Biomechanical evaluation of the walls of abdominal aortic aneurysms

The development of an abdominal aortic aneurysm (AAA) is a long-lasting, gradual and, usually, asymptomatic process. Thus, the diagnostics of the aneurysm poses some difficulties and most cases are diagnosed by accident. An untreated aneurysm results in death when its walls are destroyed. The mortality rate in the case of the abdominal aortic aneurysms’ rupture ranges from 80% to 90% [1, 2]. A surgical repair of AAA (an aneurysmectomy) is the only effective way to treat aneurysm and prevent it rupture. This procedure, which includes inserting an artificial prosthesis of a vessel, is highly invasive and rather dangerous [1, 3]. Patients with an aneurysm with the diameter of approximately 55 mm or more are scheduled for a planned surgery in order to remove the aneurysm, as it is believed that the larger the diameter the higher the risk of a rapture [4, 5]. However, the „maximum diameter criterion” seems unjustified in the case of estimating the risk and the stage of an aneurysm development because AAA may rupture even in the vessels of a 40 mm or less diameter, in which cases the hypothetical risk is the lowest [6], whereas other aneurysms grow and reach the size of (80÷100) mm without any signs of rupturing [7]. This implies that searching for other indicators of the severity of AAA and its degree of development is essential. Recently, there has been a rise of interest in the possibilities of using the mechanical properties of abdominal aortic aneurysm’s walls in order to estimate the probability of a rupture and to assess the degree of an aneurysm development.