Poison gas could be a life-safer

CARBON monoxide, the poison gas produced by vehicle exhausts, could prove to be a life-saver for heart surgery patients, new research suggests.

Scientists found that rats exposed to the poison were less likely to suffer complications after undergoing heart operations. Carbon monoxide may therefore be beneficial in a wide range of heart and blood circulation diseases, the United States researchers believe.

Currently, the best treatment for patients with clogged arteries is bypass surgery or angioplasty.

In the first case, a section of blood vessel from another part of the body is grafted to divert blood around the blockage. Angioplasty involves the use of a balloon to widen the artery at the point where it has narrowed. Both techniques have a significant failure rate, due to thickening of artery walls at the surgery site.

The US researchers looked at the impact of carbon monoxide on rats given a transplanted aorta the large artery leading out of the heart or a "balloon" injury mimicking the side effects of angioplasty.

In both cases, exposure to carbon monoxide before surgery significantly reduced thickening. In the first group it was reduced by 61%, and in the second 74%. Rats with balloon injury improved after only an hour's exposure to carbon monoxide. Very low concentrations of carbon monoxide 250 parts per million were used.

The findings were published in an on-line article from the journal Nature Medicine. Dr Leo Otterbein, from the Pittsburgh School of Medicine in Pennsylvania, one of the research leaders, said: "If you could pre-treat patients with carbon monoxide it might result in a better long term outcome. The fact that a one-hour pre-exposure of a rat to low levels of CO markedly diminished the intimal proliferation that usually follows balloon injury, used here as a model of angioplasty, supports the use of CO clinically." The scientists observed no negative effects in the rats.