Biodegradable Surgical Tools Studied

Wednesday, July 26th 2000, 12:00 am

By: News On 6

DALLAS (AP) â€” Tiny coils used to prop open the clogged arteries of heart patients now come in a biodegradable form â€” and they may work just as well as widely used metal versions, according to a new study.

Tests of the biodegradable coils, called stents, could change the way doctors perform surgery to reopen narrowed blood vessels, according to Japanese researchers who performed the tests on a small group of human patients.

No deaths, heart attacks or bypass surgeries were recorded among the 15 heart patients who were given the plastic, zigzag-shaped coils over a six-month period, according to the lead researcher, Dr. Hideo Tamai of Shiga Medical Center in Shiga, Japan.

Usually, metal stents are implanted into the blockage site of arteries through a balloon. They are used in 75 percent of all angioplasty operations.

``Since metal is a foreign material for humans, traditional stents sometimes cause inflammatory reactions in patients, and there are many long-term safety concerns associated with metallic stents,'' Tamai said.

An inflammatory reaction can lead to a re-narrowing of the inside of the arteries, which could lead to problems as severe as heart attacks.

But the biodegradable stents, which are made of a polymer that slowly dissolves in the months after being inserted, reduce the rate of re-narrowing, he said.

Also, researchers hope to find ways to insert anti-inflammatory drugs into the biodegradable coils so the medicine could be delivered right into the arteries as the stents disssolve.

The findings appeared in Monday's issues of Circulation, a journal of the American Heart Association. Tamai is a co-inventor of the biodegradable stent used in the study; he worked on the study with officials from Kyoto-based Igaki Medical Planning Co., which plans to market the stents.

The researchers were careful to note the study involved too few patients to draw a definitive conclusion, but they noted larger human studies were being planned in the United States.

Dr. Howard Herrmann, a cardiologist at the University of Pennsylvania who was not involved in the study, said the findings were interesting. But he cautioned the researchers' claims that biodegradable stents could ultimately reduce the risk of arterial inflammation are unproven.

``The idea that one could place a stent and not have to deal with any of the latent concerns about inflammation would be great,'' Herrmann said. ``But we've got to follow patients for more than six months â€” maybe even a year â€” to know for sure.''

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On the Net: American Heart Association: http://www.americanheart.org