17. Blood Flow in an Out-of-Plane Aorto-left Coronary Sequential Bypass Graft

Coronary artery bypass graft (CABG) is a major therapy for ischemic heart disease which if left untreated can progress to failure of the heart. Restenosis, a leading cause of CABG, can be correlated with the geometric configuration and the hemodynamics of the graft. In this chapter we use computational fluid dynamics (CFD) to investigate the hemodynamics in a 3D out-of-plane sequential bypass graft model. Using a finite volume approach, quasi-steady flow simulations are performed at mid-ejection and at mid-diastole. Plots of velocity vectors, wall shear stress (WSS), and spatial WSS gradient (WSSG) distribution are presented in the aorto-left coronary bypass graft domain. Simulation results reveal a more uniform WSS and spatial WSSG distribution in the side-to-side (sequential graft) anastomosis configuration over the end-to-side (multiple graft) anastomosis. Results for the multiple bypass graft model show the peak magnitudes of the spatial WSSG are higher compared to the sequential bypass graft model. These findings suggest that sequential bypass grafting may be preferable over multiple bypass grafting to avoid non-uniformities of WSS.