National Heart, Lung and Blood Institutes
What Is an Aneurysm?
An aneurysm (AN-u-rism) is a balloon-like bulge in an artery. Arteries are blood vessels that carry oxygen-rich blood from your heart to your body.
Arteries have thick walls to withstand normal blood pressure. However, certain medical problems, genetic conditions, and trauma can damage or injure artery walls. The force of blood pushing against the weakened or injured walls can cause an aneurysm.
An aneurysm can grow large and burst (rupture) or cause a dissection. Rupture causes dangerous bleeding inside the body. A dissection is a split in one or more layers of the artery wall. The split causes bleeding into and along the layers of the artery wall.
Both conditions are often fatal.
Most aneurysms occur in the aorta—the main artery that carries blood from the heart to the rest of the body. The aorta goes through the chest and abdomen.
An aneurysm that occurs in the part of the aorta that’s in the chest is called a thoracic (tho-RAS-ik) aortic aneurysm. An aneurysm that occurs in the part of the aorta that’s in the abdomen is called an abdominal aortic aneurysm.
Aneurysms also can occur in other arteries, but these types of aneurysm are less common. This article will focus on aortic aneurysms.
About 14,000 Americans die each year from aortic aneurysms. Most of the deaths result from rupture or dissection.
Early diagnosis and medical treatment can help prevent many cases of rupture and dissection. However, aneurysms can develop and become large before causing any symptoms. Thus, people who are at high risk for aneurysms can benefit from early, routine screening.
When found in time, aortic aneurysms often can be successfully treated with medicines or surgery. Medicines may be given to lower blood pressure, relax blood vessels, and reduce the risk of rupture.
Large aortic aneurysms often can be repaired with surgery. During surgery, the weak or damaged portion of the aorta is replaced or reinforced.