Assessment of shape memory alloy stent deployment in a stenosed artery

Purpose Shape memory alloy (SMA) stents have been used increasingly for the treatment of complex arterial occlusions. There is an immediate need to quantify the mechanical performance of SMA stents to open occluded arteries. Methods The stent crimping and expanding process was assessed through both numerical modeling and in-vitro studies. The implantation of a SMA stent in curved arteries with eccentric stenosis were simulated to evaluate the effect of artery curvature on arterial mechanics. Results The crimping process stored a considerable amount of strain energy in the stent, which were then released through self-expansion until a balance between the stent and stenosed artery was achieved. The deployed SMA stent exhibited a dog-bone shape, where the longitudinal ends of the stent penetrated into the artery causing arterial stress concentrations. However, the maximum arterial stress was observed at the central portion of artery contacting the thin side of the plaque. Furthermore, stent-induced arterial mechanics were more pronounced in the curved artery than the straight artery. The maximum Von Mises stress in the curved artery with a curvature of 0.05 mm-1 was 37% larger than that found in the straight artery. The percentage of the intimal area at higher stress level (> 0.05 MPa) is 5.51% in the curved artery, compared to 1.76% in the straight artery. Conclusions This work provided a fundamental understanding of the behavior of SMA stent and its impact on the vascular wall, and illuminated the possibilities for exploiting their potential to alleviate arterial injury.