6/1/98
MEDIA CONTACT:
Ruthann Richter or M.A. Malone, (650) 723-6911.
Patient interviews may be arranged.
FOR COMMENT:
Dr. Christopher Zarins, (650) 725-7830
EMBARGOED FOR RELEASE: 9:15 a.m. Pacific Time on Monday, June 8, to correspond with presentation in San Diego at the 46th scientific meeting of the North American Chapter of the International Society for Cardiovascular Surgery.
NEW PROCEDURE EASES REPAIR OF ABDOMINAL ANEURYSMS
STANFORD -- A minimally invasive procedure for repairing abdominal aortic aneurysms gets people back on their feet sooner -- and with fewer complications -- than traditional open surgery, a Stanford surgeon reports.
The new findings come from a national, multi-center study led by Dr. Christopher Zarins, chief of vascular surgery and Chidester Professor of Surgery at Stanford University School of Medicine.
The study is the first to compare the minimally invasive procedure with the conventional surgical approach, Zarins said. Abdominal aortic aneurysms are enlargements in the lower part of the aorta, the main artery carrying blood away from the heart. They can rupture at any time and cause death.
The new technique uses a stent graft -- a Dacron tube inside a collapsed metal-mesh cylinder -- that is threaded through the arteries to the site of the aneurysm. The stent graft expands inside the wall of the aorta and serves as a substitute channel to carry blood, bypassing the aneurysm to prevent a rupture.
In the study, which involved 250 patients at 12 medical centers nationwide, the researchers found that the stent graft procedure had some major advantages over standard surgery, which can be risky and lead to major complications, Zarins said.
"It [the new procedure] allows you to repair an abdominal aortic aneurysm through a small groin operation, as opposed to a major abdominal operation," he said. "People were up sooner, eating, walking and going home, and the complication rate is less. We had some patients who went home the morning after the procedure."
Zarins will present the results Monday, June 8, at the 46th scientific meeting of the North American Chapter of the International Society for Cardiovascular Surgery, held in San Diego.
Bubble waiting to burst
The aorta, which carries blood from the heart to nearly all other arteries of the body, can sometimes develop a bubble, or aneurysm, similar to a weak spot on an old tire, Zarins said. The aneurysm may form as a result of advanced age, atherosclerosis (clogging of the arteries) or other conditions.
An aneurysm can burst at any time. In the United States, half of all patients with untreated aneurysms die of a rupture within five years, Zarins said.
Abdominal aortic aneurysms are the nation's 13th leading cause of death, killing some 15,000 Americans each year. The condition is more common in men, with approximately 5 percent of men over age 60 developing aortic aneurysms in the abdomen, Zarins said.
For the last 40 years, surgeons have repaired aortic aneurysms by opening the abdomen to remove the damaged portion of the artery and then sewing a Dacron tube in its place. But the surgery is risky and requires a long hospital stay and recuperation process, Zarins said.
In recent years, surgeons have been developing minimally invasive alternatives, using different types of stent grafts that can be guided to the site of the aneurysm without the need to cut open the patient's abdomen. The first of these grafts was installed in 1991 by Dr. Juan Parodi in Argentina, Zarins said.
Inch-long incision
The latest study used a stent graft developed at Stanford in 1994 by Dr. Thomas Fogarty, professor of surgery (cardiovascular). In the investigational procedure, surgeons make a 1-inch incision in the patient's thigh to gain access to the blood system through the femoral artery. The surgeons then guide the stent, which is about 6 inches long, inside a long plastic capsule through the arteries to the lower aorta, monitoring the stent's progress on an X-ray screen.
Once the stent is in place, the holding capsule is removed. Activated by heat, the stent automatically expands like a spring and becomes anchored to the artery wall. The aneurysm then is excluded from the blood flow and typically shrinks over time, Zarins said.
In the study, 190 patients received stent grafts, while 60 "control" patients had conventional surgery. Patients ranged in age from 45 to 97 years, and the large majority were men.
Among those receiving stent grafts, the mean time spent in the hospital was 3.4 days, compared with 9.4 days for those in the surgery group. Patients who received stent grafts were out of the intensive care unit after the first day and were up and around within 1 1/2 days. Those undergoing open surgery spent an average of 2 1/2 days in the intensive care unit and weren't up and walking until day four.
Complications reduced
Among those who received stent grafts, 12 percent experienced complications, compared with 25 percent in the surgery group. "You have twice as many complications with open surgery, and the complications are major, often requiring extended hospital stays," Zarins said.
Major complications among those undergoing conventional surgery included gastrointestinal bleeding, insufficient blood flow to the colon, and major wound infections. Complications among those receiving stent grafts were far less serious, most often involving swelling at the site of the thigh incision or narrowing of the femoral artery, Zarins said. These complications can be readily managed and usually prolong the hospital stay only a day or two, he said.
"We know that the stent graft procedure compares very favorably with open surgical repair. There is reduced morbidity, a shorter hospital stay, and earlier return to ambulation and full activity," Zarins said.
"We're very enthusiastic about this," he added. "The patients love it. They don't have to undergo a very big operation."
In the first 30 days after the operation, he said, there were two deaths among patients receiving stent grafts: one in a 45-year-old who had a previously undetected blockage of a coronary artery, and one in a 91-year- old who experienced multi-system organ failure. There were no deaths among patients in the control group, although the medical literature indicates that death rates for surgical repair of the lower aorta range from 3 to 10 percent, Zarins said. The difference in mortality rates between the two groups in the study is not considered statistically significant, he said.
The long-term benefits of the stent grafts are still unknown because of limited experience with the procedure, Zarins said. Patients with stent grafts need to be followed over time to be sure they do not develop blood leakage around the site. This occurs in about 10 percent of cases, he estimates.
'I'm just flabbergasted'
One study participant -- Richard Boemker, a retired businessman and gardener from McKinleyville, Calif. -- had spent four years living with the knowledge that he had an aneurysm that could rupture at any moment. Boemker said his doctor had told him he wouldn't be able to withstand the rigors of open surgery because he also had a heart condition. Besides, he said, "I never did like the idea of being stitched."
But when his aneurysm had grown to about 2 1/2 inches in diameter, his doctor encouraged him to go for the investigational stent graft procedure. Zarins performed the operation on May 21 at Stanford Hospital, part of UCSF Stanford Health Care. Within a day, Boemker was out of intensive care and walking around, cracking jokes and feeling minimal discomfort, he said.
"I'm just flabbergasted" at the ease of the procedure, he said. "If it can help others too, I'm certainly for it. I certainly needed the help myself."
Zarins' colleagues in the study were Dr. Rodney A. White at Los Angeles County Harbor-UCLA Medical Center; Dr. Donald E. Schwarten at St. Vincent's Hospital in Indianapolis; Dr. Edward V. Kinney of Baptist East Hospital in Louisville, Ky; Dr. Edward B. Diethrich of the Arizona Heart Institute in Phoenix; Dr. Kim J. Hodgson at Memorial Hospital in Springfield, Ill.; and Stanford's Dr. Thomas Fogarty.
The study was supported by Medtronic AneuRX, the Cupertino, Calif., company that makes the stent grafts.
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