A Patient-Specific Mesoscopic Fluid–Structure Interaction Model of the Coronary Artery

A mesoscopic fluid–structure interaction (FSI) model focusing on a small region of interest (ROI) in the left coronary artery was developed using COMSOL Multiphysics. This model was on the basis of a previously developed patient-specific coronary artery macroscopic FSI model. With element size comparable to that of endothelial cells, the spatial resolution of the mesoscopic model was significantly improved. Blood flow-induced shear stress and derivatives, vascular wall von Mises stress, and tensile strain (radial and circumferential) in normal and stenosed (50% and 71% occlusion) coronary artery ROIs were calculated, and the results were compared between the current mesoscopic model and the previously developed macroscopic model. Significant differences were observed in shear stress and circumferential strain in the 50% stenosis models. The mesoscopic stenosis model-derived shear stress and tensile strain were applied to human coronary artery endothelial cells concurrently using a shearing-stretching device, and endothelial cell responses (cell morphology and cell surface ICAM-1 expression) were measured. The results demonstrated that the difference in shear stress–tensile strain conditions calculated from the mesoscopic FSI model and the previously developed macroscopic model had a significant impact on endothelial cell responses, suggesting that large-scale FSI models may not be sufficient to characterize local biomechanical conditions at the cellular level.