Research On Hemodynamics Of Atherosclerotic Plaque Formation And In-stent Restenosis In Carotid Artery

The approximate annual incidence of stroke is 8.7% in China. Comparing with the developed countries such as USA, the incidence of stroke is more than double. According to the latest statistics, 15% of ischemic stroke is caused by carotid stenosis. The occurrence of stroke is influenced by the atherosclerotic plaque stability in the place of narrow, and different types of ischemic stroke and stroke position are caused by the stenosis rate. Stent implantation has becoming the most important tool in the treatment of stroke. But the in-stent restenosis is one of the most common complications after stent implantation. The characteristics of hemodynamic have great influence to the plaque formation and in-stent restenosis. Acquiring the distribution of hemodynamics within a cardiac cycle in the carotid artery model and typical interventional stent of the carotid artery model, exploring the mechanisation of atherosclerotic plaque formation and development and in-stent restenosis, and providing a theoretical reference for early intervention and the stent treatment of ischemic stroke and the stent design.This thesis aiming at the problem of carotid atherosclerotic plaque and stenosis of stent restenosis in the carotid artery, the carotid artery model with human carotid artery geometry parameters is established by using Pro/E5.0. The unsteady blood flow are numerical simulated by using the method of computational fluid dynamics in the stenosis rate of carotid artery model and typical stent treatment of carotid artery model..The influence of stenosis rate and section shape of link to the distribution of hemodynamic is analyzed, and revealing the mechanism of vascular wall on the hemodynamic of carotid artery. In addition, the blood flow is experimented in carotid artery model in vitro, the experimental results and simulation results are compared and analyzed, and validating the numerical simulation method is correct.The main conclusions are listed as follows:Firstly, with the carotid artery stenosis, the distribution of hemodynamic has obvious difference within different stenosis rate in carotid artery. The greater stenosis rate has more obvious influence on the distribution of blood flow in carotid artery, and the probability of further development of atherosclerotic plaque is significant increasing. Comparing with the distribution of hemodynamic in the 0.05, 0.1, 0.2, 0.3, and 0.4 stenosis rate of carotid artery, the 0.5 stenosis rate of carotid artery causes larger area small velocity of blood flow, larger area of low wall shear stress and wall pressure, the greater total mesh displacement and Von Mises stress of carotid artery. And it promotes the further development of carotid atherosclerotic plaque.The fluid-solid interaction model has important effect to the distribution of hemodynamic in carotid artery, and the vessel shoud be considered in the numerical simulation of hemodynamic.Secondly, carotid artery stenosis treated by stent, the different section shape of link of stent has different effects on the distribution of hemodynamic in internal carotid artery. Comparing with C-S type and T-S type, the velocity of blood flow distributes very uniformity in R-S type internal carotid artery interventional therapy, and the area of step blood flow is small. The variation of wall pressure is smaller, and the percentage of wall shear stress in the normal range is largest. The total mesh displacement and Von Mises stress distribute very uniformity, and this varies within a small range. R-S type stent has excellent hemodynamic effect in the treatment of carotid artery stenosis.The rate of In-stent restenosis is low.The vessel wall and stent have little influence to the hemodynamic in the numerical analysis, and it can be neglected.Finally, the experimental results in vitro are consistent with the results of numerical analysis in carotid artery. There is a complex blood flow distribution in the carotid bifurcation and the external carotid artery, and the flow stagnation in this region. And it proves the numerical analysis method used is accurate in this thesis.The research can provide a theoretical reference for early intervention and the stent treatment of ischemic strokeand the stent design in this thesis.