Three-Dimensional CFD Analysis of the Hemodynamic Effect of Different Stent-to-Artery Deployment Ratios

In vascular cardiology, stenting coronary arteries with the diameter greater than that of the native artery has been used in an attempt to securely anchor the device against the arterial wall. Various stent-to-artery deployment ratios can be used by clinicians to implant the stent into the artery. However, stent expansion beyond the native artery diameter alters vascular hemodynamic scenarios. These alterations may cause endothelial denudation and promote neo-intimal hyperplasia. The optimal level of stent-to-artery diameter ratio to reduce the severity of vascular damage and consequently the risk of adverse clinical outcome has not yet been determined. This injury of the endothelium due to stent overexpansion has been shown to be influenced by hemodynamic factors such as local wall shear stress (WSS). The information on the gradient of blood flow velocity during stent deployment is therefore of clinical interest as it is proportional to the distribution of wall shear stress. While in vivo measurement of the fluid dynamics quantities including velocity profile, pressure and wall shear stress is challenging, computational fluid dynamics (CFD) can be a valid tool to analyse these vascular fluid dynamics quantities. In this study, a three-dimensional CFD analysis was used to examine the fluid flow in a patient-specific artery with particular emphasis on the effect of various stent-to-artery ratio diameters. The fluid was assumed to be incompressible, Newtonian and homogenous. Both the stent struts and the arterial wall were considered to be rigid and non-porous. The results of this study give insight into the understanding of the mechanisms that may contribute to vascular damage from stent-expansion.