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Abdominal Aortic Aneurysm (AAA)
What is the aorta?
The aorta is the main artery of the body, arising from the base of the left ventricle of the heart. It supplies oxygenated blood to allarteries except the pulmonary artery (which caries blood to the lungs to be oxygenated). The aorta curves after it leaves the heart and goes down the chest into the abdomen, where it divides into 2 smaller arteries. The aorta is a large vessel, about 1 inch in diameter, which thick, elastic walls to withstand the changes in pressure as the heart beats.
Learn more about the AAA Medicare screening benefit
What is an abdominal aortic aneurysm (AAA)?
An abdominal aortic aneurysm (AAA) is a bulge or balloon that forms in the wall of the aorta, the largest blood vessel in the body. When the wall of the aorta is weakened, the pressure inside the vessel can cause it to balloon outward. An aneurysm is most commonly the result of an accumulation of fatty deposits on the vessel wall, but may also relate to heredity, trauma or other diseases that weaken the vessel wall. Eventually, the force of normal blood flow through the weakened aortic wall can cause the aneurysm to tear or rupture, which may lead to serious internal bleeding or even death. Approximately 80% of ruptured AAAs result in death.
In the majority of cases, aneurysms grow gradually over a period of time, increasing by an average of only 2 to 3 millimeters each year. It can take nearly 10 to 15 years for an aneurysm to reach a size at which surgery is deemed necessary. At this time, the aneurysm measures 5 to 6 centimeters (cm) and is 1.5 times its normal size. When the aneurysm reaches this size, the risk of rupture increases by 20% per year, and the 1-year survival rate for patients without surgery is estimated to be 50%.
How prevalent is AAA in the United States?
Abdominal aortic aneurysms are the 17th leading cause of death in the United States, accountable for the death of approximately 15,000 Americans each year. It is estimated that approximately 2 million people in the US have AAA disease, with 200,000 new cases diagnosed annually.
There is considerable evidence in the medical literature that people with a higher risk of developing AAA disease include:
- Men over the age of 55
- Women over the age of 65
- Smokers or those with a history of smoking
- Caucasians
- People with a family history of AAA disease
- People who have atherosclerosis (fatty deposits on the blood vessel wall), diabetes, high blood pressure, or high cholesterol
What symptoms are associated with AAA?
Most people with AAA do not experience any symptoms or warning signs. In most cases, a person with AAA does not know it's there until the artery walls become severely dilated and the aneurysm has grown to a dangerous size. Occasionally, a doctor may detect AAA by noticing or feeling a throbbing, tender mass in the middle or lower part of the abdomen. However, this mass is not evident in all patients with AAA. Other symptoms of AAA may include:
- Intense back or abdominal pain
- Side pain
- Nausea and vomiting
- Excessive sweating
When an AAA gets large enough, a person may experience back pain. The first sign of rupture is usually characterized by extreme pain in the lower abdomen and back. The rupture of an AAA can lead to loss of consciousness, stroke, shock, or a heart attack. The severe internal bleeding caused by a rupture is often fatal.
The AAA screening exam is the best method for early detection. A healthcare professional can detect AAA using painless, noninvasive, diagnostic tests such as x-rays and ultrasound imaging technology. Both of these methods help take pictures (images) of the abdominal aorta.
During an ultrasound, an acoustic gel is applied to the skin in the stomach area. A healthcare professional glides the transducer around the stomach area and views images of the abdominal aorta on a computer monitor.
How are AAAs treated?
An abdominal aortic aneurysm is treated if your doctor feels there is a risk that the aneurysm will rupture. There are 2 main treatment options to consider, open surgical repair and endovascular treatment using a stent graft.
The open surgical procedure is performed under general anesthesia and takes about 3 to 4 hours to complete. The surgeon accesses the aneurysm throgh an incision in the abdomen. The portion of the vessel with the aneurysm is excised and replaced with a synthetic graft, which is sewn into place. Patients typically spend 1 night in an intensive care unit and remain in the hospital for an additional 5 to 7 days. Full recovery to normal activity can take 4 to 6 weeks. Although open surgical repair is an effective treatment, it carries risks similar to major invasive surgery.
An effective alternative treatment for patients who are not good candidates for surgery, or who prefer not to undergo major surgery, is endovascular stent grafting. Endovascular stent grafting is a procedure whereby an endovascular stent graft, a synthetic fabric tube (graft) supported by a metal structure (stent), is placed inside the abdominal aorta. This allows blood to continue to flow through the abdominal aorta while eliminating the pressure on the vessel wall. The stent graft is inserted into the femoral artery (the artery in the upper thigh) to the aorta through a small incision in the upper leg. Because it is a smaller incision and a much less invasive procedure, recovery time may be quicker compared to open surgery.
(Permission of this article was granted by Medtronic).