Numerical Model Study of Flow Dynamics through an End-to-Side Anastomosis: Choice of Anastomosis Angle and Prosthesis Diameter

The purpose of this numerical model study was to determine the angle of anastomosis and prosthesis-to-artery diameter ratio that theoretically limits development of myointimal hyperplasia (MIH). Blood flow patterns were investigated in a model simulating a distal end-to-side anastomosis on a 2-mm-diameter artery. Tests were carried out under steady and pulsatile flow conditions with and without taking into account the non-Newtonian behavior of blood and compliance. The wall shear stress gradient (WSSG), a potential factor for development of MIH, was analyzed as a function of the angle of anastomosis (18°, 25°, 35°, and 45°) and prosthesis diameter (4, 5, and 6 mm). The angle of anastomosis that minimized WSSG was 18°. Prosthesis diameter had no effect on WSSG, with similar results for all three diameters. These findings suggest that surgeons should choose as acute an angle of anastomosis as possible. Prosthesis diameter played no role in reducing WSSG values.