Mechanical Properties of the Aortic Arch as a Function of Growth

Abstract

The aortic arch is defined as the portion of aorta that curves between the ascending and descending segments. The thickness of the aorta varies due to differing stresses. This study assesses the regional hyperelastic mechanical properties of the aorta and its contractility. Axial strips of aortic arch taken from different anatomical positions were tested using a uniaxial pull tester. The material’s shear modulus exhibited an average maximum difference of about 35%, with larger wall thicknesses leading to a decreased modulus. Half-rings of aortic arch (varying between thickest and thinnest) were subjected to a cycles of contraction and relaxation. The inner aortic half-rings displayed twice as much contractile force compared to the outer half-rings. The decreased shear modulus and increased contractile properties observed in these experiments may indicate that much of the arterial anatomic specificity takes place within the tunica media; i.e. with recruitment of elastin fibers and smooth muscle cells.