Experimental and computational studies of poly-L-lactic acid for cardiovascular applications: recent progress

Stents are commonly used in medical procedures to alleviate the symptoms of coronary heart disease, a prevalent modern society disease. These structures are employed to maintain vessel patency and restore blood flow. Traditionally stents are made of metals such as stainless steel or cobalt chromium; however, these scaffolds have known disadvantages. An emergence of transient scaffolds is gaining popularity, with the structure engaged for a required period whilst healing of the diseased arterial wall occurs. Polymers dominate a medical device sector, with incorporation in sutures, scaffolds and screws. Thanks to their good mechanical and biological properties and their ability to degrade naturally. Polylactic acid is an extremely versatile polymer, with its properties easily tailored to applications. Its dominance in the stenting field increases continually, with the first polymer scaffold gaining FDA approval in 2016. Still some challenges with PLLA bioresorbable materials remain, especially with regard to understanding their mechanical response, assessment of its changes with degradation and comparison of their performance with that of metallic drug-eluting stent. Currently, there is still a lack of works on evaluating both the pre-degradation properties and degradation performance of these scaffolds. Additionally, there are no established material models incorporating non-linear viscoelastic behaviour of PLLA and its evolution with in-service degradation. Assessing these features through experimental analysis accompanied by analytical and numerical studies will provide powerful tools for design and optimisation of these structures endorsing their broader use in stenting. This overview assesses the recent studies investigating mechanical and computational performance of poly(l-lactic) acid and its use in stenting applications.

支架在医疗程序中常被用于缓解冠心病的症状，冠心病是现代社会一种常见疾病。这些结构被用于维持血管通畅并恢复血流。传统上，支架由不锈钢或钴铬等金属制成；然而，这些支架存在已知的缺点。临时性支架的出现越来越受欢迎，这种结构在患病动脉壁愈合所需的时间内发挥作用。聚合物在医疗器械领域占主导地位，被用于缝合线、支架和螺钉等。这得益于它们良好的机械和生物性能以及自然降解的能力。聚乳酸是一种用途极广的聚合物，其性能很容易根据应用进行调整。它在支架领域的主导地位不断增强，首个聚合物支架在2016年获得美国食品药品监督管理局的批准。然而，聚乳酸生物可吸收材料仍然存在一些挑战，特别是在理解其机械响应、评估其随降解的变化以及将其性能与金属药物洗脱支架进行比较方面。目前，仍然缺乏对这些支架的降解前性能和降解表现进行评估的研究。此外，还没有建立包含聚乳酸非线性粘弹性行为及其在使用过程中随降解演变的材料模型。通过实验分析以及分析和数值研究来评估这些特性，将为这些结构的设计和优化提供有力工具，从而促进它们在支架领域的更广泛应用。本综述评估了近期对聚L - 乳酸的力学和计算性能及其在支架应用中的研究。