More than 90% of infrarenal abdominal aneurysms are of what origin?

Infrarenal abdominal aneurysms, which are localized dilations of the abdominal aorta below the renal arteries, typically arise due to degenerative processes. This degenerative origin is primarily attributed to atherosclerosis, a condition characterized by the buildup of plaques in the arterial walls, leading to weakening and eventual dilation of the vessel. As individuals age, the cumulative damage from factors like hypertension, high cholesterol, and lifestyle choices contributes significantly to this type of aneurysm formation.

Aneurysms of congenital origin would imply a structural defect present at birth, but these types of aneurysms are far less common in comparison to those that develop due to degenerative changes. Infectious origins, although possible, are generally rare and often related to specific conditions such as mycotic aneurysms, which are not the primary cause of the majority of infrarenal abdominal aneurysms. Similarly, traumatic origins result from direct injury to the aorta, and while they can occur, they account for a minority of cases. Therefore, degenerative factors are responsible for more than 90% of infrarenal abdominal aneurysms.