In Vivo Stress Analysis Of Carotid Bifurcation And Its Plaque

Mechanical stimuli play an important role in the remodeling process of the vascular,having a direct impact on the whole process of the occurrence and development of vascular disease.It is of great significance to make a prediction of the in vivo stress of both healthy and pathological vascular in the study of mechanism related to atherosclerosis and assessment of plaque rupture.Based on average geometry parameters of human carotid bifurcation,this paper creates averaging ideal geometries of carotid bifurcation and its plaque,rebuilding the residual stress of carotid bifurcation and its plaque.After that this paper analyzes the in vivo stress of carotid bifurcation and its plaque under different blood pressure and different blood flow.This paper is trying to investigate the general distribution of in vivo stress of carotid bifurcation and its plaque,so as to provide mechanical references for the mechanisms of plaque rupture at the carotid bifurcation and the design for further medical treatment.The main work and conclusions of this paper are described below:(1)According to average geometry parameters of carotid bifurcation,this paper creates averaging ideal geometry and finite element model of carotid bifurcation and its plaque,and we rebuild the residual stress of carotid bifurcation and its plaque with “thermal-structure” coupling.After that we further rebuild the in vivo elastic stress of carotid bifurcation.By comparison with experimental observation of incision experiment of carotid bifurcation,it qualitatively demonstrates the validation of the residual stress we rebuilds.(2)With the utilization of the model we create,This paper makes a prediction of the in vivo stress of the carotid bifurcation and its plaque.Results show that,compared with the model without residual stress,the maximum principal stress of the one with consideration of residual stress is more uniform across the wall.there is a concentration of maximum principal stress and elastic shear stress on the shoulder of the plaque.And elastic shear stress increases with both blood pressure and stenosis.Tension grew gradually from the centrality to shoulder surface of the plaque.The centrality of the plaque might bear compression when the stenosis is very severe.The periodic variation of the structural stress might cause structural fatigue of the plaque,thus increasing the rupture risk.(3)Based on the clinical measurements of average blood flow velocity in adult carotid artery,this paper calculated hemodynamic parameters of carotid bifurcation and its plaque under different stenosis.Results show that wall shear stress in the upstream of the plaque was considerably higher than that of the downstream.The distribution of OSI was quite the opposite.The evolvement trend of the elastic shear stress and viscous shear stress was quite different with the change of stenosis ratios.Distinction of the hemodynamic parameters of the plaque between upstream and downstream offers the mechanical references of the study of the differences in the component and vulnerability of the plaque between upstream and downstream.