Lasers powering through coronary arteries.

Researchers from the Texas Heart Institute in Houston last week announced the first successful use in the United States of lasers to clean out plaque deposits in clogged coronary arteries.

At the American Heart Association (AHA) meeting in Washington, D.C., James J. Livesay described the laser use on 16 arterial vessels in eight patients since January. Using a different type of laser and a different mode of access, Daniel S.J. Choy of St. Luke's-Roosevelt Hospital in New York City did the procedure on eight patients in France in 1983 and 1984.

The two projects are apparently the sole possessors of U.S. Food and Drug Administration approval for evaluating the ability of lasers to clean clogged coronary arteries, and they mark the first laser forays into the living human heart.

The Texas procedures were done in conjunction with coronary artery bpass surgery. The arteries were sliced open so that a blood vessel from elsewhere in the body were open, a carbon dioxide laser was used to clear out clogged areas upstream from the planned connection.

The Houston surgeons have used the procedure, called laser coronary endarterectomy, without perforating or charring any of the arterial walls. They have completely opened 12 of the 16 vessels, Livesay says.

The laser "can remove plaque and relieve arterial stenosis [narrowing] without damage to human coronary arteries," he says.

Jeffrey M. Isner of Tufts-New England Medical Center, who cochaired the AHA session, says, "This is the most encouraging evidence yet" that lasers can vaporize plaques without harming vessel walls.

Choy's technique was also done on patients about to have bypass surgery, but he used an argon laser. The laser energy was transmitted by optical fibers threaded up to the narrowed or blocked artery. The advantage, Choy says, is that the fibers can be threaded to the blockage without the need for cutting into the artery. Ultimately he plans to do the procedure by catheter without opening the chest.

Though the longest any of his patients' arteries remained open was 25 days, Choy considers the procedures successful in establishing safety. He suspects the closures occurred because the arteries were not only lased but also bypassed. The reduced level of flow as some of the blood took the new alternate route could have allowed new atherosclerotic buildup, he told SCIENCE NEWS.

Choy plans to use the laser procedure as soon as he finds someone with the right anatomy -- a patient with occluded (blocked) arteries too small to bypass or whose condition wouldn't be threatened by reocclusion.

Also at the AHA meeting, Timothy A. Sanborn of Boston University and his colleagues from BU and England described successful use of a metal-tipped laser in arteries in the legs of five patients. The arteries were totally occluded; after using the laser to create a channel through the plaque buildup, the researchers inserted a balloon and inflated it to push out the walls of the vessel.

Kenneth I. Shine of the University of California at Los Angeles, president-elect of the AHA, cautions, "While it's true that in some studies laser therapy may melt the plaque, there's still a concern about whether you'll get vascular [vessel] injury. I don't think we yet know the overall risks versus benefits."