An abdominal aortic aneurysm (AAA) is a vascular pathology associated with permanent and localized dilatation of the abdominal aorta. Ruptures of untreated AAAs are common and catastrophic events which may account for high mortality rates, particularly in elder males. A refined understanding of the biomechanical properties of the vascular tissues in the AAA pathological progression may help to better explain intrinsic rupture mechanisms due to tissue growth and remodeling.
This work mainly focuses on experimental investigations of the biomechanical properties of aneurysmal tissues. By performing biaxial extension and peeling tests, we systematically explore biaxial mechanical responses and quantitatively determine dissection properties of intraluminal thrombi (ILT) and thrombus-covered walls, and further develop a more appropriate 3D material model to characterize the biaxial mechanical behaviors of both tissue types. Another key contribution of this work is to determine the relative thrombus age within the AAA. As a novel factor, the relative thrombus age is critically important to show the initiation and progression of the ILT and its potential effects on AAA wall mechanics. Regarding mass fraction analysis, particular attention is given the quantification of dry weight percentages of elastin and collagen within the layer-specific aneurysmal aortic structure. Moreover, gender differences in the AAA lesion are also discussed.