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In the quantification of the mechanical behaviour of the left ventricle and its compliance, focus has been mainly on fiber orientation and constitutive parameters. Although it has been shown that the left-ventricular shape plays an important role in cardiac (patho-)physiology, the dependency on left-ventricular shape has never been studied in detail. Therefore, we have quantified the influence of left-ventricular shape on the mechanical behaviour during the passive filling phase (ED) and during isovolumic contraction (IVC). Hereto, a finite element (FE) analysis of the left ventricle was performed for different shapes, ranging from an elongated ellipsoid to a sphere, but keeping the initial cavity volume constant. For each shape, the wall volume was varied to obtain ventricles with different wall thickness. The passive myocardium was described by an incompressible hyperelastic material law with transverse isotropic symmetry along the muscle fiber directions. A realistic transmural distribution in fiber orientation was assumed. A physiological contraction model was incorporated to account for the contraction during IVC. The activation pattern of the left ventricular wall was obtained by solving the eikonal-diffusion equation. This finite element analysis shows that the left ventricular shape is a major determinant of the fiber stress and strain distributions in the left ventricular wall. |
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