Numerical Simulation On Biomechanical Factors Of Coronary Plaque:A 3D Fluid-structure Interaction Model

Coronary atherosclerotic heart disease(referred to as coronary heart disease)is one of the most common and important heart diseases.The presence of plaque narrows the coronary lumen and causes myocardial ischemia.At the same time,the rupture of the plaque will form a thrombus and cause sudden cardiac death.The real coronary artery structure is rarely symmetrical.In the eccentric plaque,the edge and shoulder of the fiber cap are the weakest parts and the most likely to be ruptured.Studying the changing laws and mechanical properties of the fibrous cap of the plaque before rupture is an important part of revealing the pathogenesis of the plaque.Arterial physical model used by Professor Tang Dalin’s team is used as a reference in this article.Design Modeler,CFX and Mechanical modules in ANSYS Workbench are used to create a two-way fluid-structure coupling simulation model with 70% stenosis and 50%eccentricity.Arterial wall in the model uses the Mooney-Rivlin hyperelastic material,which is modified with measured data.The blood flow,deformation,and stress levels results of the simulation are compared with the results in the published literature.The functionality and accuracy of the model are verified.To carry out research on the biomechanical properties of coronary plaques,we establish the following model:non-stenosis and symmetrical cardiovascular wall models;50%stenosis,70% stenosis,and 75% stenosis of the vessel wall model(with the same eccentricity);50% eccentricity and 70% eccentricity,75% eccentric cardiovascular wall model(and under the same degree of stenosis).We quantify the effect of the degree of stenosis and the eccentricity of stenosis on blood flow,vessel wall deformation,and stress distribution,by carrying out two-way fluid-structure coupling simulation.The results show that for arterial structures with the same degree of stenosis,an asymmetric structure containing eccentricity will lead to higher arterial compression,higher stress and bigger wall deformation than symmetrical structures,and this effect becomes more prominent as the degree of stenosis increases.With the same degree of eccentricity,severe stenosis will lead to severe changes in blood flow at the proximal end of the tube wall,high circumferential stress and considerable wall deformation compared to smaller stenosis.It’s also observed that the deformation of the vascular wall and the changes in the magnitude of the circumferential stress level are correspond to the Noble classification,which provides theoretical support for the rationality of the Noble classification.At the same time,there has been a significant change between the comparison of 70% stenosis and 75% stenosis results,the circumferential stress reaches the critical value before plaque rupture(.This result provides further support for the severe stenosis critical value,which is the 75% in clinical medicine.The above results provide a solid theoretical basis and technical support for further revealing the pathogenesis of coronary heart disease and its early prevention.