Causes and Risk Factors of Aortic Aneurysm

Aortic aneurysms develop when an area of weakening occurs in the wall of the blood vessel. While aneurysms can occur in any artery in the body, the aorta is especially susceptible.

The heart pumps blood directly into the aorta, so this artery is subjected to higher pressures and more stress than other arteries, which can weaken the aortic walls.

Common Causes

Several issues can cause part of the aortic wall to become weak, leading to the formation of an aneurysm.

Atherosclerosis

Atherosclerosis is strongly associated with the development of abdominal aortic aneurysms. The risk factors for aortic aneurysms are identical to those of atherosclerosis, and taking steps to prevent either of these conditions helps to prevent the other.

Degenerative Changes

Aortic aneurysms, especially thoracic aortic aneurysms, may result from degenerative changes in the wall of the aorta. These degenerative changes are caused by abnormalities in the structure of the vessel wall and are most often characterized by cyst-like lesions in the medial layer (that is, the central layer) of the wall.

Hypertension greatly accelerates cystic medial degeneration and makes aneurysms more likely. Thoracic aortic aneurysms most often are caused by these non-atherosclerotic degenerative changes. In contrast, abdominal aortic aneurysms tend to be associated with atherosclerosis.

Genetics

Certain well-defined inherited conditions, especially Ehlers-Danlos syndrome, Marfan syndrome, and Turner syndrome lead to weakening of the wall of the aorta and aneurysm formation, particularly involving the thoracic aorta.

In addition, several other, less-well-defined genetic conditions that also produce a high risk of aortic aneurysms have been identified.

Inflammatory Disease

Some inflammatory diseases cause inflammation of the blood vessels and lead to aneurysms of the aorta and other arteries. The best known of these are Takayasu’s arteritis and giant cell arteritis.

Aortic aneurysms are also more prevalent in people with other chronic inflammatory conditions, such as rheumatoid arthritis and ankylosing spondylitis. 

Infections

Certain infections that enter the bloodstream can weaken the wall of the aorta, promoting the formation of an aneurysm. When an aneurysm is caused by an infection, its formation can be particularly rapid, in contrast to the usual slow, years-long development of aortic aneurysms from other causes.

Blunt Trauma

Severe blunt chest or abdominal trauma, such as may occur with an automobile accident, can damage the wall of the aorta and lead to an aortic aneurysm.

Risk Factors

Certain risk factors and lifestyle choices increase the risk of developing an aortic aneurysm. Many of these risk factors are identical to the risk factors for atherosclerosis.

These risk factors include:

In addition, several other factors specifically increase the risk for aortic aneurysms, including:

• A past history of arterial aneurysms in other blood vessels
• Family history of aneurysms—especially in families that have a genetic predisposition to aneurysms
• Bicuspid aortic valve
• A history of chronic inflammatory disease

Risk Factors for Rupture

If you've been diagnosed with an aortic aneurysm, it is important to discuss the likelihood of aneurysm rupture. If your risk of rupture is high, early surgery might be strongly considered. This risk is determined by several factors.

Size and Growth Rate

Any aortic aneurysm has the possibility of rupturing, but the risk is low for aneurysms that are small and slow-growing.

For larger aneurysms, or for aneurysms that are still relatively small but growing rapidly, the risk of rupture becomes much higher. Furthermore, the larger the aneurysm, the faster it grows—and the more substantial the risk of rupture.

A useful way to think about this is to consider blowing up a balloon. When you first begin blowing up a balloon, it is relatively difficult to get it started. But the more you expand the balloon, the easier it becomes to make it even larger. Finally, if you blow it up just a little too much, the wall can become too thin—and it will eventually pop.

An aneurysm displays similar behavior. As an aneurysm expands, the wall becomes thinner and more fragile—sometimes to the point of rupture.

Symptoms

Small, slow-growing aortic aneurysms almost never produce symptoms. Symptoms are a strong indication that rupture is becoming more likely.

Other

Other risk factors that make rupture more likely include the risk factors for atherosclerosis. When you have an aortic aneurysm, it is important that you make the lifestyle changes necessary to reduce your risk of rupture.

Of the lifestyle factors that increase the risk of aortic rupture, smoking is the most dangerous—people with an aortic aneurysm who smoke have a particularly high risk of rupture and of death. It is critical that you quit smoking as soon as possible if you have an aortic aneurysm.