Modeling and Simulation of Myocardial Hyperelastic and Viscoelastic Properties with Incorporation of Active Stress

Heart diseases are one of the most important causes of death in the world, and their treatment is very important from a medical and financial perspective. One of the effective ways that can be very useful in the treatment of cardiovascular diseases is computational modeling which can help medical professionals to better understand the human heart and provide more effective therapeutic approaches. The mechanical characteristics of the myocardium of human heart, known as a nonlinear and anisotropic tissue, are the most important part of the heart because it plays a key role in myocardial response to loading and unloading during heart cycle. In this study, the orthotropic hyperelastic and isotropic viscoelastic properties of the human heart were modeled by taking into account the effect of active stress on myocardium and using an idealized left ventricular geometry. Simulation results showed that the viscoelastic property cause the myocardium deformation to be damped and reduces the amount of torsion that experienced by the tissue. Also, myocardium tissue in viscoelastic case showed the hysteresis phenomenon which is found in clinical observations of heart mechanics. The Model is entirely implemented in COMSOL Multiphysics finite element software and can be used in heart electromechanical models in future studies.