An abdominal aortic aneurysm is a potentially fatal abnormal swelling (often balloon-like) of a segment of the body's largest artery, the aorta. The wall of the artery bulges out rather than remaining straight.

The aorta carries oxygen-rich blood from the heart to smaller arteries throughout the body. An abdominal aneurysm occurs in the abdominal aorta, the part of the aorta between the bottom of the chest and the pelvis.

Normally, the aorta is about one inch (2.5 centimeters) in diameter. The size increases very gradually as people age. If the abdominal section of the aorta becomes larger than 3 centimeters, the person is said to have an abdominal aortic aneurysm.

Abdominal aortic aneurysms are most common in people 60 and older. They affect about 5% to 7% of people in this age group living in the United States. Although about 20% of people with abdominal aortic aneurysms have a close relative with the same problem, no clear genetic link has been found. The family connection seems to be particularly strong among brothers.

Most aortic aneurysms are related to atherosclerosis, a condition in which fatty deposits called plaque build up along the inside walls of blood vessels. This is the same condition that contributes to coronary artery disease in the heart and stroke in the brain.

Most aortic aneurysms don't cause any symptoms. Aneurysms often are discovered during routine physical exams or during X-rays for unrelated illnesses. When symptoms develop, they can include:

• Pain in the abdomen, back or the fleshy part of your sides between the bottom of your ribs and your hips
• A feeling of fullness after eating a small meal
• Nausea and vomiting
• A pulsating mass in the abdomen

Rarely, floating blood clots (thrombi) can form near the aneurysm. These clots can break away and block blood vessels elsewhere in the body, causing symptoms of poor blood flow wherever they become stuck.

In about 20% of cases, an undiscovered abdominal aneurysm ruptures without warning, and the patient collapses and dies from massive bleeding inside the abdomen.

Your doctor will ask you about your family history of heart disease, especially about any relatives whose deaths were sudden and, perhaps, unexplained. Your doctor will ask if you smoke and determine if you have high cholesterol, high blood pressure or diabetes.

Sometimes, your doctor may suspect that you have an aortic aneurysm based on hearing the sound of abnormal blood flow in your abdomen during a physical exam. If you have an abdominal aortic aneurysm, your doctor may see and feel a pulsating mass in your abdomen when you are lying down. This mass usually is in the center of the abdomen, just above the navel.

In 75% of people with an abdominal aortic aneurysm, the aneurysm is found when an X-ray or other type of scan is done for an unrelated illness. Aortic aneurysms can be discovered on plain X-rays, ultrasound, magnetic resonance imaging (MRI), computed tomography (CT) scans and angiography (a view of the blood vessels obtained by injecting a radioactive substance into the patient).

To test for abdominal aortic aneurysms, ultrasound is very accurate and relatively inexpensive. It also doesn't expose people to radiation.

Once an aortic aneurysm develops, it is a lifelong condition. Most abdominal aortic aneurysms grow larger with time, expanding at an average rate of .33 centimeters to .5 centimeters each year.

You may be able to reduce your risk of an aortic aneurysm by controlling your risk factors for atherosclerosis, especially high cholesterol, high blood pressure, smoking and diabetes. If you have high cholesterol, follow your doctor's guidelines for eating a diet low in fats and cholesterol and, if necessary, take medication to lower your cholesterol. If you have high blood pressure, follow your doctor's recommendations for changing your diet and taking your medication. If you smoke, quit. If you are diabetic, monitor your blood sugar frequently, follow a healthy diet and take your insulin or oral medication as your doctor has prescribed. It is also wise to exercise regularly and to maintain an ideal weight.

The U.S. Preventive Services Task Force recommends a one-time screening ultrasound to look for abdominal aortic aneurysm in men aged 65 to 75 who have smoked at any time in their lives.

Treatment depends mostly on the size of the aneurysm. The larger the aneurysm, the more likely it is to burst (rupture). Emergency surgery for a ruptured aneurysm has a higher risk of death than a scheduled aneurysm repair.

Surgery is almost always recommended for an aneurysm that is leaking. Surgery generally is recommended for people with aneurysms larger than 5.5 centimeters in diameter, unless there is another illness that makes surgery unusually risky. Even with no symptoms, a person with an aneurysm larger than 6.5 centimeters would almost always have emergency surgery to repair the problem.

People with smaller aneurysms may be monitored with ultrasound tests – every 12 months for anyone with an aneurysm smaller than 3.5 centimeters and every six months for those with aneurysms larger than 3.5 centimeters. These frequent tests are done to see if the aneurysm is getting larger.

Surgeons have two options to repair abdominal aortic aneurysms. The traditional method, abdominal surgery, involves clamping the aorta temporarily, repairing the blood vessel by cutting away the damaged section and replacing the aneurysm with a plastic patch. With a newer method, endovascular surgery, small cuts are made in the groin over a branch of the artery that goes to the leg. A special tube called a stent is threaded through the artery to the site of the aneurysm. The stent protects the wall of the abdominal aorta from the pressure inside the artery and can stop the artery wall from expanding and weakening.

The choice of procedure depends on the location and appearance of the aneurysm and the patient's health. Older and frailer patients who are more likely to have complications from the surgery and prolonged anesthesia are candidates for endovascular repair. Younger and generally healthier patients are probably better served with abdominal surgery, although this may change as endovascular devices and techniques improve.

Contact your doctor's office if you notice a pulsating mass in your abdomen and otherwise feel well. If you have abdominal, back or flank pain associated with a pulsating mass, this is a medical emergency and requires immediate attention.

The outlook for an untreated abdominal aortic aneurysm depends on its size. An abdominal aortic aneurysm larger than 7 centimeters in diameter has a 75% chance of rupturing within 5 years. At 6 centimeters, the risk of rupture is 35% over 5 years. Between 5.0 and 5.9 centimeters, the rupture risk is about 25% over 5 years. The risk of rupture is much lower for aneurysms smaller than 5 centimeters (2 inches).

With successful surgical repair, the prognosis is good and depends more on the severity of atherosclerosis affecting other organs, especially the heart, brain and kidneys.

American Heart Association (AHA)
7272 Greenville Ave.
Dallas, TX 75231
Toll-Free: 1-800-242-8721
http://www.americanheart.org/

National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: 301-592-8573
TTY: 240-629-3255
Email: nhlbiinfo@rover.nhlbi.nih.gov
http://www.nhlbi.nih.gov/