Influence of graft-host diameter ratio on the hemodynamics of CABG.

The graft-host diameter ratios have impacts on the flow patterns of bypass graft. In order to clarify the influence of graft-host diameter ratios on the flow patterns and the wall shear stress in coronary artery bypass graft (CABG), the pulsatile blood flows in three CABG models, with the graft diameter larger than, equal to and smaller than that of the coronary artery, were simulated with finite element method. The temporal-spatial distributions of flow patterns, wall shear stresses (WSS), wall shear stress gradients (WSSG), oscillating shear index and shear stress ratio were depicted and compared. Of the three models evaluated, large model can bring about better hemodynamics to some extent with relatively large positive longitudinal velocity, uniform and large WSS, and small WSSG. The results suggest that larger or isodiametric graft is favorable. However, no distinct difference of WSS based temporal parameters was found between all the three models. Alternative anastomotic designs are necessary for the improvement of CABG patency rates.