Some factors that influence mechanical behavior of the left ventricle of the human heart in late systole: a feasibility study using finite element analysis
Al. Yettram et al., Some factors that influence mechanical behavior of the left ventricle of the human heart in late systole: a feasibility study using finite element analysis, HEART VESS, 13(6), 1998, pp. 290-301
In systole the left ventricle of the heart behaves mechanically in two mode
s simultaneously, passive and active. When in the former mode, the ventricl
e has to carry and react to the pressure increase within the cavity, while
in the latter, force is generated within the myocardium itself through the
contraction, i.e., active self-shortening, of the muscle fibers. When the d
eformations of these two opposing modes balance, isovolumic contraction occ
urs. After this phase, when the aortic valve has opened, the active mode do
minates. Many models of the left ventricle under passive internal pressure
have been reported, usually for analyzing the situation in diastole. Only a
few attempts have been made to incorporate the self-activation effect pres
ent in systole. In this paper, a model for systole is described in which th
e active component has been treated by analogy to thermal stress analysis m
ethods common in dealing with conventional engineering structures. The mode
l was applied to the pressure and volume data for the ventricles of four pa
tients with cardiac disease. A parametric study was then undertaken to inve
stigate the influence of some of the mechanical factors on ventricular beha
vior. It was found that fiber angle has a very significant effect on the de
formation of the ventricle and also that for ventricles with stiff myocardi
a, the passive component to the reaction of the ventricle was negligible.