Characterizing the mechanical properties of the aortic wall

Abstract

Characterizing the physical properties of the aortic wall is essential to understanding the causes of cardiovascular diseases, such as aneurysms. Modelling compliant, anisotropic, multilayered tubes such as the aorta has proven to be a challenge. In vitro studies of the mechanical properties of arteries incorporate a variety of testing methods; however, the majority of these tests fail to replicate the complex, transmural loading conditions arising from pulsatile flow. These methods include typical tensile tests, both in uniaxial and biaxial setups , bulge inflation tests and extensioninflation tests. Bulge-inflation tests grant material information in response to biaxial loading but still do not mimic proper cylindrical loading conditions. Extension-inflation tests capture the cylindrical loading but have only been performed with static pressurization and with rigid boundary conditions in effect. This review aims to present the current state of the biomechanical characterization of arterial walls, particularly the aorta, through discussion of testing methods and their findings. We emphasize literature that focuses on prediction of aneurysm rupture risk. Moreover, overarching concepts such as histological effects, age dependent effects, segmental effects, hemodynamic effects, viscoelastic modelling and torsion will be briefly explored. An understanding of the current limitations of testing will hopefully lead to the development of more robust in vitro test methods that will further elucidate the relationship between changing vessel wall mechanics and cardiovascular disease.

Investigation on the Behavior of κ ‐Carrageenan Hydrogels for Compressive Intra‐Vessel Disintegration

“…Little data on compression of vessels is reported, as vessels are usually loaded by intra‐luminal pressure for which the tensile modulus is of interest. [ 30,31 ] Compressive vessel investigations found in literature focus on blood supply during pregnancy, cardiopulmonary resuscitation or aortae calcification determination. One study reported on calcified porcine aortae up to compressive strains of 50%, [ 29 ] strains too low for hydrogel disintegration.…”

A Computational Growth Framework for Biological Tissues: Application to Growth of Aortic Root Aneurysm Repaired by the V-shape Surgery

“…Aortic walls are usually composed of three layers, the intima, media and adventitia layers [24]. The tissue of each layer is comprised of networks of collagen fibers embedded in a ground matrix and can be regarded as fiber reinforced composites, of which the mechanical properties are anisotropic [25][26][27], similar to engineering fiber-reinforced composites [28][29][30][31][32]. Schriefl at al.…”

Predictors of Abdominal Aortic Aneurysm Risks

“…This degradation affects the mechanical properties of the AAA wall, including its strength, and it varies significantly from patient to patient as well as within an AAA [ 5 ]. Because there is no current clinical test to non-invasively assess microscopic tissue composition, AAA wall properties continue to be elusive [ 95 ]. Attempts have, therefore, been made to correlate AAA wall properties, including wall strength, to non-invasive measurements such as metabolic activity (assessed by positron emission tomography scans, PET/CT) or blood biomarkers of tissue degradation activity, e.g., [ 94 , 96 ].…”