How to make the perfect anastomosis – biofluid computational analyses

One of the primary causes of arteriovenous graft failure and loss of patency is disordered blood flow, as the vein is exposed to the arterial environment with high flow and shear stress. We hypothesise that secondary flow downstream in the vein-graft anastomosis contributes to low shear regions, promoting neointima hyperplasia. With the purpose to prolong the overall graft survival, we aim to produce a strategy to optimise graft configurations with a reduced level of disturbed haemodynamics. We investigated two common configurations - straight and looped grafts – while varying vein-graft anastomotic angles and addressing anatomical mismatch at the arterial end through graft modifications. Our results indicate that overall graft curvature (looped vs straight) plays a dominant role in charactering the trend of risk metrics. Looped grafts, particularly at moderate vein-graft anastomotic angles (30°-45°), exhibited the most favourable metrics, including reduced measurements of low wall shear stress, high wall shear stress, and highly oscillatory shear index. We developed an image-based approach to build three-dimensional geometries for subsequent computational fluid dynamic (CFD) numerical simulations. This method allowed us to improve the accuracy of geometries to facilitate comparisons between different variables.