Failure Properties of Ruptured and Unruptured Abdominal Aortic Aneurysms

Rupture of abdominal aortic aneurysm (AAA) is a poorly understood phenomenon. Some aneurysms rupture as they grow larger, while many very large ones do not. There have been numerous reports on the failure properties of unruptured AAA [1], but similar data on ruptured AAA is scarce. Some reports suggest that greater pressure-induced tension in the AAA wall may predispose some to rupture [1]. But what of failure properties? It is conceivable that aneurysms which rupture are globally weaker than ones that do not or perhaps have very localized weak spots. Such key issues have not been explored because of lack of specimens from ruptured AAA. In this exploratory study between clinical and engineering investigators, unruptured and ruptured AAA were wholly harvested from fresh cadavers and the regional variations in wall thickness, mechanical properties and cellular content were compared.