Oct. 13, 1997 By Melanie Fridl Ross
GAINESVILLE, Fla---Although bypass surgery is keeping heart disease patients alive longer, the veins most often used to circumvent their obstructed coronary arteries are prone to developing fatty blockages years later.
Now a national study shows a minuscule metallic device used to prop open the clogged vessels is better at restoring blood flow than traditional balloon angioplasty -- and does so more safely.
Physicians have known for some time that the device, known as a stent, frequently is better suited for opening diseased arteries, but their use hadn't been put to the scientific test in vein bypass grafts, says cardiologist Carl Pepine, chief of cardiovascular medicine at the University of Florida College of Medicine. Pepine participated in the Saphenous Vein De Novo (SAVED) trial along with physicians from 11 other medical centers, led by Philadelphia's Thomas Jefferson University.
The scaffold-like stents yielded three benefits: The procedure typically went more smoothly than angioplasty; the diameter of the vein grafts was wider at a six-month follow-up examination; and the risk of death or serious complications such as heart attack, repeat bypass surgery or repeat angioplasty dropped 36 percent, researchers wrote in the September issue of The New England Journal of Medicine.
Each year, an estimated 500,000 Americans undergo coronary bypass surgery, said Dr. Michael P. Savage, the study's principal investigator and director of the cardiac catheterization laboratory at Thomas Jefferson University Hospital. Savage also is an associate professor of medicine in the division of cardiology at Jefferson Medical College.
Researchers tracked 220 patients with obstructed bypass grafts who had chest pain and/or signs of impaired blood flow to the heart. Participants were randomly assigned to stent placement or standard balloon angioplasty. X-ray images were taken during the initial procedure and at a six-month follow-up visit.
Both times, the images showed that individuals who received stents had a larger channel for blood to flow through, said UF cardiologist Richard Kerensky, director of the cardiac catheterization lab at Shands at UF. In addition, physicians were able to reduce the blockage without major complications 92 percent of the time with the stent, compared with only 69 percent in the angioplasty group, he said.
Eight months after the procedure, 73 percent of patients in the stent group were still alive, had not had a heart attack and did not have to undergo repeated bypass surgery or angioplasty, compared with 58 percent of those in the angioplasty group.
The most commonly used blood vessel to make the bypass is a vein removed from the leg at the time of the heart surgery. Yet within a decade, half of all so-called saphenous-vein bypass grafts are riddled with atherosclerosis.
"This is an increasingly common problem as patients are surviving many years after bypass surgery," Savage said. "Once the bypasses become blocked, it can lead to problems like heart attacks or chest pain and may necessitate a second operation, which is obviously something everyone would like to avoid."
Traditionally, physicians have performed conventional balloon angioplasty to treat the obstructed vein bypasses, but this has proven problematic because of frequent complications -- and because the veins often reclose within six months, he said.
During angioplasty, cardiologists maneuver a thin guide wire through a small incision in a vessel in the leg up to the blockage. A balloon-tipped catheter is then threaded over the guide wire and inflated to compress the fatty build-up and enlarge the artery's interior diameter, improving blood flow.
In contrast, the stent is mounted on a balloon, slid into the vein graft, and expanded when the balloon expands. The balloon is removed, and the stent is left behind to bolster the vein graft and keep it open.
"This really gives new hope to patients who have had prior bypass surgery -- new hope for avoiding problems and new hope for possibly avoiding repeated operations," Savage said.
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