Biological tissue for transcatheter aortic valve: The effect of crimping on fatigue strength

IF 3.3 2区医学 Q2 ENGINEERING, BIOMEDICAL Journal of the Mechanical Behavior of Biomedical Materials Pub Date : 2024-09-11 DOI:10.1016/j.jmbbm.2024.106741

Foued Khoffi , Amanda C. Mills , Martin W. King , Frederic Heim

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Abstract

Transcatheter aortic valve replacement (TAVR) has become today the most attractive procedure to relieve patients from aortic valve disease. However, the procedure requires crimping biological tissue within a metallic stent for low diameter catheter insertion purpose. This step induces specific stress in the leaflets especially when the crimping diameter is small. One concern about crimping is the potential degradations undergone by the biological tissue, which may limit the durability of the valve once implanted. The purpose of the present work is to investigate the mechanical damage undergone by bovine pericardium tissue during compression and analyze how this degradation evolves with time under fatigue testing conditions. Pericardium 500 μm thick pericardium ribbons (5 mm large, 70 mm long) were crimped down to 12 Fr for 30 and 50 min within a metallic stent to replicate the heart valve crimping configuration. After crimping, samples underwent cyclic fatigue flexure and pressure loading over 0.5 Mio cycles. Samples were characterized for mechanical performances before crimping, after crimping and after fatigue testing in order to assess potential changes in the mechanical properties of the tissue after each step. Results bring out that the ultimate tensile strength is not modified through the process. However an increase in the modulus shows that the crimping step tends to stiffen the pericardium. This may have an influence on the lifetime of the implant.

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用于经导管主动脉瓣的生物组织：卷边对疲劳强度的影响

经导管主动脉瓣置换术（TAVR）已成为当今治疗主动脉瓣疾病最有吸引力的方法。然而，该手术需要在金属支架内卷曲生物组织，以便插入低直径导管。这一步骤会对瓣叶产生特定的应力，尤其是在卷曲直径较小时。卷曲的一个顾虑是生物组织可能会发生降解，这可能会限制瓣膜植入后的耐用性。本研究的目的是调查牛心包组织在压缩过程中受到的机械损伤，并分析在疲劳测试条件下这种退化是如何随时间演变的。将 500 μm 厚的心包膜带（5 mm 大，70 mm 长）在金属支架内分别卷曲 30 和 50 分钟至 12 Fr，以复制心脏瓣膜的卷曲结构。卷曲后，样品经历了超过 0.5 百万次的循环疲劳弯曲和压力加载。对样品进行了卷曲前、卷曲后和疲劳测试后的机械性能表征，以评估每个步骤后组织机械性能的潜在变化。结果表明，极限拉伸强度在这一过程中没有发生变化。但模量的增加表明，卷曲步骤往往会使心包变硬。这可能会影响植入物的使用寿命。

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来源期刊

Journal of the Mechanical Behavior of Biomedical Materials 工程技术-材料科学：生物材料

CiteScore

7.20

自引率

7.70%

发文量

505

审稿时长

46 days

期刊介绍： The Journal of the Mechanical Behavior of Biomedical Materials is concerned with the mechanical deformation, damage and failure under applied forces, of biological material (at the tissue, cellular and molecular levels) and of biomaterials, i.e. those materials which are designed to mimic or replace biological materials. The primary focus of the journal is the synthesis of materials science, biology, and medical and dental science. Reports of fundamental scientific investigations are welcome, as are articles concerned with the practical application of materials in medical devices. Both experimental and theoretical work is of interest; theoretical papers will normally include comparison of predictions with experimental data, though we recognize that this may not always be appropriate. The journal also publishes technical notes concerned with emerging experimental or theoretical techniques, letters to the editor and, by invitation, review articles and papers describing existing techniques for the benefit of an interdisciplinary readership.