Fegan Katie L, Green Naomi C, Britton Melanie M, Iqbal Asif J, Thomas-Seale Lauren E J
Physical Sciences for Health Centre for Doctoral Training, University of Birmingham, Birmingham, United Kingdom.
Department of Mechanical Engineering, University of Birmingham, Birmingham, United Kingdom.
Front Cardiovasc Med. 2022 Jun 24;9:883179. doi: 10.3389/fcvm.2022.883179. eCollection 2022.
Coronary artery disease is among the primary causes of death worldwide. While synthetic grafts allow replacement of diseased tissue, mismatched mechanical properties between graft and native tissue remains a major cause of graft failure. Multi-layered grafts could overcome these mechanical incompatibilities by mimicking the structural heterogeneity of the artery wall. However, the layer-specific biomechanics of synthetic grafts under physiological conditions and their impact on endothelial function is often overlooked and/or poorly understood. In this study, the transmural biomechanics of four synthetic graft designs were simulated under physiological pressure, relative to the coronary artery wall, using finite element analysis. Using poly(vinyl alcohol) (PVA)/gelatin cryogel as the representative biomaterial, the following conclusions are drawn: (I) the maximum circumferential stress occurs at the luminal surface of both the grafts and the artery; (II) circumferential stress varies discontinuously across the media and adventitia, and is influenced by the stiffness of the adventitia; (III) unlike native tissue, PVA/gelatin does not exhibit strain stiffening below diastolic pressure; and (IV) for both PVA/gelatin and native tissue, the magnitude of stress and strain distribution is heavily dependent on the constitutive models used to model material hyperelasticity. While these results build on the current literature surrounding PVA-based arterial grafts, the proposed method has exciting potential toward the wider design of multi-layer scaffolds. Such finite element analyses could help guide the future validation of multi-layered grafts for the treatment of coronary artery disease.
冠状动脉疾病是全球主要死因之一。虽然合成移植物能够替代病变组织，但移植物与天然组织之间不匹配的力学性能仍是移植物失效的主要原因。多层移植物可以通过模拟动脉壁的结构异质性来克服这些力学不相容性。然而，合成移植物在生理条件下的层特异性生物力学及其对内皮功能的影响常常被忽视和/或理解不足。在本研究中，使用有限元分析，相对于冠状动脉壁，在生理压力下模拟了四种合成移植物设计的跨壁生物力学。以聚乙烯醇（PVA）/明胶冷冻凝胶作为代表性生物材料，得出以下结论：（I）移植物和动脉的最大周向应力均出现在管腔表面；（II）周向应力在中膜和外膜上呈不连续变化，并受外膜刚度的影响；（III）与天然组织不同，PVA/明胶在舒张压以下不表现出应变硬化；（IV）对于PVA/明胶和天然组织，应力和应变分布的大小在很大程度上取决于用于模拟材料超弹性的本构模型。虽然这些结果基于目前有关基于PVA的动脉移植物的文献，但所提出的方法对于多层支架的更广泛设计具有令人兴奋的潜力。这种有限元分析有助于指导未来用于治疗冠状动脉疾病的多层移植物的验证。
