The Basics | Symptoms | Detection & Treatment

What Is an Aneurysm?

An aneurysm is a permanent ballooning in the wall of an artery. The pressure of blood passing through can force part of a weakened artery to bulge outward, forming a thin-skinned blister.

Although any weak blood vessel can be affected, aneurysms usually form in the abdominal or thoracic portions of the aorta, the main blood vessel that carries blood from the heart, or in arteries nourishing the brain. Aneurysms in any of these places are serious, while those in more peripheral locations such as the leg are often less hazardous.

The gravest threat an aneurysm poses is that it will burst and cause a stroke or life-threatening massive bleeding (hemorrhage). If an aneurysm ruptures, the patient must be treated within minutes in order to have a chance of survival.

The gravest threat an aneurysm poses is that it will burst and cause a stroke or life-threatening massive bleeding (hemorrhage). If an aneurysm ruptures, the patient must be treated within minutes in order to have a chance of survival.

There are many types of aneurysms. Here are a few:

• Aortic aneurysm. The aneurysm is located within the wall of the aorta. Typically, the widened part of the aorta is considered to be an aneurysm when it is more than 1.5 times its normal size. They are often due to the build-up of plaques due to hardening of the arteries or atherosclerosis. Aneurysms may also be an inherited condition or a complication of high blood pressure (hypertension).
• Cerebral aneurysm. Also known as a berry aneurysm, this occurs in the wall of a blood vessel in the brain. Smoking increases a person's risk of developing a cerebral aneurysm.
• Ventricular aneurysm. This is a ballooning out of part of the wall of the heart. Ventricular aneurysms may be a present since birth or may be due to a previous heart attack or severe chest trauma.

What Causes It?

Any condition that causes arterial walls to weaken or deteriorate can result in an aneurysm. The most common culprits are atherosclerosis and high blood pressure. Penetrating wounds and infections can also lead to an aneurysm. Some types are the result of congenital, or inherited, weakness in artery walls.

Medically Reviewed by Cynthia Haines, MD, July 2005.

SOURCES: American Heart Association

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