Hemodialysis arterio-venous graft design reducing the hemodynamic risk of vascular access dysfunction

Although arterio-venous grafts (AVGs) represent the second choice as permanent vascular access forhemodialysis, this solution is still affected by a relevant failure rate due to graft thrombosis, and devel-opment of neointimal hyperplasia (IH) at the distal vein. As a key role in these processes has been attrib-uted to the abnormal hemodynamics establishing in the distal vein, the optimization of AVGs designaimed at minimizing flow disturbances would reduce AVG hemodynamic-related risks. In this studywe used computational fluid dynamics to investigate the impact of alternative AVG designs on the reduc-tion of IH and thrombosis risk at the distal venous anastomosis. The performance of the newly designedAVGs was compared to that of commercially available devices. In detail, a total of eight AVG models inclosed-loop configuration were constructed: two models resemble the commercially available straightconventional and helical-shaped AVGs; six models are characterized by the insertion of a flow divider(FD), straight or helical shaped, differently positioned inside the graft. Unfavorable hemodynamic condi-tions were analyzed by assessing the exposure to disturbed shear at the distal vein. Bulk flow was inves-tigated in terms of helical blood flow features, potential thrombosis risk, and pressure drop over the graft.Findings from this study clearly show that using a helically-shaped FD located at the venous side of thegraft could induce beneficial helical flow patterns that, minimizing flow disturbances, reduce the IH-related risk of failure at the distal vein, with a clinically irrelevant increase in thrombosis risk and pres-sure drop over the graft.