Numerical Study On Biomechanics Of Left Coronary Artery Considering Cardiac Motion

Coronary atherosclerosis,as a typical cardiovascular disease,is threatening the lives of many people around the world.However,the formation,development and pathogenesis of atherosclerosis are still not very clear.This thesis uses fluid-structure coupling simulation methods to explore the effects of cardiac motion,stenosis,plaques of different materials and plaques of different growth cycles on left coronary artery biomechanics.Promote more accurate analysis of coronary atherosclerosis hemodynamics and structural mechanics,and improve people’s understanding of calcified plaques and the vulnerability of plaque growth.To investigate the effects of cardiac motion and stenosis on left coronary artery biomechanics,a left coronary artery model and a coronary motion model were constructed using CT images of the left coronary artery and coronary motion measurements,respectively.The results of deformation volume,Von Mises force(VMS),and wall shear force(WSS)were used to evaluate the hazard of each factor on the left coronary artery.The results showed that the model considering cardiac motion had greater deformation and a greater risk of coronary plaque rupture.When comparing the VMS distribution within the different arterial models,the difference between the model considering cardiac motion and the model without cardiac motion was small,and the difference between the stenosis model and the model without stenosis was large.In other words,the effect of arterial motion on blood flow patterns and stresses was much smaller than that of arterial stenosis.The effect of plaques with different characteristics on the biomechanics of the left coronary artery considering cardiac exercise conditions was studied.Calcified plaques,cellular plaques,and low-cellular plaques were established for numerical simulation according to the stress-strain characteristics of different atherosclerotic coronary arteries,and UDF was written in c language for processing the time-averaged wall shear stress(TAWSS),oscillatory shear index(OSI)and relative residence time(RRT)of the coronary artery wall.The results showed that plaques with different characteristics had little effect on the parameters of left coronary artery deformation,VMS,and hemodynamics.Comparing the minor differences in various parameters between different models,the low-cell plaque model had the largest VMS,OSI,and RRT among all models,indicating that the low-cell plaque coronary motion risk was greater.A study was conducted on the effect of plaques at different stages of growth on the biomechanics of the left coronary artery considering cardiac exercise conditions.A model of the left coronary artery containing plaque at different stages of growth was created from anatomical images and stress-strain properties of the atheromatous plaque for simulation.The results showed that in the coronary artery wall,the size of the VMS increased with the degree of stenosis.The VMS gap between the plaque and the surrounding area also increased with the degree of stenosis,making the fibrous cap more prone to tear and producing acute events.In the early stage of coronary atherosclerosis,WSS had a small value area at the bifurcation,which was conducive to the accumulation of high-density lipoprotein and other substances in the blood and promoted plaque growth.After coronary artery stenosis,WSS had a maximum value on the fiber cap area,which promoted the rupture of the fiber cap.