Computational Fluid Dynamics Analysis of Blood Flow in Helical Arterio-Venous Bypass Graft for Enhanced Flow Performance

Bypass graft is widely used, especially in cardiovascular diseases, to detour clogged blood vessels, alleviating and correcting the manifestation of the symptoms of damaged blood vessels. Bypass grafting is also used in hemodialysis treatment, specifically an arteriovenous bypass graft, considering the repeated withdrawal of blood, for the dialysis machine to filter the blood and return it to the body to circulate. Nonetheless, bypass grafts are susceptible to failure due to the abnormal hemodynamic performance of the blood flowing to the graft, leading to complications such as thrombosis, intimal hyperplasia, and atherosclerosis. Multiple bypass graft designs are continuously developed to optimize the desirable hemodynamics of the blood, which is essential to avoid complications. This study examines helical arteriovenous bypass graft (AVG) hemodynamic performance using Computational Fluid Dynamics (CFD) simulations to identify enhanced blood flow characteristics. The analysis concentrated on area-weighted average wall shear stress (AWA-WSS), helicity, pressure drop, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT) from twenty-seven graft models changing anastomosis angles, helical diameters, and helical pitches. Model 25-13-30 (25-degree anastomosis angle, 13 mm helical diameter, 30 mm helical pitch) demonstrated the most favorable overall hemodynamic performance based on the variables considered. The results indicate that integrating helical shape into bypass grafts improves hemodynamic performance, reduces intimal hyperplasia risk, and may prolong graft durability. These findings provide valuable insights and suggestions for enhancing AVG designs to support patient outcomes.