Causes and Risk Factors of Aortic Aneurysm

Show Article Table of Contents

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 seems more susceptible to aneurysms than other vessels.

This is likely because the heart pumps blood directly into the aorta, so this artery is subjected to higher pressures and more stress than other arteries. So, if the wall of the aorta is weakened for any reason, an aneurysm is particularly likely to occur.

aortic aneurysm causes
Illustration by Joshua Seong. © Verywell, 2018.

Common Causes

Several pathologies 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, though there remains some controversy as to whether it is actually a direct cause.

In any case, the risk factors for aortic aneurysms are identical to those of atherosclerosis, and taking steps to prevent one 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 biology 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.

This cystic medial degeneration weakens the aortic wall and promotes the formation of an aneurysm. Cystic medial degeneration is usually associated with aging, but it also can be seen in some younger people, presumably due to a genetic predisposition.

In a person with cystic medial degeneration, hypertension greatly accelerates the condition and makes rapidly-developing aneurysms much 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 syndromeMarfan 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 have been identified that also produce a high risk of aortic aneurysms.

More of these genetic conditions are being identified all the time. Consequently, aortic aneurysms—especially thoracic aortic aneurysms—often seem to run in families, even if no specific genetic abnormality has yet 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.

Infections that can produce aortic aneurysms include poorly treated syphilissalmonella, or infectious endocarditis.

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 greatly 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 are important in determining the risk for aortic aneurysms, including:

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

Risk Factors for Rupture

In people who have been diagnosed with an aortic aneurysm, it is important to pay attention to the likelihood that the aneurysm may rupture. If the risk of rupture is high, early surgery should 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 pronounced 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, it pops.

An aneurysm displays similar behavior. In smaller aneurysms, the properties of the vessel wall tend to resist dilation. But as the aneurysm gradually grows, wall resistance is reduced, and the aneurysm expands ever more easily—to the point of rupture.

For this reason, anyone who has been diagnosed with an aortic aneurysm, even if the aneurysm is small, must be followed carefully. If the aneurysm becomes large or shows signs of accelerated growth, it is time to strongly consider surgical repair.

Symptoms

Small, slow-growing aortic aneurysms almost never produce symptoms. So, if symptoms occur that turn out to be caused by an aortic aneurysm, that is a strong indication that rupture is becoming more likely.

Other

Other risk factors that make rupture more likely include the same risk factors for atherosclerosis that were listed earlier. So, for anyone who has been diagnosed with an aortic aneurysm, it is particularly important to make the lifestyle changes necessary to reduce that risk.

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 anyone who has an aortic aneurysm quit smoking.

Was this page helpful?
Article Sources
  • Geisbüsch S, Stefanovic A, Schray D, Et Al. A Prospective Study Of Growth And Rupture Risk Of Small-To-Moderate Size Ascending Aortic Aneurysms. J Thorac Cardiovasc Surg 2014; 147:68.
  • Kuzmik Ga, Sang Ax, Elefteriades Ja. Natural History Of Thoracic Aortic Aneurysms. J Vasc Surg 2012; 56:565.
  • Lo Rc, Lu B, Fokkema Mt, Et Al. Relative Importance Of Aneurysm Diameter And Body Size For Predicting Abdominal Aortic Aneurysm Rupture In Men And Women. J Vasc Surg 2014; 59:1209.
  • Sweeting Mj, Thompson Sg, Brown Lc, Et Al. Meta-Analysis Of Individual Patient Data To Examine Factors Affecting Growth And Rupture Of Small Abdominal Aortic Aneurysms. Br J Surg 2012; 99:655.
  • Yiu Rs, Cheng Sw. Natural History And Risk Factors For Rupture Of Thoracic Aortic Arch Aneurysms. J Vasc Surg 2016; 63:1189.