Numerical Simulation Of Atherosclerosis Based On Low Shear Stress Theory

According to "China’s cardiovascular disease prevention and control of the status quo Blue Book·2015" reported.At present,China has about 290 million cardiovascular disease patients and showing a rising trend year by year.An average of about 2.6 million people die each year caused by cardiovascular disease,every 12 seconds there is a loss of life due to cardiovascular disease,its morbidity and mortality rank first in all diseases.Now,atherosclerosis has become a serious public health hazards to human health problems,urgent need to be resolved through multi-study.Atherosclerosis(AS)is one of the most common cardiovascular diseases.It may cause serious complications such as stroke,coronary heart disease,and myocardial infarction.For the elderly over the age of 60,the incidence of atherosclerosis as high as 79.9%.If accompanied by cardiovascular disease,the survival rate of patients within 5 years is only 59%,for high blood pressure,hyperglycemia,hyperlipidemia patients,the survival rate is even lower.Thus,atherosclerosis for human health has a serious potential threat.However,the pathogenesis and development mechanism of atherosclerosis is very complex,and has not yet fully grasp the master.Therefore,to explore the pathogenesis of atherosclerosis and specific reasons,has great significance for disease control,risk assessment and clinical prognosis.A large number of studies have shown that the development of atherosclerosis is affected by biological,physical,chemical and other stimuli.Based on the relevant cases and experimental results,scholars put forward many theories trying to explain the emergence and development of atherosclerosis mechanism.But these doctrines do not have a systematic analysis of the mechanics during the atherosclerosis generation and development.During the autopsy study,Caro found that atherosclerosis mainly occurs in the bifurcation,stenosis,bending and other hemodynamic vulnerable parts,showing a very significant difference between the local focal characteristics.Thus proving that changes in hemodynamic environment have an important impact on the formation and development of atherosclerosis,but the understanding of the specificmode of action and the extent of its impact is not enough.The research idea of this paper is to adopt reverse engineering modeling to explore the effect of vascular geometry on the hemodynamics,resulting in low wall shear stress.Then,according to the Caro low shear stress theory,we use the wall shear stress as a criterion,to stimulate the dynamic development process of atherosclerosis.The simulation work of this paper is done by the computational fluid dynamics software FLUENT.The operation interface is simple,it has abundant physical model,advanced numerical algorithm and the matching Pre-processing and post-processing features.FLUENT is highly recognized in the field of computational fluid,the results are accurate and reliable.FLUENT also provides a secondary development program interface(UDF)to facilitate the user to achieve a more diversified model solution.In this paper,we make the hemodynamics as the starting point,taking into account the low shear stress on the plaque proliferation and the flow field boundary changes in blood flow redistribution,to achieve the vascular wall boundary changes and hemodynamics of the coupling effect,this is also the technical difficulty of this method.To this end,after investigating the active dynamic mesh and the cell filling method,it was found that the simulation results and the computational efficiency were insufficient,so we developed a innovative UDF(User Defined Function)dynamic mesh program to extract vascular wall shear stress in the calculation process and make judgments,and then adjust the movement of the mesh nodes to simulate the vascular plaque hyperplasia process.After the final comparison,we found that the simulation results were similar to some clinical angiography,and proved the feasibility of this method.