The influence of left-ventricular shape on end-diastolic fiber stress and strain.

Passive filling is a major determinant for the pump performance of the left ventricle and is determined by the filling pressure and the ventricular compliance. We quantified the influence of left-ventricular shape on the overall compliance and the distribution of passive fiber stress and strain during the filling period in normal myocardium. Hereto, fiber stress and strain were calculated in a finite element analysis during the inflation of left ventricles of different shape, ranging from an elongated ellipsoid to a sphere, but keeping the initial cavity and wall volume constant. The passive myocardium was described by an incompressible hyperelastic material law with transverse isotropic symmetry along the muscle fiber directions. A realistic transmural gradient in fiber orientation was assumed. While compliance was not altered, the transmural distribution of both passive fiber stress and strain was highly dependent on ventricular shape, where more spherical ventricles exhibited a higher subendocardial gradient in both quantities.