Computational modeling of effects of intravascular stent design on key mechanical and hemodynamic behavior

Atherosclerosis, a condition related to cholesterol build-up and thickening of the inner wall of the artery, narrows or occludes the artery lumen. A stent is a miniature medical device deployed in a stenotic artery to restore the blood flow. In this paper, we propose to apply the parametric design concept onto the stent design and integrate it with the developed FEA/CFD models to evaluate several key clinically-relevant functional attributes recommended by the FDA. These key clinical attributes include stresses/strains, fatigue resistance, radial strength, expansion recoil, and wall shear stresses, which have yet to be systematically investigated. Finite element models were developed to predict the mechanical integrity of a balloon-expandable stent at various stages such as crimping onto a balloon catheter, stent expansion, radial strength to resist blood vessels from collapsing, and service life in the human body when subjected to pulsatile blood pressure. Computational fluid dynamics models were developed to predict the wall shear stress distribution in stented arteries. A stent parametric analysis was conducted using the integrated computational schemes to systematically evaluate the effects of varying stent design parameters on key clinically-relevant functional attributes. Each stent design parameter was varied in its dimension from -30% to +30% (compared to the standard case) for sensitivity studies in attempts to find the most dominant design parameter for each key clinical attribute. The developed design/analytical schemes allow us to gain deeper insight into the fundamental stent issues and evaluate the mechanical/hemodynamic behavior of various stent designs.