Effect of Myocardial Motion on Coronary Hemodynamics*

Coronary artery disease is the most common type of heart disease, which is the leading cause of death. Significant advances were made in modeling coronary blood flow to the point of clinical translation and personalized treatment planning. Although it is postulated that myocardial motion could substantially impact coronary flow, computational models rarely account for it. We developed a multiscale moving-domain model to simulate blood flow through coronary arteries moving with the myocardium. Time-dependent CT data was used to segment, register, and extract motion of the proximal ascending aorta and coronary arteries. We employed a closed-loop multiscale model of the circulatory system, coupling the 3D model with a 0D lumped parameter model (LPN), with its parameters tuned to match patient data. We model the blood flow in moving coronaries using the arbitrary Lagrangian-Eulerian (ALE) formulation of Navier-Stokes equations, discretized using a stabilized finite element method. Computed flow metrics, including pressure gradients, shear profiles, and helicity, were compared against the rigid wall case. We then extended our model to evaluate the effect of myocardial motion on predicting fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) in stenosed coronaries.