Abdominal aortic aneurysm (AAA) is the term for enlargement and weakening of a portion of the abdominal aorta.
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.
Many people with an abdominal aortic aneurysm have no symptoms. Sometimes, however, the AAA is very painful. The pain is often felt in the lower back or the abdomen. It is usually a steady pain that does not go away, although it may be relieved by changing position.
Sometimes the person can sense an abnormal pulse in the abdomen. Circulation to the lower extremities can be affected.
Rupture of an abdominal aortic aneurysm is usually associated with sudden, excruciating pain in the lower abdomen and back. Depending on the severity of the internal bleeding, the person may go into shock, and death may rapidly follow.
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 crashinherited conditions that cause weakened or abnormal blood vessel wallsinfection 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.
People can lower their risk of abdominal aortic aneurysm by: controlling high blood pressureavoiding or treating high cholesterolquitting smokingobtaining effective treatment for chronic obstructive pulmonary disease
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.
A ruptured abdominal aortic aneurysm can cause death. Small aneurysms that have not ruptured are monitored closely to prevent rupture.
Abdominal aortic aneurysms are not contagious and pose no risk to others.
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 symptomswhen the aneurysm is bigger than 5 cm acrosswhen 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.
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.
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.
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.
