Research On Hemodynamics Of Two-phase Flow Within Vascular And Stent

According to statistics, at present, patients with cardiovascular disease 290 million people, the national average of every five adults in one person suffering from cardiovascular disease, and the prevalence is rising phase. In the maiming and killing of cardiovascular disease, more than 75% are caused by vascular stenosis lesions of atherosclerotic plaque, stenosis plaque on artery blood flow has a blocking effect, as the degree of stenosis gradually deepened, eventually leading to blood vessel blockage and induce cardiovascular disease. Currently, interventional stent therapy is one of the primary means of treatment of vascular stenosis, but after stenting often have problems of in-stent restenosis. Hemodynamic parameters distribution has a close relationship with the formation of atherosclerotic plaques and thrombus within vascular or stents, and hemodynamic study in favor of proved plaque formation, development mechanism and in-stent restenosis mechanism, for the diagnosis, treatment and stent design of cardiovascular disease provide a theoretical basis.In this paper, for the problem of vascular stenosis and in-stent restenosis caused by atherosclerosis plaques, left coronary artery in the human body as the research object, established the left coronary artery model of different stenosis rate and stent model of different structures, based on fluid-structure coupling between vascular, atherosclerotic plaque, stent and blood, considering the impact of blood components, blood is treated as two-phase fluid, the left coronary artery and stent model has been hemodynamic numerical simulation by computational fluid dynamics method, analyzed the stenosis rate and stent structure influence on hemodynamic characteristics. In addition, validated the numerical methods in this article is correct by hemodynamics experiments in vitro.The main research work and conclusions as follows:Firstly, using Pro/E established the left coronary artery geometric model, analyzed the distribution of the hemodynamic parameters of newton blood model and two-phase blood model in the left coronary artery, obtained the flow properties of red blood cells in two-phase blood model influence on hemodynamic characteristics, provides research methods and technical conditions for the study of hemodynamics.Secondly, established the left coronary artery model of different stenosis rate, analyzed the stenosis rate influence on hemodynamic characteristics in the left coronary artery, explored development process of vascular stenosis from the perspective of hemodynamics, reveals the formation and development mechanism of artery atherosclerotic plaque, and it’s great significance for understand the pathogenesis of vascular stenosis and clinical diagnosis and treatment.Thirdly, established the left coronary model of stent implantation and stent model of different structures, analyzed the stent implantation influence on hemodynamic characteristics in the stenosis artery, and the stent structure influence on hemodynamic characteristics in the stents, explored the restenosis mechanism in the stents, provides theoretical guidance for the stent design and stent implantation in the treatment of cardiovascular disease.Finally, the left coronary artery model has conducted hemodynamic experiments in vitro, the experimental results and numerical simulation results were analyzed, the results show that it appears some blood stagnation zone in outside of the artery bifurcation,it has lower blood flow velocity and the particles generated deposition, it is consistent with the numerical simulation of hemodynamic characteristics, and the correctness of numerical method in this paper was validated.