Circumferential variation in mechanical characteristics of porcine descending aorta

Abstract

Arterial characterization of healthy descending thoracic aorta (DTA) is indispensable in determining stress distributions across wall thickness and different regions that may be responsible for aorta inhomogeneous dilation, rupture, and dissection when aneurysm occurs. Few studies have shown the inhomogeneity of DTA along the aorta tree considering changes in circumferential direction. The present study aims to clarify the circumferential regional characterization of DTA. Porcine DTA tissues were tested according to region and orientation using uniaxial tension. For axial test, results show that the difference in circumferential direction was mainly in collagen fiber modulus, where the anterior collagen fiber modulus was significantly lower than the posterior quadrant. For circumferential test, the difference in circumferential direction was mainly in the recruitment parameter, where the circumferential stiffness is significantly higher in the posterior region at physiological maximum stress. The proximal posterior quadrant and left quadrant showed significantly lower axial collagen fiber stiffness than the right and anterior quadrants, which may be a factor in aneurysm development. Furthermore, the constitutive parameters for similar detailed regions can be used by biomedical engineers to investigate improved therapies and thoroughly understand the initial stage of aneurysm development. The regional collagen fiber modulus can help improve our understanding of the mechanisms of arterial dilation and aortic dissection.