BACKGROUND: In heart transplants, left ventricular function may be impaired in the absence of rejection or graft atherosclerosis. Matching between left ventricle and arterial receptor, i.e., ventriculoarterial coupling, and left ventricular efficiency have never been studied. METHODS: Left ventricular pressure-volume loops and single beat analysis were used to determine effective ...

As a result of a number of factors, there is tremendous diversity in the pattern of cardiac mechanics encountered in athletes. Nevertheless, several trends can be identified, and several conclusions are possible. Hypertrophy of a mild to moderate degree and out of proportion to body size is a common finding. ...

OBJECTIVE: Assessment of right ventricular volume and mass with three dimensional echocardiography and comparison with magnetic resonance imaging. METHODS: Measurements of right ventricular volumes performed on three dimensional datasets acquired by transthoracic echocardiography were compared to those obtained from magnetic resonance imaging performed on the same day. Volumes were measured ...

Although an increase in vagal tone is known to slow heart rate (HR), whether it also depresses left ventricular contractility through mechanisms independent of the bradycardic effect remains unknown. The chief aim of this investigation, therefore, was the separation of the observed vagally mediated depression of ventricular contractility into direct ...

Hemodynamic and oxygenation parameters were determined during the first 24 h in 13 burned patients with concomitant inhalation injury (burn surface area 40-60 percent). In all patients right ventricular function was severely compromised evidenced as a significant increase in end-diastolic volumes, decrease in ejection fractions, low stroke work indices and ...

BACKGROUND: We examined the ability of zinc-bis-histidinate to preserve postarrest myocardial function when added to a standard crystalloid cardioplegic solution. METHODS: Domestic pigs (35 to 50 kg) on left-sided cardiopulmonary bypass were subjected to 90 minutes of regional ischemia followed by 60 minutes of hypothermic cardioplegic arrest induced by antegrade ...

This study examines the accuracy of the conductance catheter technique and, in particular, parallel conductance [expressed as offset volume (Vc)] changes during the cardiac cycle in the human left ventricle. Two groups of patients were assessed: group 1, with an open atrial septal defect, and group 2, with an interventricular ...

OBJECTIVES: Reports of improved ejection fraction, coupled with decreased filling pressures, have prompted a number of centers to begin evaluating the efficacy of heart reduction surgery to ameliorate symptoms of heart failure. However, the impact of this operation on cardiac mechanics is unknown. We applied a multiple compartment elastance model ...

The ability to clinically assess myocardial contractility in a load-independent fashion facilitates the selection of appropriate inotropes, when needed, during shock resuscitation. Within the framework of the ventricular pressure-volume diagram, the slope of the ventricular end-systolic pressure-volume relationship (expressed as ventricular end-systolic elastance, Ees), has been shown to accurately reflect ...

BACKGROUND: Mechanical ventilation resulted in increased, decreased or unchanged end-diastolic volumes together with either profoundly decreased or unchanged right ventricular ejection fraction (RVEF). The goal of our study was, therefore, to evaluate the effects of positive end-expiratory pressure on measurements of RVEF performed during apneic periods with different levels of ...

Three-compartment elastance modeling predicts that the magnitude of gain is solely dependent on the ratio of free wall and septal elastances. However, when nonlinearities in pressure-volume relationships are considered, the same model predicts that gain is load dependent. We therefore studied left-to-right ventricular interactions in the isolated cross-perfused canine heart ...

BACKGROUND: Coronary bypass grafting of posterior circumflex branches requires full displacement of the heart (apex pointing ventrally), which, in the beating heart, results in an arterial pressure drop. We analyzed its origin. METHODS: To facilitate displacement, the Utrecht "Octopus" method was applied in 8 anesthetized beta-blocked pigs and the beating ...

OBJECTIVES: The effects of changes in preload on paradoxical myocardial wall motion during ischemia have been previously studied. However, the studies have been performed using slow volume changes. It was decided to study the effects of fast changes in preload, which would occur during caval occlusion, on the regional pressure-length ...

STUDY OBJECTIVES: Electrical impedance tomography (EIT) offers the possibility to study blood volume changes within the right atrium during the cardiac cycle. The aim of this study was to determine the applicability of EIT in the assessment of right ventricular diastolic function in COPD. DESIGN: By means of region of ...

To evaluate changes in the right ventricular volume in early human neonates, twenty fullterm infants were examined at 2, 24 and 120 h of age by two-dimensional echocardiography. End-diastolic and end-systolic right ventricular volumes (RVEDV and RVESV, respectively) were calculated with a computer system based on the bi-plane Simpson's rule ...

Ventriculo-arterial coupling is expressed as the ratio Emax/eam (maximum ventricular elastance/arterial elastance). Different areas under the end-systolic pressure-volume relation (ESPVR) are expressed in terms of Emax/eam. The explicit inclusion of the active force of the myocardium in the mathematical formalism describing the pressure-volume relation (PVR) leads to new insight into ...

OBJECTIVES: The aim of this study was to examine the left ventricular mechanoenergetic effects of a novel Ca2+ sensitizing agent, MCI-154, on diseased human hearts compared with dobutamine. BACKGROUND: Unlike conventional cardiotonic agents, a Ca2+ sensitizer that could produce a positive inotropic action by altering the responsiveness of myofilament to ...

To automate analysis of left ventricular pressure-volume data, we used LabVIEW to create applications that digitize and display data recorded from conductance and manometric catheters. Applications separate data into cardiac cycles, calculate parallel conductance, and calculate indices of left ventricular function, including end-systolic elastance, preload-recruitable stroke work, stroke volume, ejection ...

This contribution reviews the regulation of left ventricular pressure (LVP) fall by load and relates this regulation to left ventricular contractility. Load regulation of LVP fall has to be distinguished from neurohumoral regulation, from effects induced by arterial reflected waves and from long-term load effects on contractility. The response of ...

We investigated whether strain softening (or the Mullins effect) may explain the reduced left ventricular stiffness previously associated with the strain-history-dependent preconditioning phenomenon. Passive pressure-volume relations were measured in the isolated, arrested rat heart during LV balloon inflation and deflation cycles. With inflation to a new higher maximum pressure, the ...

We investigated the acute effects of the positive inotropic agents (dobutamine and a novel phosphodiesterase inhibitor OPC-18790) on left ventricular diastolic chamber stiffness in patients with idiopathic dilated cardiomyopathy (DCM). We obtained pressure-volume (PV) data before and after drug administration in 17 patients with DCM by using a conductance catheter ...

Stroke volume estimates and left ventricular ejection time (1) derived from calibrated finger pulse pressure recordings (Portapres 2, TNO-BMI, Amsterdam) based on the Model Flow method and (2) derived from impedance cardiography were compared in 20 student subjects. The recordings were made for seven conditions: supine rest, standing, mental arithmetic, ...

Myocardial mechanics and energetics were investigated in an animal model of moderate chronic heart failure (CHF) created by repeated coronary microembolizations in six dogs. The final fractional area change was 34 +/- 4%. Hearts of these animals were isolated and cross-perfused, and balloons were placed in the left ventricle (LV). ...

OBJECTIVE: The classical description of ventriculoarterial coupling by calculating the ratio between the effective arterial elastance Ea to the end-systolic elastance Ees does not give insight into the underlying dynamics of the interaction between left-ventricular pressure (LVP) and aortic pressure (AOP) and flow (AOF). The aim of this study was ...

We investigated rat left ventricular (LV) mechanoenergetics in three different preparations. We obtained an upward convex curvilinear end-systolic pressure-volume relation (ESPVR) regardless of left ventricular (LV) contractility in in situ and excised cross-circulated rat hearts. We also obtained a linear myocardial O2 consumption per beat (VO2)-end-systolic pressure-volume area (PVA; a ...

The aim of this study was to clarify that the depressed mechanoenergetics in patients with idiopathic dilated cardiomyopathy (DCM) resulted from compensation for the decreased contractility. The study population consisted of eight control subjects, with normal left ventricular size and ejection fraction and 31 patients with DCM. Left ventricular end-systolic ...

Ventricular preload is an important determinant of cardiac function, which is indirectly measured in the clinical setting by the pulmonary capillary wedge pressure (PCWP). Transesophageal echocardiography (TEE) is rapidly gaining acceptance as a monitor of cardiac function. Although it provides high-resolution images of cardiac structures, clinical assessment of ventricular preload ...

This article reviews the determinants of myocardial oxygen supply (MVO2) and consumption and revisits the effects of IABC on each. Measurements of MVO2, including diastolic pressure-time index (DPTI), tension-time index (TTI), and endocardial viability ratios (EVR), demonstrate the dramatic effects of balloon deflation and the resulting afterload reduction on MVO2. ...

A new method of presenting the in vivo left ventricular pressure-flow data is developed in the present study. This separates left ventricle ejection into unrestricted, progressively restricted and severely restricted cases. This method uses ejection volume and time to define a normalizing 'stroke' pressure, which is successful in collapsing the ...

BACKGROUND: The end-systolic pressure-volume relation (ESPVR) provides a useful measure of contractile function. However, the need to acquire multiple cardiac cycles at varying loads limits its applicability. We therefore developed and tested a novel single-beat estimation method that is based on normalized human time-varying elastance curves [EN(tN)]. METHODS AND RESULTS: ...

The dynamics of intraventricular blood flow, i.e. its rapid evolution, implies the rise of intraventricular pressure gradients (IPGs) characteristic of the inertia-driven events as experimentally observed by Pasipoularides (1987, 1990) and by Falsetti et al. (1986). The IPG time course is determined by the wall contraction which, in turn, depends ...

BACKGROUND: Nonischemic segmental performance, assessed by end-systolic measures of shortening and thickening, decreases during ischemia. These changes in performance are likely to be dependent on the size, and, possibly, the site of the ischemic zone. This study was designed to examine the effect of preload, independently from ischemic zone size, ...

OBJECTIVE: Our purpose was to evaluate cardiac variables, including right and left end-diastolic and end-systolic dimensions by use of M-mode echocardiography during fetal, neonatal (transitional), and infancy periods to understand hemodynamic adaptation during these periods. STUDY DESIGN: Fifty-three fetuses were enrolled in this study. Echocardiography evaluations were started as early ...

Coronary artery disease and ischemic myocardial damage form the most common cause of failure of the heart to pump enough blood for oxygenation of the body at a healthy blood pressure and at a low pressure in the veins. This paper gives an overview of the mechanisms involved in excitation-contraction ...

BACKGROUND: Previous studies in cardiac muscle and isolated heart preparations generally have attributed positive effects of ejection to greater length-dependent activation. However, there have been some reports of an ejection-related increase in contractile function that is independent of end-diastolic volume (EDV) history. The present study was designed to more fully ...

The effect of inferior vena cava occlusion (IVCO) on end-systolic pressure-volume relations (ESPVR) of the left ventricle was studied in intact canine hearts. In 12 anesthetized open-chest dogs, left ventricular (LV) pressure and volume were measured simultaneously using a microtip catheter and a conductance catheter, respectively. ESPVR was constructed from ...

BACKGROUND: Mechanoelectric feedback, the process by which changes in mechanical activity change the electrophysiology of the myocardium, has been linked to the genesis of arrhythmias. We investigated possible arrhythmogenic mechanisms by measuring changes in steady-state action potential duration and, more particularly, electrical restitution on a transiently applied load change, because ...

BACKGROUND: The Frank-Starling mechanism is one of the most important physiological principles for regulation of contractile performance. We therefore studied the question of whether this mechanism may be absent or attenuated in end-stage failing human left ventricular myocardium. METHODS AND RESULTS: Different methodological approaches were used to analyze the effects ...

BACKGROUND: The effects of desflurane, sevoflurane, and isoflurane on left ventricular-arterial coupling and mechanical efficiency were examined and compared in acutely instrumented dogs. METHODS: Twenty-four open-chest, barbiturate-anesthetized dogs were instrumented for measurement of aortic and left ventricular (LV) pressure (micromanometer-tipped catheter), dP/dtmax, and LV volume (conductance catheter). Myocardial contractility was ...

Clinical and experimental observations in humans and animals have shown that different cardiac adaptations occur in response to different types of hemodynamic overload. However, very little is known about how different hemodynamic loads lead to these different cardiac adaptations. Accordingly, we studied the acute response of ejecting isolated rabbit hearts ...

A series of 14 patients with heart failure due to coronary artery disease and impaired left ventricular function underwent radionuclide ventriculography with simultaneous thermodilution measurement of cardiac output by pulmonary artery catheter on two occasions (m1, m2) separated by 6 weeks in order to determine the reproducibility of haemodynamic and ...

AIMS: Increased sympathetic stimulation is known to be arrhythmogenic. Likewise increased loading of the myocardium can directly generate arrhythmias. The interaction between the two on the electrophysiology of the myocardium has not been investigated before. We investigated the effect of dobutamine infusion on the shortening of the monophasic action potential ...

OBJECTIVE: To investigate the functional and metabolic changes in the myocardium after successful resuscitation from cardiac arrest. DESIGN: Prospective, randomized, sham-controlled study. SETTING: Animal laboratory at a university center. SUBJECTS: Domestic pigs. INTERVENTIONS: Electric induction of ventricular fibrillation by alternating current delivered to the right ventricular endocardium through a pacing ...

OBJECTIVE: To determine if left ventricular torsion, as measured by magnetic resonance tissue tagging, is afterload dependent in a canine isolated heart model in which neurohumoral responses are absent, and preload is constant. METHODS: In ten isolated, blood perfused, ejecting, canine hearts, three afterloads were studied, while keeping preload constant: ...

BACKGROUND: Correct timing of mechanical interaction between wrapped latissimus dorsi muscle (LDM) and the heart during cardiac systole has been poorly understood and remains a controversial issue. Therefore, left ventricular pressure-volume relations were analyzed in acute cardiomyoplasty while changing the synchronization delays. METHODS: Effects of different delays between the sensed ...

The objective of this study was to examine the effects of wave propagation properties (global reflection coefficient gamma IG; pulse wave velocity, c(ph); and characteristic impedance zeta(o) on the mechanical performance of the coupled left ventricle-arterial system. Specifically, we sought to quantify effects on aortic pressure (P(ao)) and flow Q(ao) ...

Animal data indicate that chronic, overnight pacing at normal evening heart rates impairs cardiac function. We examined the relationship of pacing rate and cardiac function in nine patients with dual-chamber pacemakers. We investigated two, 3-week pacing regimens (80 and 50 ppm: DDD mode) in a cross-over design. Doppler echocardiograms were ...

Evaluating cardiac gene therapy in the intact animal requires an index of cardiac function capable of detecting regional differences in contractility in a load-independent fashion. Potentially load-insensitive measures of ventricular performance were therefore evaluated in 10 open- and closed-chested, anesthetized rabbits. LV transmural pressure and myocardial segment length were measured ...

OBJECTIVE: We investigated whether ibuprofen could prevent early decrease in left ventricular contractility that occurs during porcine endotoxemia. DESIGN: Prospective, randomized, controlled animal study. SETTING: University research laboratory. SUBJECTS: Adolescent crossbred pigs (n = 28). INTERVENTIONS: Anesthetized pigs were instrumented to measure hemodynamics and left ventricular pressures (using a Millar ...

The Frank-Starling relationship between left ventricular stroke work and end-diastolic minor-axis cross-sectional area was evaluated as a load-insensitive measure of inotropic state by two-dimensional echocardiography in 10 conscious dogs. Stroke work was calculated as the product of systolic change in cross-sectional area and either (1) beat-to-beat mean arterial pressure or ...