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Results 601 - 650 of 1604
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Casillas C B - - 1994
Heart rate (HR), developed pressure, and stroke volume (SV) increase dramatically during cardiac morphogenesis. During acute changes in cycle length (CL), the chick embryo maintains cardiac output by a compensatory change in SV. We determined embryonic pressure-volume relations during alterations in CL in the stage 21 while Leghorn chick embryo ...
Hardman S M - - 1994
OBJECTIVES: The purpose of this study was to explore the physiology underlying the beat-to-beat variations of ventricular function during atrial fibrillation (AF). METHODS: Left ventricular pressure, and its first derivative (LVdP/dtmax, an index of contractility, and aortic blood velocity (and its integral AVI, an ejection index), were recorded using cathetermounted ...
Crottogini A J - - 1994
BACKGROUND: End-systolic elastance (Ees), the slope parameter of the end-systolic pressure (ESP)-volume (ESV) relation (ESPVR), is usually estimated in patients by producing stepwise, steady-state pharmacological afterload variations and collecting one ESP-ESV point from each step. The ESPVR is then constructed by fitting a linear equation to these points. In sedated, ...
Mori M - - 1994
We examined the effects of a novel water-soluble forskolin derivative, NKH477 (0.5 microgram/kg/min), on arterial-ventricular (A-V) coupling and mechanical energy transduction from heart to circulatory bed in comparison with those of dobutamine (3 micrograms/kg/min) in 8 patients with left ventricular (LV) systolic dysfunction using a conductance catheter method. A-V coupling ...
Burkhoff D - - 1994
In anesthetized dogs, isradipine has been reported to induce peripheral vasodilation and increase cardiac output (CO) and myocardial contractility, whereas myocardial oxygen consumption (MVO2) decreases, suggesting that isradipine may increase overall metabolic efficiency of the ventricle of intact animals. Whether isradipine has any direct myocardial effects that could cause intrinsic ...
Harkin C P - - 1994
BACKGROUND: Volatile anesthetics depress left ventricular mechanical performance during multiple phases of the cardiac cycle. The effects of sevoflurane on systolic and diastolic function have yet to be fully evaluated. This investigation characterized the systemic and coronary hemodynamic, inotropic, and lusitropic actions of sevoflurane in chronically instrumented dogs in the ...
Applegate R J - - 1994
OBJECTIVE: Since portions of autonomic nerves and receptors are located superficially on the heart, it is possible that neuromodulatory substances in pericardial fluid may modulate cardiac contractile function by altering autonomic neurotransmission. The aim of the study was to examine this hypothesis in anaesthetised dogs instrumented to measure left ventricular ...
Goodman L S - - 1994
A miniaturized nuclear probe (MNP) and multiple gated cardiac blood pool imaging (RCBI) were used to measure left ventricular function during positive pressure breathing (PPB) while wearing an extended-coverage (EC) vs. standard-coverage (SC) anti-G-suit. Seven subjects were exposed to 4.0 and 9.3 kPa PPB wearing each anti-G-suit during 3 min ...
Miller W P - - 1994
The purpose of these studies was to determine the effect of altered regional contractility on the linearity of regional left ventricular end-systolic relations. Significant change in the shape of these relations would limit their application as load-independent indices of regional contractility. In a paced, open-chest pig heart preparation (n = ...
Hellyer P W - - 1994
The cardiac effects of hypertonic saline (HS, 7.5% NaCl) were evaluated using a number of indices derived from the left ventricular (LV) pressure-volume relationship. Left ventricular end-systolic elastance (elastance), the slope of the end-systolic pressure-volume relationship, end-systolic elastance normalized for end-diastolic volume (elastance(norm)), the rate of rise of LV pressure ...
Kawaguchi O - - 1994
The purpose of this study was to analyze left ventricular mechanics during asynchronous, pulsatile left atrial-aortic bypass before and after microsphere injection with the pressure-volume relationship. In 14 anesthetized Holstein calves, left ventricular pressure was measured with a micromanometer and ultrasonic dimension transducers measured left ventricular orthogonal diameters. Ellipsoidal geometry ...
Suga H - - 1994
Viewing canine left ventricular performance through the pressure-volume (P-V) window, I proposed a new index of ventricular contractility (Emax: end-systolic P-V ratio or maximum elastance) in my doctoral thesis at the University of Tokyo in 1969. After I joined Dr. Kiichi Sagawa (deceased in 1989) at Johns Hopkins University, we ...
Steltzer H - - 1994
Fourteen patients with severe hypotension and adult respiratory distress syndrome after trauma (n = 7), general surgery (n = 6) or burns (n = 1) were studied. After volume loading with 6 ml.kg-1 hydroxyethyl starch over 30 min (time I), dobutamine was infused intravenously at 5 micrograms.kg-1.min-1 (time II) and ...
Tomai F - - 1994
Cardiac suction has been previously demonstrated in the normal heart and in cardiac diseases characterized by a normal or reduced end-diastolic ventricular pressure. We report a patient with tight mitral stenosis and severe tricuspid regurgitation who provides the evidence of cardiac suction, despite the presence of increased end-diastolic pressures. The ...
Schiereck P - - 1994
OBJECTIVE: The aim was to investigate whether the end diastolic pressure-end diastolic volume (EDP-EDV) relationship of the left ventricle can be influenced by calcium dependent elements, especially at low values of end diastolic pressure. METHODS: Isolated rat hearts were perfused in a modified Langendorff perfusion system. The EDP-EDV relationship of ...
Wallace A - - 1994
INTRODUCTION: Most of the cardiac surgery done today is performed with aortic cross-clamping and cardioplegic arrest. Despite improvements in cardioplegic techniques, ventricular dysfunction following cardioplegic arrest is a major cause of perioperative morbidity and mortality. This experiment will quantify the changes in left ventricular systolic function with cold cardioplegia. Four ...
Hata K - - 1994
Left ventricular (LV) contractile dysfunction during acidosis has been reported to be almost reversible in crystalloid-perfused hearts after correction of acidosis. In contrast, we have found that, in blood-perfused hearts, contractile function is paradoxically depressed after correction of acidosis with a transient overshoot of contractility during the recovery of pH. ...
Cohen-Solal A - - 1994
OBJECTIVE: To clarify the spectrum of the left ventricular responses in hypertension in man by means of coupled analysis of elastances. In the present study we analysed the 'functional' coupling of the left ventricle and the arterial system in terms of the arterial effective elastance (E(a)) divided by a value ...
Sharir T - - 1994
BACKGROUND: Noninvasive cardiac-specific analysis of contractile function in patients with dilated heart failure remains problematic. This study tests whether maximal power divided by the square of end-diastolic volume (PWRmx/EDV2, or preload-adjusted PWRmx) can provide such assessment. METHODS AND RESULTS: To validate the load insensitivity of the PWRmx index and determine ...
Saal J P - - 1994
OBJECTIVES: To assess the effects of piroximone, a phosphodiesterase inhibitor, on right ventricular function in patients with heart failure. DESIGN: Randomized study: patients were randomly assigned to the piroximone infusion rate of 5 or 10 micrograms/kg/min. SETTING: Cardiologic intensive care unit. PATIENTS: 12 consecutive patients with severe heart failure. INTERVENTIONS: ...
Birkeland S - - 1994
In patient and experimental models of regions of the left ventricle subjected to ischaemia and thus made dysfunctional it is important to characterize the inotropic state of the remaining myocardium. Eighteen pentobarbitone-anaesthetized open-chest cats with an acute circumflex coronary artery occlusion were therefore studied during either sympathetic nerve stimulation (n ...
Hoit B D - - 1994
BACKGROUND: Contractile function of the ex vivo, isolated left atrium (LA) has been described by a time-varying elastance, but this atrial chamber property has not been shown in vivo. METHODS AND RESULTS: Instantaneous LA pressure-volume (P-V) relations were studied in 12 anesthetized, autonomically blocked, atrially paced dogs. LA volume was ...
Shintani H - - 1994
The reversible upward shift of the diastolic pressure-volume curve that occurs during pacing-induced ischemia has not been fully explained by increases in passive chamber stiffness or reductions in relaxation rate. We measured the fully relaxed pressure-volume relation defined by both filling and nonfilling beats and the isovolumic relaxation time constant ...
Slinker B K - - 1994
OBJECTIVE: The aim was to test directly the hypothesis that the magnitude of previous beat contraction history will be greatest for short pulse intervals, will become smaller as pulse interval is lengthened, and will vanish when pulse interval is long enough to allow complete restitution. METHODS: Experiments were performed in ...
Hellyer P W - - 1994
Effects of endotoxemia on left ventricular contractility and systemic hemodynamics were determined in pentobarbital-anesthetized swine. A multielectrode conductance (volume) catheter and a high-fidelity pressure transducer catheter were passed retrograde into the left ventricle to continuously measure pressure and volume. End-systolic pressure-volume relationships were determined during transient (8 to 10 s) ...
Martin C - - 1994
The effects of propofol on right ventricular function were studied in 11 ICU patients who needed sedation for acute respiratory failure or neurological diseases. Right ventricular function was studied using a thermodilution method at patients' bedside. Right ventricular ejection fraction (RVEF), cardiac output (CO), right ventricular end-diastolic volume (RVEDV), right ...
Waksman D G - - 1994
A new technique, utilizing scattered X-rays, has been developed that is capable of measuring isolated working rat heart left ventricular (LV) volumes continuously throughout the cardiac cycle. The technique was validated by comparing cardiac outputs measured via fluid collections (r = 0.959, n = 10). The new methodology will permit ...
Mohan J C - - 1994
The purpose of this study was to investigate possible differences between juvenile and adult variety of mitral stenosis (MS) with regard to left ventricular preload, afterload, contractile function and geometry by two-dimensional echocardiography. Thirty six consecutive children and adolescents with MS (Group 1, mean age +/- 1 standard deviation 16 ...
Shoucri R M - - 1994
On the basis of a mathematical formalism derived in previous studies, properties of the end-systolic pressure-volume (P-V) relation were analyzed to define indexes that can characterize a normal or failing left ventricle. Careful analysis of different areas under the P-V line can lead to new indexes that describe the performance ...
Martin G R - - 1994
Echocardiography now permits tracking of the blood-endocardial border and automatic measurement of ventricular area throughout the cardiac cycle. To determine the accuracy of this technique, we compared echocardiographic measurements of area with similar measurements made by radionuclide technique in 19 children, ages 4-24 years (mean 13 years). The blood-endocardial border ...
Kawaguchi O - - 1994
The purpose of this study was to determine the role of ventricular size or contractility in the effectiveness of dynamic cardiac compression in terms of the pressure-volume relationship and myocardial oxygen consumption. In 10 isolated cross-circulated dog hearts, the ventricle was directly compressed during systole. For the volume run, measurements ...
Lin I E - - 1994
During early embryonic development, the heart bends into a curved tube in a vital morphogenetic process called looping. Since looping involves poorly understood biomechanical forces that are difficult to measure, this paper presents a theoretical model for the tubular chick heart, whose development is similar to that of the human ...
Mihailescu L S - - 1994
This study presents an improved method for the measurement of intramyocardial pressure (IMP) using the servo-nulling mechanism. Glass micropipettes (20-24 microns OD) were used as transducers, coated to increase their mechanical resistance to breakage, and placed inside the left ventricular wall with a micropipette holder and manipulator. IMP was measured ...
Martin G R - - 1994
Echocardiography now permits tracking of the blood-endocardial border and automatic measurement of ventricular area throughout the cardiac cycle. To determine the accuracy of this technique, we compared echocardiographic measurements of area with similar measurements made by radionuclide technique in 19 children, ages 4-24 years (mean 13 years). The blood-endocardial border ...
Sandor G G - - 1994
Systolic and diastolic function were assessed at preoperative cardiac catheterization in 6 patients with classic tricuspid atresia and were compared with those in control subjects. All patients had systemic-to-pulmonary shunts. Left ventricular end-systolic and end-diastolic volumes and masses were significantly larger in the patient group; stroke volume and the ratio ...
Nakajima H - - 1994
The mechanism of effectiveness of cardiomyoplasty was evaluated in the setting of chronic left ventricular dysfunction in terms of the pressure-volume relationship. The distal branches of the left coronary artery were ligated in 12 sheep. Seven sheep died and the 5 survivors underwent cardiomyoplasty using a left latissimus dorsi graft ...
Gilchrist I C - - 1994
The measurement of instantaneous left ventricular volumes throughout the cardiac cycle in a rat heart beating at rates of 300 to 600 min-1 with a chamber volume of only a few tenths of a milliliter is difficult. Combining an x-ray scatter detection system with a small x-ray source collimated to ...
Asanoi H - - 1994
To investigate the role of autonomic reflexes in stroke-work optimization, we studied ventriculoarterial coupling in unanesthetized dogs with the autonomic system intact and blocked. Ventricular contractility was quantified by the slope of the end-systolic pressure-volume relation, ventricular elastance (Ees). Arterial system properties were quantified by the ratio of end-systolic pressure ...
Szwarc R S - - 1994
OBJECTIVE: It has recently been suggested that conductance catheter parallel conductance (alpha Vc) is a function of left ventricular volume. To confirm this, alpha Vc was measured in this study over a wide range of steady state volumes. In addition, conductance derived volumes were compared to those obtained by radionuclide ...
Campbell K B - - 1994
OBJECTIVE: In order to evaluate possible artefact in interpretations of contractile behaviour in isolated heart experiments, the relative elastances of series coupled non-contractile and contractile components of the left ventricle of the isolated heart were evaluated. METHODS: Hearts were isolated from ferrets and rabbits and mounted on a servo-controlled volume ...
Nozawa T - - 1994
BACKGROUND: The relation between left ventricular (LV) oxygen consumption (MVO2) and pressure-volume area (PVA) developed in isolated hearts provides a powerful method to understand cardiac energetics. We investigated application of this relation to the intact circulation, determining its response to steady-state and transient load alterations and enhanced contractility in conscious ...
Foëx P - - 1994
Analysis of ventricular function in terms of pressure-volume or pressure-dimension relationships allows global and regional ventricular dynamics to be fully analyzed. In addition, this approach allows the relationships between muscle function (contractility, stiffness, potential energy) and pump function (stroke volume, stroke work) to be determined and predicted. Alterations in ventricular ...
Yasumura Y - - 1994
Ventricular ejection is known to have dual effects on the end-systolic pressure: the ejecting deactivation by a relatively large ejection against a low afterload versus the ejecting activation by a relatively small ejection against a high afterload. We studied how the increase in contractility index (Emax) by the ejecting activation ...
Regen D M - - 1994
The peak pressure which a chamber would develop in isovolumic contraction at end-diastolic distention (peak source pressure) is an expression of contractile vigor and a determinant of systolic performance. One can predict source pressure of an ejecting beat by fitting its isovolumic phases with a model isovolumic-wave function. Characteristics of ...
Amory H - - 1994
This study was designed to test the applicability and the reproducibility of the thermodilution method in the measurement of right ventricular ejection fraction (EF), end-diastolic volume (EDV) and end-systolic volume (ESV) in unsedated cattle. In the 16 healthy calves studied, it was possible, using a fast response thermodilution catheter, to ...
Coriat P - - 1994
As suggested by experimental studies, systolic pressure variation (SPV), the difference between maximum and minimum values of systolic blood pressure after a single positive pressure breath, may be a fair indicator of left ventricular preload. SPV was quantified in 21 patients who had undergone abdominal aortic surgery and were sedated ...
Witsenburg M - - 1994
Right ventricular overload of volume and/or pressure type may affect left ventricular systolic and diastolic function. This has been shown in animal studies and has been suggested in non-invasive studies in man. Altered geometry of the left ventricle, myocardial hypertrophy and changes in contractile state may be responsible for the ...
Rahko P S - - 1994
OBJECTIVES: The purpose of this study was to serially evaluate the response and variability of the end-systolic pressure-volume relation, the left ventricular end-diastolic volume-peak positive first derivative of left ventricular pressure (dP/dt) relation and the left ventricular end-diastolic volume-stroke work relation in the development of progressive left ventricular dysfunction. BACKGROUND: ...
Desideri A - - 1994
OBJECTIVE: To test the hypothesis that chelation therapy with deferoxamine would prevent alterations in left ventricular systolic and diastolic function due to transfusional iron overload in patients with thalassemia major. DESIGN: A consecutive series of patients receiving chronic transfusional and chelation therapy were studied by two-dimensional and Doppler echocardiography. SETTING: ...
Aubert A E - - 1994
To evaluate relaxation mechanics in the wall of the left ventricle needle mounted miniature pressure transducers were inserted at the subendocardial (ENDO) and subepicardial (EPI) level of the anterior wall of the left ventricle during acute open-chest experiments in 10 mongrel dogs. Pressures were recorded during control, volume load and ...
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