Parametric optimization of stent design based on numerical methods

Abstract

© Springer Nature Switzerland AG 2020. Today, endovascular prosthesis—stents are used as a solution for treating many health disorders and diseases. Their major application is found in treating cardiovascular diseases. One of the problems in stent implantation is a process called in stent restenosis (ISR). In the pre-stent era, the occurrence of restenosis ranged between 32 and 55% of all angioplasties, and in bare-metal stent (BMS) era this range dropped to 17–41%. Many factors have influence on this phenomenon. Some studies show that in stent restenosis, strut shape and thickness have significant impact, especially if the stent is implanted in the small arteries. For better stent geometry modeling, in this paper authors suggested novel approach—parametric optimization on the existing stent design. For evaluation of the parametric optimization and mechanical performance of nitinol stents as well as comparison of differences between old design (non-optimized) and new optimized design the finite element method was used. Simulation was performed assuming that the stent devices used for this research were made by laser cutting, from tube form, by application of expanding and crushing force. The behavior of two different stent models was analyzed: old Palmaz-Schatz design and novel optimized design. Novel design based on the results from parametric optimization preceded on the Palmaz-Schatz design. Performed simulation on stent models showed that the new modern design has better clinical behavior due to lower contacting surface, higher radial resistive strength and much better superplastic behavior. Optimization process was based on two optimization rules: minimization of the model volume and provide the best possible strain field in the model. Comparison of result from FE analyses from old an optimized design show that based on this approach it is possible to engineers in the future create a new and much beater stents very easy.