Source parameters of the left ventricle related to the physiological characteristics of the cardiac muscle

Sideman, S.

doi:10.1016/s0006-3495(86)83746-8

Cited by 9 publications

(3 citation statements)

References 30 publications

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“…10 Under these conditions, ventricular cavity elongation occurs (ie, mitral valve billowing 19 ), yet muscle contraction causes this effect. The observed differentiation between initial narrowing and later shortening opposes the concept of synchronous contraction 21,22 with a uniform or concomitant strain field across the ventricular wall 23,24 because inhomogeneous strain (deformation) develops during contractile wave propagation. 25 Until now, evaluation of regional strain during global ventricular motion was limited by insufficient spatial and temporal resolution of imaging technology.…”

Section: Basic Ventricular Function Updatedmentioning

confidence: 74%

Cardiac Mechanics Revisited

et al. 2008

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Abstract-The keynote to understanding cardiac function is recognizing the underlying architecture responsible for the contractile mechanisms that produce the narrowing, shortening, lengthening, widening, and twisting disclosed by echocardiographic and magnetic resonance technology. Despite background knowledge of a spiral clockwise and counterclockwise arrangement of muscle fibers, issues about the exact architecture, interrelationships, and function of the different sets of muscle fibers remain to be resolved. This report (1) details observed patterns of cardiac dynamic directional and twisting motions via multiple imaging sources; (2) summarizes the deficiencies of correlations between ventricular function and known ventricular muscle architecture; (3) correlates known cardiac motions with the functional anatomy within the helical ventricular myocardial band; and (4) defines an innovative muscular systolic mechanism that challenges the previously described concept of "isovolumic relaxation Key Words: diastole Ⅲ heart failure Ⅲ muscles Ⅲ ventricles C ongestive heart failure, due usually to both left ventricular (LV) and right ventricular failure, is an increasing problem worldwide. In the United States, Ϸ5 million patients suffer from congestive heart failure, and each year Ϸ500 000 new patients develop the condition. 1 Originally, this syndrome was believed to be due to failure of the LV to pump blood efficiently (ie, systolic ventricular failure). More recently, emphasis has been placed on diastolic ventricular failure, in which systolic function appears to be normal but diastolic ventricular function is impaired. 2-4 Diastolic dysfunction, in fact, may be the cause of congestive heart failure in up to 50% of these patients. 5,6 We have had treatment for systolic ventricular failure for many years, even if it is imperfect; at present, however, no agreement has been reached about the best ways of treating diastolic ventricular failure. To develop better treatments for congestive heart failure, both systolic and diastolic, we need first to understand the basic physiology of normal and abnormal ventricular contraction and relaxation.The heart is a muscular pump that supplies blood to the body. This goal is achieved by electric excitation that produces sequential ventricular emptying and filling. Figure 1a demonstrates the physiological sequence of ventricular function: an isovolumic contraction phase to develop preejection tension, ejection, a postejection isovolumic phase, and then rapid and slow periods for filling. LV volume decreases rapidly early in systole and slowly thereafter, corresponding to the rapid early acceleration in the flow curve. The volume then increases rapidly in early filling and more slowly during late filling.The information shown in Figure 1a is still correct, but it is only slightly more informative than the concept of William Harvey, who concluded, after dissecting cadaver hearts, that the heart squeezed by constriction to eject and dilated passively to fill. This accepted view of car...

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Section: Basic Ventricular Function Updatedmentioning

confidence: 74%

Cardiac Mechanics Revisited

et al. 2008

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“…*)• Reported experimental data ( Figure 3B shows that with self-perfusion of the ventricle, the computer-simulated end-systolic pressurevolume relation adopted a nonlinear shape as experimentally observed in isolated canine heart. 20 19). Note that end-systolic pressurevolume points follow a nonlinear curve as observed by Sunagawa et al 20 Vtf end-diastolic volume; Sp, self-perfusion.…”

Section: Substitution Of E(t) In Equation 4 By Its Definition In Equamentioning

confidence: 79%

“…For simplicity we will substitute P[t, CS, V(t), dV/dt(t)] by P(t), and Pe[t, CS, V(t)] by Pe(t). To model ventricular properties 19 in both isolated heart 12 and isolated muscle, Rj(t) was found to be related to Pe(t) in the following way:…”

Section: Mathematical Foundations Of Digital Simulation Of Left Ventrmentioning

confidence: 99%

A computer study of the relation between chamber mechanical properties and mean pressure-mean flow of the left ventricle.

Negroni

Lascano

Pichel

1988

Circulation Research

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Computer simulation of left ventricular contraction was used to analyze the mean left ventricular pressure-mean flow relation with changes of parameter values: end-diastolic volume, contractile state, internal resistance, characteristic resistance, capacitance, end-diastolic stiffness, and heart rate and with changes of experimental conditions: filling kinetics (constant atrial pressure as opposed to constant end-diastolic volume) and coronary perfusion pressure (constant or varying with atrial pressure, i.e., self-perfused). The chamber mechanical properties used in the simulation were defined in terms of a modified purely elastic behavior model with a flow-dependent resistive component. Computed results showed that at constant end-diastolic volume and constant ventricular perfusion pressure the mean pressure-mean flow relation was linear, except for changes in internal resistance where a cubic fit of points was more appropriate. In these conditions, parameter variations in the accepted linear relation produced changes in the slope and mean pressure axis intercept. Imposition of changes in experimental conditions gave rise to nonlinear mean pressure-mean flow relations. The results indicate that with elastic-resistive chamber mechanical properties as a starting point, the experimental conditions would be responsible for the different shapes of the mean pressure-mean flow relation obtained in isolated heart experiments. However, a more complete description of chamber properties (such as the addition of a deactivation component) could also give rise to nonlinear pump function graphs.

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Integrative and Interactive Studies of the Cardiac System: Deciphering the Cardionome

Sideman

1997

Advances in Experimental Medicine and Biology

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Source parameters of the left ventricle related to the physiological characteristics of the cardiac muscle

Cited by 9 publications

References 30 publications

Cardiac Mechanics Revisited

Cardiac Mechanics Revisited

A computer study of the relation between chamber mechanical properties and mean pressure-mean flow of the left ventricle.

Integrative and Interactive Studies of the Cardiac System: Deciphering the Cardionome

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