Reducing In-Stent Restenosis Through Novel Stent Flow Field Augmentation

In-stent restenosis (ISR), manifested as a re-narrowing of the arterial lumen post-implantation of a stent, is a detrimental limitation of stent technology. Understanding and consequently devising ways of reducing the frequency of ISR has been a continuing goal of research into improved stent designs. The biological processes that can lead to ISR have been found to be partially flow dependent with the local hemodynamics at the arterial wall of crucial importance. This paper investigates these biological processes and their instigating factors. Furthermore, the history and theory behind three stent technologies which endeavour to reduce ISR rates through stent flow field augmentation are presented: a flow divider which increases the blood-flow velocity and consequently the wall shear stress through a stented region, and two novel stent technologies which induce helical flow that mimics the natural blood flow present in healthy arteries. This paper serves as a thorough introduction to both the investigation of ISR, particularly the influence of the local hemodynamics, and to the three novel stent technologies which aim to reduce ISR rates.