Quintupling fatigue resistance of intravascular stents via a simple design concept

Vascular stenting has received great attention from the medical community since its introduction. The endovascular self-expanding stent is used to treat peripheral artery diseases; however, after implantation, these stents suffer from various cyclic motions caused by pulsatile blood pressure and daily body activities. Due to this challenging environment, fatigue performance has become a major issue for stent design. In this paper, a simple and interesting concept of stent design aimed at enhancing pulsatile fatigue life is investigated. The concept of this design is to shift the highly concentrated stresses/strains away from the crown and re-distribute them along the stress-free bar arm by tapering its strut width. Two types of design approaches were applied in attempts to quantize the degrees of such fatigue enhancement for the first time. Finite element models were developed to evaluate the mechanical integrity and pulsatile fatigue resistance of the stent to various loading conditions. Simulation results show that the fatigue safety factor jumped to a whopping 5.4 times that of the standard stent with constant strut width. The findings of this paper provide an excellent guide to the optimization of future stent design to greatly improve stent fatigue performance.