The role of vessel geometry and material properties on the mechanics of stenting in the coronary and peripheral arteries

Abstract

Abstract

There have been notably higher rates of restenosis with stents used to restore blood flow to many stenosed peripheral arteries compared with their coronary counterparts. The mechanical environment of arteries such as the femoral and popliteal (and the stent fracture that this can cause) has previously been identified as a contributing factor to the relatively low success rates for this procedure. The aim of this study was to investigate how other factors, namely the differences in geometries and mechanical properties of the arteries and the stents used in them, might influence the outcome in these different arteries. Finite element models of the stents and arteries were created, and the results compared in terms of stresses induced in the arteries, the lumen gain, and the deformation of the stent due to pulsatile loading. It was found that deploying a Nitinol stent in a peripheral artery induced lower stresses in the vessel wall than expanding a stainless steel stent in a coronary artery, although the lumen gain was also lower. The predicted strain amplitude induced in Nitinol stents by the cardiac cycle was below the value required to cause fatigue failure. This study does not provide any evidence to suggest that differences in the geometry and material properties between peripheral and coronary arteries, or the types of stent used to restore vessel patency, are the dominate factors responsible for the higher rates of restenosis observed in peripheral arteries.