A comparative study of helical-type and traditional-type artery bypass grafts: numerical simulation.

Preliminary studies on an individual helical graft indicated that its hemodynamics might be improved while pressure drop increased compared with a traditional graft. Aiming to investigate whether the benefits of a helical graft to hemodynamics dominate its deficits, this study numerically carried out comparative study of helical-type artery bypass graft (ABG) and traditional-type ABG under both steady and pulsatile flow conditions. The results showed that a helical-type ABG resulted in reduced oscillating shear index, improved wall shear stress, enhanced flow mixing and three-dimensionality, and improved flow behavior at the distal anastomosis and occluded section of the host vessel compared with traditional-type ABG. More important, although a helical-type ABG did increase the pressure drop compared with a traditional one, its maximum percentage increase during a cardiac cycle was <21% which is still within physiological sense. Therefore, we believe that the adoption of helical bypass could help to prevent intimal hyperplasia (IH) and thrombosis at the distal anastomosis and improve the graft patency while keeping clinical maintenance. This investigation provided an important basis for the clinical applications and theory support of helical graft.