Influence of atherosclerosis on anisotropy and incompressibility of the human thoracic aortic wall

In this study, we analysed the influence of atherosclerosis on the anisotropic and incompressible behaviour of the human thoracic aortic wall under mechanical loads. The mechanical tests involved preparations of the human thoracic aortic wall, which were evaluated based on the six-stage histological classification of atherosclerosis proposed by Stary. Anisotropy was evaluated on the basis of directional tests of mechanical properties, which were determined based on a uniaxial tensile test conducted in two directions, i.e. longitudinal and circumferential. The evaluation of incompressibility was carried out based on the product of the stretch ratios obtained in the x-y and y-z planes and on the basis of Poisson's ratio. The results presented in this study indicate that the blood vessel wall is an anisotropic material only in the case of normal vessels and in early atherosclerotic lesions. Atherosclerosis progression causes a gradual loss of the anisotropic character of the work of the thoracic aortic wall in moderate and very advanced stages of atherosclerosis under mechanical loads. The results show that the wall of the thoracic aorta is an incompressible material. Development of atherosclerosis does not cause a loss of incompressibility of the thoracic aorta. This study is the only one so far that presents changes in the mechanical properties at all stages of atherosclerotic development. A large number of preparations were included in the study, which is important for the results obtained due to the multi-factorial etiology of atherosclerosis development. (c) 2020 Nalecz Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Automated summary

This study analyzed the influence of atherosclerosis on the anisotropic and incompressible behavior of the human thoracic aortic wall under mechanical loads. It found that atherosclerosis progression leads to a gradual loss of anisotropic character in the thoracic aortic wall, while the incompressibility remains unaffected. The study is the first to present changes in mechanical properties at all stages of atherosclerotic development.