Structrure Design And Performance On Magnesium Alloy Heart Stents

Coronary artery stent implantation has become the preferred method of treating coronaryheart disease worldwide. The stent design directly affects its mechanical properties. The stentrequires high mechanical property, which has good expansion capability and flexibility.Biodegradable magnesium alloy can degrade in body, so it has good blood compatibility, beharmless to human, and has become popurlar material as rising stent material at present.According to the characteristics of magnesium alloys and the principle of stent designs,several kind of stent structures were designed. The influence of material and geometricstructure on the mechanical behaviors of stent were analyzed via finite element softwareANSYS.The results show that the expansion and flexibility behaviors of stents mainly depend onthe structure and material. The internal pressure of WE43magnesium alloy was less than thatof316L stainless steel when the stent was expanded to the same diameter. Simultaneously, thelonger struct length and the smaller struct width could decrease the internal pressure whenexpanded the stent with same structure to a same diameter. When internal pressure wasdifferent, the radial recoil rate decreases with expansion diameter increased.With a same deformation, the deformation resistance of WE43magnesium alloy wasgreatly less than that of316L stainless steel, which show that flexibility of WE43magnesiumalloy was excellent. Structure of stent had a relatively large influence on flexibility, andflexibility of the open-loop structure was more excellent than that of the closed-loop.Meanwhile, struct size of stent influenced flexibility to a certain degree, and flexibilitydecreased with increased struct width. Though the expansion, it is found that the axial recoilrate was independent of the material used, conversely being related to structure and expansionsize. The larger expansion connected with lager axial recoil rate.By finite element analysis, the designed stent had good enough and uniform expansionperformance, favourable axial flexibility and lesser axial recoil rate, which was suitable for thedesign requirements of stent which contributed to stent design and analysis.