A heterogeneous finite-element model incorporating a transversely isotropic endocardial region provides a more accurate representation of left ventricular mechanical behavior and stress distribution than traditional homogeneous models.
A finite-element model is used to analyze the mechanical behavior of the left ventricle. The ventricle is treated as a heterogeneous, linearly elastic, thickwalled solid of revolution. The inner third of the ventricular wall is assumed to be transversely isotropic with a longitudinal Young's modulus, transverse modulus, and shear modulus of 60 g/cm 2 , 30 g/cm 2 , and 15.5 g/cm 2 , respectively. In the outer two-thirds of the ventricular wall the myocardium is assumed to be isotropic with a Young's modulus of 60 g/cm 2 . Polsson's ratio is assumed to be equal to 0.45 throughout the ventricular wall. The valvular ring at the base of the ventricle is simulated by a homogeneous layer cf collagen. The model appears to predict gross free-wall deformation in the left ventricle of the potassium-arrested rat heart fixed in situ. The presence of a relatively compliant transversely isotropic region near the endocardial surface results in significantly lower axial and circumferential stresses in this region than are present in a homogeneous, isotropic model. The presence of a simulated valvular ring results in a concentration ofrelatively large stresses near the base of the ventricle.
Janz et al. (Tue,) studied this question.