Integrating Darcy Poromechanics Myocardial Perfusion into a Multiphysics Framework of Cardiac Electromechanics and Coronary Flow ​

Background: Coupling cardiac electromechanics with coronary flow is an evolving area in cardiology research, with most computational models simplify the ventricular mechanics and neglect coronary arterial motion. Myocardial perfusion is often represented using Darcy’s law in a fixed domain without incorporating poroelastic interactions between myocardial tissue and microvascular flow. This study develops a computationally efficient framework integrating poromechanical myocardial perfusion model into the coupled cardiac electromechanics-coronary flow framework to investigate how electrical and mechanical dysfunction in heart affects coronary hemodynamics and perfusion.Methods: We adopted our previously developed subject-specific geometry biventricular electromechanical model coupled with epicardial coronary flow. The coronary outlet boundary conditions are replaced with a three-element Windkessel model representing flow in smaller vessels, combined with a poromechanical Darcy model describing downstream microvascular perfusion. The myocardium is modelled as a homogeneous porous medium using a single-compartment Darcy formulation and fully coupled poroelastic accounting solid deformation and pore fluid pressure. A coupling operator mathematically synchronized ventricular motion with coronary arterial displacement without physically attaching the computational domains. Simulations are performed sequentially by solving the biventricular electromechanics and Darcy myocardial perfusion, followed by 3D Navier-Stokes epicardial coronary artery flow.Results: Results demonstrated a progressive pressure drop across the epicardial arteries, Windkessel smaller vessels, and myocardial perfusion region. Epicardial flow exhibited systolic dominance whereas myocardial perfusion showed reduced systolic inflow and enhanced diastolic inflow, reflecting the influence of ventricular mechanics on the perfusion.Conclusion: The framework provides basis of subject-specific cardiac electromechanical-coronary flow modelling with myocardial perfusion enabling investigations of various cardiac and coronary diseases.