Effects Of The Left Coronary Artery Bifurcation Angle On Hemodynamics Characteristics

Cardiovascular disease is a kind of circulatory system disease with high morbidity and mortality,and it seriously threatens the life safety of Chinese residents.Atherosclerosis is a major contributor to cardiovascular disease,and often occurs in vessel bifurcation,such as left coronary artery bifurcation.There are often no clinical symptoms in the early stage of the disease.Several studies have shown that abnormal blood flow parameters can accelerate the formation of atherosclerotic plaque.Therefore,it is important to study the blood flow in the bifurcation of the left coronary artery(LCA)and bifurcation angle effects on the blood flow for understanding the pathogenesis and disease prediction.In this paper,clinical CT images were used for the three-dimensional reconstruction to extract the geometric structure of LCA's first-stage bifurcation.Then,numerical simulations were carried out to obtain the flow field,pressure field and the wall shear stress in a cardiac cycle.The results show that a large area of low velocity region often appears near the region where low wall shear stress occurs.Moreover,the time-averaged wall shear stress(TAWSS),oscillatory shear index(OSI)and relative residence time(RRT)were calculated to assess the location and risk of the disease.To study the bifurcation angle effects on the blood flow and disease risk,three types of ideal LCA models with several different bifurcation angles were constructed according to the literature.In this paper,the bifurcation angle effects on hemodynamic parameters were analyzed using CFD methods,and the influences of vascular structure and the bifurcation angle on the risk of disease were evaluated.The results show that the structure of blood vessels will also affect the magnitude and distribution of hemodynamic parameters,even the vessel diameters and bifurcation angle are the same.Besides,the critical values of the parameters will also affect the results.It is unreasonable to use the area of low TAWSS or high OSI to assess the risk of disease.However,RRT is feasible to assess the risk of disease.RRT was used to assess the risk of disease,and it was found that the susceptible area usually appeared on LCx on the opposite side of the carina.Then,the risk of blood vessels with different bifurcation angles was compared.The risk of the disease with a large bifurcation angle is small,and the highest risk appeared with the bifurcation angle close to 75°.The analysis of bifurcation angle effects on the cardiovascular disease risk and the different results of the critical parameter values will be useful for clinical diagnostics.