Experimental and numerical study of a novel inbuilt helical ridge small-caliber graft for artery bypass surgery

Abstract

Small-caliber (≤ 6 mm) vascular grafts are commonly used to treat vascular diseases, yet intimal hyperplasia at the distal end-to-side anastomosis remains a significant complication with long-term use. Helical flow has been shown to reduce the risk of cardiovascular complications effectively. Integrating helical flow through an inbuilt helical ridge in vascular grafts is intended to improve hemodynamic performance and mitigate issues such as flow-induced thrombosis and intimal hyperplasia. However, inadequate helical flow strength may limit its effectiveness. This study proposes a novel design for an inbuilt helical ridge in small-caliber grafts to achieve enhanced helical flow. Two novel small-caliber vascular grafts with variable-pitch helical ridges, incorporating both decreasing and increasing pitches, were designed. Their effectiveness was assessed through numerical simulations and in vitro experiments to evaluate their performance in arterial graft applications. The small-caliber vascular grafts incorporating variable-pitch helical ridges significantly improved helical flow structure and distribution, optimized wall shear stress distribution, and reduced platelet adhesion compared to conventional and constant-pitch helical ridge grafts. Among the various new designs, the small-caliber vascular graft featuring decreasing variable-pitch helical ridges has demonstrated better performance. This design is well-suited for small-caliber bypass surgeries, as it is effective in improving hemodynamic performance by improving helical flow into asymmetric structures and increasing helical flow density distribution.