生物可吸收式血管模架機械行為之電腦模擬

Abstract

心血管支架為一項微型醫療器材，部署於血管中可以維持血管管徑並恢復血流暢通，目前血管支架手術已經成為心血管疾病的主要治療方式，然而手術後仍會有晚期血栓的風險，於是生物可吸收式血管模架因應而生，它在完成階段性的任務之後，隨即被人體完全分解，預期將成為未來治療心血管疾病的趨勢。本研究透過有限元素分析法模擬生物可吸收式血管模架的機械行為，內容主要分為兩部分，第一部分探討設計樣式及使用材料對血管模架機械性質的影響，選用了VYW-shaped和V-shaped兩款設計樣式與兩種強度不同的生物可吸收式材料互相搭配進行研究。有鑑於3D列印技術的快速發展，第二部分提出利用此技術製造材料分層之生物可吸收式血管模架的概念，將傳統單一材料的血管模架改為分層指定不同材料，並觀察血管模架不同部位的材料性質差異會對血管模架的表現產生何種影響，以期能找到提升血管模架整體機械性能的方法。第一部分的模擬結果顯示血管模架的機械性質主要是由材料主導，設計樣式差異的影響則較小，比較特別的是設計樣式對血管模架彎曲的影響因材料不同而有所差異；第二部分的研究結果顯示血管模架的機械性質受到不同部位的材料影響程度不同，需要考量血管模架需求的優先順序來調整血管模架的表現。本研究能提供後繼者研究生物可吸收式血管模架的參考，文中提出結合3D列印技術將血管模架材料分層的創新概念，有望成為改善血管模架整體機械性能的新方法，協助生物可吸收式血管模架的研發進展。

Stents are miniature medical devices that can be inserted into arteries and expanded during angioplasty to maintain patency and re-establish flow through the vessel. They have been the primary treatment for cardiovascular diseases. However, after stenting, potential risks associated with late stent/scaffold thrombosis may occur. This problem promises to be solved with the advent of bioresorbable vascular scaffolds which offer the possibility of transient scaffolding of the vessel to prevent acute vessel closure and recoil. In this study, finite element models were developed to investigate the mechanical behaviors of bioresorbable vascular scaffolds. In the first part of this thesis, computational simulations were performed on two scaffold design patterns assigned with two different materials in attempts to quantify individual effects of the scaffold design patterns and materials on the mechanical performance. Simulation results show that the material properties plays the most significant role in all three finite element models. In the second part, a novel scaffold design concept associated with 3D printing was introduced for the purpose of enhancing mechanical properties Struts of the scaffolds were separated into many layers and each of them was assigned with different materials in certain order. Simulation results shows that the scaffold materials at particular location may have larger impacts on certain mechanical behaviors. If used appropriately, this phenomenon can improve the mechanical performance of scaffolds. This study provides great insight for the future design optimization and physician practice to help achieve the best possible clinical outcomes.