Cardiovascular diseases are among the leading causes of mortality worldwide, necessitating advanced computational modeling to study their underlying mechanisms and explore potential treatments. In this paper, we present a multiphysics computational model that integrates cardiac mechanics, electrophysiology, and mass transport, implemented within the PAKFIS version of the PAK finite element (FE) code. Our model employs state-of-the-art FE techniques for macroscale fluid-structure interactions in the left ventricle, capturing the complex biomechanical behavior of the heart. For cardiac mechanics, we introduced a FE methodology incorporating standard 3D models and an original shell/membrane FE formulation tailored to the heart's tissue structure. A nonlinear, orthotropic material model for the human heart wall is developed based on experimental investigations of passive myocardium properties. The constitutive behavior is described using Cauchy stress-stretch and shear stress-shear amount relations derived from biaxial extension and triaxial shear experiments. The computational framework determines stresses at FE integration points under various loading conditions. Cardiac contractions are driven by electrical signals propagating through the Purkinje network and myocardial tissue. To model electrophysiology, we apply the smeared physical field methodology (Kojic Transport Model, KTM) to solve electrostatic problems related to cardiac excitation. By coupling cardiac mechanics and electrophysiology, our model provides a comprehensive tool for simulating heart function under physiological and pathological conditions. These advancements contribute to a deeper understanding of cardiac behavior and offer a foundation for future research in cardiovascular disease treatment and prevention.
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