Radiation Limits Common Heart Bypass Complication

A recent study has found that a jolt of radiation can help keep the blood vessels of the heart from getting clogged up with scar tissue after coronary bypass surgery.

While the approach is still in an experimental stage, it could help solve a problem that effects many of the one million Americans who get bypass surgery or angioplasty every year.

When performing bypass surgery, doctors frequently use a vein taken from the leg to reroute blood around clogged arteries. But these grafts are prone to becoming clogged as well. Approximately 40 percent fill up within 10 years.

To combat this, doctors often perform angioplasty on the graft, squeezing it open with a tiny balloon and then inserting a metal mesh tube, called a stent, to keep it open. But muscle cells inside the graft sometimes form scars tissue that grows over the sateen, limiting blood flow.

Researchers at Washington Hospital Center tested radiation on 120 bypass patients who had clogged stents. The results are reported in the New England Journal of Medicine.

What researchers found was that those patients who received the radiation were only half as likely as other patients to have a heart attack or experience new re-narrowing of their grafts, or even die during the following year.

Many times, a repeat bypass operation is necessary on patients whose stents become clogged again.
This can be risky.

The study's director, Dr. Ron Waksman, said that "We really want to see if we can salvage those veins grafts so we can prevent a second bypass surgery."

The Food and Drug Administration has approved two systems for delivering radiation to the heart. The latest study involved the Cordis system which is manufactured by Johnson & Johnson.

Clogging is also a major problem after angioplasty is done on the heart's own arteries rather than the graft. Doctors hope that most of this problem can be eliminated by the invention of a new drug coated from of stent that appears to inhibit clogging.

At least eight varieties of these experimental stents, coated with different medicines are now being tested. The results are showing promise on a relatively small number of patients.

According to Dr. Richard O. Cannon III of the National Heart, Lung and Blood Institute, clogging is likely to remain a problem, at least for a while and solutions like radiation will be needed.

The the most recent study, half of the patients were selected randomly for radiation, and a tiny ribbon containing radioactive seeds was threaded through the graft and inside the stent, then left there for 20 minutes.

In another group of patients, a ribbon holding an inactive substance was used, without anyone knowing who got what.

Six months later, clogging had occurred in 21 percent of the radiation patients, compared with 44 percent of those patients getting the dummy treatments.