What Causes an Aneurysm?

The force of blood pushing against the walls of an artery combined with damage or injury to the artery's walls can cause an aneurysm.

A number of factors can damage and weaken the walls of the aorta and cause aortic aneurysms.

Aging, smoking, high blood pressure, and atherosclerosis (ath-er-o-skler-O-sis) are all factors that can damage or weaken the walls of the aorta. Atherosclerosis is the hardening and narrowing of the arteries due to the buildup of a fatty material called plaque (plak).

Rarely, infections, such as untreated syphilis (a sexually transmitted infection), can cause aortic aneurysms. Aortic aneurysms also can occur as a result of diseases that inflame the blood vessels, such as vasculitis (vas-kyu-LI-tis).

Family history also may play a role in causing aortic aneurysms.

In addition to the factors above, certain genetic conditions may cause thoracic aortic aneurysms (TAAs). Examples include Marfan syndrome, Loeys-Dietz syndrome, and Ehlers-Danlos syndrome (the vascular type).

These conditions can weaken the body's connective tissues and damage the aorta. People who have these conditions tend to develop aneurysms at a younger age and are at higher risk for rupture or dissection.

Trauma, such as a car accident, also can damage the aorta walls and lead to TAAs.

Researchers continue to look for other causes of aortic aneurysms. For example, they're looking for genetic mutations that may contribute to or cause aneurysms.