Hemodynamic abnormalities in stented carotid artery – A fluid structure interaction study

Balloon-stented angioplasty is a common treatment for carotid arterial atherosclerosis. Clinical studies have shown that within 6 months of the initial procedure, 25% of all stented-angioplasty patients develop restenosis, a postoperative narrowing of the artery due to plaque accumulation onto the stent. While hemodynamics, and more specifically low oscillatory wall-shear stress have been identified as key players in atherogenesis, their role in restenosis following stent implantation remains unclear. We hypothesize that the implantation of a stent generates hotspots on the arterial wall characterized by low wall shear stresses and low fluid velocities, which correlate with regions prone to restenosis. The objective of this study is to compare computationally the hemodynamics of healthy and stented carotid bifurcations using fluid-structure interaction (FSI) simulations in order to assess the potential contribution of hemodynamic stresses to postoperative stent angioplasty restenosis. We have developed three-dimensional models of healthy and stented human carotid bifurcations using the computer-assisted design software Pro-Engineer. Characteristic dimensions of these models were derived from previously published data. The stented model was designed by applying fixity to the interior wall of the healthy model in order to simulate the implantation of a stent. FSI simulations were performed in ANSYS to predict the hemodynamics of each model. Results demonstrate the existence of decreased wall shear stress regions in the stented model, in comparison to the healthy model, which may correlate with regions of restenosis. Future studies will further analyze the results of this investigation to pinpoint the potential hotspots for restenosis and compare these computational locations to actual in vivo clinical restenosis areas. The results of this study will provide insight into the mechanisms causing restenosis, and will provide critical information to the development of improved stent designs, which are hemodynamically resistant to restenosis.