to reduced forward cardiac output would contribute to submaximal exercise intolerance in older HF patients. METHODS AND RESULTS: Twelve HF patients both with preserved and reduced left ventricular ejection fraction (LVEF) (aged 68 ± 10 years)

Chirapa Puntawangkoon; Dalane W Kitzman; Stephen B Kritchevsky; Craig A Hamilton; Barbara Nicklas; Xiaoyan Leng; Peter H Brubaker; W Gregory Hundley

2009-01-01

108

The decreased oxygen uptake during progressive exercise in ischemia-induced heart failure is due to reduced cardiac output rate  

Microsoft Academic Search

We tested the hypothesis that the inability to increase cardiac output during exercise would explain the decreased rate of oxygen uptake (VO2) in recent onset, ischemia-induced heart failure rats. Nine nor- mal control rats and 6 rats with ischemic heart failure were studied. Myocardial infarction was induced by coronary ligation. VO2 was measured during a ramp protocol test on a

N. P. L. Rolim; K. C. Mattos; P. C. Brum; M. V. C. Baldo; H. R. Middlekauff; C. E. Negrão

2006-01-01

109

Cardiac Output Measurement in Patients Undergoing Liver Transplantation: Pulmonary Artery Catheter Versus Uncalibrated Arterial Pressure Waveform Analysis  

Microsoft Academic Search

BACKGROUND: Cardiac output (CO) and invasive hemodynamic measurements are useful during liver transplantation. The pulmonary artery catheter (PAC) is commonly used for these patients, despite the potential complications. Recently, a less invasive device (Vigileo®\\/FloTrac™) became available, which estimates CO using arterial pressure waveform analysis without external calibration. In this study, we compared CO obtained with a PAC using automatic thermodilution,

Biais Matthieu; Nouette-Gaulain Karine; Cottenceau Vincent; Vallet Alain; Cochard Jean François; Revel Philippe; Sztark François

2008-01-01

110

Pulmonary diffusing capacity, capillary blood volume, and cardiac output during sustained microgravity  

NASA Technical Reports Server (NTRS)

We measured pulmonary diffusing capacity (DL), diffusing capacity per unit lung volume, pulmonary capillary blood volume (Vc), membrane diffusing capacity (Dm), pulmonary capillary blood flow or cardiac output (Qc), and cardiac stroke volume (SV) in four subjects exposed to nine days of microgravity. DL in microgravity was elevated compared with preflight standing values and was higher than preflight supine because of the elevation of both Vc and Dm. The elevation in Vc was comparable to that measured supine in 1 G, but the increase in Dm was in sharp contrast to the supine value. We postulate that, in 0 G, pulmonary capillary blood is evenly distributed throughout the lung, providing for uniform capillary filling, leading to an increase in the surface area available for diffusion. By contrast, in the supine 1-G state, the capillaries are less evenly filled, and although a similar increase in blood volume is observed, the corresponding increase in surface area does not occur. DL and its subdivisions showed no adaptive changes from the first measurement 24 h after the start of 0 G to eight days later. Similarly, there were no trends in the postflight data, suggesting that the principal mechanism of these changes was gravitational. The increase in Dm suggests that subclinical pulmonary edema did not result from exposure to 0 G. Qc was modestly increased inflight and decreased postflight compared with preflight standing. Compared with preflight standing, SV was increased 46 percent inflight and decreased 14 percent in the 1st week postflight. There were temporal changes in Qc and SV during 0 G, with the highest values recorded at the first measurement, 24 h into the flight. The lowest values of Qc and SV occurred on the day of return.

Prisk, G. K.; Guy, Harold J. B.; Elliott, Ann R.; Deutschman, Robert A., III; West, John B.

1993-01-01

111

Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation  

NASA Technical Reports Server (NTRS)

OBJECTIVES: To develop and validate an automated noninvasive method to quantify mitral regurgitation. BACKGROUND: Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR). METHODS: First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied. RESULTS: In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml). CONCLUSIONS: We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.

Sun, J. P.; Yang, X. S.; Qin, J. X.; Greenberg, N. L.; Zhou, J.; Vazquez, C. J.; Griffin, B. P.; Stewart, W. J.; Thomas, J. D.

1998-01-01

112

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.

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

2009-01-01

113

Cardiac output, at rest and during exercise, before and during myocardial ischemia, reperfusion, and infarction in conscious mice.  

PubMed

Multiple systems and regulatory strategies interact to control cardiac homeostasis. In fact, regulated systems, feedback controls, and redundant control mechanisms dominate in whole animals. Accordingly, molecular and cellular tools and techniques must be utilized in complex models with multiple systems and regulatory strategies to fully appreciate the physiological context. Currently, these techniques are mainly performed under conditions remote from the normal in vivo condition; thus, the extrapolation of molecular changes to the in vivo situation and the facilitation of translational aspect of the findings are limited. A major obstacle has been the reliance on preparations that do not mimic the clinical or physiological situation. This is particularly true regarding measurements of cardiac function in mice. To address these concerns, we used a permanently implanted Doppler ultrasonic flow probe on the ascending aorta and coronary artery occluder for repeated measurements of ascending aortic blood flow (cardiac output) in conscious mice, at rest and during exercise, before and during coronary artery occlusion/reperfusion and infarction. The conscious mouse model permits detailed monitoring of within-animal changes in cardiac function during myocardial ischemia, reperfusion, and infarction in an intact, complex model free of the confounding influences of anesthetics, surgical trauma, and restraint stress. Results from this study suggest that previous protocols may have overestimated resting baseline values and underestimated cardiac output reserve. Using these procedures in currently available spontaneous or engineered mouse mutants has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular research. PMID:23302959

Lujan, Heidi L; DiCarlo, Stephen E

2013-02-15

114

Combined first pass and gated blood pool radionuclide studies in the hemodynamic-cardiac evaluation of patients with low cardiac output  

SciTech Connect

Cardiac output (CO) is frequently used in the evaluation of cardiac function but low CO does not necessarily reflect heart failure. Similarly, low ejection fraction (EF) can be present in compensated heart diseases. In order to evaluate cardiac performance in relation to systematic hemodynamics, the authors used a multifactorial approach for the determination of CO, EF, pulmonary mean transit time (MTT), ratio of cardiopulmonary volume over total blood volume (CPV/TBV as an index of venous tone) all obtained from a single injection of 99m Tc-HSA. Four different conditions associated with low CO (less than or equal to 2.1 L/min/m/sup 2/) were evaluated. The combined use of CO, EF, MTT and CPV/TBV allowed a better understanding of the myocardial and peripheral circulatory factors associated with low CO states. This is helpful in the selection and follow-up of appropriate therapeutic intervention.

Abi-Mansour, P.; Fouad, F.M.; Sheeler, L.R.; Bravo, E.L.; MacIntyre, W.J.; Tarazi, R.C.

1984-01-01

115

Semi-invasive monitoring of cardiac output by a new device using arterial pressure waveform analysis: a comparison with intermittent pulmonary artery thermodilution in patients undergoing cardiac surgery  

Microsoft Academic Search

Background. Thermodilution technique using a pulmonary artery catheter (PAC) is a widely used method to determine cardiac output (CO). It is increasingly criticized because of its inva- siveness and its unclear risk-benefit ratio. Thus, less invasive techniques for measuring CO are highly desirable. We compared a new, semi-invasive device (FloTrac\\/VigileoTM) using arterial pressure waveform analysis for CO measurement in patients

J. Mayer; J. Boldt; T. Schollhorn; K. D. Rohm; A. M. Mengistu; S. Suttner

2007-01-01

116

Phlebotomy eliminates the maximal cardiac output response to six weeks of exercise training.  

PubMed

With this study we tested the hypothesis that 6 wk of endurance training increases maximal cardiac output (Q?max) relatively more by elevating blood volume (BV) than by inducing structural and functional changes within the heart. Nine healthy but untrained volunteers (V?o2max 47 ± 5 ml·min(-1)·kg(-1)) underwent supervised training (60 min; 4 times weekly at 65% V?o2max for 6 wk), and Q?max was determined by inert gas rebreathing during cycle ergometer exercise before and after the training period. After the training period, blood volume (determined in duplicates by CO rebreathing) was reestablished to pretraining values by phlebotomy and Q?max was quantified again. Resting echography revealed no structural heart adaptations as a consequence of the training intervention. After the training period, plasma volume (PV), red blood cell volume (RBCV), and BV increased (P < 0.05) by 147 ± 168 (5 ± 5%), 235 ± 64 (10 ± 3%), and 382 ± 204 ml (7 ± 4%), respectively. V?o2max was augmented (P < 0.05) by 10 ± 7% after the training period and decreased (P < 0.05) by 8 ± 7% with phlebotomy. Concomitantly, Q?max was increased (P < 0.05) from 18.9 ± 2.1 to 20.4 ± 2.3 l/min (9 ± 6%) as a consequence of the training intervention, and after normalization of BV by phlebotomy Q?max returned to pretraining values (18.1 ± 2.5 l/min; 12 ± 5% reversal). Thus the exercise training-induced increase in BV is the main mechanism increasing Q?max after 6 wk of endurance training in previously untrained subjects. PMID:24622974

Bonne, Thomas C; Doucende, Gregory; Flück, Daniela; Jacobs, Robert A; Nordsborg, Nikolai B; Robach, Paul; Walther, Guillaume; Lundby, Carsten

2014-05-15

117

A comparison of pulse contour wave analysis and ultrasonic cardiac output monitoring in the critically ill.  

PubMed

Cardiac output (CO) is a key determinant of major organ blood flow and solute delivery to drug eliminating organs. As such, CO assessment is a key covariate in understanding altered drug handling in the critically ill. Newer minimally-invasive devices are providing unique platforms for such an application, although comparison data are currently lacking. In this study we evaluated the Vigileo (Edwards Lifesciences, Irvine, CA, USA) and USCOM (USCOM Ltd, Sydney, NSW) devices in 62 critically ill patients requiring antibacterial therapy. The mean COVigileo and COUSCOM for the first paired measurements were 8.20±2.65 l/minute and 6.84±2.57 l/minute respectively (P <0.001). A significant correlation was evident in all patients (r=0.537, P <0.001) although the recorded bias was large (1.36±2.51 l/minute, limits of agreement -3.6 to±6.3 l/minute). The overall percentage error was 65%. There was an improved correlation in those admitted with sepsis (r=0.639, P <0.001), compared to trauma (r=0.373, P=0.066), although bias, precision and percentage error were similar in both subgroups. In 54 patients a second paired assessment was obtained at three hours. A weak, although significant correlation (r=0.377, P=0.005) was observed suggesting that gross trends over time were similar. In conclusion, our findings demonstrate poor agreement between these techniques suggesting that these devices are not simply interchangeable when assessing CO in a research or clinical setting. PMID:22813490

Udy, A A; Altukroni, M; Jarrett, P; Roberts, J A; Lipman, J

2012-07-01

118

The role of histamine in the increased cardiac output in hyperdynamic endotoxemia.  

PubMed

The role of histamine in the hyperdynamic circulatory response to endotoxin (ETX) was investigated in 32 anesthetized dogs by means of histamine H1- and H2-receptor blockade. A hyperdynamic circulation was elicited with a prolonged, slow infusion of a low dose of ETX, and hemodynamic parameters were examined in control and histamine receptor-blocked groups. The following groups were studied: Group ETX received a 2 h infusion of Escherichia coli 055:B5 endotoxin in a total dose of 13.75 micrograms/kg at a rate of 10 micrograms/kg for 45 min and then 5 micrograms/kg for 75 min. In addition to the same dose of ETX, Groups ETX+TPA and ETX+RAN received 0.5 mg/kg of the H1-blocker tripelennamine (TPA) or 2 mg/kg of the H2-blocker ranitidine (RAN), respectively. Infusion of ETX caused a moderate decrease in arterial pressure in Group ETX, whereas TPA but not RAN inhibited this pressure fall. The cardiac output (CO) increased by 41% above the baseline level in Group ETX. Both TPA and RAN prevented this rise in CO. The total peripheral resistance was considerably lowered by ETX, but this decrease was significantly attenuated in the TPA or RAN-treated groups. The heart rate rose significantly after ETX infusion and was unaffected by TPA or RAN. The stroke volume remained unchanged following ETX but was decreased both by TPA and by RAN. TPA or RAN, when given alone, did not affect any of the measured hemodynamic parameters. These experiments provide evidence of the participation of histamine in the hyperdynamic circulatory response in endotoxemia. PMID:7749934

Tárnoky, K; Tutsek, L; Nagy, S

1994-02-01

119

Mechanisms of increase in cardiac output during acute weightlessness in humans.  

PubMed

Based on previous water immersion results, we tested the hypothesis that the acute 0-G-induced increase in cardiac output (CO) is primarily caused by redistribution of blood from the vasculature above the legs to the cardiopulmonary circulation. In seated subjects (n = 8), 20 s of 0 G induced by parabolic flight increased CO by 1.7 ± 0.4 l/min (P < 0.001). This increase was diminished to 0.8 ± 0.4 l/min (P = 0.028), when venous return from the legs was prevented by bilateral venous thigh-cuff inflation (CI) of 60 mmHg. Because the increase in stroke volume during 0 G was unaffected by CI, the lesser increase in CO during 0 G + CI was entirely caused by a lower heart rate (HR). Thus blood from vascular beds above the legs in seated subjects can alone account for some 50% of the increase in CO during acute 0 G. The remaining increase in CO is caused by a higher HR, of which the origin of blood is unresolved. In supine subjects, CO increased from 7.1 ± 0.7 to 7.9 ± 0.8 l/min (P = 0.037) when entering 0 G, which was solely caused by an increase in HR, because stroke volume was unaffected. In conclusion, blood originating from vascular beds above the legs can alone account for one-half of the increase in CO during acute 0 G in seated humans. A Bainbridge-like reflex could be the mechanism for the HR-induced increase in CO during 0 G in particular in supine subjects. PMID:21636570

Petersen, Lonnie G; Damgaard, Morten; Petersen, Johan C G; Norsk, Peter

2011-08-01

120

Effects of ventilation on cardiac output determined by inert gas rebreathing.  

PubMed

One of the most important methodological problems of the foreign gas rebreathing technique is that outcome of the measurements depends on procedural variables such as rebreathing frequency (RF), rebreathing bag volume (V(reb)), lung volume at start of rebreathing and intervals between measurements. Therefore, in 10 healthy males we investigated the effects of changes in ventilation pattern on cardiac output (CO) estimated by an N(2)O-rebreathing technique. Reducing the rebreathing volume (V(reb)) from 1.5 to 1.0 l diminished CO by 0.5 +/- 0.2 l min(-1), whereas an increase in V(reb) from 1.5 to 2.5 l had no effects. CO was 1.0 +/- 0.2 l min(-1) higher when, rebreathing was performed after a forced expiration than following a normal tidal expiration. Serial determinations of CO required a 3-min interval between the measurements to avoid effects of recirculation of N(2)O. Changing RF from 15 to 30 breaths min(-1) or adding serial dead space by up to 600 ml did not affect the determination of CO. In conclusion, the rebreathing procedure for determination of CO at rest should be performed following a normal tidal expiration with a rebreathing bag volume of between 1.5 and 2.5 l and with manoeuvres separated by at least 3-5 min. Variations in RF within the physiological range from 15 to 30 breaths min(-1) do not affect outcome of the measurements. PMID:15888093

Damgaard, Morten; Norsk, Peter

2005-05-01

121

Noninvasive cardiac output and blood pressure monitoring cannot replace an invasive monitoring system in critically ill patients  

PubMed Central

Background Monitoring of cardiac output and blood pressure are standard procedures in critical care medicine. Traditionally, invasive techniques like pulmonary artery catheter (PAC) and arterial catheters are widely used. Invasiveness bears many risks of deleterious complications. Therefore, a noninvasive reliable cardiac output (CO) and blood pressure monitoring system could improve the safety of cardiac monitoring. The aim of the present study was to compare a noninvasive versus a standard invasive cardiovascular monitoring system. Methods Nexfin HD is a continuous noninvasive blood pressure and cardiac output monitor system and is based on the development of the pulsatile unloading of the finger arterial walls using an inflatable finger cuff. During continuous BP measurement CO is calculated. We included 10 patients with standard invasive cardiac monitoring system (pulmonary artery catheter and arterial catheter) comparing invasively obtained data to the data collected noninvasively using the Nexfin HD. Results Correlation between mean arterial pressure measured with the standard arterial monitoring system and the Nexfin HD was r2 = 0.67 with a bias of -2 mmHg and two standard deviations of ± 16 mmHg. Correlation between CO derived from PAC and the Nexfin HD was r2 = 0.83 with a bias of 0.23 l/min and two standard deviations of ± 2.1 l/min; the percentage error was 29%. Conclusion Although the noninvasive CO measurement appears promising, the noninvasive blood pressure assessment is clearly less reliable than the invasively measured blood pressure. Therefore, according to the present data application of the Nexfin HD monitoring system in the ICU cannot be recommended generally. Whether such a tool might be reliable in certain critically ill patients remains to be determined.

Stover, John F; Stocker, Reto; Lenherr, Renato; Neff, Thomas A; Cottini, Silvia R; Zoller, Bernhard; Bechir, Markus

2009-01-01

122

The Influence of Left Lateral Position on Cardiac Output Changes after Head Up Tilt Measured by Impedance Cardiography  

Microsoft Academic Search

Background.The value of the impedance cardiography (IC) method formeasuring cardiac output (CO) with the subject in the left lateral positionhas not yet been established. We compared the CO after a 30° head-up tiltwith the subjects in the supine and left lateral position. Methods.Thirty healthy young volunteers were placed in the supine horizontalposition. CO, stroke volume (SV) and heart rate (HR)

Mirt Kamenik

1999-01-01

123

High-output cardiac failure in a fetus with thanatophoric dysplasia associated with large placental chorioangioma: case report.  

PubMed

Placental chorioangioma is an angioma arising from chorionic tissue. Fetal thanatophoric dysplasia is a lethal skeletal dysplasia due to mutation of fibroblast growth factor receptor 3 gene. These two conditions are rare and their coexistence in a given fetus is even rarer. We present a case of a fetus with thanatophoric dysplasia having high-output cardiac failure due to a large placental chorioangioma. PMID:22508320

Akercan, Fuat; Oncul Seyfettinoglu, Sevtap; Zeybek, Burak; Cirpan, Teksin

2012-05-01

124

Non-invasive measurement of cardiac output in heart failure patients using a new foreign gas rebreathing technique.  

PubMed

Values of effective pulmonary blood flow (Q(EP)) and cardiac output, determined by a non-invasive foreign gas rebreathing method (CO(RB)) using a new infrared photoacoustic gas analysing system, were compared with measurements of cardiac output obtained by the direct Fick (CO(FICK)) and thermodilution (CO(TD)) methods in patients with heart failure or pulmonary hypertension. In 11 patients, of which three had shunt flow through areas without significant gas exchange, the mean difference (bias) and limits of agreement (+/- 2 S.D.) were 0.6 +/- 1.2 litre x min(-1) when comparing CO(FICK) and Q(EP), and -0.8 +/- 1.3 litre x min(-1) when comparing CO(FICK) and CO(TD). When correction for intrapulmonary shunt flow was applied (i.e. calculation of CO(RB)) in all 11 patients, the bias between CO(FICK) and CO(RB) was 0.1 +/- 0.9 litre x min(-1), primarily because agreement improved in the three patients with significant shunt flow. In the eight patients without significant shunt flow, the agreement between Q(EP) and CO(FICK) was 0.3 +/- 0.9 litre x min(-1). In conclusion, a foreign gas rebreathing method with a new infrared photoacoustic gas analyser provided at least as reliable a measure of cardiac output as did thermodilution. In the absence of significant shunt flow, measurement of Q(EP) itself provides a reliable estimate of cardiac output in heart failure patients. The infrared photoacoustic gas analyser markedly facilitates clinical use of the rebreathing method in general, which makes the method available to a larger group of clinicians working with patients with cardiovascular diseases. PMID:11834145

Gabrielsen, Anders; Videbaek, Regitze; Schou, Morten; Damgaard, Morten; Kastrup, Jens; Norsk, Peter

2002-02-01

125

Venoarterial PCO2 difference: a marker of postoperative cardiac output in children with congenital heart disease  

Microsoft Academic Search

OBJECTIVE: To determine the relationship between venoarterial carbon dioxide gradient (DeltapCO2) and central venous oxygen saturation (ScvO2) in children after cardiac surgery.STUDY DESIGN: A cohort study.PLACE AND DURATION OF STUDY: The Paediatric cardiac intensive care unit of the Aga Khan University Hospital, Karachi, from June 2006 to May 2007.METHODOLOGY: All children admitted in the paediatric cardiac intensive care after complete

Muhammad Furqan; Fahad Hashmat; Munir Amanullah; Mansoor Khan; Hina K Durani; Anwar-ul-Haque

2009-01-01

126

Evaluation of cardiac output in intensive care using a non-invasive arterial pulse contour technique (Nexfin(®)) compared with echocardiography.  

PubMed

In this prospective study, cardiac output was measured in 38 intensive care unit patients before and after a fluid challenge, using both pulse contour analysis (Nexfin(®); BMEYE, Amsterdam, the Netherlands) and transthoracic echocardiography. The ability of the Nexfin device to detect significant changes in the velocity-time integral was evaluated. The pulse wave could not be detected by the Nexfin device in five patients (13%), leaving 33 patients for analysis. The Nexfin device adequately tracked changes in the velocity-time integral in 20 (61%) patients. Using a cut-off of a 10% increase in cardiac output estimated by the Nexfin or by echocardiography, the sensitivity of the Nexfin device to detect a response to fluid challenge was 47%, with specificity 81% and accuracy 64%. The percentage error between the Nexfin and echocardiography was 448%; lower limit of agreement -48% (95% CI -62 to -36%) and upper limit of agreement, 32% (95% CI 20-45%). We conclude that the Nexfin device does not adequately track changes in cardiac output in critically ill patients. PMID:23837860

Taton, O; Fagnoul, D; De Backer, D; Vincent, J-L

2013-09-01

127

The effect of bundle branch block on heart function and cardiac output in premature infant.  

PubMed

It is well known that hyperkalemia may cause arrhythmia, right bundle branch block, and cardiac conduction block. These dysrhythmias have the potential to affect cardiac function. We present a premature newborn with hyperkalemia and right bundle branch block causing left ventricular dyssynchrony with mitral regurgitation, which led to decreased pump function. PMID:23604222

Jawa, Gaurav; Yuen, Doris; Norozi, Kambiz

2013-12-01

128

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

PubMed Central

Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel engine exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance of normal cardiac function. To explore this putative mechanism, we examined cardiophysiologic responses to DE inhalation in a model of aged heart failure–prone rats without signs or symptoms of overt heart failure. We hypothesized that acute DE exposure would alter heart rhythm, cardiac electrophysiology, and ventricular performance and dimensions consistent with autonomic imbalance while increasing biochemical markers of toxicity. Spontaneously hypertensive heart failure rats (16 months) were exposed once to whole DE (4h, target PM2.5 concentration: 500 µg/m3) or filtered air. DE increased multiple heart rate variability (HRV) parameters during exposure. In the 4h after exposure, DE increased cardiac output, left ventricular volume (end diastolic and systolic), stroke volume, HRV, and atrioventricular block arrhythmias while increasing electrocardiographic measures of ventricular repolarization (i.e., ST and T amplitudes, ST area, T-peak to T-end duration). DE did not affect heart rate relative to air. Changes in HRV positively correlated with postexposure changes in bradyarrhythmia frequency, repolarization, and echocardiographic parameters. At 24h postexposure, DE-exposed rats had increased serum C-reactive protein and pulmonary eosinophils. This study demonstrates that cardiac effects of DE inhalation are likely to occur through changes in autonomic balance associated with modulation of cardiac electrophysiology and mechanical function and may offer insights into the adverse health effects of traffic-related air pollutants.

Farraj, Aimen K.

2013-01-01

129

Diesel exhaust inhalation increases cardiac output, bradyarrhythmias, and parasympathetic tone in aged heart failure-prone rats.  

PubMed

Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel engine exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance of normal cardiac function. To explore this putative mechanism, we examined cardiophysiologic responses to DE inhalation in a model of aged heart failure-prone rats without signs or symptoms of overt heart failure. We hypothesized that acute DE exposure would alter heart rhythm, cardiac electrophysiology, and ventricular performance and dimensions consistent with autonomic imbalance while increasing biochemical markers of toxicity. Spontaneously hypertensive heart failure rats (16 months) were exposed once to whole DE (4h, target PM(2.5) concentration: 500 µg/m(3)) or filtered air. DE increased multiple heart rate variability (HRV) parameters during exposure. In the 4h after exposure, DE increased cardiac output, left ventricular volume (end diastolic and systolic), stroke volume, HRV, and atrioventricular block arrhythmias while increasing electrocardiographic measures of ventricular repolarization (i.e., ST and T amplitudes, ST area, T-peak to T-end duration). DE did not affect heart rate relative to air. Changes in HRV positively correlated with postexposure changes in bradyarrhythmia frequency, repolarization, and echocardiographic parameters. At 24h postexposure, DE-exposed rats had increased serum C-reactive protein and pulmonary eosinophils. This study demonstrates that cardiac effects of DE inhalation are likely to occur through changes in autonomic balance associated with modulation of cardiac electrophysiology and mechanical function and may offer insights into the adverse health effects of traffic-related air pollutants. PMID:23047911

Carll, Alex P; Lust, Robert M; Hazari, Mehdi S; Perez, Christina M; Krantz, Quentin Todd; King, Charly J; Winsett, Darrell W; Cascio, Wayne E; Costa, Daniel L; Farraj, Aimen K

2013-02-01

130

Early non-invasive cardiac output monitoring in hemodynamically unstable intensive care patients: A multi-center randomized controlled trial  

PubMed Central

Introduction Acute hemodynamic instability increases morbidity and mortality. We investigated whether early non-invasive cardiac output monitoring enhances hemodynamic stabilization and improves outcome. Methods A multicenter, randomized controlled trial was conducted in three European university hospital intensive care units in 2006 and 2007. A total of 388 hemodynamically unstable patients identified during their first six hours in the intensive care unit (ICU) were randomized to receive either non-invasive cardiac output monitoring for 24 hrs (minimally invasive cardiac output/MICO group; n = 201) or usual care (control group; n = 187). The main outcome measure was the proportion of patients achieving hemodynamic stability within six hours of starting the study. Results The number of hemodynamic instability criteria at baseline (MICO group mean 2.0 (SD 1.0), control group 1.8 (1.0); P = .06) and severity of illness (SAPS II score; MICO group 48 (18), control group 48 (15); P = .86)) were similar. At 6 hrs, 45 patients (22%) in the MICO group and 52 patients (28%) in the control group were hemodynamically stable (mean difference 5%; 95% confidence interval of the difference -3 to 14%; P = .24). Hemodynamic support with fluids and vasoactive drugs, and pulmonary artery catheter use (MICO group: 19%, control group: 26%; P = .11) were similar in the two groups. The median length of ICU stay was 2.0 (interquartile range 1.2 to 4.6) days in the MICO group and 2.5 (1.1 to 5.0) days in the control group (P = .38). The hospital mortality was 26% in the MICO group and 21% in the control group (P = .34). Conclusions Minimally-invasive cardiac output monitoring added to usual care does not facilitate early hemodynamic stabilization in the ICU, nor does it alter the hemodynamic support or outcome. Our results emphasize the need to evaluate technologies used to measure stroke volume and cardiac output--especially their impact on the process of care--before any large-scale outcome studies are attempted. Trial Registration The study was registered at ClinicalTrials.gov (Clinical Trials identifier NCT00354211)

2011-01-01

131

Pulmonary Artery Catheter (PAC) Accuracy and Efficacy Compared with Flow Probe and Transcutaneous Doppler (USCOM): An Ovine Cardiac Output Validation  

PubMed Central

Background. The pulmonary artery catheter (PAC) is an accepted clinical method of measuring cardiac output (CO) despite no prior validation. The ultrasonic cardiac output monitor (USCOM) is a noninvasive alternative to PAC using Doppler ultrasound (CW). We compared PAC and USCOM CO measurements against a gold standard, the aortic flow probe (FP), in sheep at varying outputs. Methods. Ten conscious sheep, with implanted FPs, had measurements of CO by FP, USCOM, and PAC, at rest and during intervention with inotropes and vasopressors. Results. CO measurements by FP, PAC, and USCOM were 4.0 ± 1.2?L/min, 4.8 ± 1.5?L/min, and 4.0 ± 1.4?L/min, respectively, (n = 280, range 1.9?L/min to 11.7?L/min). Percentage bias and precision between FP and PAC, and FP and USCOM was ?17 and 47%, and 1 and 36%, respectively. PAC under-measured Dobutamine-induced CO changes by 20% (relative 66%) compared with FP, while USCOM measures varied from FP by 3% (relative 10%). PAC reliably detected ?30% but not +40% CO changes, as measured by receiver operating characteristic area under the curve (AUC), while USCOM reliably detected ±5% changes in CO (AUC > 0.70). Conclusions. PAC demonstrated poor accuracy and sensitivity as a measure of CO. USCOM provided equivalent measurements to FP across a sixfold range of outputs, reliably detecting ±5% changes.

Phillips, Robert A.; Hood, Sally G.; Jacobson, Beverley M.; West, Malcolm J.; Wan, Li; May, Clive N.

2012-01-01

132

Ion channel-kinase TRPM7 is required for maintaining cardiac automaticity  

PubMed Central

Sick sinus syndrome and atrioventricular block are common clinical problems, often necessitating permanent pacemaker placement, yet the pathophysiology of these conditions remains poorly understood. Here we show that Transient Receptor Potential Melastatin 7 (TRPM7), a divalent-permeant channel-kinase of unknown function, is highly expressed in embryonic myocardium and sinoatrial node (SAN) and is required for cardiac automaticity in these specialized tissues. TRPM7 disruption in vitro, in cultured embryonic cardiomyocytes, significantly reduces spontaneous Ca2+ transient firing rates and is associated with robust down-regulation of Hcn4, Cav3.1, and SERCA2a mRNA. TRPM7 knockdown in zebrafish, global murine cardiac Trpm7 deletion (KO?MHC-Cre), and tamoxifen-inducible SAN restricted Trpm7 deletion (KOHCN4-CreERT2) disrupts cardiac automaticity in vivo. Telemetered and sedated KO?MHC-Cre and KOHCN4-CreERT2 mice show episodes of sinus pauses and atrioventricular block. Isolated SAN from KO?MHC-Cre mice exhibit diminished Ca2+ transient firing rates with a blunted diastolic increase in Ca2+. Action potential firing rates are diminished owing to slower diastolic depolarization. Accordingly, Hcn4 mRNA and the pacemaker current, If, are diminished in SAN from both KO?MHC-Cre and KOHCN4-CreERT2 mice. Moreover, heart rates of KO?MHC-Cre mice are less sensitive to the selective If blocker ivabradine, and acute application of the recently identified TRPM7 blocker FTY720 has no effect on action potential firing rates of wild-type SAN cells. We conclude that TRPM7 influences diastolic membrane depolarization and automaticity in SAN indirectly via regulation of Hcn4 expression.

Sah, Rajan; Mesirca, Pietro; Van den Boogert, Marjolein; Rosen, Jonathan; Mably, John; Mangoni, Matteo E.; Clapham, David E.

2013-01-01

133

Ion channel-kinase TRPM7 is required for maintaining cardiac automaticity.  

PubMed

Sick sinus syndrome and atrioventricular block are common clinical problems, often necessitating permanent pacemaker placement, yet the pathophysiology of these conditions remains poorly understood. Here we show that Transient Receptor Potential Melastatin 7 (TRPM7), a divalent-permeant channel-kinase of unknown function, is highly expressed in embryonic myocardium and sinoatrial node (SAN) and is required for cardiac automaticity in these specialized tissues. TRPM7 disruption in vitro, in cultured embryonic cardiomyocytes, significantly reduces spontaneous Ca(2+) transient firing rates and is associated with robust down-regulation of Hcn4, Cav3.1, and SERCA2a mRNA. TRPM7 knockdown in zebrafish, global murine cardiac Trpm7 deletion (KO(?MHC-Cre)), and tamoxifen-inducible SAN restricted Trpm7 deletion (KO(HCN4-CreERT2)) disrupts cardiac automaticity in vivo. Telemetered and sedated KO(?MHC-Cre) and KO(HCN4-CreERT2) mice show episodes of sinus pauses and atrioventricular block. Isolated SAN from KO(?MHC-Cre) mice exhibit diminished Ca(2+) transient firing rates with a blunted diastolic increase in Ca(2+). Action potential firing rates are diminished owing to slower diastolic depolarization. Accordingly, Hcn4 mRNA and the pacemaker current, I(f), are diminished in SAN from both KO(?MHC-Cre) and KO(HCN4-CreERT2) mice. Moreover, heart rates of KO(?MHC-Cre) mice are less sensitive to the selective I(f) blocker ivabradine, and acute application of the recently identified TRPM7 blocker FTY720 has no effect on action potential firing rates of wild-type SAN cells. We conclude that TRPM7 influences diastolic membrane depolarization and automaticity in SAN indirectly via regulation of Hcn4 expression. PMID:23878236

Sah, Rajan; Mesirca, Pietro; Van den Boogert, Marjolein; Rosen, Jonathan; Mably, John; Mangoni, Matteo E; Clapham, David E

2013-08-01

134

Estimation of cardiac output in patients with congestive heart failure by analysis of right ventricular pressure waveforms  

PubMed Central

Background Cardiac output (CO) is an important determinant of the hemodynamic state in patients with congestive heart failure (CHF). We tested the hypothesis that CO can be estimated from the right ventricular (RV) pressure waveform in CHF patients using a pulse contour cardiac output algorithm that considers constant but patient specific RV outflow tract characteristic impedance. Method In 12 patients with CHF, breath-by-breath Fick CO and RV pressure waveforms were recorded utilizing an implantable hemodynamic monitor during a bicycle exercise protocol. These data were analyzed retrospectively to assess changes in characteristic impedance of the RV outflow tract during exercise. Four patients that were implanted with an implantable cardiac defibrillator (ICD) implementing the algorithm were studied prospectively. During a two staged sub-maximal bicycle exercise test conducted at 4 and 16 weeks of implant, COs measured by direct Fick technique and estimated by the ICD were recorded and compared. Results At rest the total pulmonary arterial resistance and the characteristic impedance were 675 ± 345 and 48 ± 18 dyn.s.cm-5, respectively. During sub-maximal exercise, the total pulmonary arterial resistance decreased (? 91 ± 159 dyn.s.cm-5, p < 0.05) but the characteristic impedance was unaffected (? 3 ± 9 dyn.s.cm-5, NS). The algorithm derived cardiac output estimates correlated with Fick CO (7.6 ± 2.5 L/min, R2 = 0.92) with a limit of agreement of 1.7 L/min and tracked changes in Fick CO (R2 = 0.73). Conclusions The analysis of right ventricular pressure waveforms continuously recorded by an implantable hemodynamic monitor provides an estimate of CO and may prove useful in guiding treatment in patients with CHF.

2011-01-01

135

Effect of increased cardiac output on liver blood flow, oxygen exchange and metabolic rate during longterm endotoxin-induced shock in pigs  

PubMed Central

We investigated hepatic blood flow, O2 exchange and metabolism in porcine endotoxic shock (Control, n=8; Endotoxin, n=10) with administration of hydroxyethylstarch to maintain arterial pressure (MAP)>60?mmHg. Before and 12, 18 and 24?h after starting continuous i.v. endotoxin we measured portal venous and hepatic arterial blood flow, intracapillary haemoglobin O2 saturation (Hb-O2%) of the liver surface and arterial, portal and hepatic venous lactate, pyruvate, glyercol and alanine concentrations. Glucose production rate was derived from the plasma isotope enrichment during infusion of [6,6-2H2]-glucose. Despite a sustained 50% increase in cardiac output endotoxin caused a progressive, significant fall in MAP. Liver blood flow significantly increased, but endotoxin affected neither hepatic O2 delivery and uptake nor mean intracapillary Hb-O2% and Hb-O2% frequency distributions. Endotoxin nearly doubled endogenous glucose production rate while hepatic lactate, alanine and glycerol uptake rates progressively decreased significantly. The lactate uptake rate even became negative (P<0.05 vs Control). Endotoxin caused portal and hepatic venous pH to fall significantly concomitant with significantly increased arterial, portal and hepatic venous lactate/pyruvate ratios. During endotoxic shock increased cardiac output achieved by colloid infusion maintained elevated liver blood flow and thereby macro- and microcirculatory O2 supply. Glucose production rate nearly doubled with complete dissociation of hepatic uptake of glucogenic precursors and glucose release. Despite well-preserved capillary oxygenation increased lactate/pyruvate ratios reflecting impaired cytosolic redox state suggested deranged liver energy balance, possibly due to the O2 requirements of gluconeogenesis.

Santak, Borislav; Radermacher, Peter; Adler, Jens; Iber, Thomas; Rieger, Karen M; Wachter, Ulrich; Vogt, Josef; Georgieff, Michael; Trager, Karl

1998-01-01

136

Pulse Wave Velocity and Cardiac Output vs. Heart Rate in Patients with an Implanted Pacemaker Based on Electric Impedance Method Measurement  

NASA Astrophysics Data System (ADS)

The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

Soukup, Ladislav; Vondra, Vlastimil; Viš?or, Ivo; Jurák, Pavel; Halámek, Josef

2013-04-01

137

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

138

Reliability of continuous cardiac output measurement during intra-abdominal hypertension relies on repeated calibrations: an experimental animal study  

PubMed Central

Introduction Monitoring cardiac output (CO) may allow early detection of haemodynamic instability, aiming to reduce morbidity and mortality in critically ill patients. Continuous cardiac output (CCO) monitoring is recommended in septic or postoperative patients with high incidences of intra-abdominal hypertension (IAH). The aim of the present study was to compare the agreement between three CCO methods and a bolus thermodilution CO technique during acute IAH and volume loading. Methods Ten pigs were anaesthetised and instrumented for haemodynamic measurements. Cardiac output was obtained using CCO by pulse power analysis (PulseCO; LiDCO monitor), using CCO by pulse contour analysis (PCCO; PiCCO monitor) and using CCO by pulmonary artery catheter thermodilution (CCOPAC), and was compared with bolus transcardiopulmonary thermodilution CO (COTCP) at baseline, after fluid loading, at IAH and after an additional fluid loading at IAH. Whereas PulseCO was only calibrated at baseline, PCCO was calibrated at each experimental step. Results PulseCO and PCCO underestimated CO, as the overall bias ± standard deviation was 1.0 ± 1.5 l/min and 1.0 ± 1.1 l/min compared with COTCP. A clinically accepted agreement between all of the CCO methods and COTCP was observed only at baseline. Whereas IAH did not influence the CO, increased CO following fluid loading at IAH was only reflected by CCOPAC and COTCP, not by uncalibrated PulseCO and PCCO. After recalibration, PCCO was comparable with COTCP. Conclusions The CO obtained by uncalibrated PulseCO and PCCO failed to agree with COTCP during IAH and fluid loading. In the critically ill patient, recalibration of continuous arterial waveform CO methods should be performed after fluid loading or before a major change in therapy is initiated.

Gruenewald, Matthias; Renner, Jochen; Meybohm, Patrick; Hocker, Jan; Scholz, Jens; Bein, Berthold

2008-01-01

139

Prevalence of nursing diagnosis of decreased cardiac output and the predictive value of defining characteristics in patients under evaluation for heart transplant.  

PubMed

The purposes of the study were to identify the prevalence of defining characteristics (DC) of decreased cardiac output (DCO) in patients with cardiac insufficiency under evaluation for heart transplantation, and to ascertain the likelihood of defining characteristics being predictive factors for the existence of reduction in cardiac output. Data was obtained by retrospective documental analysis of the clinical records of right-sided heart catheterizations in 38 patients between 2004 and 2009. The results showed that 71.1% of the patients had decreased cardiac output (measured by cardiac index). The majority of the NANDA-International defining characteristics for DCO were more frequent in individuals with reduced cardiac index levels. The study emphasizes the odds ratio (OR) for increased Systemic Vascular Resistance of OR=4.533, of the third heart sound with OR=3.429 and the reduced ejection fraction with OR=2.850. By obtaining the predictive values for the defining characteristics the study identifies them as diagnostic indicators of decreased cardiac output. PMID:22699731

Matos, Lígia Neres; Guimarães, Tereza Cristina Felippe; Brandão, Marcos Antônio Gomes; Santoro, Deyse Conceição

2012-01-01

140

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

141

Protein kinase C depresses cardiac myocyte power output and attenuates myofilament responses induced by protein kinase A  

PubMed Central

Following activation by G-protein-coupled receptor agonists, protein kinase C (PKC) modulates cardiac myocyte function by phosphorylation of intracellular targets including myofilament proteins cardiac troponin I (cTnI) and cardiac myosin binding protein C (cMyBP-C). Since PKC phosphorylation has been shown to decrease myofibril ATPase activity, we hypothesized that PKC phosphorylation of cTnI and cMyBP-C will lower myocyte power output and, in addition, attenuate the elevation in power in response to protein kinase A (PKA)-mediated phosphorylation. We compared isometric force and power generating capacity of rat skinned cardiac myocytes before and after treatment with the catalytic subunit of PKC. PKC increased phosphorylation levels of cMyBP-C and cTnI and decreased both maximal Ca2+ activated force and Ca2+ sensitivity of force. Moreover, during submaximal Ca2+ activations PKC decreased power output by 62 %, which arose from both the fall in force and slower loaded shortening velocities since depressed power persisted even when force levels were matched before and after PKC. In addition, PKC blunted the phosphorylation of cTnI by PKA, reduced PKA-induced spontaneous oscillatory contractions, and diminished PKA-mediated elevations in myocyte power. To test whether altered thin filament function plays an essential role in these contractile changes we investigated the effects of chronic cTnI pseudo-phosphorylation on myofilament function using myocyte preparations from transgenic animals in which either only PKA phosphorylation sites (Ser-23/Ser-24) (PP) or both PKA and PKC phosphorylation sites (Ser-23/Ser-24/Ser-43/Ser-45/T-144) (All-P) were replaced with aspartic acid. Cardiac myocytes from All-P transgenic mice exhibited reductions in maximal force, Ca2+ sensitivity of force, and power. Similarly diminished power generating capacity was observed in hearts from All-P mice as determined by in situ pressure–volume measurements. These results imply that PKC-mediated phosphorylation of cTnI plays a dominant role in depressing contractility, and, thus, increased PKC isozyme activity may contribute to maladaptive behavior exhibited during the progression to heart failure.

Hinken, Aaron C.; Hanft, Laurin M.; Scruggs, Sarah B.; Sadayappan, Sakthivel; Robbins, Jeffery; Solaro, R. John

2013-01-01

142

A Review of Intraoperative Goal-Directed Therapy Using Arterial Waveform Analysis for Assessment of Cardiac Output  

PubMed Central

Increasing evidence shows that goal-directed hemodynamic management can improve outcomes in surgical and intensive care settings. Arterial waveform analysis is one of the different techniques used for guiding goal-directed therapy. Multiple proprietary systems have developed algorithms for obtaining cardiac output from an arterial waveform, including the FloTrac, LiDCO, and PiCCO systems. These systems vary in terms of how they analyze the arterial pressure waveform as well as their requirements for invasive line placement and calibration. Although small-scale clinical trials using these monitors show promising data, large-scale multicenter trials are still needed to better determine how intraoperative goal-directed therapy with arterial waveform analysis can improve patient outcomes. This review provides a comparative analysis of the different arterial waveform monitors for intraoperative goal-directed therapy.

Fernandez-Bustamante, Ana

2014-01-01

143

[Heart size and left ventricular function in coronary artery disease: I. Heart size, exercise tolerance, cardiac output and filling pressures (author's transl)].  

PubMed

The possible relationship between the cardiac volume, as determined radiologically in the supine position in 119 patients with angiographically proven coronary artery disease, and the results of ergometry and balloon catheterization was investigated. There was no relationship between the heart size on the one side and the maximum exercise tolerance and the maximum cardiac output on the other, except for the fact, that these parameters tended to decrease with increasing heart size. This was especially true in patients with angina. The maximum cardiac output of patients with angina was always below the value of patients without angina but comparable heart size. Reduced cardiac output under exercise (exertional cardiac insufficiency) was present in 50% of patients with enlarged hearts but already in 22% of patients with heart volumes in the lower range of normal. The diastolic pulmonary artery pressure, determined under exercise, was the only parameter with a significant relationship to the heart size: The larger the heart size, the higher the diastolic pulmonary artery pressure. On the other hand: the diastolic pulmonary artery pressure at rest was abnormal with significant frequency only, when the heart was enlarged. Our data suggest, that the hemodynamics are determined by 2 factors: Myocardial scarring secondary to infarction and coronary insufficiency (ischemia). Of these two factors only the former influences cardiac size. Therefore, determination of the heart volume helps evaluating the respective role of these two factors in individual cases. PMID:927289

Meuret, G; Jaedicke, W; Barmeyer, J; Wink, K; König, K; Reindell, H

1977-11-01

144

The Neuromuscular Transform of the Lobster Cardiac System Explains the Opposing Effects of a Neuromodulator on Muscle Output  

PubMed Central

Motor neuron activity is transformed into muscle movement through a cascade of complex molecular and biomechanical events. This nonlinear mapping of neural inputs to motor behaviors is called the neuromuscular transform (NMT). We examined the NMT in the cardiac system of the lobster Homarus americanus by stimulating a cardiac motor nerve with rhythmic bursts of action potentials and measuring muscle movements in response to different stimulation patterns. The NMT was similar across preparations, which suggested that it could be used to predict muscle movement from spontaneous neural activity in the intact heart. We assessed this possibility across semi-intact heart preparations in two separate analyses. First, we performed a linear regression analysis across 122 preparations in physiological saline to predict muscle movements from neural activity. Under these conditions, the NMT was predictive of contraction duty cycle but was unable to predict contraction amplitude, likely as a result of uncontrolled interanimal variability. Second, we assessed the ability of the NMT to predict changes in motor output induced by the neuropeptide C-type allatostatin. Wiwatpanit et al. (2012) showed that bath application of C-type allatostatin produced either increases or decreases in the amplitude of the lobster heart contractions. We show that an important component of these preparation-dependent effects can arise from quantifiable differences in the basal state of each preparation and the nonlinear form of the NMT. These results illustrate how properly characterizing the relationships between neural activity and measurable physiological outputs can provide insight into seemingly idiosyncratic effects of neuromodulators across individuals.

Williams, Alex H.; Calkins, Andrew; O'Leary, Timothy; Symonds, Renee; Marder, Eve

2013-01-01

145

The contribution of alterations in cardiac output to changes in arterial pressure reflexly evoked from the carotid sinus in the rabbit.  

PubMed Central

1. The reflex cardiovascular effects of changes in pressure within the vascularly isolated carotid sinus were examined in seventeen anaesthetized rabbits. The opposite sinus was denervated and both aortic nerves were divided, 2. Comparison of the mean values at sinus pressures of 40 and 200 mmHg showed a large reduction in systemic arterial pressure from 126 to 58 mmHg and a moderate reduction in heart rate, from 287 to 253 beats min-1. Cardiac output, measured by thermal dilution, showed only a small change, a fall from 160 to 148 ml. min-1 kg-1. 3. By contrast with this reduction in cardiac output of just over 7%, total peripheral resistance, derived by dividing mean arterial pressure by cardiac output, was halved, falling from 0-48 to 0-41 mmHg ml.-1 min kg. 4. Thus in the anaesthetized rabbit changes in cardiac output make only a small contribution to the changes in systemic pressure evoked by alterations in carotid sinus pressure. Changes in total peripheral resistance are principally responsible for the effect on systemic pressure. 5. Though the changes in output of the heart were small, there were considerable changes in the work done by the left ventricle which was approximately halved when carotid sinus pressure was raised from 40 to 200 mmHg.

Humphreys, P W; Joels, N

1977-01-01

146

GH dependence and GH withdrawal syndrome in GH treatment of short normal children: evidence from growth and cardiac output.  

PubMed

The child's age is a significant determinant of the outcome of GH therapy; prepubertal children respond better on both short term and long term growth, whereas adolescents tend to accelerate their bone maturation more than growth. The present study was designed to evaluate the efficacy of an interrupted GH therapy protocol of young, short normal children. GH was given for a period of 3 years, or until they reached the 25th percentile, then discontinued at a young age (not more than 9 years), and then the children's growth followed until final height. Yet, after discontinuation of GH therapy, growth came close to a complete stand-still. The present report focuses on describing the period beyond GH withdrawal and its impact on growth and cardiac performance. Twenty-two children received daily s.c. injections of 0.9 mg/m2 hGH and 12 children were the control, untreated group. Growth and echocardiography were followed during therapy and 2 years thereafter. During GH treatment growth velocity accelerated markedly over the first year; it slowed down over the second and third years, and decelerated after GH withdrawal to a velocity that was significantly lower than pretreatment values. Growth rate remained low for the next year, and recovered to pretreatment velocity by the fourth semiannual measurement. To evaluate the role of the GH-IGF-I axis during the growth deceleration, serum IGF-I, insulin-like growth factor-binding protein-3 (IGFBP-3), and an arginine stimulation test were performed at 1, 3 or 6 months after GH withdrawal, and compared with pretreatment response. GH response was 70% of pretreatment values by 1 month and recovered completely by 3 months post treatment. Serum IGF-I and IGFBP-3 levels were normal throughout. End-systolic and end-diastolic left ventricular dimensions as well as cardiac output did not change during the 2 year course of GH therapy, but fell significantly during the initial 6 months of GH withdrawal. Thus, daily injections of GH to prepubertal short normal children is associated with development of drug dependence, followed during the abstinence period by deceleration of growth and reduction of cardiac output to levels that are lower than pretreatment values. After GH therapy for 30-36 months the withdrawal syndrome persists for 18 months, and is not induced by alterations of serum levels of GH or IGF-I. PMID:9578507

Lampit, M; Lorber, A; Vilkas, D L; Nave, T; Hochberg, Z

1998-04-01

147

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

PubMed Central

Cardiovascular disease (CVD) is associated with cognitive deficits even in the absence of stroke. We examined the relationship between cardiac performance, as measured by cardiac output (CO) and ejection fraction (EF), and brain activity during a verbal working memory (VWM) task in elderly CVD patients who tend to be at increased risk for vascular cognitive impairments. Seventeen patients were recruited from a cohort participating in an ongoing prospective study examining the effects of CVD on cognitive function in the elderly. Participants were diagnosed with CVD (age 68±8) and completed a 2-back VWM task in a 1.5T fMRI paradigm. CO and EF were calculated from echocardiogram measures. Task-related activation was averaged in a priori regions of interest. The relationship between CO, EF, and 2-back-related activity was modeled using partial correlations (two-tailed p<.05) controlling for age and 2-back accuracy. All participants were globally cognitively intact as indicated by Mini-Mental Status Exam and Dementia Rating Scale scores. Mean accuracy on the 2-back was 78±9% while reaction time averaged 1,027±192 ms. Mean CO and EF values showed a large range (CO: 3.55 to 6.31; EF: 0.36 to 0.76) but average values were within the normal range. After controlling for age and 2-back accuracy, lower EF was related to decrease in left insula activity (r=0.61, p=0.03). There were trends for EF to be related to accuracy (r=0.47, p=0.09) and reaction time (r=?0.48, p=0.09). CO was also related to insula activity (r=0.60, p=0.04) and activity in the supplementary motor area activity (r=0.66, p=0.01). Cardiac performance was related to decreased efficiency in task related brain areas and tended to be related to performance on a VWM task in elderly patients with CVD. Results have implications for a line of investigation indicating that cardiac and systemic vascular indices could be used as proxy measures to examine mechanisms of cerebrovascular dysfunction in the elderly.

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

2011-01-01

148

Optimized Temporary Biventricular Pacing Acutely Improves Intraoperative Cardiac Output After Weaning From Cardiopulmonary Bypass - A Sub-study of a Randomized Clinical Trial  

PubMed Central

Objective Permanent biventricular pacing benefits patients with heart failure and interventricular conduction delay, but the importance of pacing with and without optimization in patients at risk of low cardiac output after heart surgery is unknown. We hypothesized that pacing parameters independently affect cardiac output. Accordingly, we analyzed aortic flow measured with an electromagnetic flowmeter in patients at risk of low cardiac output, during an ongoing randomized clinical trial of biventricular pacing (n=11) vs. standard of care (n=9). Methods A sub-study was conducted in all 20 patients, in both groups, with stable pacing after coronary artery bypass grafting and/or valve surgery. Ejection fraction averaged 33±15%, QRS duration 116±19 msec. Effects were measured within one hour of the conclusion of cardiopulmonary bypass. Atrioventricular delay (7 settings) and interventricular delay (9 settings) were optimized in random sequence. Results Optimization of atrioventricular delay (171±8 msec), at an interventricular delay of 0 msec, increased flow 14% vs. the worst setting (111±11 msec, p < 0.001) and 7% vs. nominal atrioventricular delay (120 msec, p < 0.001). Interventricular delay optimization increased flow 10% vs. the worst setting (p < 0.001) and 5% vs. nominal interventricular delay (0 msec, p < 0.001). Optimized pacing increased cardiac output 13% vs. atrial pacing at matched heart rate (5.5±0.5 vs. 4.9±0.6 L/min; p = 0.003) and 10% vs. sinus rhythm (5.0±0.6 L/min; p = 0.019). Conclusions Temporary biventricular pacing increases intraoperative cardiac output in patients with left ventricular dysfunction undergoing cardiac surgery. Atrioventricular and interventricular delay optimization maximizes this benefit.

Wang, Daniel Y.; Richmond, Marc E.; Quinn, T. Alexander; Mirani, Ajay J.; Rusanov, Alexander; Yalamanchi, Vinay; Weinberg, Alan D.; Cabreriza, Santos E.; Spotnitz, Henry M.

2010-01-01

149

Measurement of cardiac output before and after cardiopulmonary bypass: Comparison among aortic transit-time ultrasound, thermodilution, and noninvasive partial CO 2 rebreathing  

Microsoft Academic Search

Objectives: A noninvasive continuous cardiac output system (NICO) has been developed recently. NICO uses a ratio of the change in the end-tidal carbon dioxide partial pressure and carbon dioxide elimination in response to a brief period of partial rebreathing to measure CO. The aim of this study was to compare the agreement among NICO, bolus (TDCO), and continuous thermodilution (CCO),

Monica Botero; David Kirby; Emilio B. Lobato; Edward D. Staples; Nikolaus Gravenstein

2004-01-01

150

Non-invasive assessment of cardiac output during exercise in chronic obstructive pulmonary disease: comparison of the -rebreathing method and electrical impedance cardiography  

Microsoft Academic Search

In exercise testing of patients with chronic obstructive pulmonary disease (COPD), non-invasive assessment of stroke volume (SV) and cardiac output (CO) would be valuable. Electrical impedance cardiography (EIC) has proved to be a valid and reliable instrument in healthy subjects. In this study it is investigated whether this also applies to patients with COPD. In 19 COPD patients simultaneous SV

H J Bogaard; W B G J Hamersma; J L M I Horsch; H H Woltjer; P E Postmus; P M J M de Vries

1997-01-01

151

No difference in the hemodynamic response to Nordic pole walking vs. conventional brisk walking — A randomized exercise field test using the ultrasonic cardiac output monitor (USCOM)  

Microsoft Academic Search

IntroductionNordic pole walking (NW) has gained significant attention to increase caloric expenditure vs. conventional walking without poles. However data are pending regarding the hemodynamic response of Nordic pole walking vs. walking. We hypothesized that NW increases cardiac output stronger than conventional walking at a given perceived level of physical exertion in a field test.

Karsten Knobloch

2009-01-01

152

A comparative evaluation of thermodilution and partial CO 2 rebreathing techniques for cardiac output assessment in critically ill patients during assisted ventilation  

Microsoft Academic Search

Objective To evaluate the reliability and clinical value of partial noninvasive CO 2 (NICO 2) rebreathing technique for measuring cardiac output compared with standard thermodilution in a group of intensive care nonpostoperative patients. Design and setting Clinical investigation in a university hospital ICU. Patients Twelve mechanically ventilated patients with high ( n=6) and low ( n=6) pulmonary shunt fractions. Measurements

Monica Rocco; Gustavo Spadetta; Andrea Morelli; Donatella Dell’Utri; Patrizia Porzi; Giorgio Conti; Paolo Pietropaoli

2004-01-01

153

Mitral Doppler Indices Are Superior to Two-Dimensional Echocardiographic and Hemodynamic Variables in Predicting Responsiveness of Cardiac Output to a Rapid Intravenous Infusion of Colloid  

Microsoft Academic Search

We hypothesized that mitral flow (MF) Doppler meas- urements could be used to predict cardiac output (CO) responsiveness to fluid challenge. Fourteen patients with normal systolic and diastolic function, scheduled for coronary artery bypass graft surgery, were evalu- ated as part of a pilot study in which preload was varied immediately before the beginning of cardiopulmonary bypass. A Validation group

Robert Lattik; Pierre Couture; Michel Carrier; Jean Taillefer; Jean-Claude Tardif

2002-01-01

154

Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery  

PubMed Central

Introduction Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB). Methods Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (?CITPTD, ?CIPPnon-cal./PPcal.) were calculated to analyse directional changes. Results Before CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (?CIPPcal.) showed a correlation with changes in CITPTD (?CITPTD) only after CPB (r2 = 0.52, P = 0.005). Conclusions Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

2011-01-01

155

Defining output-based standards to achieve and maintain tuberculosis freedom in farmed deer, with reference to member states of the European Union.  

PubMed

Within the European Union (EU), detailed legislation has been developed for cattle, but not deer, to minimise disease risks associated with trade in animals and animal products. This legislation is expressed as input-based standards, providing a detailed outline of the activity required (for example, testing of animals and application of defined control measures), on the expectation that an adequate output (for example, confidence in freedom) will be achieved. Input-based standards are at odds with the increasing shift towards output-based standards, particularly in OIE rules governing international trade. In this paper, we define output-based standards to achieve and maintain freedom from tuberculosis (TB) in farmed deer, with reference to EU member states. After considering the probability of freedom achieved for cattle under existing EU legislation, we defined a 'free farmed deer holding' as one with a probability of freedom from infection of at least 99%. We then developed an epidemiological model of TB surveillance systems for deer holdings, incorporating different surveillance strategies, including combinations of diagnostic tests, and a variety of different scenarios relating to the potential for introduction of infection. A range of surveillance strategies were identified to achieve and maintain a free farmed deer holding, and worked examples are presented. The surveillance system sensitivity for varying combinations of screening and confirmatory tests in live animals, animals at slaughter and on-farm deaths is also presented. Using a single test at a single point in time, none of the TB tests routinely used in farmed deer is able to achieve an acceptable probability of TB freedom. If repeat testing were undertaken, an acceptable probability of TB freedom could be achieved, with differing combinations of the surveillance system sensitivity, frequency of testing and risk of introduction. The probability of introduction of infection through the importation of infected deer was influenced by the use of a pre-movement test (assumed 90% test sensitivity and negative test results), the TB prevalence in the source herd and the number of animals imported. A surveillance system sensitivity of at least 81% was achieved with different combinations of annual live animal surveillance and surveillance of animals at slaughter or on-farm deaths. This methodology has broad applicability and could also be extended to other diseases in both deer and other species with relevance to trade in animals and animal products. PMID:19464742

More, Simon J; Cameron, Angus R; Greiner, Matthias; Clifton-Hadley, Richard S; Rodeia, Sandra Correia; Bakker, Douwe; Salman, Mo D; Sharp, J Michael; De Massis, Fabrizio; Aranaz, Alicia; Boniotti, M Beatrice; Gaffuri, Alessandra; Have, Per; Verloo, Didier; Woodford, Michael; Wierup, Martin

2009-08-01

156

Exercise-related change in airway blood flow in humans: Relationship to changes in cardiac output and ventilation  

PubMed Central

This study examined the relationship between airway blood flow (Q?aw), ventilation (V?E) and cardiac output (Q?tot) during exercise in healthy humans (n = 12, mean age 34 ± 11 yr). Q?aw was estimated from the uptake of the soluble gas dimethyl ether while V?E and Q?tot were measured using open circuit spirometry. Measurements were made prior to and during exercise at 34 ± 5W (Load 1) and 68 ± 10 W (Load 2) and following the cessation of exercise (recovery). Q?aw increased in a stepwise fashion (P < 0.05) from rest (52.8 ± 19.5 µl min?1 ml?1) to exercise at Load 1 (67.0 ± 20.3 µl min?1 ml?1) and Load 2 (84.0 ± 22.9 µl min?1 ml?1) before returning to pre-exercise levels in recovery (51.7 ± 13.2 µl min?1 ml?1). Q?aw was positively correlated with both Q?tot (r = 0.58, P < 0.01) and V?E (r = 0.50, P < 0.01). These results demonstrate that the increase in Q?aw is linked to an exercise related increase in both Q?tot and V?E and may be necessary to prevent excessive airway cooling and drying.

Morris, Norman R.; Ceridon, Maile L.; Beck, Kenneth C.; Strom, Nicholas A.; Schneider, Donald A.; Mendes, Eliana S.; Wanner, Adam; Johnson, Bruce D.

2009-01-01

157

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.

Grollmuss, Oswin; Gonzalez, Patricia

2014-01-01

158

Use of cardiac output to improve measurement of input function in quantitative dynamic contrast-enhanced MRI  

PubMed Central

Purpose: To validate a new method for converting MR arterial signal intensity versus time curves to arterial input functions (AIF). Materials and Methods: The method constrains AIF with patient's cardiac output (Q). Monte Carlo simulations of MR renography and tumor perfusion protocols were carried out for comparison with two alternative methods: direct measurement and population-averaged input function. MR renography was performed to assess the method's inter- and intra-day reproducibility for renal parameters. Results: In simulations of tumor perfusion, the precision of the parameters (Ktrans and ve) computed using the proposed method was improved by at least a factor of three compared to direct measurement. Similar improvements were obtained in simulations of MR renography. Volunteer study for testing inter-day reproducibility confirmed the improvement of precision in renal parameters when using the proposed method, compared to conventional methods. In another patient study (two injections within one session), the proposed method significantly increased the correlation coefficient (R) between GFR of the two exams (0.92 vs. 0.83), compared to direct measurement. Conclusion: A new method significantly improves the precision of DCE parameters. The method may be especially useful for analyzing repeated DCE examinations, such as monitoring tumor therapy or ACE-inhibitor renography.

Zhang, Jeff L.; Rusinek, Henry; Bokacheva, Louisa; Chen, Qun; Storey, Pippa; Lee, Vivian S.

2009-01-01

159

Method of assessing the reproducibility of blood flow measurement: factors influencing the performance of thermodilution cardiac output computers.  

PubMed Central

Measurements of blood flow by three different makes of thermodilution cardiac output computer in an artificial circulation were analysed by linear regression against absolute flow measured by timed blood volume collection. For each computer the horizontal distance between the 95% confidence limits for a single prediction was calculated at a standard flow rate of 5 litres per minute. This measurement represents the range of flow rates that could give rise to an identical measurement and provides a summary of the reproducibility of the computer's results and its ability to detect a change of flow rate. This measurement was used to evaluate the effect on each computer's performance of pulsatile or continuous flow, injectate volume, and injectate temperature. With continuous flow the optimum results were 1.8, 0.85, and 0.85 litres per minute and with pulsatile flow they were 1.3, 1.05, and 1.65 litres per minute. There was generally a deterioration in performance when pulsatile flow was evaluated. Under the conditions of the experiment optimum performance in both flow modes was obtained with 5 ml of ice cold injectate, but these findings cannot necessarily be extrapolated to the clinical situation. With pulsatile flow the overall range of blood flows that could give rise to identical measurements were for each computer 2.0, 1.5, and 3.1 litres per minute, corresponding to 40, 30, and 62% changes of the standard flow rate of 5 litres per minute.

Mackenzie, J D; Haites, N E; Rawles, J M

1986-01-01

160

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

EPA Science Inventory

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

161

Lung diffusion capacity, oxygen uptake, cardiac output and oxygen transport during exercise before and after an himalayan expedition.  

PubMed

Studies were made of pulmonary diffusion capacity and oxygen transport before and after an expedition to altitudes at and above 4900 m. Maximum power (Pmax) and maximal oxygen uptake (VO2max) were measured in 11 mountaineers in an incremental cycle ergometer test (25W.min-1) before and after return from basecamp (30 days at 4900 m or higher). In a second test, cardiac output (Qc) and lung diffusion capacity of carbon monoxide (DL,cg) were measured by acetylene and CO rebreathing at rest and during exercise at low, medium and submaximal intensities. After acclimatization, VO2max and Pmax decreased by 5.1% [from 61.0 (SD 6.2) to 57.9 (SD 10.2) ml.kg-1, n.s.] and 9.9% [from 5.13 (SD 0.66) to 4.62 (SD 0.42) W.kg-1, n.s.], respectively. The maximal cardiac index and DL,cg decreased significantly by 15.6% [14.1 (SD 1.41) 1.min-1.m-2 to 11.9 (SD 1.44)1.min-1.m-2, P < 0.05] and 14.3% [85.9 (SD 4.36) ml.mmHg-1. min-1 to 73.6 (SD 15.2) ml.mmHg-1.min-1, P < 0.05], respectively. The expedition to high altitude led to a decrease in maximal Qc, oxygen uptake and DL,cg. A decrease in muscle mass and capillarity may have been responsible for the decrease in maximal Qc which may have resulted in a decrease of DL,cg and an increase in alveolar-arterial oxygen difference. The decrease in DL,cg especially at lower exercise intensities after the expedition may have been due to a ventilation-perfusion mismatch and changes in blood capacitance. At higher exercise intensities diffusion limitation due to reduced pulmonary capillary contact time may also have occurred. PMID:8891518

Steinacker, J M; Liu, Y; Böning, D; Halder, A; Maassen, N; Thomas, A; Stauch, M

1996-01-01

162

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.

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

2004-01-01

163

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

164

Pharmacokinetics, hemodynamic and metabolic effects of epinephrine to prevent post-operative low cardiac output syndrome in children  

PubMed Central

Introduction The response to exogenous epinephrine (Ep) is difficult to predict given the multitude of factors involved such as broad pharmacokinetic and pharmacodynamic between-subject variabilities, which may be more pronounced in children. We investigated the pharmacokinetics and pharmacodynamics of Ep, co-administered with milrinone, in children who underwent open heart surgical repair for congenital defects following cardiopulmonary bypass, including associated variability factors. Methods Thirty-nine children with a high risk of low cardiac output syndrome were prospectively enrolled. Ep pharmacokinetics, hemodynamic and metabolic effects were analyzed using the non-linear mixed effects modeling software MONOLIX. According to the final model, an Ep dosing simulation was suggested. Results Ep dosing infusions ranged from 0.01 to 0.23 ?g.kg-1.min-1 in children whose weight ranged from 2.5 to 58 kg. A one-compartment open model with linear elimination adequately described the Ep concentration-time courses. Bodyweight (BW) was the main covariate influencing clearance (CL) and endogenous Ep production rate (q0) via an allometric relationship: CL(BWi)?=??CL x (BWi)3/4 and q0(BWi)?=??q0 x (BWi )3/4. The increase in heart rate (HR) and mean arterial pressure (MAP) as a function of Ep concentration were well described using an Emax model. The effect of age was significant on HR and MAP basal level parameters. Assuming that Ep stimulated the production rate of plasma glucose, the increases in plasma glucose and lactate levels were well described by turnover models without any significant effect of age, BW or exogenous glucose supply. Conclusions According to this population analysis, the developmental effects of BW and age explained a part of the pharmacokinetic and pharmacodynamics between-subject variabilities of Ep administration in critically ill children. This approach ultimately leads to a valuable Ep dosing simulation which should help clinicians to determine an appropriate a priori dosing regimen.

2014-01-01

165

System and method for measuring cardiac output via thermal dilution using an implantable medical device with an external ultrasound power delivery system  

US Patent & Trademark Office Database

The implantable device is capable of performing thermal dilution analysis of the cardiac output of a patient using power delivered from an external source. By using power from an external source, the implantable device conserves its power resources for other purposes, such as for pacing or defibrillation therapy. In one example, an external programmer or bedside monitor provides power through a hand-held power delivery wand via electromagnetic induction, with the power routed from a subcutaneous coil to a heating element implanted in the right atrium, which heats blood as it passes through the right atrium. In another example, the heating element is formed of a material that generates heat in response to a beam of ultrasound provided by the wand. In either case, a downstream blood temperature profile is detected using a thermistor implanted in the pulmonary artery and cardiac output is then estimated by analyzing the temperature profile.

2009-12-15

166

An On-line Data Acquisition And Analysis System To Determine Cardiac Output: A One-step C02 Rebreathing Technique  

Microsoft Academic Search

This paper presents a computer-based automated data acquisition and analysis system to help determine cardiac output using a one-step CO, rebreathing technique. The one-step technique generates all the data required to solve the Fick equation for CQ by continuously monitoring expired CQ concentrations at the mouth during a 20-25 second rebreathing maneuver. Through use of digital signal processing techniques, the

D. F. Sittig; J. A. Pawelczyk

1991-01-01

167

Differences of cardiac output measurements by open-circuit acetylene uptake in pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a cohort study  

PubMed Central

Background As differences in gas exchange between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been demonstrated, we asked if cardiac output measurements determined by acetylene (C2H2) uptake significantly differed in these diseases when compared to the thermodilution technique. Method Single-breath open-circuit C2H2 uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients. Results In PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min). In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min). Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p < 0.001) and the mean arterial to end-tidal CO2 gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p < 0.001) were significantly elevated among CTEPH patients. Conclusion Cardiac output evaluation by the C2H2 technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH.

2012-01-01

168

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

169

A case of external iliac arteriovenous fistula and high-output cardiac failure after endovenous laser treatment of great saphenous vein.  

PubMed

Valvular incompetence in the great saphenous vein (GSV) is the most common cause of superficial venous insufficiency and symptomatic varicose vein development. Recently, less invasive modalities such as foam sclerotherapy, radiofrequency ablation (RFA), and endovenous laser treatment (EVLT) have gained popularity in the treatment of saphenofemoral junction and saphenous truncal incompetence over the traditional approach of surgical ligation and stripping. Here, we present the case of a 32-year-old woman who underwent EVLT and was diagnosed subsequently with ipsilateral external iliac arteriovenous (AV) fistula and high-output cardiac failure. She was stabilized medically and treated surgically with a covered stent placed in the external iliac artery with complete resolution of the fistula and cardiac failure. We reviewed the literature and discuss the complications of AV fistulae after EVLT. PMID:20100645

Ziporin, Scott J; Ifune, Catherine K; MacConmara, Malcolm P; Geraghty, Patrick J; Choi, Eric T

2010-03-01

170

Glucagon-like peptide-1 (7-36) but not (9-36) augments cardiac output during myocardial ischemia via a Frank-Starling mechanism.  

PubMed

This study examined the cardiovascular effects of GLP-1 (7-36) or (9-36) on myocardial oxygen consumption, function and systemic hemodynamics in vivo during normal perfusion and during acute, regional myocardial ischemia. Lean Ossabaw swine received systemic infusions of saline vehicle or GLP-1 (7-36 or 9-36) at 1.5, 3.0, and 10.0 pmol/kg/min in sequence for 30 min at each dose, followed by ligation of the left circumflex artery during continued infusion at 10.0 pmol/kg/min. Systemic GLP-1 (9-36) had no effect on coronary flow, blood pressure, heart rate or indices of cardiac function before or during regional myocardial ischemia. Systemic GLP-1 (7-36) exerted no cardiometabolic or hemodynamic effects prior to ischemia. During ischemia, GLP-1 (7-36) increased cardiac output by approximately 2 L/min relative to vehicle-controls (p = 0.003). This response was not diminished by treatment with the non-depolarizing ganglionic blocker hexamethonium. Left ventricular pressure-volume loops measured during steady-state conditions with graded occlusion of the inferior vena cava to assess load-independent contractility revealed that GLP-1 (7-36) produced marked increases in end-diastolic volume (74 ± 1 to 92 ± 5 ml; p = 0.03) and volume axis intercept (8 ± 2 to 26 ± 8; p = 0.05), without any change in the slope of the end-systolic pressure-volume relationship vs. vehicle during regional ischemia. GLP-1 (9-36) produced no changes in any of these parameters compared to vehicle. These findings indicate that short-term systemic treatment with GLP-1 (7-36) but not GLP-1 (9-36) significantly augments cardiac output during regional myocardial ischemia, via increases in ventricular preload without changes in cardiac inotropy. PMID:25005062

Goodwill, Adam G; Tune, Johnathan D; Noblet, Jillian N; Conteh, Abass M; Sassoon, Daniel; Casalini, Eli D; Mather, Kieren J

2014-09-01

171

Substrate stiffness-regulated matrix metalloproteinase output in myocardial cells and cardiac fibroblasts: Implications for myocardial fibrosis.  

PubMed

Cardiac fibrosis, an important pathological feature of structural remodeling, contributes to ventricular stiffness, diastolic dysfunction, arrhythmia and may even lead to sudden death. Matrix stiffness, one of the many mechanical factors acting on cells, is increasingly appreciated as an important mediator of myocardial cell behavior. Polydimethylsiloxane (PDMS) substrates were fabricated with different stiffnesses to mimic physiological and pathological heart tissues, and the way in which the elastic modulus of the substrate regulated matrix-degrading gelatinases in myocardial cells and cardiac fibroblasts was explored. Initially, an increase in cell spreading area was observed, concomitant with the increase in PDMS stiffness in both cells. Later, it was demonstrated that the MMP-2 gene expression and protein activity in myocardial cells and cardiac fibroblasts can be enhanced with an increase in PDMS substrate stiffness and, moreover, such gene- and protein-related increases had a significant linear correlation with the elastic modulus. In comparison, the MMP-9 gene and protein expressions were up-regulated in cardiac fibroblasts only, not in myocardial cells. These results implied that myocardial cells and cardiac fibroblasts in the myocardium could sense the stiffness in pathological fibrosis and showed a differential but positive response in the expression of matrix-degrading gelatinases when exposed to an increased stiffening of the matrix in the microenvironment. The phenomenon of cells sensing pathological matrix stiffness can help to increase understanding of the mechanism underlying myocardial fibrosis and may ultimately lead to planning cure strategies. PMID:24508540

Xie, Jing; Zhang, Quanyou; Zhu, Ting; Zhang, Yanyan; Liu, Bailin; Xu, Jianwen; Zhao, Hucheng

2014-06-01

172

Coconut Haustorium Maintains Cardiac Integrity and Alleviates Oxidative Stress in Rats Subjected to Isoproterenol-induced Myocardial Infarction  

PubMed Central

The present study evaluates the effect of aqueous extract of coconut haustorium on isoproterenol-induced myocardial infarction in Sprague Dawley rats. Rats were pretreated with aqueous extract of coconut haustorium (40 mg/100 g) orally for 45 days. After pretreatment, myocardial infarction was induced by injecting isoproterenol subcutaneously (20 mg/100 g body weight) twice at an interval of 24 h. Activity of marker enzymes like lactate dehydrogenase, creatinine kinase-MB, aspartate transaminase and alanine transaminase were increased in the serum and decreased in the heart of isoproterenol treated rats indicating cardiac damage. These changes were significantly reduced in haustorium pretreated rats. Moreover, an increase in the activities of antioxidant enzymes and decrease in the levels of peroxidation products were observed in the myocardium of coconut haustorium pretreated rats. Histopathology of the heart of these rats showed almost normal tissue morphology. From these results, it is clear that aqueous extract of coconut haustorium possess significant cardioprotective and antioxidant properties during isoproterenol-induced myocardial infarction in rats.

Chikku, A. M.; Rajamohan, T.

2012-01-01

173

Coconut Haustorium Maintains Cardiac Integrity and Alleviates Oxidative Stress in Rats Subjected to Isoproterenol-induced Myocardial Infarction.  

PubMed

The present study evaluates the effect of aqueous extract of coconut haustorium on isoproterenol-induced myocardial infarction in Sprague Dawley rats. Rats were pretreated with aqueous extract of coconut haustorium (40 mg/100 g) orally for 45 days. After pretreatment, myocardial infarction was induced by injecting isoproterenol subcutaneously (20 mg/100 g body weight) twice at an interval of 24 h. Activity of marker enzymes like lactate dehydrogenase, creatinine kinase-MB, aspartate transaminase and alanine transaminase were increased in the serum and decreased in the heart of isoproterenol treated rats indicating cardiac damage. These changes were significantly reduced in haustorium pretreated rats. Moreover, an increase in the activities of antioxidant enzymes and decrease in the levels of peroxidation products were observed in the myocardium of coconut haustorium pretreated rats. Histopathology of the heart of these rats showed almost normal tissue morphology. From these results, it is clear that aqueous extract of coconut haustorium possess significant cardioprotective and antioxidant properties during isoproterenol-induced myocardial infarction in rats. PMID:23716867

Chikku, A M; Rajamohan, T

2012-09-01

174

Short term correction of anaemia with recombinant human erythropoietin and reduction of cardiac output in end stage renal failure.  

PubMed Central

Children with end stage renal failure and anaemia have an increased cardiac index and often gross ventricular hypertrophy. The contribution of anaemia to these abnormalities is uncertain. Eleven children with end stage renal failure and anaemia (haemoglobin concentration < 90 g/l) were enrolled into a single blind, placebo controlled, crossover study to assess the cardiovascular effects of reversing anaemia using subcutaneous human recombinant erythropoietin (r-HuEpo). Each limb lasted 24 weeks; seven children completed both limbs of the study. Haemoglobin increased with r-HuEpo, remaining above 100 g/l for a mean of 11 weeks. Cardiac index fell as a result of a reduction in both left ventricular stroke volume and heart rate. Left ventricular end diastolic diameter also decreased. In five children left ventricular wall thickness and left ventricular mass decreased with r-HuEpo, but this failed to reach significance for the whole group. Blood pressure did not change in six normotensive children completing an r-HuEpo limb; the decrease in cardiac index was therefore balanced by an increase in peripheral vascular resistance. Three children were taking anti-hypertensive treatment at the start of the study; one required an increase, and one a decrease, in treatment during the r-HuEpo limb. Short term treatment with r-HuEpo reduces cardiac index. A longer study is needed to determine whether this will, in time, result in a significant reduction in left ventricular hypertrophy.

Morris, K P; Skinner, J R; Hunter, S; Coulthard, M G

1993-01-01

175

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

176

[The influence of LAP and cardiac output on the pulmonary gas exchange. Intraoperative studies in cardio-surgical patients (author's transl)].  

PubMed

In 21 patients haemodynamic parameters and pulmonary gas exchange were investigated after open heart surgery with cardio-pulmonary bypass (aortic valve replacement, AVR (n = 8); mitral valve replacement, MVR (n = 6); aorto coronary bypass; ACB (n = 7). For describing gas exchange function of the lung the O2-CO2 diagram was used. Stepwise increase of left atrial pressure (LAP) was followed by increasing cardiac output (CO) only in the AVR and ACB groups, whereas in the MVR group CO did not increase. Rising venous admixture (Qs/Qt) under these circumstances was related to CO only in the AVR and ACB groups. In the MVR group Qs/Qt did not change. Qs/Qt is related to low VA/Q areas in the lung. Increased CO leads to rising Qs/Qt from these low VA/Q-areas. PMID:6787948

Voigt, E; van Deyk, K; Seybold-Epting, W

1981-05-01

177

A Case of Femoral Arteriovenous Fistula Causing High-Output Cardiac Failure, Originally Misdiagnosed as Chronic Fatigue Syndrome  

PubMed Central

Percutaneous arterial catheterisation is commonly undertaken for a range of diagnostic and interventional procedures. Iatrogenic femoral arteriovenous fistulas are an uncommon complication of these procedures. Most are asymptomatic and close spontaneously, but can rarely increase in size leading to the development of symptoms. We report a case of an iatrogenic femoral arteriovenous fistula, causing worsening congestive cardiac failure, in a 34-year-old marathon runner. This was originally diagnosed as chronic fatigue syndrome. Following clinical examination, duplex ultrasound, and CT angiography a significant arteriovenous fistula was confirmed. Elective open surgery was performed, leading to a dramatic and rapid improvement in symptoms. Femoral arteriovenous fistulas have the potential to cause significant haemodynamic effects and can present many years after the initial procedure. Conservative, endovascular, and open surgical management strategies are available.

Porter, J.; Al-Jarrah, Q.; Richardson, S.

2014-01-01

178

A case of femoral arteriovenous fistula causing high-output cardiac failure, originally misdiagnosed as chronic fatigue syndrome.  

PubMed

Percutaneous arterial catheterisation is commonly undertaken for a range of diagnostic and interventional procedures. Iatrogenic femoral arteriovenous fistulas are an uncommon complication of these procedures. Most are asymptomatic and close spontaneously, but can rarely increase in size leading to the development of symptoms. We report a case of an iatrogenic femoral arteriovenous fistula, causing worsening congestive cardiac failure, in a 34-year-old marathon runner. This was originally diagnosed as chronic fatigue syndrome. Following clinical examination, duplex ultrasound, and CT angiography a significant arteriovenous fistula was confirmed. Elective open surgery was performed, leading to a dramatic and rapid improvement in symptoms. Femoral arteriovenous fistulas have the potential to cause significant haemodynamic effects and can present many years after the initial procedure. Conservative, endovascular, and open surgical management strategies are available. PMID:24959370

Porter, J; Al-Jarrah, Q; Richardson, S

2014-01-01

179

Continuous cardiac output and left atrial pressure monitoring by long time interval analysis of the pulmonary artery pressure waveform: proof of concept in dogs.  

PubMed

We developed a technique to continuously (i.e., automatically) monitor cardiac output (CO) and left atrial pressure (LAP) by mathematical analysis of the pulmonary artery pressure (PAP) waveform. The technique is unique to the few previous related techniques in that it jointly estimates the two hemodynamic variables and analyzes the PAP waveform over time scales greater than a cardiac cycle wherein wave reflections and inertial effects cease to be major factors. First, a 6-min PAP waveform segment is analyzed so as to determine the pure exponential decay and equilibrium pressure that would eventually result if cardiac activity suddenly ceased (i.e., after the confounding wave reflections and inertial effects vanish). Then, the time constant of this exponential decay is computed and assumed to be proportional to the average pulmonary arterial resistance according to a Windkessel model, while the equilibrium pressure is regarded as average LAP. Finally, average proportional CO is determined similar to invoking Ohm's law and readily calibrated with one thermodilution measurement. To evaluate the technique, we performed experiments in five dogs in which the PAP waveform and accurate, but highly invasive, aortic flow probe CO and LAP catheter measurements were simultaneously recorded during common hemodynamic interventions. Our results showed overall calibrated CO and absolute LAP root-mean-squared errors of 15.2% and 1.7 mmHg, respectively. For comparison, the root-mean-squared error of classic end-diastolic PAP estimates of LAP was 4.7 mmHg. On future successful human testing, the technique may potentially be employed for continuous hemodynamic monitoring in critically ill patients with pulmonary artery catheters. PMID:19057003

Xu, Da; Olivier, N Bari; Mukkamala, Ramakrishna

2009-02-01

180

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

181

Reproducibility of the exponential rise technique of CO 2 rebreathing for measuring P v CO 2 and C v CO 2 to non-invasively estimate cardiac output during incremental, maximal treadmill exercise  

Microsoft Academic Search

The purpose of this study was to determine the reproducibility of the indirect Fick method for the measurement of mixed venous carbon dioxide partial pressure ( P vCO 2) and venous carbon dioxide content ( C vCO 2) for estimation of cardiac output ( Q c), using the exponential rise method of carbon dioxide rebreathing, during non-steady-state treadmill exercise. Ten

W. Todd Cade; Sharmila R. Nabar; Randall E. Keyser

2004-01-01

182

Use of a capillary input function with cardiac output for the estimation of lesion pharmacokinetic parameters: preliminary results on a breast cancer patient  

NASA Astrophysics Data System (ADS)

The objective of this work was to propose and demonstrate a novel technique for the assessment of tumour pharmacokinetic parameters together with a regionally estimated vascular input function. A breast cancer patient T2*-weighted dynamic contrast enhanced MRI (DCE-MRI) dataset acquired at high temporal resolution during the first-pass bolus perfusion was used for testing the technique. Extraction of the lesion volume transfer constant Ktrans together with the intravascular plasma volume fraction vp was achieved by optimizing a capillary input function with a measure of cardiac output using the principle of intravascular indicator dilution theory. For a region of interest drawn within the breast lesion a vp of 0.16 and a Ktrans of 0.70 min-1 were estimated. Despite the value of vp being higher than expected, estimated Ktrans was in accordance with the literature values. In conclusion, the technique proposed here, has the main advantage of allowing the estimation of breast tumour pharmacokinetic parameters from first-pass perfusion T2*-weighted DCE-MRI data without the need of measuring an arterial input function. The technique may also have applicability to T1-weighted DCE-MRI data.

Di Giovanni, P.; Ahearn, T. S.; Semple, S. I.; Azlan, C. A.; Lloyd, W. K. C.; Gilbert, F. J.; Redpath, T. W.

2011-03-01

183

Direct recording of cardiac output- and venous return-curves in the dog heart-lung preparation for a graphical analysis of the effects of cardioactive drugs.  

PubMed

The dog heart-lung preparations were prepared. The "equilibrium point", which could be defined as the point at which the cardiac output (CO)-curve and the venous return (VR)-curve crossed, when the CO and VR were plotted against the right atrial pressure, was recorded directly by utilizing an X-Y recorder. The CO-curve was obtained, as a locus of the equilibrium point, by raising and lowering the level of blood in the venous reservoir (competence test). The meaning of the procedure was shown to increase or decrease the mean systemic pressure, and to cause the corresponding parallel shift in the VR-curve. The VR-curve was obtained by changing myocardial contractility. When heart failure was induced by pentobarbital or by chloroform, the equilibrium point shifted downwards to the right, depicting the VR-curve. During development of the failure, the slopes of CO-curves decreased gradually. Effects of cinobufagin and norepinephrine were also analyzed. Utilization of the X-Y recorder enabled us to settle the uniform experimental conditions more easily, and to follow the effects of drugs continuously on a diagram equating the CO- and VR-curves (Gyton's scheme). PMID:731938

Ishikawa, N; Taki, K; Hojo, Y; Hagino, Y; Shigei, T

1978-09-01

184

Effects of reduced rebreathing time, in spontaneously breathing patients, on respiratory effort and accuracy in cardiac output measurement when using a partial carbon dioxide rebreathing technique: a prospective observational study  

Microsoft Academic Search

Introduction  New technology using partial carbon dioxide rebreathing has been developed to measure cardiac output. Because rebreathing\\u000a increases respiratory effort, we investigated whether a newly developed system with 35 s rebreathing causes a lesser increase\\u000a in respiratory effort under partial ventilatory support than does the conventional system with 50 s rebreathing. We also investigated\\u000a whether the shorter rebreathing period affects the

Kazuya Tachibana; Hideaki Imanaka; Muneyuki Takeuchi; Tomoyo Nishida; Yuji Takauchi; Masaji Nishimura

2005-01-01

185

Non-invasive measurement of cardiac output by whole-body bio-impedance during dobutamine stress echocardiography: Clinical implications in patients with left ventricular dysfunction and ischaemia  

Microsoft Academic Search

Objectives: To compare non-invasive determination of cardiac index (CI) by whole body electrical bioimpedance using the NICaS apparatus and Doppler echocardiography, and the role of cardiac power index (Cpi) and total peripheral resistance index (TPRi) calculation during dobutamine stress echocardiography (DSE). Subjects and methods: We enrolled 60 consecutive patients undergoing DSE. Patients were prospectively divided into 3 groups: Group 1

Marina Leitman; Edgar Sucher; Edo Kaluski; Ruth Wolf; Eli Peleg; Yaron Moshkovitz; Olga Milo-Cotter; Zvi Vered; Gad Cotter

186

Auditory stimulation of opera music induced prolongation of murine cardiac allograft survival and maintained generation of regulatory CD4+CD25+ cells  

PubMed Central

Background Interactions between the immune response and brain functions such as olfactory, auditory, and visual sensations are likely. This study investigated the effect of sounds on alloimmune responses in a murine model of cardiac allograft transplantation. Methods Naïve CBA mice (H2k) underwent transplantation of a C57BL/6 (B6, H2b) heart and were exposed to one of three types of music--opera (La Traviata), classical (Mozart), and New Age (Enya)--or one of six different single sound frequencies, for 7 days. Additionally, we prepared two groups of CBA recipients with tympanic membrane perforation exposed to opera for 7 days and CBA recipients exposed to opera for 7 days before transplantation (pre-treatment). An adoptive transfer study was performed to determine whether regulatory cells were generated in allograft recipients. Immunohistochemical, cell-proliferation, cytokine, and flow cytometry assessments were also performed. Results CBA recipients of a B6 cardiac graft that were exposed to opera music and Mozart had significantly prolonged allograft survival (median survival times [MSTs], 26.5 and 20 days, respectively), whereas those exposed to a single sound frequency (100, 500, 1000, 5000, 10,000, or 20,000 Hz) or Enya did not (MSTs, 7.5, 8, 9, 8, 7.5, 8.5 and 11 days, respectively). Untreated, CBA mice with tympanic membrane perforations and CBA recipients exposed to opera for 7 days before transplantation (pre-treatment) rejected B6 cardiac grafts acutely (MSTs, 7, 8 and 8 days, respectively). Adoptive transfer of whole splenocytes, CD4+ cells, or CD4+CD25+ cells from opera-exposed primary allograft recipients resulted in significantly prolonged allograft survival in naive secondary recipients (MSTs, 36, 68, and > 100 days, respectively). Proliferation of splenocytes, interleukin (IL)-2 and interferon (IFN)-? production was suppressed in opera-exposed mice, and production of IL-4 and IL-10 from opera-exposed transplant recipients increased compared to that from splenocytes of untreated recipients. Flow cytometry studies showed an increased CD4+CD25+ Forkhead box P3 (Foxp3)+ cell population in splenocytes from those mice. Conclusion Our findings indicate that exposure to opera music, such as La traviata, could affect such aspects of the peripheral immune response as generation of regulatory CD4+CD25+ cells and up-regulation of anti-inflammatory cytokines, resulting in prolonged allograft survival.

2012-01-01

187

NONINVASIVE CARDIAC OUTPUT MONITORING DURING EXERCISE TESTING: NEXFIN PULSE CONTOUR ANALYSIS COMPARED TO AN INERT GAS REBREATHING METHOD AND RESPIRED GAS ANALYSIS  

Microsoft Academic Search

Purpose. Exercise testing is often used to assess cardiac function during physical exertion to obtain diagnostic information. However, this procedure is limited to measuring the electrical activity of the heart using electrocardiography and intermittent blood pressure (BP) measurements and does not involve the continuous assessment of heart functioning. In this study, we compared continuous beat-to-beat pulse contour analysis to monitor

S. A. Bartels; W. J. Stok; R. Bezemer; R. J. Boksem; J Goudoever; T. G. V. Cherpanath; Lieshout van J. J; B. E. Westerhof; J. M. Karemaker; C. Ince

2011-01-01

188

The estimation of cardiac output by the Nexfin device is of poor reliability for tracking the effects of a fluid challenge.  

PubMed

ABSTRACT: INTRODUCTION: The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CInoninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge. METHODS: We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CIinv, PiCCO device) and in CInoninv were recorded. RESULTS: In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CIinv and CInoninv was 0.2 (-1.8 to 2.2) L/min/m2. The mean change in CInoninv was 10 ± 11%. The percentage error of CInoninv was 57%. The correlation between the changes in CIinv and CInoninv observed during volume expansion was significant (P = 0.0002) with an r2 = 0.31. CONCLUSIONS: The estimation of CI by the Nexfin device in critically ill patients is not reliable, neither for estimating absolute values of CI nor for tracking its changes during volume expansion. PMID:23107227

Monnet, Xavier; Picard, Fabien; Lidzborski, Elsa; Mesnil, Malcie; Duranteau, Jacques; Richard, Christian; Teboul, Jean-Louis

2012-10-29

189

The estimation of cardiac output by the Nexfin device is of poor reliability for tracking the effects of a fluid challenge  

PubMed Central

Introduction The Nexfin device estimates arterial pressure by the volume clamp method through a finger pneumatic cuff. It also allows to estimate cardiac index (CInoninv) by pulse contour analysis of the non-invasive arterial pressure curve. We evaluated the ability of the device to track changes in cardiac index induced by a fluid challenge. Methods We included 45 patients for whom a volume expansion (500 mL of saline infused over 30 min) was planned. The volume expansion-induced changes in cardiac index measured by transpulmonary thermodilution (CIinv, PiCCO device) and in CInoninv were recorded. Results In seven patients, the Nexfin could not record the arterial curve due to finger hypoperfusion. Considering both the values obtained before and after volume expansion (n = 76 pairs of measurements), the bias (lower and upper limits of agreement) between CIinv and CInoninv was 0.2 (-1.8 to 2.2) L/min/m2. The mean change in CInoninv was 10 ± 11%. The percentage error of CInoninv was 57%. The correlation between the changes in CIinv and CInoninv observed during volume expansion was significant (P = 0.0002) with an r2 = 0.31. Conclusions The estimation of CI by the Nexfin device in critically ill patients is not reliable, neither for estimating absolute values of CI nor for tracking its changes during volume expansion.

2012-01-01

190

Development of a Pacemaker Monitor with Cardiac Simulator.  

National Technical Information Service (NTIS)

A cardiac pacemaker monitoring system was developed for use in testing cardiac pacemakers in RF fields. The system provided for both continuous monitoring of the pacemaker output and simulating normal cardiac activity at the pacemaker leads. Fiber optics ...

T. O. Steiner

1975-01-01

191

Exceptional cardiac anoxia tolerance in tilapia (Oreochromis hybrid).  

PubMed

Anoxic survival requires the matching of cardiac ATP supply (i.e. maximum glycolytic potential, MGP) and demand (i.e. cardiac power output, PO). We examined the idea that the previously observed in vivo downregulation of cardiac function during exposure to severe hypoxia in tilapia (Oreochromis hybrid) represents a physiological strategy to reduce routine PO to within the heart's MGP. The MGP of the ectothermic vertebrate heart has previously been suggested to be ?70 nmol ATP s(-1) g(-1), sustaining a PO of ?0.7 mW g(-1) at 15°C. We developed an in situ perfused heart preparation for tilapia (Oreochromis hybrid) and characterized the routine and maximum cardiac performance under both normoxic (>20 kPa O(2)) and severely hypoxic perfusion conditions (<0.20 kPa O(2)) at pH 7.75 and 22°C. The additive effects of acidosis (pH 7.25) and chemical anoxia (1 mmol l(-1) NaCN) on cardiac performance in severe hypoxia were also examined. Under normoxic conditions, cardiac performance and myocardial oxygen consumption rate were comparable to those of other teleosts. The tilapia heart maintained a routine normoxic cardiac output (Q) and PO under all hypoxic conditions, a result that contrasts with the hypoxic cardiac downregulation previously observed in vivo under less severe conditions. Thus, we conclude that the in vivo downregulation of routine cardiac performance in hypoxia is not needed in tilapia to balance cardiac energy supply and demand. Indeed, the MGP of the tilapia heart proved to be quite exceptional. Measurements of myocardial lactate efflux during severe hypoxia were used to calculate the MGP of the tilapia heart. The MGP was estimated to be 172 nmol ATP s(-1) g(-1) at 22°C, and allowed the heart to generate a PO(max) of at least ?3.1 mW g(-1), which is only 30% lower than the PO(max) observed with normoxia. Even with this MGP, the additional challenge of acidosis during severe hypoxia decreased maximum ATP turnover rate and PO(max) by 30% compared with severe hypoxia alone, suggesting that there are probably direct effects of acidosis on cardiac contractility. We conclude that the high maximum glycolytic ATP turnover rate and levels of PO, which exceed those measured in other ectothermic vertebrate hearts, probably convey a previously unreported anoxia tolerance of the tilapia heart, but a tolerance that may be tempered in vivo by the accumulation of acidotic waste during anoxia. PMID:22442374

Lague, Sabine L; Speers-Roesch, Ben; Richards, Jeffrey G; Farrell, Anthony P

2012-04-15

192

Devices used in cardiac arrest.  

PubMed

Even the best conventional manual cardiopulmonary resuscitation (CPR) is highly inefficient, producing only a fraction of normal cardiac output. Over the past several decades, many therapeutic devices have been designed to improve on conventional CPR during cardiac arrest and increase the probability of survival. This article reviews several adjuncts and mechanical alternatives to conventional CPR for use during cardiac arrest. Recent clinical studies comparing conventional resuscitation techniques with the use of devices during cardiac arrest are reviewed, with a focus on clinical implications and directions for future research. PMID:22107983

Brooks, Steven C; Toma, Alina; Hsu, Jonathan

2012-02-01

193

FoxO, Autophagy, and Cardiac Remodeling  

PubMed Central

In response to changes in workload, the heart grows or shrinks. Indeed, the myocardium is capable of robust and rapid structural remodeling. In the setting of normal, physiological demand, the heart responds with hypertrophic growth of individual cardiac myocytes, a process that serves to maintain cardiac output and minimize wall stress. However, disease-related stresses, such as hypertension or myocardial infarction, provoke a series of changes that culminate in heart failure and/or sudden death. At the other end of the spectrum, cardiac unloading, such as occurs with prolonged bed rest or weightlessness, causes the heart to shrink. In recent years, considerable strides have been made in deciphering the molecular and cellular events governing pro- and anti-growth events in the heart. Prominent among these mechanisms are those mediated by FoxO (Forkhead box-containing protein, O subfamily) transcription factors. In many cell types, these proteins are critical regulators of cell size, viability, and metabolism, and their importance in the heart is just emerging. Also in recent years, evidence has emerged for a pivotal role for autophagy, an evolutionarily conserved pathway of lysosomal degradation of damaged proteins and organelles, in cardiac growth and remodeling. Indeed, evidence for activated autophagy has been detected in virtually every form of myocardial disease. Now, it is clear that FoxO is an upstream regulator of both autophagy and the ubiquitin-proteasome system. Here, we discuss recent advances in our understanding of cardiomyocyte autophagy, its governance by FoxO, and the roles each of these plays in cardiac remodeling.

Ferdous, Anwarul; Battiprolu, Pavan K.; Ni, Yan G.; Rothermel, Beverly A.

2010-01-01

194

FoxO, autophagy, and cardiac remodeling.  

PubMed

In response to changes in workload, the heart grows or shrinks. Indeed, the myocardium is capable of robust and rapid structural remodeling. In the setting of normal, physiological demand, the heart responds with hypertrophic growth of individual cardiac myocytes, a process that serves to maintain cardiac output and minimize wall stress. However, disease-related stresses, such as hypertension or myocardial infarction, provoke a series of changes that culminate in heart failure and/or sudden death. At the other end of the spectrum, cardiac unloading, such as occurs with prolonged bed rest or weightlessness, causes the heart to shrink. In recent years, considerable strides have been made in deciphering the molecular and cellular events governing pro- and anti-growth events in the heart. Prominent among these mechanisms are those mediated by FoxO (Forkhead box-containing protein, O subfamily) transcription factors. In many cell types, these proteins are critical regulators of cell size, viability, and metabolism, and their importance in the heart is just emerging. Also in recent years, evidence has emerged for a pivotal role for autophagy, an evolutionarily conserved pathway of lysosomal degradation of damaged proteins and organelles, in cardiac growth and remodeling. Indeed, evidence for activated autophagy has been detected in virtually every form of myocardial disease. Now, it is clear that FoxO is an upstream regulator of both autophagy and the ubiquitin-proteasome system. Here, we discuss recent advances in our understanding of cardiomyocyte autophagy, its governance by FoxO, and the roles each of these plays in cardiac remodeling. PMID:20577843

Ferdous, Anwarul; Battiprolu, Pavan K; Ni, Yan G; Rothermel, Beverly A; Hill, Joseph A

2010-08-01

195

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

196

Design for the Maintainer.  

National Technical Information Service (NTIS)

This report documents a project to study design-for-the- maintainer (DFM) issues relative to the maintenance of Navy aircraft. One task of the project was to identify design features influencing maintenance effectiveness. Toward this end, a new analytical...

F. Fuchs K. Inaba

1981-01-01

197

Cardiac Effect of Thyrotoxicosis in Acromegaly  

Microsoft Academic Search

Cardiac structure and function are affected both by acromegaly and hyperthyroidism. Whereas the former is mainly characterized by ven- tricular hypertrophy as well as diastolic and systolic impairment, the latter frequently leads to increased heart rate and enhancement of contractility and cardiac output. To further investigate this issue, we designed this two-arm study. In the first cross-sectional study, we compared

PAOLO MARZULLO; ALBERTO CUOCOLO; DIEGO FERONE; ROSARIO PIVONELLO; MARCO SALVATORE; GAETANO LOMBARDI; ANNAMARIA COLAO

198

Urine output - decreased  

MedlinePLUS

Decreased urine output means that you produce less than 500 milliliters of urine in 24 hours. ... A large decrease in urine output may be a sign of a serious, or even life-threatening, condition. However, urine output can usually be restored ...

199

Use of Negative Extrathoracic Pressure to Improve Hemodynamics After Cardiac Surgery  

Microsoft Academic Search

Background. Little attention is given to the mode of mechanical ventilation after cardiac surgery. Positive pressure ventilation with positive end-expiratory pres- sure (PEEP) has been shown to reduce cardiac output. We hypothesized that positive pressure ventilation with continual negative pressure applied to the chest through a cuirass would increase cardiac output in coronary artery bypass graft patients immediately after surgery.

Rakesh K. Chaturvedi; Arnold A. Zidulka; Peter Goldberg; Sameena Iqbal; Elham Rahme; Kevin Lachapelle

200

Maintaining DACUM Quality.  

ERIC Educational Resources Information Center

This document discusses the importance of maintaining the quality of DACUM (Developing a Curriculum) occupational analyses and presents a 2-page checklist detailing DACUM quality performance criteria. The introduction to the checklist discusses various "infractions" discovered during an analyses of some curriculum/program developers' attempts to…

Norton, Robert E.

201

Reagan: Maintain Antarctic program  

Microsoft Academic Search

President Ronald Reagan has decided that the United States should maintain an `active and influential presence' in Antarctica to support the nation's interests. Following a review of a study by the Antarctica Policy Group, Reagan issued a memorandum, dated February 5, to the heads of 14 government agencies, including the National Science Foundation (NSF), the Office of Science and Technology

Barbara T. Richman

1982-01-01

202

Maintaining the corporate memory  

Microsoft Academic Search

A well known fact is that corporations don’t have memories. This is because the majority of the knowledge is maintained in the employees’ heads and when they leave that knowledge walks out with them. This continues to be the bane of process safety as errors get perpetuated and incidents repeated. A system can be created, though, to form and keep a

Jack Chosnek

2010-01-01

203

Acoustic Levitator Maintains Resonance  

NASA Technical Reports Server (NTRS)

Transducer loading characteristics allow resonance tracked at high temperature. Acoustic-levitation chamber length automatically adjusted to maintain resonance at constant acoustic frequency as temperature changes. Developed for containerless processing of materials at high temperatures, system does not rely on microphones as resonance sensors, since microphones are difficult to fabricate for use at temperatures above 500 degrees C. Instead, system uses acoustic transducer itself as sensor.

Barmatz, M. B.; Gaspar, M. S.

1986-01-01

204

Maintaining radiation protection records  

SciTech Connect

This Report is part of a series prepared under the auspices of Scientific Committee 46 on Operational Radiation Safety. It provides guidance on maintaining radiation protection records. Record keeping is an essential element of every radiation protection program. This Report describes the elements that should enter into the design of a program for the maintenance of operational radiation safety records. The problems of the length of time for retention of records for operational, regulatory, epidemiologic and legal uses are discussed in detail.

Not Available

1992-11-30

205

About Cardiac Arrest  

MedlinePLUS

... High Blood Pressure Tools & Resources Stroke More About Cardiac Arrest Updated:Nov 25,2013 What is cardiac arrest? ... content was last reviewed on 02/26/2013. Cardiac Arrest • Home • About Cardiac Arrest • Warning Signs for Cardiac ...

206

Maintainability Applications Using the Matrix FMEA Technique  

Microsoft Academic Search

The Matrix Method of Failure Modes and Effects Analysis (FMEA) provides an organized and traceable analysis from the piece-part failure-mode through all indenture levels to system-level failure effects. This paper describes a methodology for reversing the buildup process for maintainability analysis. The output of this reverse process identifies each system-failure effect individually and the related indentured, lower-level composition of contributing

Stephanie A. Herrin

1981-01-01

207

Responses of Atlantic Salmon Parr to Output of Pulsed Ultrasonic Transmitters  

Microsoft Academic Search

The output from some pulsed ultrasonic transmitters commonly used in fish movement studies is faintly audible to humans. This study was undertaken to determine if the output from these and some other transmitters is detectable by Atlantic salmon (Salmo salar) parr. Classical conditioning of cardiac deceleration was attempted using the transmitter's output as the conditioned stimulus. The results from 29

DOUGLAS E. FACEY; JAMES D. MCCLEAVE; GLEN E. DOYON

1977-01-01

208

[High-output congestive heart failure due to congenital iliac arteriovenous fistula].  

PubMed

A 54-year-old man was admitted to hospital because of chronic right-sided heart failure. Echocardiography revealed dilatation of all chambers of the heart. Cardiac catheterization showed high-output heart failure due to left-to-right shunt caused by a congenital fistula between the right iliac artery and vein. The fistula was closed by percutaneous implantation of a covered stent. 15 months later, the patient denied any cardiac complaint. On echocardiography, the size of all chambers had almost normalized, cardiac catheterization proved a normal cardiac output. By angiography and oximetry, neither a residual nor a relapsing shunt were seen. PMID:17149681

Götze, Christine J; Secknus, Maria A; Strauss, Hans J; Lauer, Bernward; Ohlow, Marc A

2006-11-01

209

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

210

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.

211

Cardiac Ochronosis  

PubMed Central

We report the case of 67-year-old woman who underwent aortic valve replacement and mitral valve repair due to ochronotic valvular disease (alkaptonuria), which was diagnosed incidentally during cardiac surgery.

Erek, Ersin; Casselman, Filip P.A.; Vanermen, Hugo

2004-01-01

212

Cardiac catheterization  

MedlinePLUS

... amyloidosis Causes of congestive heart failure or cardiomyopathy Coronary artery disease Heart defects that are present at birth ( ... include: Cardiac tamponade Heart attack Injury to a coronary artery Irregular heartbeat Low blood pressure Reaction to the ...

213

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 ...

214

Cardiac MRI  

MedlinePLUS

... from the NHLBI on Twitter. What Is Cardiac MRI? Magnetic resonance imaging (MRI) is a safe, noninvasive test that creates detailed ... and no instruments are inserted into your body. MRI uses radio waves, magnets, and a computer to ...

215

Cardiac Angiosarcoma  

PubMed Central

Despite cardiac metastases are found in about 20% of cancer deaths, the presence of primary cardiac tumors is rare. Most primary tumors are benign, and malignant tumors comprise about 15%. We report a 21-year-old man with fever, dyspnea, and hemoptysis that was diagnosed with angiosarcoma of the right atrium and pulmonary metastasis. Patient was submitted to surgical tumor resection without adjuvant therapy and died four months after diagnosis.

Cardoso, Monique Esteves; Canale, Leonardo Secchin; Ramos, Rosana Grandelle; Salvador Junior, Edson da Silva; Lachtermacher, Stephan

2011-01-01

216

Input-Output Experiment.  

National Technical Information Service (NTIS)

The objective of the suggested Input-Output experiment was to determine the feasibility of using auroral phenomena to simulate the ionizing effects produced by high-altitude nuclear detonations. Present objectives are focused primarily on the measurement ...

R. E. Meyerott

1964-01-01

217

Maintaining proper dental records.  

PubMed

Referred to as Standard of Care, the legal duty of a dentist requires exercising the degree of skill and care that would be exhibited by other prudent dentists faced with the same patient-care situation. Primarily, the goal of keeping good dental records is to maintain continuity of care. Diligent and complete documentation and charting procedures are essential to fulfilling the Standard of Care. Secondly, because dental records are considered legal documents they help protect the interest of the dentist and/or the patient by establishing the details of the services rendered. Patients today are better educated and more assertive than ever before and dentists must be equipped to protect themselves against malpractice claims. Every record component must be handled as if it could be summoned to a court room and scrutinized by an attorney, judge or jury. Complete, accurate, objective and honest entries in a patient record are the only way to defend against any clinical and/or legal problems that might arise. Most medical and dental malpractice claims arise from an unfavorable interaction with the dentist and not from a poor treatment outcome. By implementing the suggestions mentioned in this course, dental health care professionals can minimize the legal risks associated with the delivery of dental care to promote greater understanding for patients of their rights and privileges to their complete record. PMID:24834675

Leeuw, Wilhemina

2014-01-01

218

ADAS Update and Maintainability  

NASA Technical Reports Server (NTRS)

Since 2000, both the National Weather Service Melbourne (NWS MLB) and the Spaceflight Meteorology Group (SMG) have used a local data integration system (LOIS) as part of their forecast and warning operations. The original LOIS was developed by the Applied Meteorology Unit (AMU) in 1998 (Manobianco and Case 1998) and has undergone subsequent improvements. Each has benefited from three-dimensional (3-D) analyses that are delivered to forecasters every 15 minutes across the peninsula of Florida. The intent is to generate products that enhance short-range weather forecasts issued in support of NWS MLB and SMG operational requirements within East Central Florida. The current LDIS uses the Advanced Regional Prediction System (ARPS) Data Analysis System (AD AS) package as its core, which integrates a wide variety of national, regional, and local observational data sets. It assimilates all available real-time data within its domain and is run at a finer spatial and temporal resolution than current national or regional-scale analysis packages. As such, it provides local forecasters with a more comprehensive understanding of evolving fine-scale weather features. Over the years, the LDIS has become problematic to maintain since it depends on AMU-developed shell scripts that were written for an earlier version of the ADAS software. The goals of this task were to update the NWS MLB/SMG LDIS with the latest version of ADAS, incorporate new sources of observational data, and upgrade and modify the AMU-developed shell scripts written to govern the system. In addition, the previously developed ADAS graphical user interface (GUI) was updated. Operationally, these upgrades will result in more accurate depictions of the current local environment to help with short-range weather forecasting applications, while also offering an improved initialization for local versions of the Weather Research and Forecasting (WRF) model used by both groups.

Watson, Leela R.

2010-01-01

219

The Canadian Society of Cardiac Surgeons perspective on the cardiac surgery workforce in Canada.  

PubMed

As the professional society representing cardiac surgeons in Canada, the Canadian Society of Cardiac Surgeons (CSCS) recognizes the importance of maintaining a stable cardiac surgical workforce. The current reactive approach to health human resource management in cardiac surgery is inadequate and may result in significant misalignment of cardiac surgeon supply and demand. The availability of forecasting models and high quality, consistent data on productivity, workload, utilization, and demand is a prerequisite for our profession's capacity to predict and plan for changes in health human resources. The CSCS recognizes that improved workforce management is a key component to providing optimal cardiac surgical care for Canadians in the future and has developed the recommendations in this document as a call to action to interested stakeholders and policymakers to bring substantial improvements to health human resource management in cardiac surgery. PMID:22906803

Feindel, Christopher M; Ouzounian, Maral; Latham, Timothy B; Hendry, Paul; Langlois, Yves; Peniston, Charles; Hassan, Ansar; Macarthur, Roderick; Scully, Hugh; Hirsch, Gregory M

2012-01-01

220

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.

2013-01-01

221

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

222

Cardiac sarcoidosis.  

PubMed

Cardiac sarcoidosis (CS) is a rare and under-recognized clinical entity that requires a high level of suspicion and low threshold for screening in order to make the diagnosis. CS may manifest in a variety of ways, and its initial presentation can range from asymptomatic electrocardiographic abnormalities to overt heart failure to sudden cardiac death. The aim of this literature review is to provide a comprehensive overview of CS, with an emphasis on clinical manifestations and special diagnostic and management considerations, while highlighting recent studies that have provided new insights into this unique disease. PMID:24969032

Zipse, Matthew M; Sauer, William H

2014-08-01

223

Pituitary Adenylate Cyclase-Activating Polypeptide Expression and Modulation of Neuronal Excitability in Guinea Pig Cardiac Ganglia  

Microsoft Academic Search

Cardiac output is regulated by the coordinate interactions of stimulatory sympathetic and inhibitory parasympathetic sig- nals. Intracardiac parasympathetic ganglia are integrative cen- ters of cardiac regulation, and modulation of the parasympa- thetic drive on the heart is accomplished by altering intrinsic cardiac ganglion neuron excitability. The pituitary adenylate cyclase-activating polypeptide (PACAP)\\/vasoactive intestinal peptide (VIP) family of peptides modulates cardiac function,

Karen M. Braas; Victor May; Susan A. Harakall; Jean C. Hardwick; Rodney L. Parsons

1998-01-01

224

Adult respiratory distress syndrome after cardiac surgery.  

PubMed

Adult respiratory distress syndrome, characterized by high permeability pulmonary oedema caused by endothelial cell damage, resulting in refractory hypoxemia, has a very high mortality. Cardiopulmonary bypass is said to be responsible for the development of adult respiratory distress syndrome after cardiac surgery. The present study was performed in order to identify predicting and aetiological factors of adult respiratory distress syndrome and multiple organ failure after cardiac surgery. Between January 1984 and December 1993, 3848 patients underwent cardiac surgery with cardiopulmonary bypass in the authors' institution, and were analysed in a retrospective manner. The operations performed were 3444 coronary artery bypass grafts (CABG), 267 valve and 137 combined (CABG + valve) procedures. The incidence of adult respiratory distress syndrome was 1.0% (38 of 3848) with an overall mortality rate of 68.4% (26 patients); 24 of these died from multiple organ failure. Multivariate regression analysis identified hypertension, current smoking, emergency surgery, preoperative New York Heart Association (NYHA) class 3 and 4, low postoperative cardiac output and left ventricular ejection fraction < 40% as significant, independent predictors for adult respiratory distress syndrome. Combined cardiac surgery and diffuse coronary disease were also significant predictors; cardiopulmonary bypass time was not. Thirty-six of the 38 patients that later developed adult respiratory distress syndrome had low postoperative cardiac output, 12 requiring intra-aortic balloon pump support. The remaining two had severe hypotension caused by postoperative bleeding. Twenty-six adult respiratory two had severe hypotension caused by postoperative bleeding. Twenty-six adult respiratory distress syndrome patients (68%) had confirmed gastrointestinal complication (e.g. intestinal ischaemia). Adult respiratory distress syndrome is a rare complication after cardiac surgery but is associated with a very high mortality. Preoperative predictors were identified. Cardiopulmonary bypass alone was not found to be an important factor. Postoperative low cardiac output leading to splanchnic hypoperfusion may be the most important single factor in developing adult respiratory distress syndrome after cardiac surgery. PMID:8634840

Christenson, J T; Aeberhard, J M; Badel, P; Pepcak, F; Maurice, J; Simonet, F; Velebit, V; Schmuziger, M

1996-02-01

225

Engine Maintainability: Objectives and Methods.  

National Technical Information Service (NTIS)

Major considerations used to improve engine maintainability are identified. The basis for maintainability features are a lot of requirements. These requirements are defined by the customer and created using several analyses. Criteria for good maintainabil...

A. Senft

1989-01-01

226

High-output heart failure secondary to arteriovenous fistula.  

PubMed

In the hemodialysis patient population, a surgically created arteriovenous fistula is the preferred vascular access option. Development of high-output heart failure may be an underappreciated complication in patients who have undergone this procedure. When a large proportion of arterial blood is shunted from the left-sided circulation to the right-sided circulation via the fistula, the increase in preload can lead to increased cardiac output. Over time, the demands of an increased workload may lead to cardiac hypertrophy and eventual heart failure. Patients may present with the usual signs of high-output heart failure including tachycardia, elevated pulse pressure, hyperkinetic precordium, and jugular venous distension. Typically, the AV fistula is quite large and is likely located in the upper arm, more proximal to the heart. Routine access flow monitoring should demonstrate blood flows (Qa) >2000?ML/min. Echocardiogram may reveal either a low or high left ventricular ejection fraction, and right-heart catheterization demonstrates an elevated cardiac output with a low to normal systemic vascular resistance. When addressing the problem of high-output heart failure, the nephrologist is faced with the dilemma of preventing progression of heart failure at the expense of loss of vascular access. Nevertheless, treatment should be directed at correcting the underlying problem by surgical banding or ligation of the fistula. PMID:21223485

Stern, Adam B; Klemmer, Philip J

2011-01-12

227

Cardiac Output, Rates of Change and Accumulation: Unit Overview  

NSDL National Science Digital Library

Created by Illuminations: Resources for Teaching Mathematics, this unit plan contains four lessons that explore rates of change and accumulation in the context of the amount of blood being pumped by the heart. The measurement is done from a discrete perspective, but can be easily generalized to a continuous perspective that includes use of integral calculus. The individual lessons are titled: make a conjecture, gather data, analyze the data and reflecting on your work. The author states the goal of this lesson as: "[The] rich exploration of rates of change and accumulation in context."

2009-02-23

228

Linear output nitinol engine  

Microsoft Academic Search

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

1986-01-01

229

Comparison of Diagnostic Criteria for Acute Kidney Injury in Cardiac Surgery  

PubMed Central

Background There is considerable controversy regarding the diagnosis of Acute Kidney Injury (AKI), and there are over 30 different definitions. Objective To evaluate the incidence and risk factors for the development of AKI following cardiac surgery according to the RIFLE, AKIN and KDIGO criteria, and compare the prognostic power of these criteria. Methods Cross-sectional study that included 321 consecutive patients (median age 62 [53-71] years; 140 men) undergoing cardiac surgery between June 2011 and January 2012. The patients were followed for up to 30 days, for a composite outcome (mortality, need for dialysis and extended hospitalization). Results The incidence of AKI ranged from 15% - 51%, accordingly to the diagnostic criterion adopted. While age was associated with risk of AKI in the three criteria, there were variations in the remaining risk factors. During follow-up, 89 patients developed the outcome and all criteria were associated with increased risk in the univariate Cox analysis and after adjustment for age, gender, diabetes, and type of surgery. However, after further adjustment for extracorporeal circulation and the presence of low cardiac output, only AKI diagnosed by the KDIGO criterion maintained this significant association (HR= 1.89 [95% CI: 1.18 - 3.06]). Conclusion The incidence and risk factors for AKI after cardiac surgery vary significantly according to the diagnostic criteria used. In our analysis, the KDIGO criterion was superior to AKIN and RIFLE with regard its prognostic power.

Sampaio, Marcio Campos; Maximo, Carlos Alberto Goncalves; Montenegro, Carolina Moreira; Mota, Diandro Marinho; Fernandes, Tatiana Rocha; Bianco, Antonio Carlos Mugayar; Amodeo, Celso; Cordeiro, Antonio Carlos

2013-01-01

230

Monitoring cardiac output in beating heart coronary artery bypass graft surgery: use of pulse contour cardiac output  

Microsoft Academic Search

60% of which involved members of staff. The mean number of ‘normal’ events remembered in the ICU was significantly higher in group D (P < 0.001). Sepsis and midazolam usage were more common in group D (odds ratios 3.6, 95% confidence interval 1.7?7.3 for sepsis; odds ratio 2.9, 95% confidence interval 1.3?6.2 for midazolam). The development of new neurological signs

TML Chan; R Bhagrath; EMC Ashley

2001-01-01

231

Working Group Report Extracorporeal circulation in non-cardiac surgery  

Microsoft Academic Search

Summary Tradition and experience of cardiopulmonary bypass in the hand of cardiac surgeons led to several spin-offs of this extracorporeal technique. Acute organ support is realized for situations of failing cardiac output, circulatory arrest respectively, of pulmonary failure and of drowning. Extracorporeal circulation is a promising adjunct to aim in better surgical technique and treatment in neurosurgery, thoracic aortic surgery,

Dietrich E. Birnbaum

232

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

PubMed

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

Nelson, O Lynne; Rourke, Bryan C

2013-12-15

233

Cardiac fibroblast in development and wound healing.  

PubMed

Cardiac fibroblasts are the most abundant cell type in the mammalian heart and comprise approximately two-thirds of the total number of cardiac cell types. During development, epicardial cells undergo epithelial-mesenchymal-transition to generate cardiac fibroblasts that subsequently migrate into the developing myocardium to become resident cardiac fibroblasts. Fibroblasts form a structural scaffold for the attachment of cardiac cell types during development, express growth factors and cytokines and regulate proliferation of embryonic cardiomyocytes. In post natal life, cardiac fibroblasts play a critical role in orchestrating an injury response. Fibroblast activation and proliferation early after cardiac injury are critical for maintaining cardiac integrity and function, while the persistence of fibroblasts long after injury leads to chronic scarring and adverse ventricular remodeling. In this review, we discuss the physiologic function of the fibroblast during cardiac development and wound healing, molecular mediators of activation that could be possible targets for drug development for fibrosis and finally the use of reprogramming technologies for reversing scar. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium." PMID:24625635

Deb, Arjun; Ubil, Eric

2014-05-01

234

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.

2013-01-01

235

Cardiac optogenetics.  

PubMed

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

Entcheva, Emilia

2013-05-01

236

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

237

Warning Signs for Cardiac Arrest  

MedlinePLUS

... Pressure Tools & Resources Stroke More Warning Signs for Cardiac Arrest Updated:Oct 5,2011 Cardiac arrest strikes immediately ... content was last reviewed on 07/12/2011." Cardiac Arrest • Home • About Cardiac Arrest • Warning Signs for Cardiac ...

238

Using a human cardiovascular-respiratory model to characterize cardiac tamponade and pulsus paradoxus  

Microsoft Academic Search

BACKGROUND: Cardiac tamponade is a condition whereby fluid accumulation in the pericardial sac surrounding the heart causes elevation and equilibration of pericardial and cardiac chamber pressures, reduced cardiac output, changes in hemodynamics, partial chamber collapse, pulsus paradoxus, and arterio-venous acid-base disparity. Our large-scale model of the human cardiovascular-respiratory system (H-CRS) is employed to study mechanisms underlying cardiac tamponade and pulsus

Deepa Ramachandran; Chuan Luo; Tony S Ma; John W Clark Jr

2009-01-01

239

Fluxgate: tuned vs. untuned output  

Microsoft Academic Search

Fluxgate voltage output contains information about the measured DC magnetic field in amplitude of even harmonic components. Tuning the sensor output causes the concentration of output energy to specific harmonics (usually 2f) and parametric amplification. A short-circuited output current fluxgate cannot be tuned, but it in principle requires less turns of the pick-up coil. The noise measurements performed on amorphous

P. Ripka; S. W. Billingsley

1998-01-01

240

Tips to Maintain Good Posture  

MedlinePLUS

Tips to Maintain Good Posture We often hear that good posture is essential for good health. We recognize poor posture when we see ... real grasp of the importance and necessity of good posture. Why is good posture important? Good posture ...

241

Verification of Quantitative Maintainability Requirements.  

National Technical Information Service (NTIS)

This document develops basic concepts for treating Maintainability quantitatively, with particular attention devoted to probabilistic aspects. It focuses on the special characteristics of the Lognormal Distribution as they relate to specifying and demonst...

G. Grippo R. M. DeMilia

1965-01-01

242

Effect on the cardiac function of repeated LBNP during a 1-month head down tilt  

NASA Astrophysics Data System (ADS)

Cardiovascular assessment by ultrasound methods was performed during two long duration (1 month) Head Down Tilt (HDT) on 6 healthy volunteers. On a first 1 month HDT session, 3 of the 6 subjects (A, B, C) had daily several lower body negative pressure tests (LBNP), whereas the 3 subjects remaining (D, E, F) rested without LBNP. On a second 1 month HDT session subjects D, E, and F had daily LBNP tests and the A, B and C subjects did not. The cardiac function was assessed by Echocardiography (B mode, TM mode). On all the "6 non LBNP" subjects the left ventricule diastolic volume (LVDV), the stroke volume (SV) and the cardiac output (CO) increase (+10%, -15%) after HDT then decrease and remain inferior (-5%, -5%) or equal to the basal value during the HDT. Immediately after the end of the HDT the heart rate (HR) increase (+10%, +30%) whereas the cardiac parameters decrease weakly (-5%, -10%) and normalize after 3 days of recovery. On the "6 LBNP" subjects the LVDV, SV and CO increase (+10%, +15%) after 1 h HDT as in the previous group then decrease but remain superior (+5%, +15%) or equal to the basal value. After the HDT session, the HR is markedly increased (+20%, +40%) the LVDV and SV decrease (-15%, -20%) whereas the CO increases or decreases depending on the amplitude of the HR variations. These parameters do not completely normalize after 3 days recovery. Repeated LBNP sessions have a significant effect on the cardiovascular function as it maintains all cardiac parameters above the basal value. The LBNP manoeuvre can be considered as an efficient countermeasure to prevent cardiac disadaptation induced by HDT position and probably microgravity.

Arbeille, Ph.; Lebouard, D.; Massabuau, M.; Pottier, J. M.; Patat, F.; Pourcelot, L.; Guell, A.

243

ARTIST tape output formats  

NASA Astrophysics Data System (ADS)

The format of the ARTIST data and raw data records written to magnetic tape are described. The contents of each record type are fully explained making possible an unpacking of the data for subsequent analysis. A new generation of modern ionosondes is now being deployed world wide. These are the University of Lowell Center for Atmospheric Research (ULCAR) Digisonde 256 and AN/FMQ-12 DISS systems. The Digisonde 256 network will provide a consistent data set of ionospheric parameters that are automatically scaled in real time. The automated stations output the standard ionospheric parameters, the h'N(f) traces with amplitudes and Doppler frequencies, and the electron density profiles. There are currently 32 systems in operation or are close to being installed. The global station distribution is very uneven, the majority of sites lying in the northern hemisphere, and there are no equatorial stations. Nevertheless this network provides an extensive data base of ionospheric parameters in digital form, making it easy to process and analyze the data in terms of average diurnal variations, storms, and irregularities. This data base will be invaluable for the testing of global ionosphere models.

Tang, Jane; Dozois, Claude G.; Gamache, Robert R.

1990-07-01

244

NEOHFOOD: A Northeast Ohio Food Industries Input-Output Model  

Microsoft Academic Search

NEOHFOOD, an acronym for Northeast Ohio food, is a sophisticated input-output model. The model is designed specifically to capture the inter-dependencies and linkages among various sectors and industries composing the complex economy of Ohio. The input-output model of Ohio's economy also maintains substantial detail on the food and agricultural sectors. The interindustry model describes the linkages among various sectors of

Thomas L. Sporleder

245

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.

Zeisberg, Elisabeth M.; Kalluri, Raghu

2011-01-01

246

Effects of perhexiline-induced fuel switch on the cardiac proteome and metabolome  

PubMed Central

Perhexiline is a potent anti-anginal drug used for treatment of refractory angina and other forms of heart disease. It provides an oxygen sparing effect in the myocardium by creating a switch from fatty acid to glucose metabolism through partial inhibition of carnitine palmitoyltransferase 1 and 2. However, the precise molecular mechanisms underlying the cardioprotective effects elicited by perhexiline are not fully understood. The present study employed a combined proteomics, metabolomics and computational approach to characterise changes in murine hearts upon treatment with perhexiline. According to results based on difference in-gel electrophoresis, the most profound change in the cardiac proteome related to the activation of the pyruvate dehydrogenase complex. Metabolomic analysis by high-resolution nuclear magnetic resonance spectroscopy showed lower levels of total creatine and taurine in hearts of perhexiline-treated mice. Creatine and taurine levels were also significantly correlated in a cross-correlation analysis of all metabolites. Computational modelling suggested that far from inducing a simple shift from fatty acid to glucose oxidation, perhexiline may cause complex rebalancing of carbon and nucleotide phosphate fluxes, fuelled by increased lactate and amino acid uptake, to increase metabolic flexibility and to maintain cardiac output. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism".

Yin, Xiaoke; Dwyer, Joseph; Langley, Sarah R.; Mayr, Ursula; Xing, Qiuru; Drozdov, Ignat; Nabeebaccus, Adam; Shah, Ajay M.; Madhu, Basetti; Griffiths, John; Edwards, Lindsay M.; Mayr, Manuel

2013-01-01

247

Extracellular Matrix Roles During Cardiac Repair  

PubMed Central

The cardiac extracellular matrix (ECM) provides a platform for cells to maintain structure and function, which in turn maintains tissue function. In response to injury, the ECM undergoes remodeling that involves synthesis, incorporation, and degradation of matrix proteins, with the net outcome determined by the balance of these processes. The major goals of this review are a) to serve as an initial resource for students and investigators new to the cardiac ECM remodeling field, and b) to highlight a few of the key exciting avenues and methodologies that have recently been explored. While we focus on cardiac injury and responses of the left ventricle (LV), the mechanisms reviewed here have pathways in common with other wound healing models.

Jourdan-LeSaux, Claude; Zhang, Jianhua; Lindsey, Merry L.

2010-01-01

248

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

249

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.

250

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

251

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

252

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.

Sommer, Joachim R.; Johnson, Edward A.

1968-01-01

253

Dynamically Maintaining the Visibility Graph  

Microsoft Academic Search

An algorithm is presented to maintain the visibility graph of a set of N line segments in the plane in O(log2N+K log N) time, where K is the total number of arcs of the visibility graph that are destroyed or created upon insertion or deletion of a line segment. The line segments should be disjoint, except possibly at their end-points.

Gert Vegter

1991-01-01

254

Green world maintained by adaptation  

Microsoft Academic Search

An ecological theory (HSS hypothesis) predicts that carnivores maintain the terrestrial ecosystem with abundant plants (green\\u000a world) by regulating herbivore abundance. However, a weak density dependence of herbivores will make the equilibrium unstable\\u000a and results in population oscillations with a large amplitude. Here, we study a possibility that the dynamics can be stabilized\\u000a if defence trait by herbivores and offence

Akihiko Mougi; Yoh Iwasa

2011-01-01

255

NMG documentation, part 3: maintainer`s guide  

SciTech Connect

This is the third of a three-part report documenting NMG, the Numerical Mathematics Guide. Part I is aimed at the user of the systenL It contains an introduction, with an out- line of the complete report, and Chapter 1, User`s Point of View. Part II is aimed at the programmer and contains Chapter 2, How It Works. Part III is aimed at the maintainer of NMG and contains Chapter 3, Maintenance, and Chapter 4, Validation. Because its contents are so specialized, Part III will receive only limited distribution. Note that each chapter has its own page numbering and table of contents.

Fritsch, F.N.; Dickinson, R.P. Jr.

1996-07-01

256

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

257

Enhanced performance CCD output amplifier  

DOEpatents

A low-noise FET amplifier is connected to amplify output charge from a che coupled device (CCD). The FET has its gate connected to the CCD in common source configuration for receiving the output charge signal from the CCD and output an intermediate signal at a drain of the FET. An intermediate amplifier is connected to the drain of the FET for receiving the intermediate signal and outputting a low-noise signal functionally related to the output charge signal from the CCD. The amplifier is preferably connected as a virtual ground to the FET drain. The inherent shunt capacitance of the FET is selected to be at least equal to the sum of the remaining capacitances.

Dunham, Mark E. (Los Alamos, NM); Morley, David W. (Santa Fe, NM)

1996-01-01

258

Biphasic intra-thoracic pressure regulation augments cardiac index during porcine peritonitis: a feasibility study.  

PubMed

Preservation of cardiac output (CO) and pulmonary artery pressure (PAP) is vital to maintaining tissue oxygenation in sepsis. This feasibility study tested the hypothesis that therapeutic intra-thoracic pressure regulation (tIPR), delivered with a novel device, was designed to non-invasively enhance venous return by creating sub-atmospheric intra-thoracic pressure during the expiratory phase of mechanical ventilation, improves CO without fluid resuscitation in a porcine E. coli peritonitis model of sepsis. Seven pigs were intubated, anaesthetized and instrumented with a Swan-Ganz and femoral artery catheter. After a 30?min basal period, a fibrin clot containing 4-5?×?10(9) cfu kg(-1) E. coli O111.B4 was implanted in the peritoneum. One hour after clot implantation, tIPR was utilized for 30?min and then removed from the ventilator circuit for 30?min. This tIPR cycle was repeated 4-times. Changes in haemodynamic parameters were calculated by comparing pre-tIPR values to peak values during tIPR administration. Following peritonitis, tIPR significantly increased the peak cardiac index (mean?±?SEM) (14.8?±?2.6 vs 7.9?±?2.3?ml kg(-1)) and mean arterial pressure (10.2?±?1.5 vs 4.9?±?1.1?mmHg) and simultaneously decreased PAP (-7.7?±?1.5 vs -2.7?±?0.8?mmHg). These results support the feasibility of the concept that therapeutic application of negative expiratory pressure may provide a non-invasive and complementary approach to increase cardiac output and organ perfusion in the setting of septic shock. PMID:24328993

Cinel, Ismail; Goldfarb, Roy D; Metzger, Anja; Lurie, Keith; Jasti, Purnachandra; Knob, Christopher R; Parrillo, Joseph E; Phillip Dellinger, R

2014-01-01

259

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

260

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

261

Cardiac Risk Assessment  

MedlinePLUS

... website will be limited. Search Help? Cardiac Risk Assessment Share this page: Was this page helpful? Formal ... Questions | Related Pages What is a cardiac risk assessment? This is a group of tests and health ...

262

Automatic Contour Propagation in Cine Cardiac Magnetic Resonance Images  

Microsoft Academic Search

We have developed a method for automatic contour propagation in cine cardiac magnetic resonance images. The method consists of a new active contour model that tries to maintain a constant contour environment by matching gray values in profiles perpendicular to the contour. Consequently, the contours should maintain a constant position with respect to neighboring anatomical structures, such that the resulting

Gilion Hautvast; Steven Lobregt; Marcel Breeuwer; Frans A. Gerritsen

2006-01-01

263

Cardiac Function and Iron Chelation in Thalassemia Major and Intermedia: a Review of the Underlying Pathophysiology and Approach to Chelation Management  

PubMed Central

Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia. The two main factors that determine cardiac disease in homozygous ? thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload. The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype. Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function. For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy. Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients. If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted. In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available. With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with increasing the transfusions as need, it is hoped that the incidence of cardiac dysfunction in these syndromes will be markedly reduced. This of course depends very much on the attention to detail with the monitoring and the cooperation of the patient with both the recommended investigations and the prescribed chelation.

Aessopos, Athanasios; Berdoukas, Vasilios

2009-01-01

264

Change of cardiac function, but not form, in postprandial pythons  

Microsoft Academic Search

Pythons are renowned for a rapid and pronounced postprandial growth of the heart that coincides with a several-fold elevation of cardiac output that lasts for several days. Here we investigate whether ventricular morphology is affected by digestive state in two species of pythons (Python regius and Python molurus) and we determine the cardiac right-to-left shunt during the postprandial period in

Bjarke Jensen; Casper Kornbech Larsen; Jan Møller Nielsen; Lasse Stærdal Simonsen; Tobias Wang

2011-01-01

265

Role of breathing in cardiac performance: experimental and mathematical models  

Microsoft Academic Search

Due to the close proximity of the heart and lungs within a closed chest environment, we expect breathing to affect various cardiac performance parameters and hence cardiac output. We present an integrative approach to study heart-lung interactions, combining a mathematical formulation of the circulation system with imaging techniques using echo-planar magnetic resonance imaging (EPI) and dynamic x-ray CT (EBCT). We

Binh Q. Tran; Eric A. Hoffman

1999-01-01

266

PLAID as a maintainability tool  

NASA Technical Reports Server (NTRS)

PLAID is a computer-aided design tool for human factors engineering which has been used successfully in the Space Shuttle program and for design analysis of Space Station Freedom. PLAID capability includes analysis of visual fields of view, of the ability to reach a specified point, and of spatial conflicts. It enables the creation of animations which depict whole sequences of motions of astronauts and equipment. The PLAID graphics capability is described and its application to man-systems integration is briefly examined. The use of PLAID for maintainability is addressed, and future plans for PLAID are discussed.

Woolford, Barbara J.; Orr, Linda S.; Mount, Frances E.

1989-01-01

267

Cardiac sodium channelopathies  

Microsoft Academic Search

Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward\\u000a depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies,\\u000a i.e., arrhythmogenic diseases in patients with mutations in SCN5A,

Ahmad S. Amin; Alaleh Asghari-Roodsari; Hanno L. Tan

2010-01-01

268

Adult cardiac anaesthesia.  

PubMed

The widespread increase in adult cardiac surgery over the last decade has meant that many more junior anaesthetists have become involved in the management of anaesthesia for cardiac surgery before they have taken the final part of the FRCA examination. Although cardiac anaesthesia is still a specialized area, FRCA candidates are expected to have a working knowledge of the principles involved. PMID:8826042

Freeman, J M; Clutton-Brock, T H

269

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

270

Reducing Spurious Output Of NCO's  

NASA Technical Reports Server (NTRS)

Spurious frequency components in output of numerically controlled oscillator (NCO) reduced by dithering appropriate digital signals with small random noise signal prior to truncation. Enables reduction of word length without increasing spurious signal power.

Zimmerman, George A.; Flanagan, Michael J.

1994-01-01

271

Measuring Air-Ionizer Output  

NASA Technical Reports Server (NTRS)

Test apparatus checks ion content of airstream from commercial air ionizer. Apparatus ensures ion output is sufficient to neutralize static charges in electronic assembly areas and concentrations of positive and negative ions are balanced.

Lonborg, J. O.

1985-01-01

272

Model Output Statistics Forecast Guidance.  

National Technical Information Service (NTIS)

This publication describes data in the National Weather Services's Model Output Statistics Final Forecast Guidance teletype bulletins. It is intended to serve as a comprehensive guide to the interpretation and use of the forecast bulletins by AWS forecast...

H. Hughes

1976-01-01

273

Igniter and actuator output testing  

SciTech Connect

Closed system mechanical work output measurements were made for five types of thermal battery igniters and one type of valve actuator. Each unit was fired into a high-precision fit piston/cylinder arrangement, and the work output was determined from measuring the rise of a known weight. The results showed that work output for an individual igniter type varied over a considerable range while the mean work output values of the various igniter types appeared to depend principally on the type of closure disc and the details of the charge mix. The large variability in igniter output was the principal inducement to build a second apparatus, with approximately 10 times the capacity of the first, to investigate the output actuators. Compared with igniters, the actuator work output was appropriately in scale, but the variability was considerably reduced (R=1.5), and was attributed to increase in scale. Motion picture photography at 8000 to 9000 frames per second was used to determine the motion of the rising weight and the associated output pressure, which exhibited three distinct phases. Initially, the average acceleration of the weight was of the order of 100 g during the first half-millisecond of weight rise and corresponded to average pressures of 15,000 to 37,000 psi, depending principally on the mass of the weight. This was followed by a significant weight rise at a constant pressure of approximately 150 to 450 psi. Finally, the weight decelerated to rest under gravity to reach the maximum recorded height. 2 refs., 9 figs., 2 tabs.

Evans, N.A.

1988-01-01

274

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

275

Maintaining consistency in distributed systems  

NASA Technical Reports Server (NTRS)

In systems designed as assemblies of independently developed components, concurrent access to data or data structures normally arises within individual programs, and is controlled using mutual exclusion constructs, such as semaphores and monitors. Where data is persistent and/or sets of operation are related to one another, transactions or linearizability may be more appropriate. Systems that incorporate cooperative styles of distributed execution often replicate or distribute data within groups of components. In these cases, group oriented consistency properties must be maintained, and tools based on the virtual synchrony execution model greatly simplify the task confronting an application developer. All three styles of distributed computing are likely to be seen in future systems - often, within the same application. This leads us to propose an integrated approach that permits applications that use virtual synchrony with concurrent objects that respect a linearizability constraint, and vice versa. Transactional subsystems are treated as a special case of linearizability.

Birman, Kenneth P.

1991-01-01

276

Cardiac Effects of Persistent Hemodialysis Arteriovenous Access in Recipients of Renal Allograft  

Microsoft Academic Search

In hemodialysis patients, large arteriovenous (AV) fistulas for vascular access may cause ventricular hypertrophy and high-output cardiac failure. The long-term cardiac consequences of functional AV fistulas in renal transplant patients are unclear. A precise knowledge of these consequences is important to decide if and when such fistulas should be closed in successfully transplanted patients. In this retrospective study including 61

José Jayme G. De Lima; Marcelo Luis Campos Vieira; Laszlo J. Molnar; Caio Jorge Medeiros; Luís Estevan Ianhez; Eduardo M. Krieger

1999-01-01

277

Bench-to-bedside review: Inotropic drug therapy after adult cardiac surgery – a systematic literature review  

Microsoft Academic Search

Many adult patients require temporary inotropic support after cardiac surgery. We reviewed the literature systematically to establish, present and classify the evidence regarding choice of inotropic drugs. The available evidence, while limited in quality and scope, supports the following observations; although all ?-agonists can increase cardiac output, the best studied ?-agonist and the one with the most favourable side-effect profile

Michael Gillies; Rinaldo Bellomo; Laurie Doolan; Brian Buxton

2005-01-01

278

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) ...

279

Neuroadaptive output feedback control for automated anesthesia with noisy EEG measurements  

Microsoft Academic Search

Critical care patients, whether undergoing surgery or recovering in intensive care units, require drug administration to regulate physiological variables such as blood pressure, cardiac output, heart rate, and degree of consciousness. The rate of infusion of each administered drug is critical, requiring constant monitoring and frequent adjustments. Nonnegative and compartmental models provide a broad framework for biological and physiological systems,

Wassim M. Haddad; Konstantin Y. Volyanskyy; James M. Bailey

2008-01-01

280

Neuroadaptive Output Feedback Control for Automated Anesthesia With Noisy EEG Measurements  

Microsoft Academic Search

Critical care patients, whether undergoing surgery or recovering in intensive care units, require drug administration to regulate physiological variables such as blood pressure, cardiac output, heart rate, and degree of consciousness. The rate of infu- sion of each administered drug is critical, requiring constant moni- toring and frequent adjustments. Nonnegativeand compartmental modelsprovideabroadframeworkforbiologicalandphysiological systems, including clinical pharmacology, and are well suited

Wassim M. Haddad; Kostyantyn Y. Volyanskyy; James M. Bailey; Jeong Joon Im

2011-01-01

281

Bioreactor maintained living skin matrix.  

PubMed

Numerous reconstructive procedures result in wounds that require skin grafting. Often, the amount of tissue available from donor sites is limited. In vivo tissue expanders have been used clinically to generate larger sections of skin, and other methods exist to cover large wounds, but all have significant limitations. We investigated whether these difficulties could be overcome by increasing the surface area of skin in vitro while maintaining tissue viability. Human foreskin was incrementally expanded in a computer-controlled bioreactor system over 6 days to increase its surface dimensions under culture conditions. Morphological, ultrastructural, and mechanical properties of the foreskin were evaluated before and after expansion using histology, scanning electron microscopy, mercury porosimetry, and tensile testing. The surface area of the tissue was 110.7% +/- 12.2% greater, with maintenance of cell viability and proliferative potential. Histomorphological and ultrastructural analyses showed that dermal structural integrity was preserved. The pore diameter of the expanded skin was 64.49% +/- 32.8% greater. The mechanical properties were not adversely affected. These findings show that expansion of living skin matrices can be achieved using a computer-controlled bioreactor system. This technique provides an opportunity to generate large amounts of skin for reconstructive procedures. PMID:18821843

Ladd, Mitchell R; Lee, Sang Jin; Atala, Anthony; Yoo, James J

2009-04-01

282

Remotely maintained waste transfer pump  

SciTech Connect

Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

Eargle, J.C.

1990-01-01

283

Remotely maintained waste transfer pump  

SciTech Connect

Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

Eargle, J.C.

1990-12-31

284

Physiologic control of cardiac assist devices.  

PubMed

Total artificial hearts (TAHs) and biventricular assist devices (BVADs) have varying levels of acceptance and reliability, and the research on both focuses on their control mechanisms. Efforts generally aim to achieve a response to physiologic demand and left/right output balance, and beneficial cardiac output (CO) and effective control mechanisms have been achieved by eliciting a Starting-like response to preload and afterload. Such control mechanisms, however, generally base device output on a single parameter, such as the preload on the heart. Current TAHs and BVADs provide relatively fixed oxygen delivery to patients with large physiologically induced variations in oxygen consumption. This paper aims to document fluctuations in oxygen consumption that are normal in BVAD and TAH patients, identify a number of patient-generated signals that reflect these fluctuations, and describe a multitiered control algorithm based upon these signals. Such a control system may offer better response times and more physiologic cardiac outputs. There currently exists a microprocessor-based control mechanism that can be adapted to control TAHs and BVADs using input from a variety of sensors, and it can be found in modern implantable pulse generators (IPGs). Today's pacemakers are capable of rate control and can run diagnostic programs and store data that could be valuable in the evaluation of the patient's condition. PMID:8694700

Hall, A W; Soykan, O; Harken, A H

1996-03-01

285

Output saturation in fiber lasers  

SciTech Connect

An analytical theory is developed for a four-level cw fiber laser which accounts for saturation of the output due to bleaching of the pump transition. A simple closed form expression is obtained which relates the pump power and output power. Output saturation is most important for systems having at least one long lived excited state other than the upper laser level. The model is used to optimize the fiber length, core radius, and mirror reflectivities for an Er{sup 3+} doped fluorozirconate fiber laser operating at 2.7 {mu}m. The optimized efficiency is found to be independent of pump power. Maximum efficiencies of 9.8 and 12.9% are calculated for fibers with attenuation coefficients of 100 and 10 dB/km, respectively. Key words: Fiber lasers, optimization, saturation.

Quimby, R.S. (Worcester Polytechnic Institute, Physics Department, Worcester, Massachusetts 01609-2280 (USA))

1990-03-20

286

Salacia oblonga root improves cardiac lipid metabolism in Zucker diabetic fatty rats: Modulation of cardiac PPAR-?-mediated transcription of fatty acid metabolic genes  

Microsoft Academic Search

Excess cardiac triglyceride accumulation in diabetes and obesity induces lipotoxicity, which predisposes the myocytes to death. On the other hand, increased cardiac fatty acid (FA) oxidation plays a role in the development of myocardial dysfunction in diabetes. PPAR-? plays an important role in maintaining homeostasis of lipid metabolism. We have previously demonstrated that the extract from Salacia oblonga root (SOE),

Tom Hsun-Wei Huang; Qinglin Yang; Masaki Harada; Jasna Uberai; Jane Radford; George Q. Li; Johji Yamahara; Basil D. Roufogalis; Yuhao Li

2006-01-01

287

Genetic Alterations That Inhibit In Vivo Pressure-Overload Hypertrophy Prevent Cardiac Dysfunction Despite Increased Wall Stress  

Microsoft Academic Search

Background—A long-standing hypothesis has been that hypertrophy is compensatory and by normalizing wall stress acts to maintain normal cardiac function. Epidemiological data, however, have shown that cardiac hypertrophy is associated with increased mortality, thus casting doubt on the validity of this hypothesis. Methods and Results—To determine whether cardiac hypertrophy is necessary to preserve cardiac function, we used 2 genetically altered

Giovanni Esposito; Antonio Rapacciuolo; Sathyamangla V. Naga Prasad; Hideyuki Takaoka; Steven A. Thomas; Walter J. Koch; Howard A. Rockman

288

Cardiac sodium channelopathies.  

PubMed

Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (INa) during phase 0 of the cardiac action potential. The importance of INa for normal cardiac electrical activity is reflected by the high incidence of arrhythmias in cardiac sodium channelopathies, i.e., arrhythmogenic diseases in patients with mutations in SCN5A, the gene responsible for the pore-forming ion-conducting alpha-subunit, or in genes that encode the ancillary beta-subunits or regulatory proteins of the cardiac sodium channel. While clinical and genetic studies have laid the foundation for our understanding of cardiac sodium channelopathies by establishing links between arrhythmogenic diseases and mutations in genes that encode various subunits of the cardiac sodium channel, biophysical studies (particularly in heterologous expression systems and transgenic mouse models) have provided insights into the mechanisms by which INa dysfunction causes disease in such channelopathies. It is now recognized that mutations that increase INa delay cardiac repolarization, prolong action potential duration, and cause long QT syndrome, while mutations that reduce INa decrease cardiac excitability, reduce electrical conduction velocity, and induce Brugada syndrome, progressive cardiac conduction disease, sick sinus syndrome, or combinations thereof. Recently, mutation-induced INa dysfunction was also linked to dilated cardiomyopathy, atrial fibrillation, and sudden infant death syndrome. This review describes the structure and function of the cardiac sodium channel and its various subunits, summarizes major cardiac sodium channelopathies and the current knowledge concerning their genetic background and underlying molecular mechanisms, and discusses recent advances in the discovery of mutation-specific therapies in the management of these channelopathies. PMID:20091048

Amin, Ahmad S; Asghari-Roodsari, Alaleh; Tan, Hanno L

2010-07-01

289

Asphyxial Cardiac Arrest  

Microsoft Academic Search

Sudden cardiac arrest is a significant source of morbidity and mortality, with neurological injury affecting the majority\\u000a of persons who initially have restoration of pulses. The rat asphyxial cardiac arrest is an established model for neurological\\u000a injury after cardiac arrest. This model reproduces many aspects of neurological injury observed in humans — transient coma,\\u000a evolving motor deficits and persistent sensorimotor

Clifton W. Callaway; Eric S. Logue

290

Hypocalcaemic cardiac failure.  

PubMed Central

A 35-year-old patient who presented with recurrent chest infection, pulmonary oedema and cardiac failure was found to be grossly hypocalcaemic owing to previously undiagnosed hypoparathyroidism. The cardiac failure was not easily relieved by digoxin and diuretics but it quickly responded when the plasma calcium was restored to normal with dihydrotachysterol. With dihydrotachysterol as sole treatment for more than 2.5 years he had normal exercise tolerance and no features of cardiac failure. Images Fig. 1

Brenton, D. P.; Gonzales, J.; Pollard, A. B.

1978-01-01

291

Maintaining quality in blood banking.  

PubMed

Regulation of transfusion or blood banking facilities has followed, rather than preceded the regulation of the pharmaceutical industry and today we find, in Europe and the United States, the basic regulations developed for the pharmaceutical industry being extended to blood transfusion centres (BTC)*. In this article we explore the role of voluntary accreditation or registration to quality systems standards such as ISO 9000 and discuss how these can be used to advantage and how these standards can provide a substantial base for meeting legislative requirements. In the UK there is also a voluntary accreditation procedure available for all clinical laboratories, known as Clinical Pathology Accreditation (CPA). Comparisons between ISO 9000, CPA and other standards are made. We also discuss how voluntary registration, particularly to ISO 9000 can provide an excellent basis for moving into more extensive and progressive Total Quality Management (TQM) programmes which in turn bring a variety of benefits, not least of which is increased staff involvement in your organisation. Experience of the route to quality through voluntary accreditation suggests that external assessment delivers new insights into the organisation that cannot easily be supplanted by internal audit. In Europe legislation relating to pharmaceuticals has steadily increased in scope and in detailed requirements from those set out in the 1965 Directive 65/65/EEC. The legislative framework has steadily increased, bringing plasma and plasma products as well as others such as radiopharmaceuticals, into the product licensing requirements. The progression of legislation seems unlikely to cease and it is debatable how long the Medicines Control Agency (MCA) and its Inspectorate will accept that BTCs can operate at a level which is different from that of the majority of pharmaceutical manufacturers. The change in emphasis in legislation particularly in Europe means that harm that is caused to a patient by a blood component will warrant redress. The degree of fault attributed to the producer will in part depend on whether they have met the best available standards at all stages in the preparation of the product. If a Transfusion Service can show that it's operation has external accreditation, particularly to an internationally recognised standard such as ISO 9000 and they can show that staff have been properly trained, that equipment is properly supplied and maintained and that the facility is appropriate to the work being carried out, then the liability that exists when something goes wrong will be reduced.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7795421

Harvey, E; Hewison, C; Nevalainen, D E; Lloyd, H L

1995-03-01

292

Experimental Control of Cardiac Muscle Alternans  

NASA Astrophysics Data System (ADS)

We demonstrate that alternans in small pieces of in vitro paced bullfrog (Rana Catesbeiana) myocardium can be suppressed by making minute adjustments to the pacing period in response to real time measurements of the action potential duration. Control is possible over a large range of physiological conditions over many animals and the self-referencing control protocol can automatically adjust to changes in the pacing interval. Our results suggest the feasibility of developing low-energy methods for maintaining normal cardiac function.

Hall, G. Martin; Gauthier, Daniel J.

2002-05-01

293

Hippo pathway effector Yap promotes cardiac regeneration.  

PubMed

The adult mammalian heart has limited potential for regeneration. Thus, after injury, cardiomyocytes are permanently lost, and contractility is diminished. In contrast, the neonatal heart can regenerate owing to sustained cardiomyocyte proliferation. Identification of critical regulators of cardiomyocyte proliferation and quiescence represents an important step toward potential regenerative therapies. Yes-associated protein (Yap), a transcriptional cofactor in the Hippo signaling pathway, promotes proliferation of embryonic cardiomyocytes by activating the insulin-like growth factor and Wnt signaling pathways. Here we report that mice bearing mutant alleles of Yap and its paralog WW domain containing transcription regulator 1 (Taz) exhibit gene dosage-dependent cardiac phenotypes, suggesting redundant roles of these Hippo pathway effectors in establishing proper myocyte number and maintaining cardiac function. Cardiac-specific deletion of Yap impedes neonatal heart regeneration, resulting in a default fibrotic response. Conversely, forced expression of a constitutively active form of Yap in the adult heart stimulates cardiac regeneration and improves contractility after myocardial infarction. The regenerative activity of Yap is correlated with its activation of embryonic and proliferative gene programs in cardiomyocytes. These findings identify Yap as an important regulator of cardiac regeneration and provide an experimental entry point to enhance this process. PMID:23918388

Xin, Mei; Kim, Yuri; Sutherland, Lillian B; Murakami, Masao; Qi, Xiaoxia; McAnally, John; Porrello, Enzo R; Mahmoud, Ahmed I; Tan, Wei; Shelton, John M; Richardson, James A; Sadek, Hesham A; Bassel-Duby, Rhonda; Olson, Eric N

2013-08-20

294

PGC-1 coactivators in cardiac development and disease  

PubMed Central

The beating heart requires a constant flux of ATP to maintain contractile function, and there is increasing evidence that energetic defects contribute to the development of heart failure. The last ten years have seen a resurgent interest in cardiac intermediary metabolism, and a dramatic increase in our understanding of transcriptional networks that regulate cardiac energetics. The PPAR-gamma coactivator (PGC)-1 family of proteins plays a central role in these pathways. The mechanisms by which PGC-1 proteins regulate transcriptional networks and are regulated by physiological cues, and the roles they play in cardiac development and disease, are reviewed here.

Rowe, Glenn C.; Jiang, Aihua; Arany, Zolt

2010-01-01

295

Output Interference in Recognition Memory  

ERIC Educational Resources Information Center

Dennis and Humphreys (2001) proposed that interference in recognition memory arises solely from the prior contexts of the test word: Interference does not arise from memory traces of other words (from events prior to the study list or on the study list, and regardless of similarity to the test item). We evaluate this model using output

Criss, Amy H.; Malmberg, Kenneth J.; Shiffrin, Richard M.

2011-01-01

296

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

297

Tuned current-output fluxgate  

Microsoft Academic Search

The current-output fluxgate may be tuned by using a serial capacitor. Such tuning increases the sensor sensitivity in the situation when the pick-up coil has a low number of turns. We achieved a signal\\/feedthrough ratio improvement by a factor of 5. The measured parameters fit the simplified theoretical model within 20% deviation.

Pavel Ripka; Fritz Primdahl

2000-01-01

298

Output regulation of nonlinear systems  

Microsoft Academic Search

The problem of controlling a fixed nonlinear plant in order to have its output track (or reject) a family of reference (or disturbance) signal produced by some external generator is discussed. It is shown that, under standard assumptions, this problem is solvable if and only if a certain nonlinear partial differential equation is solvable. Once a solution of this equation

A. Isidori; C. I. Byrnes

1990-01-01

299

Publication output of European physics  

Microsoft Academic Search

More recently, samples have been drawn from Physics Abstrscts to reveal publication output in the Netherlands, Belgium, Denmark, Sweden and Canada \\/6,7\\/, Spain \\/8\\/ and Czechoslovakia \\/3\\/. Seversl ~inds of trends and proportions have been computed for the journals participating in the Euro- physics scheme \\/5\\/ and for citation analyses of world and European physics journals \\/9\\/. Physics Abstracts also

Jan Vlachý

1979-01-01

300

Compact Circuit Preprocesses Accelerometer Output  

NASA Technical Reports Server (NTRS)

Compact electronic circuit transfers dc power to, and preprocesses ac output of, accelerometer and associated preamplifier. Incorporated into accelerometer case during initial fabrication or retrofit onto commercial accelerometer. Made of commercial integrated circuits and other conventional components; made smaller by use of micrologic and surface-mount technology.

Bozeman, Richard J., Jr.

1993-01-01

301

A Portable Miniature Transistorized Radio-Frequency Coupled Cardiac Pacemaker  

Microsoft Academic Search

A miniature, transistorized radio-frequency-coupled cardiac pacemaker was developed to eliminate wires penetrating the skin when electrodes are placed on the heart to drive it. The design also eliminates the need for totally implanting a pacemaker with its batteries. The stimulating impulse is transmitted via amplitude modulation to a tuned circuit and detector assembly implanted below the skin. The output of

D. M. Hickman; L. A. Geddes; H. E. Hoff; M. Hinds; A. G. Moore; C. K. Francis; T. Engen

1961-01-01

302

Liver abnormalities in cardiac diseases and heart failure.  

PubMed

Heart failure (HF) is characterized by the inability of systemic perfusion to meet the body's metabolic demands and is usually caused by cardiac pump dysfunction and may occasionally present with symptoms of a noncardiac disorder such as hepatic dysfunction. The primary pathophysiology involved in hepatic dysfunction from HF is either passive congestion from increased filling pressures or low cardiac output and the consequences of impaired perfusion. Passive hepatic congestion due to increased central venous pressure may cause elevations of liver enzymes and both direct and indirect serum bilirubin. Impaired perfusion from decreased cardiac output may be associated with acute hepatocellular necrosis with marked elevations in serum aminotransferases. Cardiogenic ischemic hepatitis ("shock liver") may ensue following an episode of profound hypotension in patients with acute HF. We discuss pathophysiology and identification of liver abnormalities that are commonly seen in patients with HF. PMID:22942628

Alvarez, Alicia M; Mukherjee, Debabrata

2011-09-01

303

MRI of pediatric cardiac masses.  

PubMed

OBJECTIVE. The purpose of this article is to describe the characteristic cardiac MRI features of primary and secondary cardiac tumors, including differentiation from masslike lesions, such as thrombus or focal myocardial hypertrophy. CONCLUSION. The frequency and type of cardiac tumors in children differ from those in adults. Although transthoracic echocardiography is the initial imaging technique of choice for evaluation of cardiac tumors, cardiac MRI is an important complementary modality for characterization of the mass and effect on cardiac function. PMID:24758649

Mahani, Maryam Ghadimi; Lu, Jimmy C; Rigsby, Cynthia K; Krishnamurthy, Rajesh; Dorfman, Adam L; Agarwal, Prachi P

2014-05-01

304

Studies on Feedback Control of Cardiac Alternans  

PubMed Central

A beat-to-beat variation in the electric wave propagation morphology in myocardium is referred to as cardiac alternans and it has been linked to the onset of life threatening arrhythmias and sudden cardiac death. Experimental studies have demonstrated that alternans can be annihilated by the feedback modulation of the basic pacing interval in a small piece of cardiac tissue. In this work, we study the capability of feedback control to suppress alternans both spatially and temporally in an extracted rabbit heart and in a cable of cardiac cells. This work demonstrates real-time control of cardiac alternans in an extracted rabbit heart and provides an analysis of the control methodology applied in the case of a one-dimensional (1D) cable of cardiac cells. The real-time system control is realized through feedback by proportional perturbation of the basic pacing cycle length (PCL). The measurements of the electric wave propagation are obtained by optical mapping of fluorescent dye from the surface of the heart and are fed into a custom-designed software that provides the control action signal that perturbs the basic pacing cycle length. In addition, a novel pacing protocol that avoids conduction block is applied. A numerical analysis, complementary to the experimental study is also carried out, by the ionic model of a 1D cable of cardiac cells under a self-referencing feedback protocol, which is identical to the one applied in the experimental study. Further, the amplitude of alternans linear parabolic PDE that is associated with the 1D ionic cardiac cell cable model under full state feedback control is analyzed. We provide an analysis of the amplitude of alternans parabolic PDE which admits a standard evolutionary form in a well defined functional space. Standard modal decomposition techniques are used in the analysis and the controller synthesis is carried out through pole-placement. State and output feedback controller realizations are developed and the important issue of measurement noise in the controller implementation is addressed. The analysis of stabilization of the amplitude of alternans PDE is in agreement with the experimental results and numerical results produced by the ionic 1D cable of cardiac cells model. Finally, a discussion is provided in light of these results in order to use control to suppress alternans in the human myocardium.

Dubljevic, Stevan; Lin, Shien-Fong; Christofides, Panagiotis

2011-01-01

305

Space Maintainers for Premature Tooth Loss  

MedlinePLUS

... in the child's mouth. This is called a fixed space maintainer. There are several types of fixed space maintainers. What type is used will depend ... made by a dentist or orthodontist. For a fixed space maintainer, a metal band is placed around ...

306

RELATION BETWEEN SOFTWARE METRICS AND MAINTAINABILITY  

Microsoft Academic Search

Summary: This paper presents the relation between software metrics and maintainability and the metrics which characterise the ease of the maintenance process when applied to a specific product. The criteria of maintainability and the methods through which these criteria are understood and interpreted by software programmers are analysed. Surveys and examples that show whether software metrics and maintainability are correlated

Dimitris Stavrinoudis

1999-01-01

307

Garfinkel Cardiac Data  

NSDL National Science Digital Library

Cardiac data on multiple variables for a selected population of 220 men and 338 women participating in a drug treatment study of dobutamine for heart attack prevention. Garfinkel, Alan, et. al. "Prognostic Value of Dobutamine Stress Echocardiography in Predicting Cardiac Events in Patients With Known or Suspected Coronary Artery Disease." Journal of the American College of Cardiology 33.3 (1999) 708-16.

Alan Garfinkel (University of California Los Angeles;Physiological Sci/Med-Cardio)

2009-01-10

308

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

309

Focal Cardiac Myocytolysis.  

National Technical Information Service (NTIS)

During the course of a clinical pathologic study of cardiac lesions observed in 375 autopsies at ABCC, focal cardiac myocytolysis (FCM) was found in 21 hearts. There was no evidence that FCM was related to prior exposure at the time of the bomb. Myocardia...

A. Steer T. Kawashima T. Nakashima D. S. Dock K. K. Lee

1975-01-01

310

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

311

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

312

Acoustic saturation and output regulation.  

PubMed

Acoustic saturation pressures are predicted for ultrasonic beams of a range of frequencies and focal depths. Using reasonable approximations, saturation values for mechanical index (MI) and derated spatial-peak, time-average and pulse-average intensities are calculated. These are compared with thresholds set for regulatory purposes by the U. S. Food and Drug Administration (FDA), and by the International Electrotechnical Commission (IEC). It is concluded that there are many conditions for which acoustic saturation in water prevents the values of MI and regulated intensities from exceeding thresholds set by the FDA. These conditions are particularly associated with higher frequencies and deeper focal lengths. The thresholds for action set by IEC 61157 are sufficiently low that similar problems do not arise. It is concluded that present regulations are not fully effective in limiting the output from diagnostic ultrasound equipment, and that some conditions exist that are not subject to output control. PMID:10461731

Duck, F A

1999-07-01

313

UFO - The Universal FEYNRULES Output  

NASA Astrophysics Data System (ADS)

We present a new model format for automatized matrix-element generators, the so-called Universal FEYNRULES Output (UFO). The format is universal in the sense that it features compatibility with more than one single generator and is designed to be flexible, modular and agnostic of any assumption such as the number of particles or the color and Lorentz structures appearing in the interaction vertices. Unlike other model formats where text files need to be parsed, the information on the model is encoded into a PYTHON module that can easily be linked to other computer codes. We then describe an interface for the MATHEMATICA package FEYNRULES that allows for an automatic output of models in the UFO format.

Degrande, Céline; Duhr, Claude; Fuks, Benjamin; Grellscheid, David; Mattelaer, Olivier; Reiter, Thomas

2012-06-01

314

Cardiac Resynchronization Therapy Upregulates Cardiac Autonomic Control  

PubMed Central

Objective: To determine the effect of cardiac resynchronization therapy (CRT) on sympathetic nervous function in heart failure (HF). Background: Neurohormonal dysregulation and cardiac autonomic dysfunction are associated with HF and contribute to HF progression and its poor prognosis. We hypothesized that mechanical resynchronization improves cardiac sympathetic function in HF. Methods: Sixteen consecutive patients receiving CRT for advanced cardiomyopathy and 10 controls were included in this prospective study. NYHA class, 6-minute walk distance, echocardiographic parameters, plasma norepinephrine (NE) were assessed at baseline, 3-month and 6-month follow-up. Cardiac sympathetic function was determined by 123iodine metaiodobenzylguanidine (123I-MIBG) scintigraphy and 24-hour ambulatory electrocardiography. Results: Along with improvement in NYHA class (3.1 ± 0.3 to 2.1 ± 0.4, P < 0.001) and LVEF (23 ± 6% to 33 ± 12%, P < 0.001 delayed heart/mediastinum (H/M) 123 I-MIBG ratio increased significantly (1.8 ± 0.7 to 2.1 ± 0.6, P = 0.04) while the H/M 123I-MIBG washout rate decreased significantly (54 ± 25% to 34± 24%, P = 0.01) from baseline to 6-month follow-up. The heart rate variability (HRV) measured in SD of normal-to-normal intervals also increased significantly from baseline (82 ± 30 ms) to follow-up (111 ± 32 ms, P = 0.04). The improvement in NYHA after CRT was significantly associated with baseline 123I-MIBG H/M washout rate (r = 0.65, P = 0.03). The improvement in LVESV index was associated with baseline 123I-MIBG delayed H/M ratio (r = ?0.67, P = 0.02) and H/M washout rate (r = 0.65, P = 0.03). Conclusion: After CRT, improvements in cardiac symptoms and LV function were accompanied by rebalanced cardiac autonomic control as measured by 123I-MIBG and HRV.

CHA, YONG-MEI; OH, JAE; MIYAZAKI, CHINAMI; HAYES, DAVID L.; REA, ROBERT F.; SHEN, WIN-KUANG; ASIRVATHAM, SAMUEL J.; KEMP, BRAD J.; HODGE, DAVID O.; CHEN, PENG-SHENG; CHAREONTHAITAWEE, PANITHAYA

2009-01-01

315

Absolute light output of scintillators  

Microsoft Academic Search

The absolute light outputs of BGO, CsI(Tl) and some new Ce-doped crystals have been measured to an accuracy of about ±5% using calibrated XP2020Q photomultipliers and standard S3590.03 and S2740.03 photodiodes. The use of small crystals, 9 mm in diameter and 1 mm thick, reduces the corrections for imperfections in the light collection process and in the photoelectron collection by

M. Moszynski; M. Kapusta; M. Mayhugh; D. Wolski; S. O. Flyckt

1997-01-01

316

High-Output Injection Laser  

NASA Technical Reports Server (NTRS)

Terraced double-heterojunction large optical cavity laser features high output in single optical mode. Semiconductor laser consists of body of single-crystal semiconductor material, typically composed of Group III to V compounds in form of rectangular parallelepiped. One of laser end faces partially transparent so that light may be emitted from it. Lateral thickness variation of active and guide layers in semiconductor laser produces confinement of propagating laser beam in lateral direction.

Connolly, J. C.; Botez, D.

1985-01-01

317

Humoral changes in shock induced by cardiac tamponade.  

PubMed

Cardiac tamponade was induced in dogs by the infusion of saline into the pericardial cavity. The mean arterial pressure dropped to approximately one-third and the cardiac output to one-fourth of the control level. This was accompanied by the release of vasoactive humoral mediators. Among the vasoconstrictor mediators measured in the plasma, the greatest rise during early tamponade occurred in vasopressin concentrations. Considerable elevations of epinephrine and nonrepinephrine concentrations and plasma renin activity were also demonstrated, these mediators reaching their maximum levels in late tamponade. This study for the first time demonstrates significant rises in plasma thromboxane B2 and histamine levels in cardiac tamponade. The histamine level elevation was greater in the portal venous blood than in the arterial blood. It is suggested that histamine may play a counterregulatory role in cardiac tamponade by attenuating excessive vasoconstriction caused by the activation of various vasoconstrictor systems. PMID:2684445

Kaszaki, J; Nagy, S; Tárnoky, K; Laczi, F; Vecsernyés, M; Boros, M

1989-10-01

318

Trichloroethylene Exposure during Cardiac Valvuloseptal Morphogenesis Alters Cushion Formation and Cardiac Hemodynamics in the Avian Embryo  

PubMed Central

It is controversial whether trichloroethylene (TCE) is a cardiac teratogen. We exposed chick embryos to 0, 0.4, 8, or 400 ppb TCE/egg during the period of cardiac valvuloseptal morphogenesis (2–3.3 days’ incubation). Embryo survival, valvuloseptal cellularity, and cardiac hemodynamics were evaluated at times thereafter. TCE at 8 and 400 ppb/egg reduced embryo survival to day 6.25 incubation by 40–50%. At day 4.25, increased proliferation and hypercellularity were observed within the atrioventricular and outflow tract primordia after 8 and 400 ppb TCE. Doppler ultrasound revealed that the dorsal aortic and atrioventricular blood flows were reduced by 23% and 30%, respectively, after exposure to 8 ppb TCE. Equimolar trichloroacetic acid (TCA) was more potent than TCE with respect to increasing mortality and causing valvuloseptal hypercellularity. These results independently confirm that TCE disrupts cardiac development of the chick embryo and identifies valvuloseptal development as a period of sensitivity. The hypercellular valvuloseptal profile is consistent with valvuloseptal heart defects associated with TCE exposure. This is the first report that TCA is a cardioteratogen for the chick and the first report that TCE exposure depresses cardiac function. Valvuloseptal hypercellularity may narrow the cardiac orifices, which reduces blood flow through the heart, thereby compromising cardiac output and contributing to increased mortality. The altered valvuloseptal formation and reduced hemodynamics seen here are consistent with such an outcome. Notably, these effects were observed at a TCE exposure (8 ppb) that is only slightly higher than the U.S. Environmental Protection Agency maximum containment level for drinking water (5 ppb).

Drake, Victoria J.; Koprowski, Stacy L.; Lough, John; Hu, Norman; Smith, Susan M.

2006-01-01

319

Reuse of permanent cardiac pacemakers.  

PubMed Central

Cardiac pacemakers are part of a growing group of expensive implantable electronic devices; hospitals in which 100 pacemakers are implanted per year must budget over $300 000 for these devices. This cost represents a considerable burden to health care resources. Since the "life-span" of modern pacemakers often exceeds that of the patients who receive them, the recovery and reuse of these devices seems logical. Pacemakers can be resterilized and tested with current hospital procedures. Reuse should be acceptable under Canadian law, but the manner in which the pacemakers are recovered and the patients selected should follow careful guidelines. Every patient should provide written informed consent before receiving a recovered pacemaker. Properly executed, reuse of pacemakers should provide a high level of health care while maintaining or reducing the cost of these devices.

Rosengarten, M D; Portnoy, D; Chiu, R C; Paterson, A K

1985-01-01

320

Numerical simulation of the influence of gravity and posture on cardiac performance  

NASA Technical Reports Server (NTRS)

A numerical model of the cardiovascular system was used to quantify the influences on cardiac function of intrathoracic pressure and intravascular and intraventricular hydrostatic pressure, which are fundamental biomechanical stimuli for orthostatic response. The model included a detailed arterial circulation with lumped parameter models of the atria, ventricles, pulmonary circulation, and venous circulation. The venous circulation was divided into cranial, central, and caudal regions with nonlinear compliance. Changes in intrathoracic pressure and the effects of hydrostatic pressure were simulated in supine, launch, sitting, and standing postures for 0, 1, and 1.8 G. Increasing intrathoracic pressure experienced with increasing gravity caused 12% and 14% decreases in cardiac output for 1 and 1.8 G supine, respectively, compared to 0 G. Similar results were obtained for launch posture, in which the effects of changing intrathoracic pressure dominated those of hydrostatic pressure. Compared to 0 G, cardiac output decreased 0.9% for 1 G launch and 15% for 1.8 G launch. In sitting and standing, the position of the heart above the hydrostatic indifference level caused the effects of changing hydrostatic pressure to dominate those of intrathoracic pressure. Compared to 0 G, cardiac output decreased 13% for 1 G sitting and 23% for 1.8 G sitting, and decreased 17% for 1 G standing and 31% for 1.8 G standing. For a posture change from supine to standing in 1 G, cardiac output decreased, consistent with the trend necessary to explain orthostatic intolerance in some astronauts during postflight stand tests. Simulated lower body negative pressure (LBNP) in 0 G reduced cardiac output and mean aortic pressure similar to I G standing, suggesting that LBNP provides at least some cardiovascular stimuli that may be useful in preventing postflight orthostatic intolerance. A unifying concept, consistent with the Frank-Starling mechanism of the heart, was that cardiac output was proportional to cardiac diastolic transmural pressure for all postures and gravitational accelerations.

Peterson, Kristy; Ozawa, Edwin T.; Pantalos, George M.; Sharp, M. Keith

2002-01-01

321

Expressional analysis of the cardiac NaCa exchanger in rat development and senescence  

Microsoft Academic Search

The cardiac Na-Ca exchanger NCX serves as the main calcium extrusion mechanism in heart muscle and is important in maintaining intracellular calcium homeostasis. The accumulations of NCX RNA and protein are known to be regulated in cardiac hypertrophy, by thyroid hormone and during postnatal development. In this study the temporal and spatial patterns of NCX mRNA and protein accumulations were

Maren U. Koban; Antoon F. M. Moorman; Jurgen Holtz; Magdi H. Yacoub; Kenneth R. Boheler

1998-01-01

322

Myoglobin enhances cardiac performance in antarctic icefish species that express the protein.  

PubMed

Channichthyid icefishes of Antarctica are unique among adult vertebrates. All icefish species lack hemoglobin and red blood cells in their circulating blood. All icefishes examined to date also lack the intracellular oxygen-binding protein myoglobin (Mb) in their oxidative skeletal muscles. However, some icefish species do express Mb in their heart ventricles. It is unknown whether Mb in those species in which it is present represents an evolutionary relic or has functional significance. To address this problem, we compared mechanical performance of isolated, perfused hearts from two species of icefish in which Mb is either present (Chionodraco rastrospinosus) or is absent (Chaenocephalus aceratus). Hearts were challenged with increasing afterload (2.5-4.0 kPa) under conditions of defined basal flow (approximately 100 ml.min-1.kg-1), in both the presence and absence of 5 mM sodium nitrite, a Mb poison. Unlike hearts from C. aceratus, which were unable to maintain a constant cardiac output under pressure loading, those from C. rastrospinosus retained a constant flow up to 3.5 kPa afterload. At the upper range of power outputs, hearts of Mb-lacking C. aceratus display greater oxygen utilization than those of Mb-containing C. rastrospinosus. Poisoning of Mb significantly impaired the ability of C. rastrospinosus hearts to face pressure loading without reduction in flow, whereas those of C. aceratus were refractory to the treatment. The results strongly support a functional role for Mb in the former species. PMID:9249538

Acierno, R; Agnisola, C; Tota, B; Sidell, B D

1997-07-01

323

Cardiac function of the naked mole-rat: ecophysiological responses to working underground.  

PubMed

The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fraction (43 ± 2%), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 ?m(2)) and cardiac collagen deposition of 2.2 ± 0.4%. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 ?g/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment. PMID:24363308

Grimes, Kelly M; Voorhees, Andrew; Chiao, Ying Ann; Han, Hai-Chao; Lindsey, Merry L; Buffenstein, Rochelle

2014-03-01

324

Naturally occurring cardiac glycosides.  

PubMed

Cardiac glycoside poisoning from the ingestion of plants, particularly of oleanders, occurs with reasonable frequency in tropical and subtropical areas. We have assessed a variety of plant specimens for their cardiac glycoside content by means of radioimmunoassays with antibodies that differ in their specificity for cardiac glycosides. Significant amounts of immunoreactive cardiac glycoside were found to be present in the ornamental shrubs: yellow oleander (Thevetia peruviana); oleander (Nerium oleander); wintersweet (Carissa spectabilis); bushman's poison (Carissa acokanthera); sea-mango (Cerbera manghas); and frangipani (Plumeria rubra); and in the milkweeds: redheaded cotton-bush (Asclepias curassavica); balloon cotton (Asclepias fruiticosa); king's crown (Calotropis procera); and rubber vine (Cryptostegia grandifolia). The venom gland of the cane toad (Bufo marinus) also contained large quantities of cardiac glycosides. The competitive immunoassay method permits the rapid screening of specimens that are suspected to contain cardiac glycosides. Awareness of the existence of these plant and animal toxins and their dangers allows them to be avoided and poisoning prevented. The method is also useful for the confirmation of the presence of cardiac glycosides in serum in cases of poisoning. PMID:3086679

Radford, D J; Gillies, A D; Hinds, J A; Duffy, P

1986-05-12

325

A calcified cardiac mass.  

PubMed

Cardiac fibromas are benign tumours, often diagnosed in childhood, but rarely they may be diagnosed in adults or the elderly. We present an interesting case of a middle-aged lady presenting with exertional chest pain and breathlessness, who was found to have a heavily calcified mass within the myocardium. With a previous history of chest trauma, a calcified myocardial haematoma was initially suspected. Complete surgical excision led to a total resolution of symptoms. Histological examination confirmed the diagnosis of a cardiac fibroma. Complete excision of cardiac fibromas, where possible, is advised and is associated with excellent survival. PMID:17126934

Iqbal, M Bilal; Stavri, George; Mittal, Tarun; Khaghani, Asghar

2007-02-14

326

Primary Cardiac Angiosarcoma  

PubMed Central

This is a report of a primary cardiac angiosarcoma in a woman who, several years earlier, had undergone repair of an aortic dissection with a Dacron graft prosthesis. Dacron prostheses have rarely been associated with neoplasia, and this, to our knowledge, is the first reported case of primary cardiac angiosarcoma in association with Dacron. Our patient presented with extensive metastases. If tumors are localized, they can be treated successfully with a combination of surgical resection, chemotherapy, and radiotherapy. Cardiac transplantation can also be beneficial, but the overall prognosis remains poor.

Almeida, Nathan J.; Hoang, Priscilla; Biddle, Paul; Arouni, Amy; Esterbrooks, Dennis

2011-01-01

327

Cardiac Effects of Seizures  

PubMed Central

Seizures frequently affect the heart rate and rhythm. In most cases, seizure-related cardiac changes are transient and do not appear to cause clinically significant abnormalities for the patient. Great interest in this area of research has been generated because of a possible connection with sudden unexpected death in epilepsy (SUDEP). While there are clear, but rare complications from seizure-related cardiac arrhythmias, such as ictal asystole that causes syncope, the overall risk of seizures on cardiac status and any potential connection between seizures and SUDEP still remain uncertain.

Nei, Maromi

2009-01-01

328

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.

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

2013-01-01

329

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

330

Rehabilitation of Cardiac Patients.  

National Technical Information Service (NTIS)

The five and one-half year study to evaluate methods of rehabilitating cardiac patients found that programs for rehabilitation must be individualized according to preconditions and guidelines given in detail in the report. The yoga exercise 'Shavasan' was...

K. K. Datey

1974-01-01

331

Cardiac ablation procedures  

MedlinePLUS

Ablate means "to destroy." Cardiac ablation is a procedure that is used to destroy small areas in ... be causing your heart rhythm problems . During the procedure, small wires called electrodes are placed inside your ...

332

Cardiac conduction system  

MedlinePLUS Videos and Cool Tools

... the ventricles to contract. This signal creates an electrical current that can be seen on a graph called an Electrocardiogram (EKG or ECG). Doctors use an EKG to monitor the cardiac conduction system’s electrical activity in the heart.

333

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

334

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

335

CHIP protects against cardiac pressure overload through regulation of AMPK  

PubMed Central

Protein quality control and metabolic homeostasis are integral to maintaining cardiac function during stress; however, little is known about if or how these systems interact. Here we demonstrate that C terminus of HSC70-interacting protein (CHIP), a regulator of protein quality control, influences the metabolic response to pressure overload by direct regulation of the catalytic ? subunit of AMPK. Induction of cardiac pressure overload in Chip–/– mice resulted in robust hypertrophy and decreased cardiac function and energy generation stemming from a failure to activate AMPK. Mechanistically, CHIP promoted LKB1-mediated phosphorylation of AMPK, increased the specific activity of AMPK, and was necessary and sufficient for stress-dependent activation of AMPK. CHIP-dependent effects on AMPK activity were accompanied by conformational changes specific to the ? subunit, both in vitro and in vivo, identifying AMPK as the first physiological substrate for CHIP chaperone activity and establishing a link between cardiac proteolytic and metabolic pathways.

Schisler, Jonathan C.; Rubel, Carrie E.; Zhang, Chunlian; Lockyer, Pamela; Cyr, Douglas M.; Patterson, Cam

2013-01-01

336

Autonomic cardiac innervation  

PubMed Central

Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targets, upon which target-derived trophic factors take over final maturation, synaptic strength and postnatal survival. Although target-derived neurotrophins have a central role to play in development, alternative sources of neurotrophins may also modulate innervation. Both developing and adult sympathetic neurons express proNGF, and adult parasympathetic cardiac ganglion neurons also synthesize and release NGF. The physiological function of these “non-classical” cardiac sources of neurotrophins remains to be determined, especially in relation to autocrine/paracrine sustenance during development.   Cardiac autonomic nerves are closely spatially associated in cardiac plexuses, ganglia and pacemaker regions and so are sensitive to release of neurotransmitter, neuropeptides and trophic factors from adjacent nerves. As such, in many cardiac pathologies, it is an imbalance within the two arms of the autonomic system that is critical for disease progression. Although this crosstalk between sympathetic and parasympathetic nerves has been well established for adult nerves, it is unclear whether a degree of paracrine regulation occurs across the autonomic limbs during development. Aberrant nerve remodeling is a common occurrence in many adult cardiovascular pathologies, and the mechanisms regulating outgrowth or denervation are disparate. However, autonomic neurons display considerable plasticity in this regard with neurotrophins and inflammatory cytokines having a central regulatory function, including in possible neurotransmitter changes. Certainly, neurotrophins and cytokines regulate transcriptional factors in adult autonomic neurons that have vital differentiation roles in development. Particularly for parasympathetic cardiac ganglion neurons, additional examinations of developmental regulatory mechanisms will potentially aid in understanding attenuated parasympathetic function in a number of conditions, including heart failure.

Hasan, Wohaib

2013-01-01

337

Cardiac Mapping Technology  

Microsoft Academic Search

\\u000a In general, the methodologies for cardiac electrical mapping entail registration of the electrical activation sequences of\\u000a the heart by recording extracellular electrograms. The initial use of cardiac mapping was primarily to better understand the\\u000a normal electrical excitations of the heart. However, the focus in mapping over time has shifted to the study of mechanisms\\u000a and substrates underlying various arrhythmias; these

Nicholas D. Skadsberg; Bin He; Timothy G. Laske; Paul A. Iaizzo

338

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.

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

2014-01-01

339

Abnormal Cardiac Autonomic Regulation in Mice Lacking ASIC3.  

PubMed

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; Lin, Chao-Chieh; Chen, Chih-Cheng

2014-01-01

340

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

341

Frequency divider is free of spurious outputs  

NASA Technical Reports Server (NTRS)

Frequency divider provides sixteen output states free of spurious pulses from four input circuits. The input is binary coded, and a change of one in the input only changes the number of output states by one.

Mc Dermond, D.

1966-01-01

342

Maximum output of an OTEC power plant  

Microsoft Academic Search

This paper theoretically investigates the effects of the temperature and flowrate of cold seawater on the net output of an OTEC plant. Parameters of pipe length, pipe diameter, seawater depth, and the flowrate of seawater are considered. It shows that a maximum output of the net work exists at a certain flowrate of cooling seawater. The output work is higher

Rong-Hua Yeh; Tar-Zen Su; Min-Shong Yang

2005-01-01

343

Supervised Learning by Training on Aggregate Outputs  

Microsoft Academic Search

Supervised learning is a classic data mining problem where one wishes to be able to predict an output value associated with a particular input vector. We present a new twist on this classic problem where, instead of having the training set contain an individual output value for each input vector, the output values in the training set are only given

David R. Musicant; Janara M. Christensen; Jamie F. Olson

2007-01-01

344

Processing of the fluxgate output signal  

Microsoft Academic Search

Fluxgate sensors measure magnetic field with a resolution up to 10 pT. New methods of the output signal processing allow to decrease the sensor size, lower the energy consumption and increase the working frequency. Tuning the voltage output may substantially increase the sensitivity, but in certain cases it may cause unstability. Fluxgate in current-output mode requires lower number of turns

P. Ripka; S. Kawahito

345

The Impairment of ILK Related Angiogenesis Involved in Cardiac Maladaptation after Infarction  

PubMed Central

Background Integrin linked kinase (ILK), as an important component of mechanical stretch sensor, can initiate cellular signaling response in the heart when cardiac preload increases. Previous work demonstrated increased ILK expression could induce angiogenesis to improved heart function after MI. However the patholo-physiological role of ILK in cardiac remodeling after MI is not clear. Method and Results Hearts were induced to cardiac remodeling by infarction and studied in Sprague-Dawley rats. Until 4 weeks after infarction, ILK expression was increased in non-ischemic tissue in parallel with myocytes hypertrophy and compensatory cardiac function. 8 weeks later, when decompensation of heart function occurred, ILK level returned to baseline. Followed ILK alternation, vascular endothelial growth factor (VEGF) expression and phosphorylation of endothelial nitric oxide synthase (eNOS) was significantly decreased 8 weeks after MI. Histology study also showed significantly microvessel decreased and myocytes loss 8 weeks paralleled with ILK down-regualtion. While ILK expression was maintained by gene delivery, tissue angiogenesis and cardiac function was preserved during cardiac remodeling. Conclusion Temporally up-regulation of ILK level in non-ischemic myocytes by increased external load is associated with beneficial angiogenesis to maintain infarction-induced cardiac hypertrophy. When ILK expression returns to normal, this cardiac adaptive response for infarction is weaken. Understanding the ILK related mechanism of cardiac maladaptation leads to a new strategy for treatment of heart failure after infarction.

Xie, Jun; Lu, Wen; Gu, Rong; Dai, Qin; Zong, Bin; Ling, Lin; Xu, Biao

2011-01-01

346

Acupuncture effects on cardiac functions measured by cardiac magnetic resonance imaging in a feline model.  

PubMed

The usefulness of acupuncture (AP) as a complementary and/or alternative therapy in animals is well established but more research is needed on its clinical efficacy relative to conventional therapy, and on the underlying mechanisms of the effects of AP. Cardiac magnetic resonance imaging (CMRI), an important tool in monitoring cardiovascular diseases, provides a reliable method to monitor the effects of AP on the cardiovascular system. This controlled experiment monitored the effect electro-acupuncture (EA) at bilateral acupoint Neiguan (PC6) on recovery time after ketamine/xylazine cocktail anesthesia in healthy cats. The CMRI data established the basic feline cardiac function index (CFI), including cardiac output and major vessel velocity. To evaluate the effect of EA on the functions of the autonomic nervous and cardiovascular systems, heart rate, respiration rate, electrocardiogram and pulse rate were also measured. Ketamine/xylazine cocktail anesthesia caused a transient hypertension in the cats; EA inhibited this anesthetic-induced hypertension and shortened the post-anesthesia recovery time. Our data support existing knowledge on the cardiovascular benefits of EA at PC6, and also provide strong evidence for the combination of anesthesia and EA to shorten post-anesthesia recovery time and counter the negative effects of anesthetics on cardiac physiology. PMID:18955311

Lin, Jen-Hsou; Shih, Chen-Haw; Kaphle, Krishna; Wu, Leang-Shin; Tseng, Weng-Yih; Chiu, Jen-Hwey; Lee, Tzu-Chi; Wu, Ying-Ling

2010-06-01

347

T3 and cardiac myocyte cell: a theoretical model.  

PubMed

In the last decades, the outstanding role of Thyroid gland in regulating both physiological and pathological operation of cardiovascular system has been acknowledged worldwide. Three main domains of Thyroid function, that is to say, euthyroidism -hyperthyroidism-hypothyroidism, have a direct impact on cardiac response through a variety of mechanisms. Cellular pathways mediate in cardiac contractility, cardiac output, cardiac rhythm, arterial blood pressure and peripheral vessel resistance. Particular biochemical algorithms exist not only between Thyroid hormones' serum concentration and thyroid gland but also between the hormones' serum level and heart muscle genes. These biochemical pathways primarily regulate the appropriate secretion of levothyroxine (T4) and triiodothyronine(T3) via Thyroid- Stimulating-Hormone(TSH) pituitary system, and secondly adjust the cardiac function. In this study, a mathematic model has been developed describing significant aspects of positive or negative feedback mechanisms of THYRO-CARDIAC (THY-CAR) system along with potential applications of novel up-to-date patents in this area of research. PMID:23952808

Athanasios, Tsatsaris; Antonios, Baldoukas; Antonios, Loumousiotis; Eustathios, Koukounaris; Maria, Giota; Despina, Perrea

2013-08-01

348

Permanent Implanted Cardiac Assist Device and Total Cardiac Replacement Device.  

National Technical Information Service (NTIS)

Attempts to devise satisfactory permanent mechanical cardiac assist devices and total cardiac replacement devices for humans is being undertaken by a number of investigators, and research in this area by the authors is outlined. (Author)

T. M. Runge E. A. Ripperger K. L. Wiggins D. Havemann

1969-01-01

349

A New Frontier for Cardiac Monitoring  

NASA Technical Reports Server (NTRS)

CardioDynamics International Corporation (CDIC) has created the BioZ(TM) System through a Small Business Innovation Research (SBIR) award from Johnson Space Center, providing patients and physicians with a cost-effective and highly accurate monitoring system.The BioZ non-invasive heart monitor is based on a technology known as Impedance Cardiography (ICG). BioZ provides the physician with vital information about the heart's ability to deliver blood to the body, the force one's heart exerts with each beat, and the amount of fluid in the chest. Specially designed bioimpedance sensors placed on the neck and chest monitor 12 different parameters, including cardiac output, contractility, systemic vascular resistance, and thoracic fluid content. These sensors monitor the electrical conductivity of the body-information that is converted into blood flow data and is displayed in real time on a monitoring screen. BioZ.com(TM) and BioZ.pc(TM) are two additional products that incorporate the same sensors present in the original BioZ system. The "com" in BioZ.com stands for cardiac output monitor. This fully integrated system is essentially a smaller version of the BioZ, combining the same abilities with a compact, lightweight design, while providing greater portability.

2001-01-01

350

The cardiac response to exercise in cirrhosis  

PubMed Central

BACKGROUND—Impaired exercise capacity and oxygen consumption are common in cirrhosis.?AIM—To explore the relationship between possible myocardial dysfunction and exercise tolerance in cirrhosis.?METHODS—Cardiac responses to exercise, using radionuclide angiography and graded upright cycle ergometry with oxygen consumption, were assessed before and after exercise in 39 cirrhotics patients and compared with 12 age and sex matched healthy volunteers. Baseline cardiac chamber dimensions and wall thickness, ejection fraction, and diastolic function were measured using two dimensional echocardiography is all subjects.?RESULTS—Baseline diastolic dysfunction with prolonged isovolumic relaxation times (p=0.02), left atrial enlargement, and left ventricular wall thickening were present in all cirrhotics (p=0.02), despite increased mean ejection fraction. With graded exercise, cirrhotics achieved 71 (4)% (p=0.03) (pre-ascitics) and 46 (3)% (p<0.001) (ascitics) of predicted work loads, respectively, without significant increases in ejection fraction. The smaller absolute and percentage increases in cardiac output (p=0.003) in the cirrhotics were associated with significantly reduced oxygen consumption (p=0.003) and anaerobic threshold (p<0.001), and correlated significantly with work and metabolic parameters.?CONCLUSIONS—Impaired exercise capacity in cirrhosis is associated with myocardial thickening and ventricular stiffness leading to decreased diastolic function, inotropic and chronotropic incompetence under conditions of stress, with metabolic consequences. This picture is compatible with the condition now known as cirrhotic cardiomyopathy.???Keywords: cirrhosis; exercise tolerance; myocardial function; oxygen consumption

Wong, F; Girgrah, N; Graba, J; Allidina, Y; Liu, P; Blendis, L

2001-01-01

351

Influence of gravity on cardiac performance  

NASA Technical Reports Server (NTRS)

Results obtained by the investigators in ground-based experiments and in two parabolic flight series of tests aboard the NASA KC-135 aircraft with a hydraulic simulator of the human systemic circulation have confirmed that a simple lack of hydrostatic pressure within an artificial ventricle causes a decrease in stroke volume of 20%-50%. A corresponding drop in stroke volume (SV) and cardiac output (CO) was observed over a range of atrial pressures (AP), representing a rightward shift of the classic CO versus AP cardiac function curve. These results are in agreement with echocardiographic experiments performed on space shuttle flights, where an average decrease in SV of 15% was measured following a three-day period of adaptation to weightlessness. The similarity of behavior of the hydraulic model to the human system suggests that the simple physical effects of the lack of hydrostatic pressure may be an important mechanism for the observed changes in cardiac performance in astronauts during the weightlessness of space flight.

Pantalos, G. M.; Sharp, M. K.; Woodruff, S. J.; O'Leary, D. S.; Lorange, R.; Everett, S. D.; Bennett, T. E.; Shurfranz, T.

1998-01-01

352

Cardiac involvement in hemochromatosis.  

PubMed

Cardiac hemochromatosis or primary iron-overload cardiomyopathy is an important and potentially preventable cause of heart failure. This is initially characterized by diastolic dysfunction and arrhythmias and in later stages by dilated cardiomyopathy. Diagnosis of iron overload is established by elevated transferrin saturation (>55%) and elevated serum ferritin (>300 ng/mL). Genetic testing for mutations in the HFE (high iron) gene and other proteins, such as hemojuvelin, transferrin receptor, and ferroportin, should be performed if secondary causes of iron overload are ruled out. Patients should undergo comprehensive 2D and Doppler echocardiography to evaluate their systolic and diastolic function. Newer modalities like strain imaging and speckle-tracking echocardiography hold promise for earlier detection of cardiac involvement. Cardiac magnetic resonance imaging with measurement of T2* relaxation times can help quantify myocardial iron overload. In addition to its value in diagnosis of cardiac iron overload, response to iron reduction therapy can be assessed by serial imaging. Therapeutic phlebotomy and iron chelation are the cornerstones of therapy. The average survival is less than a year in untreated patients with severe cardiac impairment. However, if treated early and aggressively, the survival rate approaches that of the regular heart failure population. PMID:24503941

Gulati, Vinay; Harikrishnan, Prakash; Palaniswamy, Chandrasekar; Aronow, Wilbert S; Jain, Diwakar; Frishman, William H

2014-01-01

353

Heart health in older adults. Import of heart disease and opportunities for maintaining cardiac health.  

PubMed Central

Coronary heart disease remains the leading cause of morbidity and mortality in older adults, despite improved survival and declining mortality. This article describes the prevalence and impact of heart disease on people's lives, singly and in combination with other diseases. It then reviews current findings as to the risk factors for CHD in older adults and the underlying physiologic changes of aging plus pathophysiologic changes of hypertension and CHD in impairing the ability of older adults to respond to exercise and other stressors, and the effects of exercise training in attenuating the adverse cardiovascular changes of aging. This information provides a basis for considering opportunities for prevention of heart disease and maximizing heart function. The article concludes by describing the known contribution of preventive measures to declines in heart disease in older adults. Images Figure 2.

Fried, L P; McNamara, R L; Burke, G L; Siscovick, D S

1997-01-01

354

The TEA CO2-Lasers with High Output Emission Intensity  

NASA Astrophysics Data System (ADS)

TEA CO2-lasers generating short pulse radiation and operating in a pulse-periodic mode with the repetition rate up to 10 Hz have been developed. It is shown that the addition of nitrogen up to 8% in the mixture of molecular gases ??2:H2 = 500:50 at a total pressure of P = 0.6 bar enhances the peak emission power maintaining the temporary pulse shape. An output beam intensity of 12.3 MW/cm2 was obtained for the 30 ns pulse at a laser efficiency of 2.8%. In a compact TEA ??2-laser with an active medium volume of 6 cm3, a beam with an output intensity of 24 MW/cm2 at pulse duration of 70 ns was obtained.

Panchenko, Yu. N.; Losev, V. F.; Puchikin, ?. V.; Jun, Yao

2014-03-01

355

Light-operated proximity detector with linear output  

DOEpatents

A light-operated proximity detector is described in which reflected light intensity from a surface whose proximity to the detector is to be gauged is translated directly into a signal proportional to the distance of the detector from the surface. A phototransistor is used to sense the reflected light and is connected in a detector circuit which maintains the phtotransistor in a saturated state. A negative feedback arrangement using an operational amplifier connected between the collector and emitter of the transistor provides an output at the output of the amplifier which is linearly proportional to the proximity of the surface to the detector containing the transistor. This direct proportional conversion is true even though the light intensity is varying with the proximity in proportion to the square of the inverse of the distance. The detector may be used for measuring the distance remotely from any target surface.

Simpson, M.L.; McNeilly, D.R.

1984-01-01

356

Hypokalemia and sudden cardiac death  

PubMed Central

Worldwide, approximately three million people suffer sudden cardiac death annually. These deaths often emerge from a complex interplay of substrates and triggers. Disturbed potassium homeostasis among heart cells is an example of such a trigger. Thus, hypokalemia and, also, more transient reductions in plasma potassium concentration are of importance. Hypokalemia is present in 7% to 17% of patients with cardiovascular disease. Furthermore, up to 20% of hospitalized patients and up to 40% of patients on diuretics suffer from hypokalemia. Importantly, inadequate management of hypokalemia was found in 24% of hospitalized patients. Hypokalemia is associated with increased risk of arrhythmia in patients with cardiovascular disease, as well as increased all-cause mortality, cardiovascular mortality and heart failure mortality by up to 10-fold. Long-term potassium homeostasis depends on renal potassium excretion. However, skeletal muscles play an important role in short-term potassium homeostasis, primarily because skeletal muscles contain the largest single pool of potassium in the body. Moreover, due to the large number of Na+/K+ pumps and K+ channels, the skeletal muscles possess a huge capacity for potassium exchange. In cardiovascular patients, hypokalemia is often caused by nonpotassium-sparing diuretics, insufficient potassium intake and a shift of potassium into stores by increased potassium uptake stimulated by catecholamines, beta-adrenoceptor agonists and insulin. Interestingly, drugs with a proven significant positive effect on mortality and morbidity rates in heart failure patients all increase plasma potassium concentration. Thus, it may prove beneficial to pay more attention to hypokalemia and to maintain plasma potassium levels in the upper normal range. The more at risk of fatal arrhythmia and sudden cardiac death a patient is, the more attention should be given to the potassium homeostasis.

Kjeldsen, Keld

2010-01-01

357

Effects of intracoronary and intravenous amrinone infusions in patients with cardiac failure and patients with near normal cardiac function.  

PubMed Central

The effects of intracoronary and intravenous infusions of amrinone were studied to distinguish the drug's direct cardiac actions from its peripheral vascular and neuroendocrine properties. Intracoronary infusions of amrinone were found to have no haemodynamic effect other than producing a slight reduction in the left ventricular ejection fraction and some suggestion of coronary vasodilatation in patients with impaired left ventricular function. They did not improve contractility, cardiac output, or filling pressures and had no significant effect on myocardial metabolism, although therapeutic concentrations of the drug were detected in coronary sinus blood. Intravenously administered amrinone reduced filling pressures and improved the cardiac index in all patients, but haemodynamic improvements were most pronounced in the patients with the worst cardiac function. These changes were accompanied by improvements in the indices of contractility only in patients in whom alterations in concentrations of free fatty acid, glycerol, and glucose suggested peripheral catecholamine release. In the patients with the best basal cardiac function intravenously administered amrinone produced a reduction in myocardial work and evidence of myocardial ischaemia, as a result of excessive reduction of coronary perfusion pressure and increased heart rate, without any appreciable increase in cardiac index. It is concluded that, at the concentrations of the drug that can be achieved in man without adverse effects, amrinone has no direct positive inotropic effect. Haemodynamic changes are predominantly the result of vasodilatation, although catecholamines may be released in some patients.

Wilmshurst, P T; Thompson, D S; Juul, S M; Dittrich, H C; Dawson, J R; Walker, J M; Jenkins, B S; Coltart, D J; Webb-Peploe, M M

1985-01-01

358

Maintainability Prediction and Analysis Study. Revision A.  

National Technical Information Service (NTIS)

Existing maintainability prediction techniques are not accurate estimators of current electronic equipment/system characteristics. A new time synthesis prediction technique is developed which directly relates diagnostic/isolation/test subsystem characteri...

F. L. Jew J. E. Angus T. F. Pliska

1978-01-01

359

Research on Computer Aided Design for Maintainability.  

National Technical Information Service (NTIS)

The objective of this research was to investigate methods for measuring and predicting equipment maintainability as a consequence of internal structure and the design of the man-machine interface. A computer-based technique has been developed for projecti...

D. M. Towne M. C. Johnson

1987-01-01

360

Handbook for Reliability and Maintainability Monitors.  

National Technical Information Service (NTIS)

Each section of this handbook deals with a particular problem area in (Reliability and Maintainability) matters and suggests methods of initiating and operating an R/M program. The material covered ranges from the basic elements of establishing a program ...

G. Grippo G. H. Allen J. E. Horowitz J. R. Barton R. M. DeMilia

1964-01-01

361

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

362

Guideline Guideline for resuscitation in cardiac arrest after cardiac surgery  

Microsoft Academic Search

Summary The Clinical Guidelines Committee of the European Association for Cardio-Thoracic Surgery provides this professional view on resuscitation in cardiac arrest after cardiac surgery. This document was created using a multimodal methodology for evidence generation including the extrapolation of existing guidelines from the International Liaison Committee on Resuscitation where possible, our own structured literature reviews on issues particular to cardiac

Joel Dunning; Alessandro Fabbri; Philippe H. Kolh; Adrian Levine; Ulf Lockowandt; Jonathan Mackay; Alain J. Pavie; Tim Strang; Michael I. M. Versteegh; Samer A. M. Nashef

363

Engineered cardiac tissues  

PubMed Central

Cardiac tissue engineering offers the promise of creating functional tissue replacements for use in the failing heart or for in vitro drug screening. The last decade has seen a great deal of progress in this field with new advances in interdisciplinary areas such as developmental biology, genetic engineering, biomaterials, polymer science, bioreactor engineering, and stem cell biology. We review here a selection of the most recent advances in cardiac tissue engineering, including the classical cell-scaffold approaches, advanced bioreactor designs, cell sheet engineering, whole organ decellularization, stem-cell based approaches, and topographical control of tissue organization and function. We also discuss current challenges in the field, such as maturation of stem cell-derived cardiac patches and vascularization.

Iyer, Rohin K.; Chiu, Loraine L. Y.; Reis, Lewis A.; Radisic, Milica

2011-01-01

364

Malignant primary cardiac tumours  

PubMed Central

OBJECTIVES Management of malignant tumours of the heart remains a poorly investigated clinical area due to the scarcity of presentations. The purpose of this series and review is to present an outline of the management emphasized by our personal experience in a regional cardiothoracic centre. METHODS We reviewed all cases presenting with primary cardiac tumours in our institution within the last 10 years, looking at presentation, management and outcomes. RESULTS Of these, the records of 3 patients, who attended the Royal Victoria Hospital in Belfast and were treated for a cardiac sarcoma, were fully evaluated. A review of current literature was conducted through a search of Pubmed and Medline databases. A review of the presentation of these patients and the generally accepted management deterioration of patients diagnosed with cardiac sarcoma is discussed. CONCLUSIONS With reference to our case series, we want to draw attention to the rapid deteriation of these patients following presentation.

Burnside, Nathan; MacGowan, Simon W.

2012-01-01

365

A dual role for integrin-linked kinase and ?1-integrin in modulating cardiac aging.  

PubMed

Cardiac performance decreases with age, which is a major risk factor for cardiovascular disease and mortality in the aging human population, but the molecular mechanisms underlying cardiac aging are still poorly understood. Investigating the role of integrin-linked kinase (ilk) and ?1-integrin (myospheroid, mys) in Drosophila, which colocalize near cardiomyocyte contacts and Z-bands, we find that reduced ilk or mys function prevents the typical changes of cardiac aging seen in wildtype, such as arrhythmias. In particular, the characteristic increase in cardiac arrhythmias with age is prevented in ilk and mys heterozygous flies with nearly identical genetic background, and they live longer, in line with previous findings in Caenorhabditis elegans for ilk and in Drosophila for mys. Consistent with these findings, we observed elevated ?1-integrin protein levels in old compared with young wild-type flies, and cardiac-specific overexpression of mys in young flies causes aging-like heart dysfunction. Moreover, moderate cardiac-specific knockdown of integrin-linked kinase (ILK)/integrin pathway-associated genes also prevented the decline in cardiac performance with age. In contrast, strong cardiac knockdown of ilk or ILK-associated genes can severely compromise cardiac integrity, including cardiomyocyte adhesion and overall heart function. These data suggest that ilk/mys function is necessary for establishing and maintaining normal heart structure and function, and appropriate fine-tuning of this pathway can retard the age-dependent decline in cardiac performance and extend lifespan. Thus, ILK/integrin-associated signaling emerges as an important and conserved genetic mechanism in longevity, and as a new means to improve age-dependent cardiac performance, in addition to its vital role in maintaining cardiac integrity. PMID:24400780

Nishimura, Mayuko; Kumsta, Caroline; Kaushik, Gaurav; Diop, Soda B; Ding, Yun; Bisharat-Kernizan, Jumana; Catan, Hannah; Cammarato, Anthony; Ross, Robert S; Engler, Adam J; Bodmer, Rolf; Hansen, Malene; Ocorr, Karen

2014-06-01

366

The intraaortic counterpulsation balloon in cardiac surgery. The importance of opportune indication.  

PubMed

The results with the use of this device in patients who develop Low Cardiac Output Syndrome after cardiac surgery with extracorporeal circulation are analyzed. Special emphasis is given to the development of the opportune indication of this procedure, on the basis of a comparison of the results of the first few years to the most recent ones. Finally, the advantages of the prophylactic use of the Intraaortic Balloon Pump are commented. PMID:1819994

Sánchez-Ramírez, O; Portilla-de Buen, E; Verdin-Vázquez, R; Argüero-Sánchez, R

1991-01-01

367

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

368

Cardiac disease in pregnancy  

PubMed Central

Summary Summary This study was a retrospective review of patient charts of a relatively large number of patients with cardiac disease in pregnancy in a developing country. Ninety-five patients were evaluated; the majority (n = 36) were in the age group 21?25 years. Rheumatic heart disease was the commonest aetiology; eight women required balloon mitral valvuloplasty and one had a valve replacement at 32 weeks’ gestation. There were no maternal deaths but morbidity was high; 13 patients were admitted in cardiac failure, nine had atrial fibrillation and three required intensive-care management. There were 86 live births of the 97 deliveries.

Nqayana, T; Moodley, J; Naidoo, DP

2008-01-01

369

Cardiac Bioelectricity and Arrhythmias  

NSDL National Science Digital Library

Deep inside a human heart, its pacemaker sends out bursts of electrical signals that keep the heart pumping rhythmically, supplying life-giving oxygen to the body. When these electrical waves become disorganized, the heart starts beating irregularly or arrhythmically. Flavio Fenton and Elizabeth Cherry of Cornell University made this interactive program to provide education on arrhythmias. It presents detailed information on cardiac anatomy, normal cardiac electrophysiology, and different kinds of arrhythmias using a combination of words, pictures, and interactive, computer simulations and animations.

Flavio Fenton (Cornell University;); Elizabeth Cherry (Cornell University;)

2006-09-22

370

Acute postoperative cardiac herniation.  

PubMed

Acute herniation of the heart is an uncommon complication in patients undergoing pneumonectomy with associated pericardial resection. We report the case of a postoperative cardiac herniation after a right extrapleural pneumonectomy following neoadjuvant chemotherapy for malignant pleural mesothelioma. After surgery the patient was completely asymptomatic, but a postoperative chest X-ray revealed unexpected massive dextrocardia. The patient was immediately brought back to the operating room: a cardiac herniation was found to be caused by a partial dehiscence of the pericardial prosthesis suture. The defect was repaired without consequences. PMID:20940166

Kawamukai, Kenji; Antonacci, Filippo; Di Saverio, Salomone; Boaron, Maurizio

2011-01-01

371

Cardiac and vascular changes in cirrhosis: Pathogenic mechanisms  

PubMed Central

Cardiovascular abnormalities accompany both portal hypertension and cirrhosis. These consist of hyperdynamic circulation, defined as reduced mean arterial pressure and systemic vascular resistance, and increased cardiac output. Despite the baseline increased cardiac output, ventricular inotropic and chronotropic responses to stimuli are blunted, a condition known as cirrhotic cardiomyopathy. Both conditions may play an initiating or aggravating pathogenic role in many of the complications of liver failure or portal hypertension including ascites, variceal bleeding, hepatorenal syndrome and increased postoperative mortality after major surgery or liver transplantation. This review briefly examines the major mechanisms that may underlie these cardiovascular abnormalities, concentrating on nitric oxide, endogenous cannabinoids, central neural activation and adrenergic receptor changes. Future work should address the complex interrelationships between these systems.

Liu, HongQun; Gaskari, Seyed Ali; Lee, Samuel S

2006-01-01

372

Perioperative management of cardiac disease.  

PubMed

Pre-existing cardiac disease contributes significantly to morbidity and mortality amongst patients undergoing non cardiac surgery. Patients with pre-existing cardiac disease or with risk factors for it, have as much as a 3.9% risk of suffering a major perioperative cardiac event (Lee et al 1999, Devereaux 2005). Furthermore, the incidence of perioperative myocardial infarction (MI) is increased 10 to 50 fold in patients with previous coronary events (Jassal 2008). PMID:24516966

Aresti, N A; Malik, A A; Ihsan, K M; Aftab, S M E; Khan, W S

2014-01-01

373

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

374

Predictors of Gastrointestinal Complications in Cardiac Surgery  

PubMed Central

Gastrointestinal problems are infrequent but serious complications of cardiac surgery, with high rates of morbidity and mortality. Predictors of these complications are not well developed, and the role of fundamental variables remains controversial. In a retrospective review of our cardiac surgery experience from July 1991 through December 1997, we found that postoperative gastrointestinal complications were diagnosed in 86 of 4,463 consecutive patients (1.9%). We categorized these 86 patients into 2 groups—Surgical and Medical—according to the method of treatment used for their complications. In the Medical group, 9 of 52 patients (17%) died; in the Surgical group, 17 of 34 (50%) died. By logistic multivariate analysis, we identified 8 parameters that predicted gastrointestinal complications: age greater than 70 years, duration of cardiopulmonary bypass, need for blood transfusions, reoperation, triple-vessel disease, New York Heart Association functional class IV, peripheral vascular disease, and congestive heart failure. Postoperative re-exploration for bleeding was a predictor specific to the Surgical group. Use of an intraaortic balloon pump was markedly higher in the Gastrointestinal group than in the Control group (30% vs 10%, respectively), as was the use of inotropic support in the immediate postoperative period (27% vs 5.6%). Our results suggest that intra-abdominal ischemic injury is a likely contributing factor in most gastrointestinal complications. In turn, the ischemia is probably caused by hypoperfusion due to low cardiac output, hypotension due to blood loss, and intra-abdominal atheroemboli. The derived models are useful for identifying patients whose risk of gastrointestinal complications after cardiac surgery may be reduced by clinical measures designed to counter these mechanisms.

Zacharias, Anoar; Schwann, Thomas A.; Parenteau, Gary L.; Riordan, Christopher J.; Durham, Samuel J.; Engoren, Milo; Fenn-Buderer, Nancy; Habib, Robert H.

2000-01-01

375

Exercise training before cardiac-specific Serca2 disruption attenuates the decline in cardiac function in mice.  

PubMed

In the heart, function of the sarco(endo)plasmic Ca(2+)-ATPase (SERCA2) is closely linked to contractility, cardiac function, and aerobic fitness. SERCA2 function can be increased by high-intensity interval training, whereas reduced SERCA2 abundance is associated with impaired cardiac function. The working hypothesis was, therefore, that exercise training before cardiomyocyte-specific disruption of the Serca2 gene would delay the onset of cardiac dysfunction in mice. Before Serca2 gene disruption by tamoxifen, untreated SERCA2 knockout mice (Serca2(flox/flox) Tg-?MHC-MerCreMer; S2KO), and SERCA2 FF control mice (Serca2(flox/flox), S2FF) were exercise trained by high-intensity interval treadmill running for 6 wk. Both genotypes responded to training, with comparable increases in maximal oxygen uptake (Vo(2max); 17%), left ventricle weight (15%), and maximal running speed (40%). After exercise training, cardiac-specific Serca2 gene disruption was induced in both exercise trained and sedentary S2KO mice. In trained S2KO, cardiac function decreased less rapidly than in sedentary S2KO. Vo(2max) remained higher in trained S2KO the first 15 days after gene disruption. Six weeks after Serca2 disruption, cardiac output was higher in trained compared with sedentary S2KO mice. An exercise-training program attenuates the decline in cardiac performance induced by acute cardiac Serca2 gene disruption, indicating that mechanisms other than SERCA2 contribute to the favorable effect of exercise training. PMID:20864565

Ericsson, Madelene; Sjåland, Cecilie; Andersson, Kristin B; Sjaastad, Ivar; Christensen, Geir; Sejersted, Ole M; Ellingsen, Øyvind

2010-12-01

376

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.

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

2012-01-01

377

Penetrating cardiac injury: a review.  

PubMed

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

378

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

379

Goal-directed fluid optimization based on stroke volume variation and cardiac index during one-lung ventilation in patients undergoing thoracoscopy lobectomy operations: a pilot study  

PubMed Central

OBJECTIVES: This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies. METHODS: Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded. RESULTS: The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group. CONCLUSION: The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation.

Zhang, Jian; Chen, Chao Qin; Lei, Xiu Zhen; Feng, Zhi Ying; Zhu, Sheng Mei

2013-01-01

380

Evidence for increased cardiac compliance during exposure to simulated microgravity  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

381

Gene Regulatory Networks in Cardiac Conduction System Development  

PubMed Central

The cardiac conduction system is a specialized tract of myocardial cells responsible for maintaining normal cardiac rhythm. Given its critical role in coordinating cardiac performance, a detailed analysis of the molecular mechanisms underlying conduction system formation should inform our understanding of arrhythmia pathophysiology and affect the development of novel therapeutic strategies. Historically, the ability to distinguish cells of the conduction system from neighboring working myocytes presented a major technical challenge for performing comprehensive mechanistic studies. Early lineage tracing experiments suggested that conduction cells derive from cardiomyocyte precursors, and these claims have been substantiated by using more contemporary approaches. However, regional specialization of conduction cells adds an additional layer of complexity to this system, and it appears that different components of the conduction system utilize unique modes of developmental formation. The identification of numerous transcription factors and their downstream target genes involved in regional differentiation of the conduction system has provided insight into how lineage commitment is achieved. Furthermore, by adopting cutting-edge genetic techniques in combination with sophisticated phenotyping capabilities, investigators have made substantial progress in delineating the regulatory networks that orchestrate conduction system formation and their role in cardiac rhythm and physiology. This review describes the connectivity of these gene regulatory networks in cardiac conduction system development and discusses how they provide a foundation for understanding normal and pathological human cardiac rhythms.

Munshi, Nikhil V.

2014-01-01

382

RUNX3 Maintains the Mesenchymal Phenotype after Termination of the Notch Signal*  

PubMed Central

Notch is a critical mediator of endothelial-to-mesenchymal transition (EndMT) during cardiac cushion development. Slug, a transcriptional repressor that is a Notch target, is an important Notch effector of EndMT in the cardiac cushion. Here, we report that the runt-related transcription factor RUNX3 is a novel direct Notch target in the endothelium. Ectopic expression of RUNX3 in endothelium induces Slug expression and EndMT independent of Notch activation. Interestingly, RUNX3 physically interacts with CSL, the Notch-interacting partner in the nucleus, and induces Slug in a CSL-dependent, but Notch-independent manner. Although RUNX3 may not be required for the initial induction of Slug and EndMT by Notch, because RUNX3 has a much longer half-life than Slug, it sustains the expression of Slug thereby maintaining the mesenchymal phenotype. CSL binds to the Runx3 promoter in the atrioventricular canal in vivo, and inhibition of Notch reduces RUNX3 expression in the cardiac cushion of embryonic hearts. Taken together, our results suggest that induction of RUNX3 may be a mechanism to maintain Notch-transformed mesenchymal cells during heart development.

Fu, YangXin; Chang, Alex Chia Yu; Fournier, Michele; Chang, Linda; Niessen, Kyle; Karsan, Aly

2011-01-01

383

RUNX3 maintains the mesenchymal phenotype after termination of the Notch signal.  

PubMed

Notch is a critical mediator of endothelial-to-mesenchymal transition (EndMT) during cardiac cushion development. Slug, a transcriptional repressor that is a Notch target, is an important Notch effector of EndMT in the cardiac cushion. Here, we report that the runt-related transcription factor RUNX3 is a novel direct Notch target in the endothelium. Ectopic expression of RUNX3 in endothelium induces Slug expression and EndMT independent of Notch activation. Interestingly, RUNX3 physically interacts with CSL, the Notch-interacting partner in the nucleus, and induces Slug in a CSL-dependent, but Notch-independent manner. Although RUNX3 may not be required for the initial induction of Slug and EndMT by Notch, because RUNX3 has a much longer half-life than Slug, it sustains the expression of Slug thereby maintaining the mesenchymal phenotype. CSL binds to the Runx3 promoter in the atrioventricular canal in vivo, and inhibition of Notch reduces RUNX3 expression in the cardiac cushion of embryonic hearts. Taken together, our results suggest that induction of RUNX3 may be a mechanism to maintain Notch-transformed mesenchymal cells during heart development. PMID:21288908

Fu, YangXin; Chang, Alex Chia Yu; Fournier, Michèle; Chang, Linda; Niessen, Kyle; Karsan, Aly

2011-04-01

384

Roles of the creatine kinase system and myoglobin in maintaining energetic state in the working heart  

PubMed Central

Background The heart is capable of maintaining contractile function despite a transient decrease in blood flow and increase in cardiac ATP demand during systole. This study analyzes a previously developed model of cardiac energetics and oxygen transport to understand the roles of the creatine kinase system and myoglobin in maintaining the ATP hydrolysis potential during beat-to-beat transient changes in blood flow and ATP hydrolysis rate. Results The theoretical investigation demonstrates that elimination of myoglobin only slightly increases the predicted range of oscillation of cardiac oxygenation level during beat-to-beat transients in blood flow and ATP utilization. In silico elimination of myoglobin has almost no impact on the cytoplasmic ATP hydrolysis potential (?GATPase). In contrast, disabling the creatine kinase system results in considerable oscillations of cytoplasmic ADP and ATP levels and seriously deteriorates the stability of ?GATPase in the beating heart. Conclusion The CK system stabilizes ?GATPase by both buffering ATP and ADP concentrations and enhancing the feedback signal of inorganic phosphate in regulating mitochondrial oxidative phosphorylation.

Wu, Fan; Beard, Daniel A

2009-01-01

385

Cardiac pacemaker power sources  

Microsoft Academic Search

A review of chemical and radioisotope batteries used in cardiac ; pacemakers is presented. The battery systems are examined in terms of longevity, ; reliability, cost, size and shape, energy density, weight, internal resistance ; versus time, end-of-life voltage, chemical compatibility, and potential failure ; mechanisms. (TFD)

K. A. Gasper; K. E. Fester

1975-01-01

386

Cardiac Resynchronization Pacing Therapy  

Microsoft Academic Search

Approximately one third of patients with congestive heart failure and systolic dysfunction have an intraventricular conduction delay that is manifested as a QRS duration >120 ms. An intraventricular conduction delay adversely affects ventricular performance by causing dyssynchrony in ventricular activation. When ventricular dyssynchrony is present, simultaneous left and right ventricular pacing or cardiac resynchronization therapy can improve ventricular synchrony. This

Cash Casey; Bradley P. Knight

2004-01-01

387

The cardiac muscle cell  

Microsoft Academic Search

Summary The cardiac myocyte is the most physically energetic cell in the body, contracting constantly, without tiring, 3 billion times or more in an average human lifespan. By coordinating its beating activity with that of its 3 billion neighbours in the main pump of the human heart, over 7,000 litres of blood are pumped per day, without con- scious effort,

Nicholas J. Severs

2000-01-01

388

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.

389

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

390

Haemodynamic responses to stimulation of the splanchnic and cardiac sympathetic nerves in the anaesthetized cat.  

PubMed Central

The changes in cardiac output and mean right atrial pressure (R.A.P.) evoked at different circulating blood volumes by stimulation of the splanchnic sympathetic nerves were investigated in adrenalectomized cats under chloralose anaesthesia, with unopened chests and spontaneous respiration and with active vascular reflexes. The cardiac autonomic nerves were cut or blocked pharmacologically. Stimulation of the distal ends of the splanchnic nerves at 4 Hz caused aortic pressure and R.A.P. to rise to maximum values at 2 min before declining slowly. Cardiac output rose more slowly to a steady state at 3 min; at higher circulating volumes it fell initially. Although the output increments were slower in development they were better sustained than those in total peripheral resistance. The proportionate output increments were largest and the R.A.P. increments least at low circulating volumes whereas at high volumes the R.A.P. increments were large but the output changes were small or negative; the pattern of changes resembled that resulting from infusion of blood. Stimulation of the cardiac sympathetic nerves evoked a rise in output and a fall in R.A.P. related in magnitude to the initial value of R.A.P. On simultaneous stimulation of the splanchnic and cardiac sympathetic nerves the changes in output combined whereas the R.A.P. changes cancelled, to give output increments of 25-50% with little change in R.A.P. at all circulating volumes. At high circulating volumes infusion of blood did not usually alter output or aortic pressure, but splanchnic nerve stimulation increased peripheral resistance and aortic pressure and commonly evoked a rise in left ventricular stroke work which could not be accounted for by known adrenergic mechanisms or by elevation of left ventricular end-diastolic pressure. Portal venous pressure was consistently elevated by splanchnic nerve stimulation; it rose more slowly than did aortic pressure or R.A.P. and was independent of a changing central venous pressure provided this did not exceed +5 mmHg. The cardiac output increments were not related to changes in the ratio between the input and output resistances of the portal vein and it is concluded that displacement blood from the peripheral to the central vasculature was induced by contraction capacitance vessels.

Barnes, R J; Bower, E A; Rink, T J

1986-01-01

391

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

392

Microstructured Cocultures of Cardiac Myocytes and Fibroblasts: A Two-Dimensional In Vitro Model of Cardiac Tissue  

NASA Astrophysics Data System (ADS)

Cardiac myocytes and fibroblasts are essential elements of myocardial tissue structure and function. In vivo, myocytes constitute the majority of cardiac tissue volume, whereas fibroblasts dominate in numbers. In vitro, cardiac cell cultures are usually designed to exclude fibroblasts, which, because of their maintained proliferative potential, tend to overgrow the myocytes. Recent advances in microstructuring of cultures and cell growth on elastic membranes have greatly enhanced in vitro preservation of tissue properties and offer a novel platform technology for producing more in vivo-like models of myocardium. We used microfluidic techniques to grow two-dimensional structured cardiac tissue models, containing both myocytes and fibroblasts, and characterized cell morphology, distribution, and coupling using immunohistochemical techniques. In vitro findings were compared with in vivo ventricular cyto-architecture. Cardiac myocytes and fibroblasts, cultured on intersecting 30-[mu]m-wide collagen tracks, acquire an in vivo-like phenotype. Their spatial arrangement closely resembles that observed in native tissue: Strands of highly aligned myocytes are surrounded by parallel threads of fibroblasts. In this in vitro system, fibroblasts form contacts with other fibroblasts and myocytes, which can support homogeneous and heterogeneous gap junctional coupling, as observed in vivo. We conclude that structured cocultures of cardiomyocytes and fibroblasts mimic in vivo ventricular tissue organization and provide a novel tool for in vitro research into cardiac electromechanical function.

Camelliti, Patrizia; McCulloch, Andrew D.; Kohl, Peter

2005-06-01

393

Three-phase uninterruptible power supply maintaining reserve energy sources in idling condition with unbalanced loads  

SciTech Connect

A control arrangement for a three-phase, uninterruptible power supply generates timing signals to drive the static switches of inverters located in each phase. This control arrangement precisely controls the phase differences of the inverter signals with relation to each other so that while the overall three-phase power supplied by the inverters is nulled, power circulation through the inverters compensates for unbalanced output loads thereby maintaining balanced phase angles between the output voltage and a balanced input impedance at the input of the power supply.

Boettcher, C.W.; Hamilton, B.H.; Zweig, W.L.

1980-12-09

394

How to Maintain a Social Reinforcement Program.  

ERIC Educational Resources Information Center

This manual presents methodology for maintaining a social reinforcement system after supervisors in industrial environments have been trained in behavior modification theory and application. The maintenance manual discusses monitoring, evaluation, and integration of a company's employee performance system with the social reinforcement system…

Arkin, Ronald; And Others

395

Alertness maintaining tasks (AMTs) while driving  

Microsoft Academic Search

We evaluated the effectiveness of alertness maintaining tasks (AMTs) on driver performance, subjective feelings, and psychophysiological state in monotonous simulated driving in two experiments. In the first experiment, 12 professional truck drivers participated in five sessions of simulated driving: driving only, driving with one of three AMTs (counterbalanced), and driving while listening to music. AMTs were not equally effective in

Tal Oron-Gilad; Adi Ronen; David Shinar

2008-01-01

396

Maintaining Hope in the Face of Evil.  

ERIC Educational Resources Information Center

P. G. Zimbardo (2001) and M. E. P. Seligman (in an interview with S. Carpenter, 2001) discuss evil and hope in response to the September 11, 2001, disaster. The implications for counseling are presented with an emphasis on how counselors can maintain hope for themselves and their clients in the face of evil. (Author)

Miller, Geri

2002-01-01

397

Maintaining ideal body weight counseling sessions  

SciTech Connect

The purpose of this program is to provide employees with the motivation, knowledge and skills necessary to maintain ideal body weight throughout life. The target audience for this program, which is conducted in an industrial setting, is the employee 40 years of age or younger who is at or near his/her ideal body weight.

Brammer, S.H.

1980-10-09

398

Storage Temperatures Necessary to Maintain Cheese Safety  

Microsoft Academic Search

SUMMARY Available information on bacterial pathogen growth, stasis, and death in cheeses was reviewed and evaluated to determine storage temperatures necessary to maintain product safety. In view of the variety and large volume of cheeses consumed throughout the world, the incidence of foodborne outbreaks associated with cheeses is extremely low. Research revealed that the inherent characteristics of most cheeses create

JAY RUSSELL BISHOP; MARIANNE SMUKOWSKI

399

ANALYZING SYSTEM MAINTAINABILITY USING ENTERPRISE ARCHITECTURE MODELS  

Microsoft Academic Search

Abstract Afast and continuously changing business environment demands ,flexible software systems easy to modify ,and maintain. Due to the ,extent of interconnection between systems and the internal quality of each system many IT decision-makers find it difficult predicting the effort of making ,changes to their systems. To aid IT-decision makers in making better decisions regarding what modifications to make to

Robert Lagerström

400

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

401

Maintaining Interest in Operator Requal Training.  

ERIC Educational Resources Information Center

A study reviewed operator training programs at Oyster Creek Nuclear Generating Station to determine their interface with plant operations and to devise new ways of maintaining interest in requalification (requal) training. The operator training review committee that was formed to implement the review documented over 100 issues and concerns…

Lapp, H. J., Jr.

402

Acceptable Practices in Maintaining Personnel Files.  

ERIC Educational Resources Information Center

Determining acceptable practices in maintaining personnel files is a pertinent issue for school personnel administrators today. Recognizing this, the Georgia Association of School Personnel Administrators accepted the study of this topic as a committee assignment from the American Association of School Personnel Administrators. A survey instrument…

American Association of School Personnel Administrators, Seven Hills, OH.

403

Reduced coronary blood flow in cardiac tamponade: mystery solved.  

PubMed

A 67-year-old male presented with several week history of progressive shortness of breath, lower extremity edema, and distended jugular veins. Transthoracic echocardiography showed moderate pericardial effusion with thickened visceral pericardium and septal bounce but no chamber collapse. Right and left cardiac catheterization showed discordance of the right and left ventricular systolic pressures during respiration and severely reduced cardiac output. There was near equalization of diastolic pressures in all four chambers suggestive of effusive-constrictive pericarditis with cardiac tamponade physiology. Simultaneous coronary angiography showed remarkably reduced coronary Thrombolysis in Myocardial Infarction (TIMI) flow (TIMI grade 2 flow). Coronary blood flow was restored to normal after pericardial drainage on repeat coronary angiography. This is the first report of reduced coronary blood flow on coronary angiography in patients with effusive-constrictive pericarditis and cardiac tamponade. Our finding complements the work of previous investigators as we show that elevated intrapericardial pressures in cardiac tamponade can reduce coronary blood flow. This is likely related to extrinsic epicardial coronary vessel compression and reduced perfusion pressures, which can lead to myocardial ischemia and eventually cardiogenic shock. PMID:23220996

Abusaid, Ghassan H; Khalife, Wissam I

2012-12-01

404

Cardiac mechanics and energetics--from Emax to PVA.  

PubMed

After these seven decades of cardiac mechanics, through the windows of Starling's cardiac output curve followed by Sonnenblick's myocardial force-velocity relation and Vmax, Frank's ventricular pressure-volume (P-V) relationship has revived as a window of cardiac mechanics over the past two decades following the proposal of the Emax concept by Suga and Sagawa. Emax is a physically sound measure of ventricular contractile compressibility or time-varying volume elastance at end systole. Although the original Emax concept has been slightly modified to improve its fitness to reality, the Emax concept has successfully survived over two decades as a basic conceptual framework of ventricular contraction in physiological, pathophysiological and clinical studies. An important expansion of the Emax concept was introduced by Suga a decade ago, and a new window for cardiac energetics was opened up by the concept of PVA as a measure of the total contractile energy generated by ventricular contraction. PVA correlates with ventricular oxygen consumption, with Emax as a decisive parameter. Moreover, Emax and PVA combined with effective arterial elastance Ea as a new afterload parameter proposed by Sunagawa and Sagawa have enabled us to predict cardiac energetics under a variety of loading and contractile conditions. The key advances of the Emax and PVA concepts are reviewed mainly in the biomedical engineering aspects by the proposer of these concepts himself. PMID:2271404

Suga, H

1990-01-01

405

Input-Output Analyses of Schools.  

ERIC Educational Resources Information Center

Cognitive and noncognitive outputs are surveyed, as well as the effects of inputs on outputs. Groups of student inputs include background characteristics, school-related characteristics, and attitudes. School inputs include conditions and instructional personnel. The literature is surveyed by population samples, data aggregation, and statistical…

Glasman, Naftaly S.; Biniaminov, Israel

1981-01-01

406

Pole assignment by gain output feedback  

Microsoft Academic Search

This short paper deals with the problem of pole assignment with incomplete state observation. It is shown that if the system is controllable and observable, and ifn leq r + m - 1, an almost arbitrary set of distinct closed-loop poles is assignable by gain output feedback, wheren, r, andmare the numbers of state variables, inputs and outputs, respectively. This

H. Kimura

1975-01-01

407

A Calorimeter for Measuring Laser Output Energy.  

National Technical Information Service (NTIS)

A new calorimeter design for measuring the output energy of pulse lasers and the output power of CW lasers is described which traces the intensity reduction of the irradiation of the walls of an absorption body and the shortening of the time for equalizin...

D. Vavrouch

1969-01-01

408

Optimal Output Trajectory Redesign for Invertible Systems  

NASA Technical Reports Server (NTRS)

Given a desired output trajectory, inversion-based techniques find input-state trajectories required to exactly track the output. These inversion-based techniques have been successfully applied to the endpoint tracking control of multi-joint flexible manipulators and to aircraft control. The specified output trajectory uniquely determines the required input and state trajectories that are found through inversion. These input-state trajectories exactly track the desired output; however, they might not meet acceptable performance requirements. For example, during slewing maneuvers of flexible structures, the structural deformations, which depend on the required state trajectories, may be unacceptably large. Further, the required inputs might cause actuator saturation during an exact tracking maneuver for example, in the flight control of conventional takeoff and landing aircraft. In such situations, a compromise is desired between the tracking requirement and other goals such as reduction of internal vibrations and prevention of actuator saturation; the desired output trajectory needs to be redesigned.

Devasia, Santosh

1996-01-01

409

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

410

Output characteristics of the Dual Channel EST  

NASA Astrophysics Data System (ADS)

Analysis of the output characteristics of the Dual Channel EST (DC-EST) is provided for the first time in this article. It is demonstrated by analytical modelling and with the aid of two dimensional numerical simulations that the output resistance in the region of current saturation is determined by the activation of the narrow base NPN transistor in the IGBT segment. Based upon this model, the experimentally observed degradation in the output resistance with an increase in the distance between the shorts in the P-base region of the main thyristor segment can be explained. This model is shown to be consistent with the experimentally observed degradation in the output resistance with larger design rules used for device fabrication because this determines the current level at which the NPN transistor becomes activated. The observed reduction in the output resistance results in a degradation in the forward bias safe operating area.

Sridhar, S.; Baliga, B. J.

1997-08-01

411

Cardiac index and oxygen delivery during low and high tidal volume ventilation strategies in patients with acute respiratory distress syndrome: a crossover randomized clinical trial  

PubMed Central

Introduction The beneficial effect of low tidal volume (TV) ventilation strategy on mortality in patients with acute respiratory distress syndrome (ARDS) has been attributed to the protective effect on ventilator-induced lung injury, and yet its effect on cardiovascular function might also play an important role. The aim of this study was to assess whether low TV ventilation improves cardiac output and oxygen delivery compared with high TV ventilation strategy in patients with ARDS. Methods In this crossover randomized clinical trial 16 ARDS patients were recruited in an intensive care unit at a university-affiliated hospital. Each patient was ventilated for 30 min with low (6 mL/kg) and 30 min with high (12 mL/kg) TV. The two experimental periods, applied in random order and with allocation concealment, were separated by 30 min of basal ventilation. Minute ventilation was constantly maintained by appropriate respiratory rate changes. Results Compared with high TV ventilation, low TV ventilation showed decreased pH (7.37 vs. 7.41, P = 0.001) and increased PaCO2 (49 vs. 43 mmHg; P = 0.002). Cardiac index and oxygen delivery index were increased with low compared with high TV ventilation (3.9 vs. 3.5 L.min-1.m-2, P = 0.012, and 521 vs. 463 mL.min-1.m-2, P = 0.002, respectively), while oxygen extraction ratio decreased (0.36 vs. 0.44, P = 0.027). In four patients oxygen extraction ratio was >0.5 during high TV but not during low TV strategy. The magnitude of the change in cardiac index was positively associated with PaCO2 variation (P = 0.004), while it was unrelated to the magnitude of changes in TV and airway pressure. The decrease of cardiac index was predicted by PaCO2 reduction, with and area under ROC curve of 0.72. Conclusions Our findings suggest that a low TV ventilation strategy increases cardiac index and oxygen delivery, thus supporting the hypothesis that the beneficial effect of low TV ventilation in patients with ARDS could be partially explained by hemodynamic improvement. In other words, low tidal volume ventilation could be protective also for the cardiovascular system and not only for the lung. The slight increase of PaCO2 during low TV ventilation seems to predict the increase of cardiac index. Trial registration ClinicalTrials.gov: NCT00713713

2013-01-01

412

Breathhold cardiac MRI and MRA.  

PubMed

Recent developments in MRI software and hardware have increased the speed and versatility of cardiac MRI by allowing image acquisition in a single breathhold. Many studies have shown that conventional cardiac MRI is as accurate as echocardiography or cardiac catheterization for diagnosing numerous cardiac conditions. In many cases cardiac MRI is the most accurate diagnostic technique but has not been widely adopted for routine cardiac imaging. One reason why the use of cardiac MRI has been limited is the long examination times required for conventional cardiac MRI. The development of better hardware, such as faster gradient amplifiers and dedicated surface coils, has allowed the implementation of much faster EKG-gated imaging sequences. These can be used in a single breathhold period, with a significant improvement in image quality compared with conventional sequences. Breathhold sequences can provide all the information provided by conventional cardiac MRI in a shorter time and with equal or better accuracy. Breathhold imaging will allow much wider application of MRI to routine cardiac diagnosis. PMID:10453413

Hartnell, G G

1999-04-01

413

Wavelength-maintaining polarization-insensitive all-optical 3R regenerator.  

PubMed

High-rate long-haul fiber communications systems will require high-speed efficient signal regeneration. By introducing a simple semiconductor-optical-amplifier wavelength converter into the folded ultrafast nonlinear interferometer, we demonstrate a polarization-insensitive wavelength-maintaining 3R all-optical regenerator. The extinction ratio between the on and off states is 21 dB. Bit-error rate data show no error floor and <0.3-dB power penalty when compared with a baseline measurement. Moreover, changes in input polarization cause no change in performance. The regenerator maintained a constant polarization and constant output power, independent of the input polarization. PMID:19503503

Savage, Shelby; Robinson, Bryan; Hamilton, Scott; Ippen, Erich

2006-03-01

414

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.

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

2010-01-01

415

Cardiac causes of stroke  

Microsoft Academic Search

Opinion statement  \\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a At least 20% of all ischemic strokes are cardioembolic.\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Cardiac conditions that cause cerebral embolism are classified as major or minor depending on whether the causal link has\\u000a or has not been fully established between the underlying cardiac condition and the stroke.\\u000a \\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a Atrial fibrillation, acute myocardial infarction, valvular heart disease, infective endocarditis, nonbacterial thrombotic\\u000a endocarditis,

Katayoun Vahedi; Pierre Amarenco

2000-01-01

416

Cardiac Resynchronization Therapy  

PubMed Central

Systolic heart failure is a major problem for Americans today, with 550,000 new cases diagnosed per year, and ultimately contributes to 287,000 deaths annually. While pharmacologic therapy has drastically improved outcomes in patients with systolic heart failure, hospitalizations from systolic heart failure continue to increase and remain a major cost burden. In response to this unmet need, recent years have seen dramatic improvements in device-based therapy targeting one cause of systolic dysfunction: dyssynchronous ventricular contraction. Cardiac resynchronization therapy aims to restore mechanical synchrony by electrically activating the heart in a synchronized manner. This review summarizes the rationale for cardiac resynchronization therapy, evidence for its use, current guidelines, and ongoing and future directions for research.

Owen, Joseph S.; Khatib, Sammy; Morin, Daniel P.

2009-01-01

417

Cardiac arrhythmias in pregnancy.  

PubMed

As more women with repaired congenital heart disease survive to their reproductive years and many other women are delaying pregnancy until later in life, a rising concern is the risk of cardiac arrhythmias during pregnancy. Naturally occurring cardiovascular changes during pregnancy increase the likelihood that a recurrence of a previously experienced cardiac arrhythmia or a de novo arrhythmia will occur. Arrhythmias should be thoroughly investigated to determine if there is a reversible etiology, and risks/benefits of treatment options should be fully explored. We discuss the approach to working up and treating various arrhythmias during pregnancy with attention to fetal and maternal risks as well as treatment of fetal arrhythmias. Acute management in stable patients includes close monitoring and intravenous pharmacologic therapy, while DC cardioversion should be used to terminate arrhythmias in hemodynamically unstable patients. Long-term management may require continued oral antiarrhythmic therapy, with particular attention to fetal safety, to prevent complications associated with arrhythmias. PMID:25037518

Knotts, Robert J; Garan, Hasan

2014-08-01

418

Cardiac arrest in children  

PubMed Central

Major advances in the field of pediatric cardiac arrest (CA) were made during the last decade, starting with the publication of pediatric Utstein guidelines, the 2005 recommendations by the International Liaison Committee on Resuscitation, and culminating in multicenter collaborations. The epidemiology and pathophysiology of in-hospital and out-of-hospital CA are now well described. Four phases of CA are described and the term “post-cardiac arrest syndrome” has been proposed, along with treatment goals for each of its four phases: immediate post-arrest, early post-arrest, intermediate and recovery phase. Hypothermia is recommended to be considered as a therapy for post-CA syndrome in comatose patients after CA, and large multicenter prospective studies are underway. We reviewed landmark articles related to pediatric CA published during the last decade. We present the current knowledge of epidemiology, pathophysiology and treatment of CA relevant to pre-hospital and acute care health practitioners.

Tress, Erika E; Kochanek, Patrick M; Saladino, Richard A; Manole, Mioara D

2010-01-01

419