Computational approach to hemodynamics in femoral bypass graft

Femoral bypassing remains an effective surgical technique to rescue lower extremity peripheral vascular diseases. A great number of grafts have moderate patency rates and fail in the long term. Geometry configuration is considered to have direct influences on the hemodynamics which is correlated with the pathological changes of bypassed femoral arteries. The overall goal of the present study is to investigate the hemodynamic influences of an anastomosis configuration on the pathological mechanisms of intimal hyperplasia and restenosis that result in the bypassing surgery failure. The authors presented an anastomosis configuration with symmetric 2-way bypass grafts for the purpose of improving the hemodynamics. The physiological blood flows in the conventional 1-way model and the presented 2-way model of fully stenosed femoral bypass grafts were simulated with computational approaches. The temporal and spatial distributions of flow patterns and wall shear stresses in the vicinity of distal anastomosis were analyzed and compared. The result of the present study indicates that the 2-way model is featured with larger longitudinal velocity, less refluence and eddy flow, more uniform wall shear stress distribution and smaller magnitude of wall shear stress gradient. All of these features demonstrate that the hemodynamics in the symmetric 2-way bypass graft is significantly improved and is quite favorable for alleviating the intimal hyperplasia and restenosis and ameliorating the patency rates of femoral bypass graft. One of the possibilities which the present study can offer is enabling the surgeon to gain an approximate idea of the hemodynamic conditions that occur after the implantation of a symmetric 2-way bypass graft and to control over the geometry configuration of the anastomosis in order to achieve optimal hemodynamics and to maximize the success rates of bypassing surgery.