Abdominal Aortic Aneurysm Pathomechanics: Current Understanding and Future Directions

Abdominal aortic aneurysms (AAAs) are permanent, local expansions of the abdominal segment of the aorta that can potentially be fatal if progressing to rupture. AAAs are rarely found in patients under age 60, but are more common in older age groups, occurring in 2-3% of the whole population. Their rupture produces up to 14,000 deaths annually in the United States alone. Because aneurysmal rupture is a mechanical phenomenon, in recent years there has been a major effort among researchers to investigate the biologic and mechanical processes surrounding AAA progression and rupture. In addition to the basic science importance of understanding AAA pathophysiology, much of this research has been directed toward the development of accurate clinical criteria for assessing the risk of rupture on a patient-by-patient basis. This review first summarizes degenerative changes of the aorta wall associated with AAA pathogenesis. Current understanding of hemodynamics, transport, and wall mechanics in AAAs is then described, and open questions in aneurysm research are discussed along with potential directions in which further understanding could lead to improved clinical evaluation and management decision processes.