Repairing Life-Threatening Abdominal Aneurysms

Research suggests a common, life-threatening aneurysm in the body's main artery often can be repaired safely with a minimally invasive technique using a small fabric tube to mend the dangerous ballooning.

Thirty research papers tracking more than 2,000 patients whose abdominal aortic aneurysms (AAA) were treated minimally invasively with stent-grafting were presented at the 25th Annual Scientific Meeting of the Society of Cardiovascular & Interventional Radiology (SCVIR). AAA, the nation's 13th leading cause of death, is easily detected with a simple ultrasound.

"Most patients with enlarging aortic abdominal aneurysms experience no symptoms. About 80 percent are discovered by accident, when a physician is testing for another condition such as gall stones or kidney stones," said James F. Benenati, M.D., medical director of the peripheral vascular disease laboratory at Miami Cardiac & Vascular Institute at Baptist Hospital. "It can sometimes be detected just by feeling the abdomen, but ultrasound is the most commonly used test for detection. For someone over 60 who is at risk, it's not a bad idea to have an ultrasound."

"Our results are similar to conventional surgery, but with numerous advantages, including a dramatic reduction in the complication rate, less anesthesia, a much shorter hospital stay and less overall risk to the heart because stent-grafting is not an open procedure," said Barry T. Katzen, M.D., medical director of Miami Cardiac & Vascular Institute and lead author of a study comparing stent-grafting to conventional surgery. "Although some patients still will require conventional surgery, about 50 to 70 percent of those with AAA are good candidates for stent-grafting."

Abdominal aortic aneurysms occur in 5 percent to 7 percent of people age 60 or older, and men are at least four times more likely to have AAA than women. Every year more than 15,000 people die of AAA.

An AAA is a weakening in the wall of the abdominal portion of the aorta, which leads from the heart to the rest of the body and is the largest blood vessel. Although most people with AAA have atherosclerosis, a gradual build up of cholesterol and scar tissue that damages the walls of blood vessels, the most important causes of the condition are unknown, although researchers are investigating.

People with high blood pressure, those who smoke and those who have a family history of AAA also are at risk. The aorta is an inch or less in diameter. Typically, aneurysms that cause enlargement of the aorta smaller than 2 inches are not treated. Aneurysms 2-1/2 inches or larger are at risk for life-threatening rupture, and usually are repaired. Patients whose aneurysms are detected at the smaller size are checked regularly by their physicians.

Stent-Grafting Versus Conventional Surgery

Vanguard, a 17-center multicenter trial comparing stent-graft repair and conventional surgery, showed similar success rates for the two procedures. A total of 268 patients were treated with stent-grafts by interventional radiologists and 98 patients had conventional surgery. After 30 days, 4 of 268 (1 percent) stent-graft patients had died, versus 3 of 98 (3 percent) surgical patients. None of the deaths in either group were due to aneurysm rupture.

"Since we began this study, we've become much better at identifying patients who are and are not good candidates," said Dr. Katzen, lead author of the study. "Our results are continuing to improve because we no longer perform the procedure on people whose access arteries are too small or are twisted and calcified."

Stent-Graft Repair 97 Percent Successful

In another study at Miami Cardiac & Vascular Institute, stent-graft procedures were performed on 200 AAA patients who were at average to extremely high risk of experiencing rupture, and 193 were successful (97 percent). Four (2 percent) procedures were aborted due to technical difficulties and 3 (2 percent) were converted to conventional surgical repair. Seven patients (4 percent) died within 50 days of the procedure, each of unrelated causes.

"None of the patients in our study had a ruptured aneurysm after stent-graft implantation," said Dr. Benenati.

The interventional radiology technique involves making an incision in the groin and, under X-ray guidance, inserting a catheter into a blood vessel that leads to the aorta. A collapsed stent-graft, also known as an endograft (a fabric tube), is inserted through the catheter and moved to the site of the aneurysm, where it is deployed, reinforcing the aorta and creating a stronger pathway for the blood. Blood flowing through the stent-graft no longer puts pressure on the ballooning walls of the aneurysm, which are outside of the graft. Typically the patient is lightly sedated and has been given epidural anesthesia. The hospital stay is usually four days or less, recovery takes an average of 11 days, and typically there are fewer complications than with surgical repair.

The alternative, conventional surgical replacement of the damaged portion of the aorta, is performed under general anesthesia. A large incision is made in the abdomen to reach the site. The aorta is clamped off, the aneurysm cut open, an artificial artery or graft is sewn into place and the aneurysm is closed up. The average hospital stay is 8 to 10 days and the average recovery time is 47 days.

About 15 percent to 20 percent of patients who have the stent-graft procedure experience leakage into the aneurysm sac. Many need no treatment, but are followed closely. Others may undergo embolization, an interventional radiological technique that cuts off blood flow to the problem area to prevent further leakage.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.