MEMBRANE FINITE ELEMENT FOR MODELING HEART WALL

Modeling of heart wall deformation remains a challenge due to complex structure of tissue, which contains different group of cells and connective tissue. Muscle cells are dominant where, besides stresses coming from tissue deformation, active stresses are generated representing the load which produces heart motion and function. These cells form a helicoidal structure within so- called wall sheets and are considered as tissue fibers. Usual approach in the finite element (FE) discretization is to use 3D isoparametric elements. The dominant stresses lie in the sheet planes, while normal stresses in the wall normal directions are of the order smaller. Taking this stress state into account, we explore a possibility to model heart wall by membrane finite elements, hence considering the wall as a thick membrane (shell without bending effects). The membrane element is composite, containing layers over the thickness and variation of the direction of fibers. The formulated element is applied to a simplified left ventricle geometry to demonstrate a possibility to simulate heart mechanics by models which are much smaller and simpler for use than 3D conventional models.