自鎖式血管支架之設計概念與可行性評估

Abstract

生物可吸收式血管模架具有可以被人體吸收，不會在體內留下永久金屬植入物的優點，預期將成為未來治療心血管疾病的趨勢；然而，生物可吸收式血管模架卻普遍有徑向支撐強度不足、回彈率偏高的問題。本研究提出兩種不同概念之自鎖式血管支架設計方向，其一是軸向的自鎖式結構設計，用以限制血管支架Crown的開合角度，其二是圓周向的自鎖式結構設計，利用圓周向的結構變化使血管支架固定在特定直徑。為了提升徑向支撐強度、降低回彈率，本研究希望從血管支架的設計端來改善，並且進行有限元素分析模擬自鎖式血管支架的機械行為，探討設計樣式及材料對自鎖式血管支架機械性質的影響，使用的材料為鈷鉻合金以及聚乳酸。研究結果顯示以圓周向設計的自鎖式結構表現較佳；而機械性質在不同材料上，會產生不同程度的影響，以聚乳酸為材料的自鎖式血管模架所受自鎖式結構的影響較大。本研究所提出的兩種設計概念皆有其可行性，有望改善生物可吸收式血管模架的徑向支撐強度，希望能提供後繼者設計自鎖式血管支架之參考，以進行最佳化設計，為高階醫療器材的開發盡一份心力。

Bioresorbable vascular scaffolds offer the possibility of transient scaffolding of the vessel to prevent acute vessel closure and restenosis, which are a tendency of stent treatment. However, bioresorbable vascular scaffolds have weaker radial strength and higher expansion recoil. This problem is sure to be solved with self-locking stents. In this study, there are two design concepts of self-locking mechanism. One is designed to constrain the open and close movement of crowns. The other is designed to fix stent diameter in θ direction. In order to improve radial strength and reduce expansion recoil, it is self-locking mechanism that achieve these goals. In this study, finite element models were developed to investigate the mechanical behaviors of self-locking stents. Computational simulations were performed on different design patterns assigned with two different materials, quantifying individual effects of the self-locking design patterns and materials on the mechanical performance of self-locking stents. In the finite element model, Co-Cr alloy and PLA were used. Simulation results show that the design concept of θ-direction has better performances, and the material properties plays the most significant role in self-locking stents. These two design concepts are both feasible to enhance the mechanical behaviors of self-locking stents. This study provides great insight for the future self-locking design optimization.