Finite deformation analysis of left ventricular wall in isovolumetric contraction period: Effects of myocardial fiber orientation on wall deformation

The aim of this study was to elucidate the effects of myocardial fiber orientation on the deformation of the left ventricular (LV) wall. An LV wall model was constructed by modeling the myocardial fiber structure as an anisotropic hyperelastic material. The shapes of the endocardium and epicardium were assumed to be two spheroids. LV wall deformation by constriction of the myocardial fibers was simulated for three fiber orientations: the myocardial fiber was oriented parallel to the short-axis plane (Case 1); the angle between the myocardial fiber andthe short-axis plane variedlinearly from ＋π/3 in the endocardium to –π/3 in the epicardium (Case 2); andthe myocardial fiber was uniformly orientedat an angle of−π/3 with respect to the short-axis plane (Case 3)．The results showedthat the LV wall deformation was governedby the interaction among the constriction of fibers, the wall deformation as a continuum body, and the geometric constrains of the LV anatomy. Comparing the results of three cases revealedthat the helical structure of fibers contributes to cause a twisting motion and efficient contraction of the LV wall, which produces a heterogeneous distribution of the deformation rates in the LV wall. © 2016, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved.