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Scientists Develop Experimental Laser Technique to Clear Clogged Arteries

December 13, 1987|LOIS TIMNICK | Times Staff Writer

An experimental laser technique that can clear clogged arteries by cutting through blockages and vaporizing them without damaging the blood vessel walls has been developed by a team of scientists at Cedars-Sinai Medical Center, the Jet Propulsion Laboratory in Pasadena and NASA.

The procedure, called excimer laser angioplasty, could become a speedier and less expensive alternative to many bypass surgeries and balloon angioplasty procedures that about 600,000 patients now undergo each year in the United States, the researchers say.

Since August, the procedure has been successfully used in four human patients, all with obstructions in the leg arteries, a condition called peripheral vascular disease that frequently affects diabetics and smokers.

The first patient was an 84-year-old diabetic man who could barely walk because of severe leg pain; the laser cleared the blocked artery in 33 seconds and he was discharged from the hospital a few days later. The next three patients went home from the hospital the day after laser treatment. All four are said to be doing well.

The team hopes to receive approval next year from the U.S. Food and Drug Administration to begin testing the excimer laser's ability to clear human coronary arteries as well, according to Dr. Warren Grundfest, director of laser surgery and research at Cedars.

The excimer laser is one of several varieties of lasers, which are devices that produce intense light beams of a single color going in a single direction. ("Laser" stands for Light Amplification by Stimulated Emission of Radiation.) The excimer laser was invented in the mid-70s and first used by scientists to measure air pollution. And medical researchers long have sought a way to harness its tremendous energy for controlled delivery to a specific point in the body for medical use.

"Our physicians have brought a piece of technology originally designed to go into space to measure the atmosphere's ozone layer into the operating room where its potential to revolutionize the treatment of coronary artery disease is extraordinary," Cedars spokesman Ron Wise said Thursday.

Grundfest reported the team's work to a meeting of 650 vascular surgeons in Chicago earlier this month.

"The property that makes the excimer laser unique and desirable for the coronaries--the main arteries supplying blood to the heart--is that it is able to vaporize blockages of both fat and calcium without heat. It makes a clean, precise cut with no sign of the charring and debris left behind by other types of lasers tested," Grundfest said.

And because it is a "cool" laser, it does not cause blood vessel spasms or clots, as do thermal lasers, added cardiologist Frank Litvack, who performed the human excimer laser procedures. In a demonstration, Grundfest cut a tiny hole through the head of a match stick--without generating enough heat to ignite the match.

Grundfest said the team of physicists and physicians has been working on adapting the excimer laser to blood vessel disease for five years.

The low-heat laser originally developed for the space program is used commercially to etch silicon chips for micro-electronics, but its medical possibilities--in ophthalmology and orthopedics as well as blood vessel disease--are only now being explored.

The excimer laser is an intense, pulsed ultraviolet light "knife" that is passed through a bundle of thin glass fibers the size of a pencil lead inside a flexible catheter. The physician punctures the skin and, with the help of X-ray imaging, snakes the catheter through the blood vessel to the point of blockage and then switches on the power.

The laser cuts through and vaporizes deposits along the artery wall by disrupting the molecular bonding that holds matter together.

"Using the excimer laser for peripheral vascular disease is here today, and its use in coronaries is on the horizon. If we are successful, it will revolutionize the treatment methods available to the cardiologist," Litvack said.

The team said tests in numerous animals and the first four patients went "flawlessly" and without adverse side effects.

The medical team is headed by Grundfest, Litvack and Dr. James Forrester, director of cardiovascular research at Cedars.

At the National Heart, Lung and Blood Institute in Bethesda, chief of cardiac diseases Thomas Robertson called the excimer laser system "a real advance."

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