April 26, 2007

(SACRAMENTO, Calif.) — The UC Davis Vascular Center is seeking participants for a clinical study that will evaluate whether early endovascular repair of small abdominal aortic aneurysms is superior to periodic surveillance, or “watchful waiting.”

An aneurysm is a bulge or balloon that forms in the wall of a blood vessel. Over time, as the vessel wall continues to lose its elasticity, the stretching force caused by normal blood pressure in the aneurysm can lead to bursting or rupture of the vessel. An aneurysm that forms in the part of the aorta (one of the body's main blood vessels) that extends through the abdominal area is called an abdominal aortic aneurysm.

Abdominal aortic aneurysms affect approximately 1.5 million people in the United States, with an additional 190,000 new diagnoses each year. The condition is dangerous, as ruptures are associated with a high rate of mortality (up to 90 percent.) Such ruptures result in about 15,000 deaths annually and are the 16th-leading cause of death in the United States.

New legislation provides one-time coverage for abdominal aortic aneurysms screenings of new Medicare patients at risk for the disorder: men over 65 with a history of smoking, and people with a first-degree relative (parent or sibling) with the condition. This coverage began Jan. 1, 2007 under part B of the Medicare program. Testing services are available at the UC Davis Vascular Laboratory.

The risk of rupture in small aneurysms, measuring between 4 and 5 centimeters in diameter, is considered low, in the range of 1 to 5 percent annually. However, the risk increases substantially as the aneurysm grows, normally at a rate of 25 to 40 percent for a 7-to-8 centimeter aneurysm.

One treatment option is endovascular stent grafting. This is a procedure in which stent grafts, fabric and metal mesh tubes, are transported through arteries in the groin via two small incisions, then passed inside and across the aneurysm, without surgically opening the abdomen.

The UC Davis Vascular Center is part of a nationwide study that is comparing endovascular stent graft repair with observation in patients with abdominal aortic aneurysms that are 4 to 5 centimeters in diameter. The study will make comparisons in regard to patient survival, aneurysm ruptures and aneurysm-related death. The current standard practice for aneurysms with a diameter of 4 to 5 centimeters is to perform regular imaging to monitor the aneurysm until it reaches a diameter of 5 centimeters, and then treat it. This study will explore the possibility that earlier intervention of small, 4-to-5-centimeter aneurysms may improve long-term outcomes.

UC Davis is among 70 clinical centers participating in the study, led by The Cleveland Clinic, which will enroll up to 1,700 patients.

David Dawson, professor of vascular surgery, is the principal investigator of the study at the UC Davis Vascular Center, and Christy Pifer is the clinical research coordinator. For more information on the study, call (916) 734-4156 or send a fax to (916) 734-7660.