This research may lead to new avenues in the treatment of many cardiovascular conditions

Professor Marlene Rabinovitch, Hospital for Sick Children, Toronto

It is a common complication of most heart and lung diseases, and it leads to heart failure.

Pulmonary hypertension can also occur more rarely as a rapidly progressive and fatal condition that requires long-term intravenous therapy, or a lung or heart-lung transplant.

The HSC doctors treated the condition by blocking the action of an enzyme called elastase.

Researcher Dr Kyle Cowan said: "We were able to completely reverse fatal pulmonary hypertension in an animal model using an elastase inhibitor.

"Not only did it stop the progression of the disease, but the blood vessel reverted to a normal condition."

Elastase causes cells in blood vessels to rapidly divide, so that the vessel becomes obstructed.

The HSC team used a synthetic, chemical compound to induce the cells to die and the excess tissue to be reabsorbed, thus opening up the blood vessel.

New Avenues

We don't know if the same results would be seen in people

British Heart Foundation

Professor Marlene Rabinovitch, who led the HSC team, said: "This research may lead to new avenues in the treatment of many cardiovascular conditions.

"While this study deals with obstructed pulmonary arteries, a similar mechanism may be applicable in reversing coronary disease as well."

Professor Rabinovitch said clinical trials of the drug on humans would be needed before it could be made widely available.

The British Heart Foundation issued a statement which said that sometimes the cause of pulmonary hypertension was unknown, making an effective treatment difficult.

"So far studies on elastase inhibition have only been carried out in a laboratory, so we don't know if the same results would be seen in people.

"Let's hope that this novel approach does bear fruit in future to help some of the people with this debilitating condition."

The research is reported in the June issue of the scientific journal Nature Medicine.