Deployment of a self-expanding stent inside an artery: A finite element analysis

The superelastic, shape memory, biocompatibility, and fatigue properties of Nitinol, a nickel–titanium alloy, have made the material attractive for medical devices such as self-expanding cardiovascular stents (tubular mesh-like structures). Self-expanding stents are used in medical surgery to restore blood flow in a diseased artery segment (narrowing of the blood vessel due to plaque build-up) and keep the artery open after angioplasty. Finite element analyses (FEAs) of Nitinol devices such as stents reduces testing and time-to-market by allowing the designer to simulate the stent delivery inside the vessel. In this paper a FEA has been performed to simulate the deployment and the pulsatile loading of a self-expanding Nitinol stent inside an artery. The results of the FEA have been used to assess the impact of the stent on the artery and to assess the influence of the artery on the deformation field within the stent. Such analyses will provide valuable information about the stent design and struts dimensions that can be optimized in order to maximize the effectiveness of the stent during the deployment process. This work was conducted using Abaqus©/standard finite element code in conjunction with a user material subroutine (umat/Nitinol).