Structural design optimization through finite element analysis of additive manufactured bioresorbable polymeric stents

Abstract

Coronary stents help to treat coronary artery disease. Polymeric-based stents are considered the next generation of these medical devices since the materials are more compatible with human cells. Developing a polymeric bioresorbable stent with a different and optimized design can improve the mechanical performance of polymeric additively manufactured coronary stents. In this study, two different polymers were processed by additive manufacturing, and their mechanical properties were analyzed: poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL). Five different designs (A, B, C, D, and E) were then conceptualized with three different thicknesses. Finite element analysis (FEA) of a stent implantation process, using the mechanical properties of the additively manufactured materials, was used to evaluate the influence of the design, after the stent expansion, on the radial recoil ratio (RRR) and foreshortening. The in-silico results demonstrated that reducing strut thickness originates more plastic deformation, which reduces the RRR and increases the absolute value of foreshortening. PLA-based stents presented less RRR but, simultaneously, more risk of fracture. In the case of PCL-based devices, only designs A, B, and C presented acceptable recoil ratios. Design A is the chosen design as it reduces the RRR for lower thicknesses without risk of fracture during the stent deployment.