Effects Of Mechanical Parameters On The Stent In Cardiovascular Interventional Surgery

Coronary wall mechanical properties and stent expansion analysis are the technical basis of percutaneous puncture coronary stent implantation.The mechanical properties of the coronary artery wall depend on factors such as race,sex,age,and health condition.The use of mechanical parameters consistent with the mechanical properties of the coronary artery wall is a prerequisite for accurately obtaining the mechanical response of the coronary artery wall during stent expansion.In most stenting analyzes,the mechanical properties of the coronary arteries are seldom considered,and in few stent dilatation analyzes involving the coronary arteries,the coronary arteries are reduced to linear elastic materials or thin-walled cylinders.The complexity of coronary wall mechanics is a difficult point in the coronary-stent combination analysis.In this paper,in-depth analysis of the mechanical properties of the coronary artery wall,the use of existing experimental data on the inverse of the mechanical parameters of the coronary wall,the establishment of finite element model of the coronary arteries,study the stent in the coronary artery wall expansion behavior,optimize the blood vessels Bracket structure.In this paper,coronary parameters of the mechanical parameters C10,k1 were inversed.In view of the complexity of the mechanical properties of the coronary artery wall,the anisotropic hyperelastic constitutive model(HGO model)proposed by Holzapfel et al is used to characterize the material properties of the coronary artery wall.In this paper,the parameter inversion is transformed into the optimization problem.The lsqnonlin function is invoked by Matlab self-programming and the mechanical parameters are modified by using Levenberg-Marquardt algorithm.The parameters matching with the domestic experimental data are obtained through 21 iterations.Coronary artery wall finite element model was established to study the residual stress and strain in coronary wall.Through the open angle of closure,study the coronary artery wall layers and the overall residual stress distribution.The linear elastic material control group was set up to compare and analyze the difference of residual stress distribution and numerical difference between linear elastic material and HGO model.The mechanical response of model under physiological pressure was studied.The residual stress and strain of all the models showed the state of internal pressure external pull.Among them,the difference between the residual strain and the distribution of each model is small,while the residual stress is quite different.The linear elastic material control group is several times more stressed than the other models.Residual stress and strain improve the stress distribution of the HGO model,but have no similar effect on the linear elastic material.We have established a coronary-stent contact model that simulates the expansion of the vascular stent and optimizes the stent structure.The inflation pressure of the balloon that is matched with the stent is replaced by a uniform pressure on the inner wall of the stent.The stent underwent non-uniform expansion under the action of inflation pressure,and the stress concentration was observed in the area of the coronary wall contacted by the end.By optimizing the support structure at the end of the support bracket,the best expansion effect of the support bracket is obtained.Among the five stent models established,model D had the least damage to the coronary artery wall and the lowest rate of dog bone during inflation,which was the optimal model among the five models.