A Transmurally Heterogeneous Orthotropic Activation Model for Ventricular Contraction and its Numerical Validation

62/2017

A Transmurally Heterogeneous Orthotropic Activation Model for Ventricular Contraction and its Numerical Validation

Thursday 23rd November 2017

Barbarotta, L.; Rossi, S.; Dede', L.; Quarteroni, A.

Models for cardiac mechanics require an activation mechanism properly representing the stress-strain relations in the contracting myocardium. In this paper, we propose a new activation model which accounts for the transmural heterogeneities observed in myocardial strain measurements. In order to take into account the anisotropy of the active mechanics, our model is based on an active strain formulation. Thanks to its multiplicative decomposition of the deformation gradient tensor, in this formulation the active strains orthogonal to the fibers can be naturally described. We compare the results of our novel orthotropic formulation against different anisotropic models of the active contraction of the cardiac muscle and, moreover, against experimental data available in the literature. We show that the currently available models can represent only some global quantities, but the strain distributions are not in agreement with the reported experimental measurements. Conversely, we show that our new transmurally heterogeneous orthotropic activation model improves the accuracy of shear strains related to in-plane rotations and torsion.