Numerical investigation of steady flow in proximal and distal end-to-side anastomoses.

Steady flow in model proximal and distal end-to-end bypass anastomoses were simulated numerically. The predictions were compared to whole field measurements of the flow in in vitro models, and were shown to match well the general features of the measured flows. The predictions confirmed that the flows in end-to-side anastomoses are complex and three dimensional, and contain areas that could allow long residence times. Careful examination of the predictions revealed certain features of the flows not seen easily in the experiments. Shear stress and pressure on the vessel walls were predicted, and areas known to be prone to intimal hyperplasia were shown to correspond to areas of high spatial gradient of shear stress. Two anastomosis angeles, 30 and 45 deg, were considered, and it was shown that the more acute angle may have some benefit in terms of the levels of shear gradients and the power required to drive the flow through the anastomosis.