Hemodynamic Analysis And Optimal Design Of Coronary Stent

In recent years,the number of patients with various vascular occlusion diseases have increased,and the patients have become more and more young,which is a serious threat to human health and life safety.Vascular stent has rapidly developed into the most commonly used method for clinical treatment of vascular occlusion diseases with its high-efficiency and minimally invasive features.However,with the development of stent,the problem of postoperative restenosis is caused.After the stent implanted in stenosis artery as a foreign body,it not only affects the vascular structure,but also the biomechanical properties of the stent and the blood flow in the blood vessels are changed.These are the key factors for postoperative restenosis.Based on the scientific problem of postoperative restenosis,this paper researches the effects of stent implanting in stenosis artery by fluid-solid coupling analysis,and on this basis,improves the structure of stent and reduces the rate of restenosis.The specific contents are as follows:Firstly,researching fluid-solid coupling model of vessel and stent by hemodynamic simulation,according to the coronary stents implant in different rates of stenosis artery,extracting the result models under unloading and reconstruct the three-dimensional models of them.The obtained models are imported into ANSYS Workbench 15.0,creating a non-Newtonian blood model in CFX and constructing a coupled model of vessel,stent and blood to perform hemodynamic analysis.Timeaveraged Wall Shell Stress(TAWSS)and Oscillatory Shear Index(OSI)are used as evaluation indexes to analyze the fluid-solid coupling results,exploring the key factors and main parts of restenosis.Secondly,researching the topology optimization of coronary stent,on the basis of the fluid-solid coupling results,the topological optimization design of the structure prone to restenosis of the stent is carried out,and the optimal distribution of materials in the design area is realized without changing its supporting performance.By solving the true response of the vessel rebound stent,and based on this,constructing the coronary stent topology optimization model with the target of maximum radial stiffness of the coronary stent,imposing the draft constraint and the minimum member size constraint.The optimized stent structure is obtained and placed into stenosis artery with different stenosis rates for simulation of the interventional process,and the results of original stent and optimized stent are compared.Finally,researching the size optimization of coronary stents,based on the results of coronary stent topology optimization,the key size parameters of coronary stent are optimized.In this paper,the thickness of the coronary stent is used as the optimal design variable,and the vascular pressure is used as the size optimization load.The peak stress of the stent is used as the constraint condition to find the optimal solution of the stent thickness in a certain range.The result of size optimization is taken into interventional process simulation to verify the accuracy and feasibility of the size optimization results.