Abdominal Aortic Aneurysm
Abdominal aortic aneurysm (AAA) is the term for enlargement and weakening of a portion of the abdominal aorta.
What is going on in the body?
The abdominal aorta is the main blood vessel that supplies blood to internal organs in the lower part of the body. Under certain conditions, a section of the aorta may weaken and swell. Swelling and weakening of a section of an artery is called an aneurysm.
If the aneurysm should burst, large amounts of blood can be lost quickly, which can mean death within minutes. Blood can also leak in between the layers of the aorta, called a dissection, and block arteries leading from it. This can cause serious damage to the organs supplied by those arteries.
What are the causes and risks of the condition?
The most common cause of an AAA is atherosclerosis. In this condition, a fatty material builds up inside the aorta. This buildup causes inflammation and weakens the affected blood vessel.
Other causes of abdominal aortic aneurysms include:
- injury, such as a crush injury from a motor vehicle crash
- inherited conditions that cause weakened or abnormal blood vessel walls
- infection carried in the bloodstream from other parts of the body
High blood pressure increases the risk of an AAA; in fact, more than half of those diagnosed with an AAA have high blood pressure. Cigarette smoking also increases the risk of an AAA and can make an AAA worse. Chronic coughing, such as the cough from chronic obstructive pulmonary diseases such as emphysema, can make the aneurysm worse.
AAA is more common among Caucasian people. It affects men 4 times more often than women. It occurs most often in people between ages 60 and 90.
What can be done to prevent the condition?
People can lower their risk of abdominal aortic aneurysm by:
- controlling high blood pressure
- avoiding or treating high cholesterol
- quitting smoking
- obtaining effective treatment for chronic obstructive pulmonary disease
How is the condition diagnosed?
On physical examination, AAA manifests as a pulsating mass in the middle of the abdomen. In a thin individual, the healthcare professional must take care to distinguish a pulsatile mass from the normal pulsations of the aorta when pressed against the backbone. He or she can sometimes hear abnormal sounds with the stethoscope over the enlarged aorta.
An ultrasound test is commonly used to confirm the diagnosis of AAA. Other imaging studies, such as an abdominal CT scan or abdominal MRI, may be done to define the exact size and location of the aneurysm, especially by way of preparation for surgery.
Long Term Effects
What are the long-term effects of the condition?
A ruptured abdominal aortic aneurysm can cause death. Small aneurysms that have not ruptured are monitored closely to prevent rupture.
What are the risks to others?
Abdominal aortic aneurysms are not contagious and pose no risk to others.
What are the treatments for the condition?
Only 40% to 50% of the people with a ruptured AAA survive long enough to have surgery, which is the only treatment for the condition. Of those individuals, only half survive and recover from the surgery. Early detection of the aneurysm, before it ruptures, is key to successful treatment of the problem.
If the aneurysm has not ruptured, surgery is recommended in the following situations:
- when the person has severe symptoms
- when the aneurysm is bigger than 5 cm across
- when it has grown by at least 1 cm over 6 to 12 months
In traditional surgery, the aorta is crossclamped, and the weakened part of the aorta is removed. An artificial graft is then used to replace the portion removed. The graft is connected at the top to the piece of aorta coming down from the heart, and at the bottom either to the remaining piece of aorta, or to the iliac arteries - in which case, a graft with two branches is used. Then the cross clamp is released gently, while blood pressure is closely monitored.
Some patients are candidates for a newer form of surgery, one in which a graft can be put into place inside the damaged portion of the aorta. The graft is inserted through an incision in the groin, into the iliac artery, and moved up into position. Recovery from this surgery is quicker and less painful, but the probability of total success is somewhat less and careful post-surgical monitoring is required. It is considered an especially good option for those patients who would have difficulty tolerating the more extensive surgery from a medical standpoint.
What are the side effects of the treatments?
If surgery has been performed before rupture, and the patient is relatively healthy, the outcome is very good. But emergency surgery for a ruptured AAA has about a 50% chance of death. Other side effects include bleeding, infection, and reactions to the anesthesia.
What happens after treatment for the condition?
After recovery from surgery, the person can slowly return to regular activities. It is important to make appropriate lifestyle changes to lower the risk of further circulatory system problems. These changes include eating a healthy diet to minimize heart disease, avoiding smoking, exercising in moderation, and maintaining a healthy weight.
How is the condition monitored?
Before surgery, the size of an aneurysm can be evaluated using an ultrasound test. After recovery from surgery, the person should have no further symptoms. Any new or worsening symptoms should be reported to the healthcare professional.
Merck Manual, 1999, Beers et al.
Harrison's Principles of Internal Medicine, 1997, Fauci et al.
Medical Knowledge Self Assessment Program, Cardiovascular Medicine Section, 1998, American College of Physicians.