A numerical study on the application of the functionally graded bioabsorbable materials in the stent design

Abstract

Background: Angioplasty with stenting is one of the primary treatment for coronary artery disease, hence, performance of the stent is deemed important. Bioabsorbable stents are the new generation of stents. Bioabsorbable magnesium alloys are a promising solution for adverse effects of long-term usage of stents. While their corrosion mechanics and biocompatibility have extensively been studied, there are no studies on application of functionally graded materials (FGM) on reduction of dogboning in bioabsorbable stents. Methods: The objective of this study was at reducing the dogboning via the application of the FGM. A combination of the finite element (FE) method and optimization algorithm were employed to analyse/optimize the mechanical behaviour of bioabsorbable stents. Proposed FGM, in this study, was a combination of AZ80 and WE43 magnesium alloys. Dogboning of the FGM stent was chosen as objective function to be minimized and heterogeneous index was chosen as control variable in the optimization algorithm. Results: The results revealed that the optimum FGM stent with heterogeneous index of 1.4625 has lower dogboning (63%) compared to that of the uniform stents made of AZ89 or WE43 magnesium alloy. Conclusions: Furthermore, the results suggested that the plastic material properties have higher impact on the mechanical behaviour of the stent in comparison to the elastic material properties.

Keywords

• Functionally graded material
• Atherosclerosis
• Stent
• Dogboning
• Finite element method
• Optimization