Structural Design And Optimization Of Nickel-titanium Alloy Stent For Intracranial Thrombus Removal

Stroke is an organ disease caused by brain tissue damage.Stroke is divided into hemorrhagic stroke and ischemic stroke.Among them,the treatment of ischemic stroke caused by acute thrombosis is a major problem in the treatment of cerebrovascular diseases.Intracranial stent for thrombus removal can effectively remove thrombus,improve vascular recanalization rate,and improve the survival rate of patients with acute brain junior high school.Therefore,the development of a new type of intracranial thrombus removal stent is of great significance and application value in the treatment of ischemic stroke.Based on the comparative analysis of the advantages and disadvantages of the main intracranial stents for thrombus removal in clinical application,a new type of intracranial stent for thrombus removal was designed using nickel-titanium alloy as the stent material based on the bionic design concept.The mechanical properties and the contact properties with the vascular wall of the stent were studied.The stent consists of distal region,middle region and proximal region.The distal area is connected and wound by several first closed-loop units in turn;the middle area is connected and wound by several second and third closed-loop units in turn;the second closed-loop unit is mainly used to pick up thrombus;the third closed-loop unit is mainly used to support the stent;the proximal area is connected by the fourth closed-loop unit and push trunk.The stent expands in the blood vessel by self-expansion.In this paper,nine groups of stents with different strut width and thickness were established.The porosity and space occupancy ratio of the stents were calculated.The results showed that the porosity of the nine groups of stents is more than 80%,and the space occupancy of the stents with 0.1mm strut width isslightly smaller.Finite element method was used to investigate the effects of different strut width and thickness on the mechanical performance of stents.The flexibility of stents,the contact analysis between stents and blood vessels,and the expansion performance of the stents were analyzed.The results showed that in a certain range,the radial load performance of the stent increased with the increase of the stent strut width,and the influence of the strut thickness also showed this rule,but the influence was small.The stent with 0.20 mm strut width and 0.15 mm and0.20 mm strut thickness had better radial load performance.The compliance and vascular contact results of stent with 0.20 mm strut width and 0.15 mm strut thickness were better than the stent with 0.20 mm strut width and 0.20 mm strut thickness,and the expansion performance of stent with 0.20 mm strut width and0.20 mm strut thickness was better than stent with 0.20 mm strut width and 0.15 mm strut thickness.Based on the above finite element simulation results,the stent structure was optimized,and the structure and location of the development point were optimized.The stent with better performance and better development effect was acquired.The results show that the optimized stent 2015 and 2020 have good mechanical properties.The optimization can improve the distribution of high stress and eliminate the influence of stent on vascular wall.