Abdominal Aortic Aneurysm
What is an Abdominal Aortic Aneurysm?
An aneurysm is a widening or localized enlargement of an artery. This widening can become a significant health problem because the aneurysm can expand enough to burst or rupture, similar to a balloon that has been blown up too far. When an aneurysm ruptures, life-threatening bleeding can occur.
Aneurysms most commonly occur in the abdominal aorta, a large blood vessel in the abdomen. Abdominal aortic aneurysms (AAAs) affect 6-9% of men over 65 years of age and are the 15th leading cause of death in the United States. Even with surgery, there is an 50-80% chance of death with a ruptured AAA. Therefore, early detection before rupture is paramount to AAA management. click on image for larger view.
The rate of aneurysm rupture is related to its size. A 4.0 cm AAA has a 1% risk of rupture per year while a 6.0 cm AAA has a 10% risk of rupture per year. Risk factors such as smoking and high blood pressure (hypertension) may increase the size of the AAA, the rate of growth, and the risk of rupture.
Signs and Symptoms
Most AAA's are asymptomatic (lack symptoms), which leads to difficulty in detection. Occasionally, patients may feel a “mass” or "lump" in their abdomen that may pulsate with each heartbeat. Some aneurysms are found during evaluation of pain in the back or side, which can occur as the aneurysm grows and presses on the spinal column and nearby nerves. Most AAAs are discovered as an incidental finding when evaluating another medical problem. When rupture occurs, the person experiences severe pain and may feel faint or become unconscious due to the significant blood loss and sudden fall in blood pressure. Unless the blood pressure can be restored and the leaking aneurysm surgically repaired, death will likely result.
To date, there is no proven treatment for abdominal aortic aneurysms other than surgical repair. Stopping smoking and controlling high blood pressure may slow aneurysm growth, but will not cure the aneurysm.
In addition to a physical examination, specific tests will be done to determine the location, size and shape of the abdominal aortic aneurysm. These tests may include ultrasound, CT scans, and MRIs. Sometimes, an arteriogram is performed to evaluate the AAA and any associated arterial blockage.
Most experts agree that almost all AAA's larger than 6 cm in diameter, and most aneurysms larger than 5.0 cm, should be repaired. In some instances, smaller aneurysms may be considered for treatment. If surgical repair is deferred, it is strongly suggested that periodic ultrasound or CT examinations be done to monitor the aneurysm. If the aneurysm significantly expands or becomes symptomatic, treatment is indicated.
Traditional surgical repair of the aorta has been extremely successful. It requires an abdominal incision and a 5-7 day hospital stay. This operation involves the placement of a synthetic graft to replace the weakened walls of the aneurysm. Complete recovery after surgical repair usually takes 4-6 weeks. Once repaired by the traditional method, only 1% of patients will require additional treatment in the future.
Another approach to AAA repair, called endovascular grafting or stent grafting, is performed through a 3 to 4 inch incision in the groin. It carries the same risks as the traditional method of surgical repair, which include bleeding and infection. However, patients usually spend fewer days in the hospital and recover more quickly. However, not all aneurysms are suitable for endovascular repair due to anatomic constraints. Also, some patients may require additional endovascular procedures after the initial repair due to incomplete aneurysm exclusion, and periodic imaging studies are necessary to continue to monitor the aneurysm.