Flow dynamic effect of the anastomotic angle: a numerical study of pulsatile flow in vascular graft anastomoses models.

Pulsatile non-Newtonian blood flow in three distal end-to-side anastomoses models of prosthetic grafts has been analysed applying computer simulation. The anastomotic angles of the three-dimensional geometric models vary over 30°, 45° and 60°. The pulsatile inflow conditions in the graft remain unchanged. Numerical results are presented for the axial and the secondary flow velocity and the wall shear stress distribution. Further, the paths of fluid particles and the particle residence times are demonstrated by means of numerical flow visualization. The quantitative study shows complex flow and wall shear stress patterns with flow separation and strong secondary motion in the host vessel and a weakly migrating flow stagnation point on the arterial floor during the entire pulse cycle in the models under consideration. The flow dynamic effects, which seem to be important in the development of intimal hyperplasia, are dependent on the anastomotic angle and increase with increasing angle.