Global and local stiffening of ex vivo-perfused stented human thoracic aortas: A mock circulation study. (15th April 2023)

• Record Type: Journal Article
• Authors: Agrafiotis, Emmanouil; Mayer, Christian; Grabenwöger, Martin; Zimpfer, Daniel; Regitnig, Peter; Mächler, Heinrich; Holzapfel, Gerhard A.
• Is Part Of: Acta biomaterialia. Volume 161(2023)
• Page Start: 170
• Page End: 183
• Publication Date: 2023-04-15
• Subjects: Endovascular repair -- Compliance mismatch -- Aortic stiffening -- Histological remodelling -- Biaxial extension test; Biomedical materials -- Periodicals; 610.28
• DOI: 10.1016/j.actbio.2023.02.028
• Languages: English
• ISSNs: 1742-7061

Abstract

Graphical abstract: Abstract: The effects of thoracic endovascular repair (TEVAR) on the biomechanical properties of aortic tissue have not been adequately studied. Understanding these features is important for the management of endograft-triggered complications of a biomechanical nature. This study aims to examine how stent-graft implantation affects the elastomechanical behavior of the aorta. Non-pathological human thoracic aortas (n = 10 ) were subjected to long-standing perfusion (8h) within a mock circulation loop under physiological conditions. To quantify compliance and its mismatch in the test periods without and with a stent, the aortic pressure and the proximal cyclic circumferential displacement were measured. After perfusion, biaxial tension tests (stress-stretch) were carried out to examine the stiffness profiles between non-stented and stented tissue, followed by a histological assessment. Experimental evidence shows: (i) a significant reduction in aortic distensibility after TEVAR, indicating aortic stiffening and compliance mismatch, (ii) a stiffer behavior of the stented samples compared to the non-stented samples with an earlier entry into the nonlinear part of the stress-stretch curve and (iii) strut-induced histological remodeling of the aortic wall. The biomechanical and histological comparison of the non-stented and stented aortas provides new insights into the interaction between the stent-graft and the aortic wall. The knowledge gained could refine the stent-graft design to minimize the stent-induced impacts on the aortic wall and the resulting complications. Statement of significance: Stent-related cardiovascular complications occur the moment the stent-graft expands on the human aortic wall. Clinicians base their diagnosis on the anatomical morphology of CT scans while neglecting the endograft-triggered biomechanical events that compromise aortic compliance and wall mechanotransduction. Experimental replication of endovascular repair in cadaver aortas within a mock circulation loop may have a catalytic effect on biomechanical and histological findings without an ethical barrier. Demonstrating interactions between the stent and the wall can help clinicians make a broader diagnosis such as ECG-triggered oversizing and stent-graft characteristics based on patient-specific anatomical location and age. In addition, the results can be used to optimize towards more aortophilic stent grafts.