A finite element computational framework coupling four-chamber heart mechanics with the systemic and pulmonary circulations

We present a computational four-chamber heart modeling framework that integrates a 3D finite element (FE) model of heart mechanics with a 0D model of the systemic and pulmonary circulations in a closed-loop system. The computational framework incorporates patient-specific geometry, rule-based myocardial fiber architecture, and nonlinear transversely isotropic tissue mechanics to simulate the full cardiac cycle. A bidirectional 3D--0D coupling strategy together with physiologic epicardial boundary conditions enables stable beat-to-beat simulations. Built on the open-source FEniCS platform with a residual-based stabilized mixed (P1--P1) FE formulation, the computational framework is able to produce pressure-volume loops of the four chambers and myocardial strain waveforms that are comparable to those measured in healthy humans. The framework is used to simulate inter-ventricular interactions arising from a reduction in contractility of the left ventricle (LV) and right ventricle (RV). A reduction in LV contractility produces a 4.9\% decrease in RV peak pressure whereas a reduction in RV contractility produces a 20\% decrease in LV peak pressure. The framework sets the foundation for patient-specific whole-heart simulations of cardiovascular diseases and treatments in future work.