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We propose a technique to reverse engineer a normal carotid bifurcation from an abnormal artery model based on B-Spline interpolation. This enables us to assess the blood flow pattern in a patient-specific artery for the stenosed and virtually stented conditions. This technique may be applied to understand the cardiovascular condition and to develo...
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... the surgical treatment of such diseased arteries, a stent can be deployed and expended uniformly to fit along the wall of the artery. In the case of asymmetric distribution of the plaque along the arterial axis, the stent was forced to bend against the artery wall and causing the sharp edge of the stent to cut through the artery wall ( Figure 1). Over time, this may lead to platelets activation and thrombosis, which can result in stenosis of artery. ...
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Citations
... After injury caused by balloon angioplasty or stent deployment in percutaneous coronary intervention, the endothelium is partially or completely denuded [6,10] , triggering inflammatory mechanisms like platelets aggregation and formation, smooth muscle cells (SMCs) migration and proliferation, extra cellular matrix (ECM) formation and, finally, ISR [2]. The presence of stent inside the artery influences the flow dynamics and induces flow re-circulation and stagnation zones around the stent struts [11,12,13]. In physiological conditions, endothelial cells are exposed to flow shear stress whereas SMCs in the medial layer are usually subjected to the cyclic strain caused by the pulsatile nature of blood flow [14]. ...
Treatment of stenosed coronary arteries by balloon angioplasty and stenting results in arterial injury including severe damage to the endothelium at the site of treatment and initiates a complex cascade of inflammatory processes that may lead to the development of in-stent restenosis (ISR). Many clinical and biological factors involved in the progression of restenotic lesions have been studied in detail over the past few years but the mystery behind the pathophysiological mechanisms of this disease is still unresolved. In the present work, the effects of re-endothelialization and nitric oxide release on neointimal growth are investigated in-silico using a two dimensional multi-scale model of ISR. The effect of stent deployment depths on the development of ISR is studied as a function of time after stenting. Two dimensional domains were prepared by deploying bare metal stent struts at three different deployment depths into the tissue. Shear stress distribution on endothelial cells, obtained by blood flow simulations, was translated into nitric oxide production that keeps the smooth muscle cells in quiescent state. The cellular growth trends were plotted as a function of time and the data indicate a positive correlation between the neointimal growths and strut deployment depths in the presence of a functional endothelium, in qualitative agreement with in-vivo data. Additionally, no ISR is observed if a functional endothelium appears much earlier.
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 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 factors promoting atherogenesis, their role in restenosis following stent implantation remains unclear. We hypothesize that the implantation of a stent generates hemodynamic abnormalities consisting of low wall shear stresses in the vicinity of arterial wall regions prone to restenosis. The objective of this study was to compare computationally the hemodynamics in normal (healthy), stenosed (atherosclerotic) and stented carotid artery bifurcation models and to investigate potential correlations between regions presenting high hemodynamic abnormalities and regions prone to postoperative stent angioplasty restenosis. Realistic, three-dimensional models of normal, stenosed and stented human carotid bifurcations consisting of the common (CCA), external (ECA) and internal (ICA) carotid arteries were developed using the computer-assisted design software Solid Edge. The characteristic dimensions of the normal and stenosed models were obtained from previously published human data. The stented model was designed by modeling the inner surface of the ICA bulb region as a rigid cylindrical surface mimicking the presence of a stent. Fluid-structure interaction (FSI) simulations were carried out using the adaptive arbitrary Lagrangian Eulerian (ALE) approach of ANSYS 14 to simulate flow and arterial wall dynamics in each model subjected to physiologic pressure and flow rate. As expected, the atherosclerotic model resulted in higher velocity and wall shear stress (WSS) levels than the normal model due to the reduced ICA lumen. In addition, while stent implantation restored the hemodynamic performance of the vessel, it generated lower WSS than in the normal model, which may contribute to restenosis. This study provides new insights into the possible hemodynamic roots of postoperative stent angioplasty restenosis.
