Unsteady simulation of distal blood flow in an end-to-side anastomosed coronary bypass graft with stenosis.

In this paper, we report on the unsteady state modeling of blood flow in an end-to-side anastomosed bypass graft, which has a stenosis upstream from the junction. In coronary artery bypass grafting/surgery (CABG), new arteries are created in order to provide blood to the heart using other blood vessels as conduits to bypass the blocked section in the patient's coronary arteries. The failure of coronary artery bypass procedures has been attributed to both intimal hyperplasia (IH) and atherosclerosis. It is believed that these two phenomena are, in turn, related to the local hemodynamic factors. In this work, a three-dimensional computational fluid dynamics analysis is used to simulate the physiological blood flow through a model of a stenosed coronary bypass graft with the realistic assumption of non-Newtonian flow for human blood. For different flow repartitions and at different times of the cycle, both the recirculating areas and wall shear stress (WSS) are studied. Based on the different distribution of flow rates in the bypass graft and the host artery, the flow features are investigated and the influence of non-Newtonian behavior is discussed in terms of separation points, reattachment points, and the wall shear stresses. Various differences are observed based on the assumption of non-Newtonian behavior of blood, which have not been reported before when a simplified Newtonian approach is utilized.