May 25 (HeartCenterOnline) - The success rate of using stent-grafts to treat abdominal aortic aneurysms has now climbed to 90 percent, according to the spring issue of ''Currents,'' a publication of the University of Iowa Health Care.

An abdominal aortic aneurysm (AAA) is a bulging or ballooning out of part of the wall of the abdominal aorta, which is the section of the aorta that travels the entire length of the abdomen. Up to 75 percent of known aortic aneurysms are AAAs. This makes AAA's far more common than thoracic aortic aneurysms, which occur in the section of the aorta that travels from the heart to the diaphragm.

The very serious risk associated with AAAs is the risk of rupture. A rupture will cause extreme abdominal or back pain and a pulsating mass in the abdomen. Blood pressure will drop drastically, causing dizziness, weakness, blurred vision or nausea. Less than 20 percent of people who suffer a ruptured AAA will survive.

Although there is low risk of rupture if an AAA is less than 4 centimeters, larger AAAs may require surgical treatment to reduce the risk of rupture. Whereas a more invasive approach used to be the standard treatment for AAAs, the minimally invasive endovascular approach is becoming increasingly popular. Using the endovascular approach, a physician prevents blood from flowing through the aneurysm by attaching one stent just above the aneurysm and a second stent just below the aneurysm. The two stents are connected by a patch of synthetic material (a graft), which provides a channel for blood to flow without entering the aneurysm.

According to the author of the "Currents" article, one complication of the minimally invasive surgery is endoleak, which means that blood is leaking from the graft. If the blood leaks into the aneurysmal sac, then the risk of rupture increases. Other types of endoleaks are less serious. Additional concerns about the endovascular approach were recently addressed by the FDA (see http://www.fda.gov/cdrh/safety/faq_aaa.html).

According the American Heart Association's 2001 Heart and Stroke Statistical Update, aortic aneurysms are responsible for more than 16,000 deaths annually in the United States and contribute to 24,000 deaths each year. They occur in more than 3 percent of individuals over the age of 50, and are five times more common in men than in women.

For additional information about aneurysms, including related illustrations, animations and news stories, visit HeartCenterOnline's Aneurysm Center.

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