Evaluation of the Effects of Anastomosis Angle on the Performance of an Optimized Spiral Flow-Inducing Graft Design using CFD

Abstract

Bypass grafting is a common medical intervention used for people suffering from atherosclerosis, but the prevalence of graft failure due to disturbed hemodynamics necessitates the improvement of graft design for optimum blood flow. Spiral flow has been proposed as a mechanism to improve hemodynamics in grafts. A previous study optimized a spiral flow-inducing graft design, but it did not consider the effects of anastomosis angle despite its significant effects on blood flow. The purpose of this research is to further enhance the performance and patency of bypass grafts by determining how the anastomosis angle affects the hemodynamics of a spiral flow-inducing graft design using computational fluid dynamics (CFD). Distal anastomoses of 6 mm ridged graft and femoral artery constructs at varying anastomosis angles of 15° increments were analysed using steady-state CFD analysis under the assumptions of laminar, isothermal, stationary, rigid, non-Newtonian, and incompressible flow to determine the anastomosis angle that would yield optimum flow parameters. A 30° anastomosis angle was found to yield the most favourable flow conditions, particularly by minimizing recirculation one millimetre and five millimetres away from the toe (0.26% and 0% of the cross-sectional area of the artery, respectively) and pressure drop (474.8 Pa), as well as the complete elimination of areas affected by pathologically high wall shear stress (WSS). The findings of this study point out the potential benefits of a smaller anastomosis angle on the performance and patency of bypass grafts through the minimization of pressure drop and areas affected by recirculation and abnormally high WSS.