Influence of curvature dynamics on pulsatile coronary artery flow in a realistic bifurcation model.

The coronary arteries undergo large dynamic variations during each cardiac cycle due to their position on the beating heart. The local artery curvature varies significantly. In this study the influence of dynamic curvature on coronary artery hemodynamics is analyzed numerically. A realistic model of the bifurcation of the left anterior descending coronary artery and its first diagonal branch is curved by attaching it to the surface of a sphere with time-varying radius based on experimental dynamic curvature data. The description of the blood flow uses the time-dependent, three-dimensional, incompressible Navier-Stokes equations for Newtonian fluids, where the influence of the time-dependent flow domain is taken into account employing the Arbitrary Lagrangian-Eulerian technique. The inlet velocity profiles used in the computer simulation are physiologically realistic. The results show that the skewing of the axial velocity profiles near the branching site is mainly determined by the vessel branch; the bifurcating flow generally dominates the effect of curvature. The influence of curvature increases downstream of the branch. During systole, when curvature is greatest and high curvature variations appear, their effect on the flow patterns and the wall shear stress is dominated by the flow wave. Due to the smaller curvature changes during diastole, only minor effects of curvature variation on the high and relatively constant diastolic flow occur. The results demonstrate the importance of including physiologically realistic flow in the correct phase relationship with vessel motion when simulating coronary artery hemodynamics.