Search Results
Results 551 - 600 of 1604
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Myrmel T - - 1995
Freeman et al. (1993) have recently introduced a new index measuring isovolumic relaxation in the in situ left ventricle. This index, called the R-average, shows less variability than the traditionally used monoexponential time constant (tau), and could therefore represent an alternative measure of isovolumic relaxation during different physiological or pathophysiological ...
Patteson M W - - 1995
Twenty-six horses were sedated with detomidine hydrochloride (Domosedan, SmithKline Beecham Animal Health, Tadworth, Surrey, UK) at a dose of 10 micrograms/kg bwt, administered i.v. Echocardiograms were recorded before and after sedation, measurements of cardiac dimensions were made and functional indices were calculated. The pre- and post sedation values were compared. ...
Nishikawa Y - - 1995
We examined endotoxin-induced myocardial depression in 31 anesthetized rabbits using left ventricular end-systolic and end-diastolic pressure-volume relationships (sonomicrometers). In the control group, endotoxin (100 micrograms/kg iv) induced systolic depression (> 10% increase in end-systolic volume at matched end-systolic pressure) in 9 of 16 and diastolic dilation (> 10% increase in ...
Herbertson M J - - 1995
It is not known how the decrease in left ventricular contractility following endotoxin exposure is mediated, or whether this decrease is preventable by antibodies to tumor necrosis factor-alpha (TNF alpha). Four groups of six anesthetized and instrumented pigs were pretreated with ovine polyclonal antibody to human TNF alpha (anti-TNF alpha), ...
Werner H A - - 1995
Systolic and diastolic dysfunction occur during human septic shock, and sensitivity to beta-adrenergic agents is reduced. We sought to determine whether amrinone, an inotropic agent independent of beta-receptors, increases left-ventricular contractility or diastolic compliance after endotoxin infusion. We measured left-ventricular volume (using a conductance catheter) and pressure (using a Millar ...
de Morais H S - - 1995
The effects of medetomidine on load-dependent and relatively load-independent indices of left ventricular contractility and hemodynamics were studied in 8 chloralose-anesthetized, autonomic-blocked dogs. Left ventricular contractility was assessed by the maximum rate of increase in pressure (dP/dtmax), the slope of the end-systolic pressure volume relationship (Ees), preload recruitable stroke work ...
Wallace A - - 1995
Measures of left ventricular (LV) contractility must be linear, load-independent, free of hysteresis, and sensitive to changes in inotropic state. These properties of measures of LV contractility have been assessed previously in animals, but never in man. Using a micromanometer and volume conductance catheter technology, we measured LV pressure and ...
Goertz A W - - 1995
BACKGROUND: Although a positive inotropic effect of hypertonic saline has been demonstrated in isolated cardiac tissue as well as in animal preparations, no information exists about a possible positive inotropic action of hypertonic saline in humans. The aim of this investigation was to determine whether a clinically relevant positive inotropic ...
Dickstein M L - - 1995
OBJECTIVE: Since the conductance catheter method has facilitated evaluation of left ventricular contractile state in both laboratory and clinical studies, the aim of this study was to determine whether the technique is similarly useful for the right ventricle. METHODS: A series of right ventricular pressure-volume loops was obtained in seven ...
Wolff M R - - 1995
To examine the role of alterations in myofibrillar function in chronic heart failure, we determined isometric tension-pCa relations in permeabilized myocardium from a canine model of dilated cardiomyopathy (DCM) produced by chronic rapid pacing. In the initial series of experiments, seven dogs were paced at 250 beats per minute for ...
Kass D A - - 1995
BACKGROUND: Cardiomyoplasty (CM) is a novel surgical therapy for dilated cardiomyopathy. In this procedure, the latissimus dorsi muscle is wrapped around the heart and chronically paced synchronously with ventricular systole. While studies have found symptomatic improvement from this therapy, the mechanisms by which CM confers benefit remain uncertain. This study ...
Klautz R J - - 1995
OBJECTIVES: We undertook the present study to determine whether afterload and contractility interact in the hearts of newborn lambs. We specifically investigated whether stepwise increases in afterload increase contractility. BACKGROUND: Several studies in the isolated and intact adult dog heart have shown that afterload and contractility are not independent determinants ...
Schreuder J J - - 1995
BACKGROUND: Since the clinical introduction of dynamic cardiomyoplasty, a discrepancy has been observed between unchanged measurements of cardiac function and improved clinical outcome. METHODS AND RESULTS: We performed a beat-to-beat analysis of cardiac performance at rest in nine cardiomyoplasty patients 6 to 24 months after operation. Conductance and micromanometer catheters ...
Kitano M - - 1995
Right ventricular function during left heart bypass was evaluated by volumetric analysis with a conductance catheter in 12 dogs with postischemic cardiac dysfunction. The conductance catheter was used to assess the volumetric status of the right ventricle and thereby allowed a right ventricular pressure-volume curve to be obtained, in which ...
Kawaguchi O - - 1995
This study assessed whether the end-systolic pressure-volume relationship obtained without any interventions during pulsatile left ventricular bypass adequately represents native heart function. In 11 anesthetized Holstein calves, left ventricular pressure was measured with a micromanometer while left ventricular volume was simultaneously calculated from orthogonal left ventricular diameters measured with ultrasonic ...
Yu M - - 1995
OBJECTIVE: To determine if treatment modalities (fluid, inotropes, and blood) would be altered based on preload measurements of right ventricular end-diastolic volume index measured by fast response thermodilution catheter, as compared with pulmonary artery occlusion pressure (PAOP). DESIGN: A prospective clinical trial. SETTING: An 11-bed surgical intensive care unit (ICU) ...
Szwarc R S - - 1995
The conductance catheter gain factor, alpha, is usually determined by an independent measure of stroke volume and, as such, is assumed to be constant. However, nonlinearity of the conductance-volume relation has been proposed on theoretical grounds. The present study was designed to establish the extent of nonlinearity, or variability of ...
Amory H - - 1995
Forty-one and 55 records of right-sided and systemic arterial pressures, cardiac output, and end-diastolic and end-systolic right ventricular volumes were collected from a group of 6 conventional and 6 double-muscled calves, respectively. In each group, the mean right ventricular pressure-volume loop was constructed. Global cardiac performance was significantly lower in ...
Araki J - - 1995
We studied the mechanoenergetic effects of a short-term Ca(2+)-free, high-Ca2+ Tyrode solution coronary perfusion in eight excised, cross-circulated canine hearts. The perfusion protocol consisted of coronary perfusion with Ca(2+)-free Tyrode solution for 10 min followed by high-Ca2+ (16 mM) Tyrode solution for 5 min. This new protocol successfully induced acute ...
Yang Y - - 1995
The effect of sublingual administration and intravenous drip of nitroglycerin (SLNTG and IVNTG) on left ventricular volumes (LVVs) were studied and systolic function was quantitatively assessed with two-dimensional echocardiography (2DE) in 28 patients with myocardial infarction (MI), including 13 cases without heart failure (MI-NHF) in one group and 15 with ...
Dalmas S - - 1995
Post-systolic shortening is a wall motion abnormality defined as shortening of cardiac muscle after the end of ejection and usually regarded as a manifestation of ischaemia. This study was designed to determine whether changes in preload may alter the magnitude of ischaemia-induced post-systolic shortening. Eleven beagles were anaesthetized (halothane 0.8%) ...
Fan D - - 1995
OBJECTIVE: Oxygen consumption (MVO2) of stunned myocardium is relatively high compared to, and poorly correlated with, systolic contractile function. The aim of this study was to investigate whether an increased afterload dependency, induced by the decreased contractility of the stunned myocardium, contributes to the large variability in the mechanical efficiency ...
Terry J D - - 1995
This study demonstrates that when vascular resistance is low, peak systolic velocity and peak flow volume increase with increasing blood pressure. We used ischemia with reactive hyperemia to create reproducible low resistance conditions in 32 volunteers. Ischemia resulted in sharp increases in systolic and diastolic velocities, while the difference between ...
Wang S Y - - 1995
BACKGROUND: Vasodilator drugs have variable effects on veins and arteries. However, direct measurements of their effects on the splanchnic veins, perhaps the most important volume reservoir, have not been reported. We assessed the effect of acute heart failure and the subsequent administration of hydralazine, enalaprilat, and nitroglycerin on the splanchnic ...
Suzuki K - - 1995
The effects of hypertonic saline-dextran (HSD) on cardiac contractility and hemodynamics after burns were studied in anesthetized animals with full-thickness 50% total body surface area burns that were resuscitated with HSD or lactated Ringer solution (LR) alone. No significant difference in cardiac contractility during 6 h postburn was observed between ...
Taylor T W - - 1995
A realistic model of the left ventricle of the heart was previously constructed, using a cast from a dog heart which was in diastole. Previous studies of the three-dimensional heart model were conducted in systole only. The purpose of this investigation was to extend the model to both systole and ...
O'Brien P D - - 1995
BACKGROUND: Ultrasonic backscatter demonstrates a cardiac cycle-dependent modulation. The exact mechanism of the modulation is under debate. The objective of the present study was to test the hypothesis that a change in size and configuration of myofilaments from systole to diastole alters acoustic propagation properties and backscatter. METHODS AND RESULTS: ...
Takaoka H - - 1995
Studies reported in the literature show that the stroke work (SW) versus end-diastolic volume (Ved) relationship, namely, the preload recruitable stroke work relation (PRSW), is experimentally linear in closed-chest dog hearts and its slope reflects left ventricular contractility. We considered the theoretical cardiodynamic conditions necessary for the linearity of the ...
Burkhoff D - - 1995
The impact of ventricular volume on the relationship between intracellular calcium and ventricular pressure under steady-state conditions was determined in intact ferret hearts. The results reveal major quantitative differences and minor qualitative differences between these relations and those previously measured in isolated intact and skinned cardiac muscle. The importance of ...
Gibbs C L - - 1995
1. Recent developments which attempt to identify the mechanical determinants of myocardial oxygen consumption (mVO2) are considered, with emphasis being placed on the pressure-work and pressure-volume area (PVA) indices. 2. The difficulty of establishing a realistic in vivo basal mVO2 value is explained and the experimental reasons for the controversy ...
Gallo P - - 1995
Dilated cardiomyopathy is characterized by an increase in myocardial mass. In order to study the functional significance of myocellular hypertrophy in dilated cardiomyopathy, 40 left ventricular endomyocardial biopsies were investigated, by comparing morphometrical data with functional indexes. The extent of myofibril volume fraction was directly associated with a better functional ...
Wang Z - - 1995
Left ventricles of control dog hearts and dog hearts failing due to chronic tachycardia were examined in vivo by echocardiography for systolic function and size, then subsequently studied with an isolated-heart system (artificial perfusion, artificial loading). During 3 weeks of tachycardia (250 bt/min), area ejection fraction fell by 58%, while ...
Eichhorn E J - - 1995
OBJECTIVES: The aim of this study was to determine which patients will have systolic and diastolic improvement after beta-blockade with metoprolol. BACKGROUND: Beta-adrenergic blocking agents improve systolic and diastolic function in patients with heart failure. However, it is unclear which patients will respond best to therapy. METHODS: We retrospectively examined ...
You J - - 1995
Although cardiomyoplasty has become a recognized treatment for end-stage heart failure, the effects of this procedure on systolic and diastolic function are still unclear. To determine the effects of paced and non-paced latissimus dorsi cardiomyoplasty on systolic and diastolic function, the maximal elastance of the left ventricle (Emax), stroke volume, ...
Bloch K E - - 1994
Thoracocardiography noninvasively estimates left ventricular performance by recording ventricular volume curves with inductive plethysmography. We studied timing of these curves to evaluate their potential to accurately track systolic time intervals in comparison with standard methods. Thoracocardiographic left ventricular volume curves, carotid pressure pulses determined by applanation tonometry, the phonocardiogram and ...
Marsch S C - - 1994
Though a sustained post-ischemic decrease in contractile function has been clearly established, post-ischemic diastolic function has not been thoroughly investigated. Accordingly, 11 anesthetized (isoflurane 1%) open-chest beagles were instrumented to measure left ventricular pressure and dimensions (circumferential length and wall thickness) in an apicoanterior area supplied by the left anterior ...
Huguet M - - 1994
Monoclonal 111In antimyosin (AMS) uptake indicates the presence of ongoing myocyte damage. In idiopathic dilated cardiomyopathy (IDC), there is diffuse myocyte damage. We have attempted to find a correlation between AMS uptake and functional myocardial parameters. With this purpose in mind, we studied two groups of subjects: group 1 comprised ...
Parker M M - - 1994
OBJECTIVE: To evaluate left ventricular performance in patients with septic shock, using a load-independent measure of left ventricular systolic function, the peak systolic pressure/end-systolic volume index ratio. SETTING: National Institutes of Health research facility. DESIGN: Prospective study with retrospective analysis of data. PATIENTS: Twenty-seven patients with septic shock, 13 critically ...
Ezzaher A - - 1994
BACKGROUND: Systolic shortening is known to produce muscle deactivation. The present study was designed to analyze whether the velocity and the timing of ejection play a role on end-systolic pressure-volume relations (ESPVR). METHODS AND RESULTS: In isolated rabbit hearts, left ventricular pressure and volume were recorded and digitized, and left ...
Aklog L - - 1994
BACKGROUND: Dynamic cardiomyoplasty remains a promising but poorly understood surgical modality for selected patients with dilated cardiomyopathy. Despite encouraging clinical results, objective evidence of enhanced ventricular function using traditional indexes (cardiac output, ejection fraction, and dP/dt) has been difficult to document after cardiomyoplasty. Several investigators have suggested that cardiomyoplasty acts ...
Morris-Thurgood J - - 1994
BACKGROUND AND PURPOSE: Heterotopic cardiac transplantation is a valuable surgical technique that maximizes the use of donor organs. However, recipient heart function may decline steadily postoperatively with resulting clinical deterioration. Paced linkage has the potential of reducing afterload and enhancing coronary flow of both hearts, thereby improving recipient- and donor-heart ...
Shoucri R M - - 1994
The concept of external work reserve (EWR) related to the end-systolic pressure-volume relation in the left ventricle and introduced in previous publications is investigated. The potential clinical usefulness of indexes related to EWR as well as to different areas under the end-systolic pressure volume line (ESPVL) is indicated. The possibility ...
Coulshed D S - - 1994
INTRODUCTION: Contraction-excitation feedback may be an important factor in arrhythmogenesis in patients with heart failure. We have previously demonstrated the contrasting effects of raising left ventricular end-diastolic pressure on action potential duration in dog and guinea pig hearts. The current study was undertaken to assess whether these differing effects might ...
Noble M I - - 1994
1. An increase in length in isolated animal muscles causes an immediate increase in contractile force, which is followed by a slower further progressive increase: the slow component. However, the pressure-volume concept, used in characterizing left ventricular function, is dependent on a constant relationship between pressure and volume. 2. We ...
van der Linden L P - - 1994
Because of the strong dependency of the end-systolic pressure-volume relation on the type of transient loading intervention in the in situ left ventricle (LV), experiments in the basal inotropic state in 16 open-chest anesthetized dogs were reanalyzed to find additional variables to model and predict end-systolic pressure (ESP) of both ...
Eichhorn E J - - 1994
The factors that determine left ventricular end-diastolic pressure (LVEDP) are not completely understood. While many investigators measure relaxation in patients with heart failure, its relative functional importance remains unclear. The authors studied 22 patients with cardiomyopathy before and after 3 months of therapy with metoprolol or placebo. At catheterization, LVEDP, ...
González-Fernández Robert A. - - 1994
To investigate the dose-related hemodynamic effects of angiotensin-converting enzyme inhibition (ACEI) in patients with angina pectoris (AP), five patients underwent right and left heart catheterization, and left ventriculogram before and 10 min after administration of 1.25 mg enalaprilat intravenously (Group 1). The results were compared with those of five patients ...
Cowell R - - 1994
It has been shown that following heterotopic heart transplantation the recipient left ventricle ejects more effectively when it contracts out of phase with the donor left ventricle. However, this is rarely the situation, as the two hearts beat independently of one another and the denervated donor heart tends to beat ...
Moon M R - - 1994
During chordal-sparing mitral valve replacement (MVR), some recommend anatomic reattachment of the anterior leaflet chordae to the anterior annulus; others advocate shifting the chordae to the posterior annulus. To compare the results of these techniques with those of conventional MVR (total chordal excision), 21 dogs were studied 5 to 12 ...
van Daele M E - - 1994
BACKGROUND: Preoperative acute hypervolemic hemodilution is used in anesthesia to reduce the loss of blood cells during intraoperative bleeding. Indications for use of the technique might be broadened if it can be shown to be safe in older as well as younger patients. Few data are available describing heart function ...
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