Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 57 1 2025 03 21 Simulating Cardiac Function Using a Multiphysics Viscoelastic Biventricular Model Simulating Cardiac Function Using a Multiphysics Viscoelastic Biventricular Model 69 88 5735 10.22060/mej.2025.23809.7815 FA Pezhman Namashiri Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran 0009-0005-3421-0270 Akbar Allahverdizadeh Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran Journal Article 2025 01 05 Studying the behavior of the heart muscle is important to increase the knowledge and understanding of this tissue. Modeling cardiac function is effective in improving treatment methods and can be utilized to evaluate invasive medical devices. In this study, an electromechanical model for the biventricular structure of the heart has been developed, which includes electrophysiology, mechanics, and ventricular pressure. The microstructure of the heart including fiber, sheet, and normal-to-sheet has been defined to take into account the anisotropic properties of the cardiac muscle. Gap junction-based method is used for the electrophysiology of the heart and myocardial activation is simulated through the inclusion of Purkinje fibers. Myocardial mechanics is considered viscoelastic, and the modeling of ventricular pressure has been expanded in order to include closed-loop circulation. Three consecutive cardiac cycles have been simulated and evaluated. The results showed that the activation of the heart starts from the endocardial wall and the excitation wave moves towards the epicardial wall. Furthermore, changes in blood flow and deformation of both ventricles occur simultaneously. The presented model reproduced the electrical response, activation time, left and right ventricular pressure-volume loops, and isovolumetric contraction, ejection, isovolumetric relaxation, and filling phases for the healthy human heart. The results of the model can be used in the future as a criterion to evaluate the behavior of a healthy heart. Studying the behavior of the heart muscle is important to increase the knowledge and understanding of this tissue. Modeling cardiac function is effective in improving treatment methods and can be utilized to evaluate invasive medical devices. In this study, an electromechanical model for the biventricular structure of the heart has been developed, which includes electrophysiology, mechanics, and ventricular pressure. The microstructure of the heart including fiber, sheet, and normal-to-sheet has been defined to take into account the anisotropic properties of the cardiac muscle. Gap junction-based method is used for the electrophysiology of the heart and myocardial activation is simulated through the inclusion of Purkinje fibers. Myocardial mechanics is considered viscoelastic, and the modeling of ventricular pressure has been expanded in order to include closed-loop circulation. Three consecutive cardiac cycles have been simulated and evaluated. The results showed that the activation of the heart starts from the endocardial wall and the excitation wave moves towards the epicardial wall. Furthermore, changes in blood flow and deformation of both ventricles occur simultaneously. The presented model reproduced the electrical response, activation time, left and right ventricular pressure-volume loops, and isovolumetric contraction, ejection, isovolumetric relaxation, and filling phases for the healthy human heart. The results of the model can be used in the future as a criterion to evaluate the behavior of a healthy heart. https://mej.aut.ac.ir/article_5735_6d34d468ac8876333c4d7173b85efed9.pdf