The famous little blue pill, Viagra, may have yet another use. According to a Canadian study, the drug helps treat life-threatening high blood pressure in children.

Pulmonary hypertension is an incurable disease that causes continuous high blood pressure in the arteries leading from the heart to the lungs.

As a result, vessels in the lung gradually constrict and the heart struggles to maintain blood flow.

Patients in that condition go on to suffer chronic heart failure -- a condition that leaves them typically suffering from fatigue, shortness of breath and eventually death. Among children, that entire decline can take place within a year.

The condition is traditionally treated with a non-stop continual intravenous infusion of the drug prostacyclin. But that means patients must always carry their pump with them, and mix the drug fresh daily.

According to a new study published online in the American Heart Association journal Circulation on Monday, simply treating the condition with Viagra is not as far-fetched as it may sound.

Viagra actually works by relaxing the smooth muscle of blood vessels, increasing blood flow. Known generically as sildenafil, it was actually developed to treat heart disease.

To test the drug's effectiveness in fighting blood pressure, researchers at the Childhood Pulmonary Hypertension Clinic at Toronto's Hospital for Sick Children gave various doses of the drug to 14 children.

After a year, researchers found that the young test subjects, aged 5 to 18, were actually able to breathe easier and exercise more.

For example, on average the distance they could cover in minutes increased by more than 500 feet.

But even better, all of the test subjects were alive. Among similar patients not treated with the drug, less than 40 per cent are still alive after one year.

"We were really happy that we could give children with this dreadful disease some hope," study author Dr. Tilman Humpl told CTV.

Putting Viagra to other uses is not new, however. Its use in the treatment of adults with pulmonary arterial hypertension has already been approved in the United States and Europe.

Dr. John Gratton says the little pill raises a few eyebrows among adults with the same disorder.

"They often smile or are quite surprised that we would use this medication for pulmonary hypertension but for those who have the opportunity to use it, we have had some good experiences," Gratton said.

To clear up any confusion among hypertension patients who might benefit from Viagra, the pills' manufacturer plans to change their colour from blue to white, and their name from Viagra to Revatio.

The Toronto study was funded by Pfizer, the maker of Viagra.

With a report from CTV's Avis Favaro