July 13, 1999 CHAPEL HILL - Physicians at the University of North Carolina at Chapel Hill are testing a new, less invasive method for repairing abdominal aortic aneurysms, potentially dangerous defects of the body's major artery found often in the elderly.
If clinical trials continue to show promise, the newer repair method could offer an alternative to the standard major operation that requires opening the entire abdomen, a hospital stay of seven to 10 days and six weeks for recovery. In early experience with the newer procedure, patients were able to leave the hospital in about two days and were back to normal activity within two weeks, according to Dr. William Marston, assistant professor of surgery at UNC-CH School of Medicine.
"The standard surgery for abdominal aortic aneurysm is very good and has been used extensively over the last 25 years," Marston says. "On the downside, mortality rates are between two and four percent and may prove too risky for people with cardiac, pulmonary, or other disorders."
In the less invasive endovascular repair, an incision of about two inches is made in the groin, through which a thin artery graft supported by a metal framework, or stent, is threaded via a guide wire into the defective segment of aorta. The stented graft, when heated by normal body temperature, quickly expands to the width of a normal aorta. Positioned inside the ballooned-out aneurysm, the graft is anchored to healthy aorta above and below it.
"You must have normal aorta above and below the aneurysm to anchor the device so that the blood flows through the stented graft inside it. This prevents blood flow pressure from rupturing the thinned-out aneurysm," Marston explains.
According to the UNC vascular surgeon, he and Dr. Matthew Mauro, an interventional radiologist and professor of radiology, are principal investigators at one of selected sites conducting clinical trials evaluating the Vanguard prosthesis. This is one of several stented grafts undergoing studies in the U.S.
"To effectively treat the aneurysm, we have to know if these devices will exclude the aneurysm over the long run. So far, in almost two years, our UNC group has had success in aneurysm exclusion in 90% of patients, Marston says, adding that clinical reports from Europe of similar repairs have noted acceptable success for longer periods of time.
At UNC, a multi-specialty center has been developed to offer endovascular techniques combining the skills of surgical and interventional radiology experts. Marston points out that the unique skills these specialists bring to the procedure "have combined to produce optimal results."
"This is clearly a procedure that requires extensive training to develop the skills necessary to do it safely and to do it with the best outcomes for patients," he states. "At UNC, we've performed over 30 cases with successful results, an accomplishment matched by only a few centers nationally."
The procedure is performed in an operating suite especially modified to ensure that a standard operation can be performed if necessary, which has occurred in fewer that 5% of cases, notes Marston .
The UNC team will soon open another clinical trial for people with abdominal aortic aneurysms that require repair. "We will again have prostheses available for any patient who has an aneurysm that is anatomically correctable with the device," Marston says.
"It's definitely a technology that needs longer-term follow-up. We're following our patients very carefully and recommend they come back to us every six months for examination. But we believe that for some patients it clearly has the potential to reduce the risks of aneurysm repair."
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