Search Results
Results 401 - 450 of 1604
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Farias S - - 1999
BACKGROUND: Compliance is a complex parameter to measure both clinically and in the laboratory. Investigations in recent years have interpreted changes in the end-diastolic pressure-volume relationship (EDPVR) as changes in compliance. However, without considering the equilibrium chamber volume (LV volume when transmural pressure = 0), changes in the EDPVR may ...
Gutiérrez-Carretero E - - 1999
We have studied the alterations produced in the diastolic function of the left ventricle after applying a protocol of cryopreservation at subzero temperatures. Isolated rabbit hearts and 5% polyethylene glycol (PM 4000) as the cryoprotective agent were used for the study. Following cryopreservation we found a statistically significant increase in ...
Omoto T - - 1999
BACKGROUND: The bidirectional cavopulmonary shunt has been increasingly accepted as an interim step to the Fontan operation. However, the effect(s) of chronic volume overload on ventricular function are not yet well understood. METHODS: Twelve mongrel dogs, with (chronic volume overload group), or without (control group) a femoral arteriovenous shunt created ...
Mezzacappa E S - - 1999
The effects of epinephrine administration on cardiovascular function were examined in 26 men who were given a bolus injection of either 1:10,000 epinephrine hydrochloride or physiological saline. Impedance cardiographic and continuous blood pressure measures were recorded during a 2-min pre-injection baseline and in the post-injection period. Compared to a saline ...
Zannoli R - - 1999
The aim of this study was to evaluate how the timing of the pressure pulse produced by peripheral reflection affects the left ventricle (stroke volume, ventricular work, coronary driving pressure). Ten isolated perfused rabbit hearts were attached to rubber tubes of different lengths (0.5, 0.8 and 1 m) connected to ...
Fantini F - - 1999
OBJECTIVE: To investigate left ventricular elastance (Emax) and effective arterial elastance (Ea) in postinfarction left ventricular aneurysm and evaluate their role in left ventricular function improvement after endoventricular circular patch plasty (EVCPP). Ventriculoarterial coupling has never been studied in these patients. PATIENTS: 22 consecutive patients (49 to 73 years) with ...
Safcsak K - - 1999
Accurate assessment of preload status is a major concern in the resuscitation of the critically injured patient. Of the three physiologic determinants of stroke volume, preload is the variable that is most frequently influenced by an insult or intervention or both in the trauma patient. In the critically injured patient, ...
Nosir Y F - - 1999
OBJECTIVES: Three-dimensional echocardiography (3DE) calculates left ventricular volumes (LVV) and ejection fraction (EF) without geometric assumptions, but prolonged analysis time limits its routine use. This study was designed to validate a modified 3DE method for rapid and accurate LVV and EF calculation compared with magnetic resonance imaging (MRI). METHODS: Forty ...
Sites C K - - 1999
OBJECTIVE: To determine the effect of hormone replacement therapy (HRT) on cardiac structure and function and whether these changes are related to changes in blood volume. DESIGN: Open-label pilot study. SETTING: Academic medical center. PATIENT(S): Eighteen healthy postmenopausal women. INTERVENTION(S): We administered medroxyprogesterone acetate orally, 5 mg/d for 2 months ...
Meyer T E - - 1999
Nonischemic end-systolic performance decreases during ischemia. These changes in performance are likely to be dependent on the size and site of the ischemic zone, as well as the prevailing loading conditions. This study was designed to examine the effect of regional and generalized changes in inotropy on nonischemic end-systolic performance, ...
Ferrari G F - - 1999
The aim of this study is the evaluation of end systolic ventricular elastance trend (as a measure of heart contractility) by hemodynamic variables available in intensive care units or during heart surgery: heart rate, cardiac output, left atrial, mean and diastolic arterial pressure. Its basic assumption is the description of ...
Victor S - - 1999
We studied the evolution of ventricles by macroscopic examination of the hearts of marine cartilaginous and bony fish, and by angiocardiography and gross examination of the hearts of air-breathing freshwater fish, frogs, turtles, snakes, and crocodiles. A right-sided, thin-walled ventricular lumen is seen in the fish, frog, turtle, and snake. ...
Miyano H H Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita, Osaka, - - 1999
We hypothesized that tumor necrosis factor-alpha (TNF-alpha) acutely alters left ventricular mechanoenergetics in blood-perfused hearts. To test this hypothesis, we examined the relation between left ventricular mechanics and energetics, both before and after infusion of TNF-alpha. Prospective, experimental study. Research laboratory. Nine isolated, blood-perfused canine hearts. Recombinant human TNF-alpha (90 ...
Tavernier B - - 1998
BACKGROUND: Monitoring left ventricular preload is critical to achieve adequate fluid resuscitation in patients with hypotension and sepsis. This prospective study tested the correlation of the pulmonary artery occlusion pressure, the left ventricular end-diastolic area index measured by transesophageal echocardiography, the arterial systolic pressure variation (the difference between maximal and ...
Karlocai K - - 1998
The end-systolic wall stress (sigma(es))-velocity of circumferential fiber shortening (V(cfsc)) relation was defined during the respiratory cycle, in order to obtain a totally noninvasive measure of left ventricular contractility. Eight young, healthy subjects were studied with echocardiography and calibrated carotid pulse tracings, while performing slow paced breathing. Left ventricular sigma(es) ...
Hinder F - - 1998
Conventional evaluation of cardiovascular volume status by filling pressures is unreliable in critically ill patients. Measurements of left ventricular end diastolic area index by transoesophageal echocardiography and of intrathoracic blood volume index by dye indicator dilution are new approaches to this problem. In this study, different indices of cardiovascular volume ...
Cassidy S C - - 1998
The use of doxorubicin as an anticancer drug is limited by its cardiac toxicity. To examine the adverse effects of doxorubicin on cardiac function and ventricular-vascular coupling in piglets, eight piglets received five doses of intravenous doxorubicin, 1.5 mg/kg/dose, every 4-7 days starting at 3 weeks of age. A control ...
Abel F L - - 1998
Sunagawa and coworkers have proposed an ejecting, single beat, cosine curve matching method for the estimation of the maximum potential left ventricular pressure during an isovolumic contraction. We tested the hypothesis that this same information could be obtained from maximum dp/dt and the length of the ventricular contraction curve using ...
Pagliaro P - - 1998
The present study was planned to investigate the effect of left ventricular pressure and inotropic state on coronary arterial inflow in systole in the anaesthetized dog. A wide range of left ventricular systolic pressures, including the physiological range, were studied. Experiments were done under conditions of maximal vasodilatation and low ...
Krieg P - - 1998
OBJECTIVE: Pulmonary hypertension (PHT) is a life-threatening complication after isolated heart and lung transplantation. Recent work has shown that inhaled nitric oxide (NO) in combination with inhaled prostaglandin E1 (PGE1) reduce pulmonary hypertension but their influence on cardiac contractility is less well defined. METHODS: This study investigated left ventricular contractility ...
Brookes C I - - 1998
BACKGROUND: The variation in stroke volume and pulse pressure characteristic of atrial fibrillation is usually ascribed to time-dependent ventricular filling, implying a single positive relationship between end-systolic pressure and volume, which defines a single state of myocardial contractility. We tested the hypothesis that contractility also varies. METHODS AND RESULTS: We ...
Chang K C - - 1998
Systolic mechanical behavior of the ventricular pump can be quantified by both maximal systolic elastance and theoretical maximal flow. How sensitive these two model parameters are to changes in loading conditions has never been examined, however. The aim of the study is to determine the roles of these two parameters ...
Ratcliffe M B - - 1998
OBJECTIVES: Ventricular volume reduction surgery has been proposed by Batista to improve cardiac function in patients with dilated cardiomyopathy. However, limited clinical data exist to determine the efficacy of this operation. A finite element simulation is therefore used to determine the effect of volume reduction surgery on left ventricular end-systolic ...
Yamaguchi K - - 1998
We evaluated the usefulness of the newly defined Doppler index combining systolic and diastolic myocardial performance, in assessing right-heart dysfunction in 29 patients with chronic respiratory failure caused by old tuberculosis who were on 24-h home oxygen therapy. We measured tricuspid inflow velocity, right-ventricular outflow velocity, late/early diastolic peak velocities ...
Krösl P - - 1998
The use of end-systolic elastance as a parameter of left ventricular contractility is based on a theory put forward by Sagawa and is limited by an assumed linearity of the model for a time varying compliance. A major problem is the contractility-dependent curvilinearity of the end-systolic pressure-volume relationship (ESPVR), which ...
Hata Y - - 1998
We have already reported a curvilinear end-systolic pressure-volume relation and a linear oxygen consumption per beat (Vo2)-systolic pressure-volume area (PVA) relation of the left ventricle in the rat blood-perfused whole heart preparation. Recently, we have proposed that a PVA at an appropriate left-ventricular end-diastolic volume (0.15 ml/g), such as PVA0.15 ...
Nitenberg A - - 1998
Contractile performance of hypertrophied left ventricle may be depressed in arterial hypertension. Ventriculoarterial coupling is impaired when myocardial contractile performance is reduced and when afterload is increased. The left ventricular contractile performance and the ventriculoarterial coupling were evaluated in 30 hypertensive patients with moderate left ventricular hypertrophy and 20 control ...
Schertel E R - - 1998
There are three distinct phases of the cardiac cycle (contraction, active relaxation, and passive relaxation) which should be examined in order to perform a thorough assessment of global left-ventricular function. Accurate measurements of left-ventricular pressure and volume are necessary to assess these phases of the cardiac cycle. The ideal index ...
Steendijk P - - 1998
OBJECTIVES: In this study we quantified the effects of a critical coronary stenosis on global systolic function using pressure-volume relations at baseline and during incremental dobutamine stress. BACKGROUND: The effects of coronary stenosis have previously been analyzed mainly in terms of regional (dys)function. Global hemodynamics are generally considered normal until ...
Li B - - 1998
We applied the principles of cardiac mechanics to study the contraction cycles of postnodal sheep mesenteric lymphatic vessels in an in situ preparation. A segment of intestinal lymphatic was isolated from lymph input and provided with Krebs solution from a reservoir. Pressure-volume relationships were assessed under various transmural pressure conditions ...
Sundeman H - - 1998
The purpose of the investigation was to assess the effects of desflurane (DES) on left ventricular heart function during basal barbiturate anesthesia in a closed-pericardium, closed-chest acute swine model. The study was performed in 11 normoventilated adult pigs. Hemodynamic measurements were obtained using arterial, central venous, and pulmonary artery catheters, ...
Tanaka K - - 1998
The ratio of effective arterial elastance (Ea) to left ventricular elastance (Ees) is an indicator of the coupling between ventricular properties and arterial load properties. Another criterion for the coupling between an energy source and its load is the principle of economical fuel consumption, or mechanical efficiency, which is defined ...
Nakayama M - - 1998
BACKGROUND: Maximal left ventricular power (PWRmax) can index contractile function and reserve; however, its marked preload dependence mandates load adjustment to yield a more cardiac-specific measurement. Prior studies have used varying methods, but supporting data have generally been lacking. We hypothesized that the optimal approach for preload adjustment varies with ...
Pak P H - - 1998
BACKGROUND: Dual-chamber pacing can improve symptoms in hypertrophic cardiomyopathy (HCM), but the mechanism remains unclear. We hypothesized that pacing generates discoordinate contraction and a rightward shift of the end-systolic pressure-volume relation (ESPVR) and that benefits from this mechanism do not depend on the presence of resting outflow pressure gradients or ...
Ochiai Y - - 1998
OBJECTIVE: Amrinone, a selective phosphodiesterase III inhibitor, is reported to have a potent inotropic effect on the left ventricle, but the effects of this drug on right ventricular contractility in the clinical setting are unknown. The concept of ventricular/arterial coupling was applied to investigate the effects of amrinone on right ...
Kurotobi S - - 1998
Previous studies have demonstrated that regional wall motion abnormalities are common in univentricular hearts; however, the mechanism of this abnormality and its relation to hemodynamics remain unclear. The aim of this study was to document and analyze the etiology of regional wall motion abnormality and its relation to hemodynamics in ...
Bell S P - - 1998
Restoring forces, which are generated when the left ventricle contracts below its equilibrium volume (Veq), are responsible for diastolic suction. Their magnitude is inversely related to end-systolic volume (ESV). In previous studies in which the mitral valve was replaced with a prosthesis, increased contractility was shown to augment restoring forces ...
Dagianti A - - 1998
Although exercise stress echocardiography is currently used to evaluate coronary artery disease (CAD) patients, the best exercise methodology is still undefined. The objectives of the study were: (1) to compare supine bicycle stress echocardiography (SBSE) and treadmill in the evaluation of CAD; and (2) to define, in normal subjects, the ...
Hata Y - - 1998
We measured rat left ventricular pressure, volume, and oxygen consumption ( = arteriovenous oxygen content differencexcoronary flow) to establish a new evaluation of its mechanoenergetics in the whole heart preparation by using the cross-circulation method. We obtained a curved end-systolic pressure-volume relation in contrast to a linear end-systolic pressure-volume relation ...
Toyoda Y - - 1998
BACKGROUND: Although cardiomyoplasty (CMP) is thought to improve ventricular systolic function, its effects on ventricular diastolic function are not clear. Especially the effects on right ventricular diastolic filling have not been fully investigated. Because pericardial influences are more pronounced in the right ventricle than in the left ventricle, CMP with ...
Kawaguchi O - - 1998
OBJECTIVE: Cardiomyoplasty is a surgical procedure to support the failing heart, in which a burst-stimulated latissimus dorsi muscle flap is transposed and wrapped around the ventricles. The effect of dynamic cardiac compression, implemented as cardiomyoplasty, on left ventricular performance remains controversial; the mechanism by which clinical symptoms are improved remains ...
Williams R V - - 1998
The purposes of this study were to assess load-independent, end-systolic relationships in mice and compare these relationships to ejection phase indexes in assessing contractility. In 13 mice, ejection phase indexes (shortening fraction and velocity of fiber shortening) and end-systolic relationships [pressure-dimension relationship (ESPDR) and stress-velocity relationship (ESSVR)] were determined using ...
MacGowan G A - - 1998
OBJECTIVES: We sought to determine the precise myocardial effects of OPC-18790 as demonstrated by intracoronary administration. BACKGROUND: Although previous studies have determined the cardiovascular effects of a novel intravenous inotrope, OPC-18790, the observed benefits on contractile and diastolic function may have been confounded by the marked changes in peripheral loading ...
Asou T - - 1998
We developed a new method to estimate the end-diastolic pressure-volume relation (EDPVR) of the ejecting ventricle without directly measuring the ventricular volume. The following equation is derived from the ventricular elastance concept; Pes = Ees (Ved-Vo-Vj), where Pes is end-systolic pressure; Ees, end-systolic elastance; Ved, end-diastolic volume; Vo, an empirical ...
Sato T - - 1998
We developed a miniaturized conductance catheter for in situ rat left ventricular (LV) volumetry. After the validation study of the conductance volumetry in 11 rats, we characterized the end-systolic pressure-volume relationship (ESPVR) in 24 sinoaortic-denervated, vagotomized and urethan-anesthetized rats. Stroke volume (SV) measured with the conductance catheter correlated closely with ...
Gödje O - - 1998
OBJECTIVE: Monitoring of cardiac preload is mainly performed by measurement of central venous and pulmonary capillary wedge pressure in combination with assessment of cardiac output, applying the pulmonary arterial thermal dilution technique. However, the filling pressures are negatively influenced by mechanical ventilation and the pulmonary artery catheter is criticized because ...
Georgakopoulos D - - 1998
The mouse is the species of choice for creating genetically engineered models of human disease. To study detailed systolic and diastolic left ventricular (LV) chamber mechanics in mice in vivo, we developed a miniaturized conductance-manometer system. alpha-Chloralose-urethan-anesthetized animals were instrumented with a two-electrode pressure-volume catheter advanced via the LV apex ...
Urzua J - - 1998
We propose that it is possible to estimate cardiovascular parameters from the arterial pressure waveform, including ventricular maximal elastance and end-diastolic volume, if cardiac output is also known. We tested this hypothesis by means of a parameter estimation algorithm applied to simulated arterial pressure signals. The program first estimated three ...
Hanton G - - 1998
We have set up M-mode echocardiographic (EC) recording in beagles in our laboratory and generated reference values for EC indicators of left ventricle function and morphology. Additionally we assessed the effects of sex, strain and body weight on these parameters and the correlation between parameters. M-mode EC under two-dimensional guidance ...
Uozaki Y - - 1998
BACKGROUND: Little is known about left ventricular performance during venoarterial bypass and left heart bypass (LHB) after cross-clamping the descending thoracic aorta. We evaluated the effects of venoarterial bypass and LHB on ventricular load optimization and left ventricular work efficiency. METHODS: We used the left ventricular conductance catheter and a ...
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