Mechanical behavior of fully expanded commercially available endovascular coronary stents

The mechanical behavior of endovascular coronary stents influences their therapeutic efficacy. Through computational studies, researchers can analyze device performance and improve designs. We developed a 1-dimensional finite element method, net-based algorithm and used it to analyze the effects of radial loading and bending in commercially available stents. Our computational study included designs modeled on the Express, Cypher, Xience, and Palmaz stents.We found that stents that did not fully expand were less rigid than the fully expanded stents and, therefore, exhibited larger displacement. Stents with an open-cell design, such as Express-like or Xience-like stents, had a higher bending flexibility. Stents with in-phase circumferential rings, such as the Xience-like stent, had the smallest longitudinal extension when exposed to radial compression forces. Thus, the open-cell model that had in-phase circumferential rings connected by straight horizontal struts exhibited radial stiffness, bending flexibility, and the smallest change in stent length during radial forcing. The Palmaz-like stent was the most rigid of all. These findings are supported by clinical experience.Computer simulations of the mechanical properties of endovascular stents offer sophisticated insights into the mechanical behavior of different stent designs and should be used whenever possible to help physicians decide which stent is best for treating a given lesion. Our 1-dimensional finite element method model is incomparably simpler, faster, and more accurate than the classical 3-dimensional approaches. It can facilitate stent design and may aid in stent selection in the clinical setting.