Radiation Technique For Angioplasty

Bathing a heart artery with radiation after it has been reopened with an inflated balloon increases the chance that the artery will not close again, a study in Thursdays New England Journal of Medicine reported.

Long-term effects of the radiation are unknown but doctors call it a promising technique against heart disease.

The goal is to improve the success rate of angioplasty, an operation in which a balloon-tipped tube is threaded into the arteries feeding the heart muscle and inflated at a point where an artery has been narrowed by heart disease.

The procedure squashes the debris against the walls of the artery and allows blood to flow freely again, but in 30 to 60 per cent of the cases the artery closes or becomes blocked again, a process known as restenosis.

A mesh-like cylinder known as a stent is then inserted into the artery to support it, which cuts the likelihood the vessel will re-close by about 30 per cent. But in some cases the walls of the artery react to the angioplasty by producing new tissue, which starts plugging up the artery all over again.

The radiation technique is designed to discourage the artery from producing that tissue.

In tests of 26 volunteers, doctors put a stent in place and kept a tiny radioactive ribbon in the once-narrowed artery for 20 to 45 minutes. Another 29 people, who served as the placebo group, had a tiny non-radioactive ribbon inserted.

Six months later, the blood vessels had closed again in 17 per cent of the patients who had the radiation treatment versus 54 per cent from the placebo group. The benefits were sustained a year after the treatment.

The patients treated with iridium-192 had a striking reduction in the risk of having arteries narrow again, said the research team led by Paul Teirstein of the Scripps Clinic & Research Foundation in La Jolla, California.

The long-term effects of the treatment remain a mystery. People who have received high doses of radiation to treat cancer have a slightly higher risk of heart disease. Although researchers still need to refine the treatment, at the present time, a radiation device looks very promising as a potential solution to the problem of restenosis, David Holmes of the Mayo Clinic in Rochester, Minnesota, said in an editorial in the Journal.

In another study in the same issue, doctors from 69 medical centres in the United States and Canada reported that the drug abciximab prevented complications while doctors probed for signs of heart disease.

In past tests of the drug, made by Centocor Inc of Malvern, Pennsylvania, the medicine seemed to increase the risk of unwanted bleeding even though it helped keep the heart muscle healthy while doctors probed the arteries feeding it.

But the latest research suggests excess bleeding was caused by the anti-clotting drug heparin that was given in addition to the abciximab.

When the amount of heparin was reduced, that unwanted side effect disappeared.