Doctors at Vanderbilt Children's Hospital have found a whole new use for the popular erectile dysfunction drug Viagra.
Sildenafil, as it is called by its more anonymous chemical name, may have the power to save babies. Chronic pulmonary hypertension is virtually a death sentence in newborn babies. It can begin with a heart defect, or for reasons that are not well explained; but when the blood pressure rises inside the lungs and stays that way, there is often little that can be done.
But a few small studies have recently suggested that babies with deadly pulmonary hypertension may respond with good success to Sildenafil.
In the case of 6-month-old Hartley Wilson, Don Moore, M.D., a pediatric cardiologist at Vanderbilt Children's Hospital, had to make a difficult decision. Shortly after birth, Hartley had emergency surgery to correct a heart defect known as total anomalous pulmonary venous return. He remained in the hospital for the next two months.
"After a brief stay at home, he was readmitted to the hospital," Moore said. "The blood pressure in his lungs was five or six times normal and the right side of his heart was struggling to function," recalled Moore.
Time was ticking away from the moment then-3-month-old Hartley returned to Vanderbilt Children's Hospital. Very high pressures, like his can cause heart failure and death. Hartley was rushed to cardiac catheterization in order to get an accurate reading of the pressure in his lungs.
Even after a successful heart surgery, like Hartley's, problems may develop that result in pulmonary hypertension. It could be vessels that are prone to clotting or scarring after surgery, or vessels throughout the lungs that have a tendency to tighten, reducing the freedom of blood flow from the lungs back to the heart.
During the procedure, Moore tried a drug well known to reduce deadly pulmonary hypertension in infants: an inhaled drug called nitric oxide.
"It dilates, or relaxes the blood vessels in the lungs, but is extremely expensive and impractical to use long term," said Moore.
"It's more of a stop-gap measure until you find another solution but also helps us identify those children who might have a response to other medicines."
Recent studies have shown that adults whose pulmonary hypertension is reduced with nitric oxide, can often get similar results with Viagra taken orally. A small but growing body of preliminary studies have shown it works in babies too. The chemical pathways are similar. Both drugs work on a chemical messenger that causes smooth muscle to relax. While nitric oxide increases the amount of the chemical produced, Viagra keeps it around longer.
"There was some evidence in the medical literature that babies would respond safely but little information regarding children who have Hartley's specific heart defect," Moore said. "We called up several centers experienced in the use of Viagra in children. They agreed that because of Hartley's specific symptoms and circumstances, Viagra would be a good option."
Within a day of the cath-lab procedure that brought them such bad news about their son's condition, Krista and James Wilson met with Moore. Moore told them there was a drug he wanted to try right away. "Dr. Moore said it was Viagra and we were shocked," Krista said. "Actually it lightened the mood a bit. It had been such a day of bad news and here the doctor was telling us Viagra might help with his lungs. We could almost laugh."
The Wilsons didn't hesitate to give permission because they knew their son needed a miracle.
"I was skeptical, and fearful of jumping on the bandwagon with so little data on this specific heart condition," Moore said. "But I felt it was the most reasonable alternative we could offer given the circumstances."
A small dose of Viagra was begun and then the nitric oxide was slowly weaned away. Hartley's pressures stayed low.
That was months ago. Hartley's pulmonary pressure began to rise again several weeks ago and the dose of Viagra has been increased. Hartley is still quite ill. His pulmonary blood pressure is still about twice normal, but he can live with that, perhaps for years.
And Hartley isn't the first infant at Vanderbilt Children's Hospital to receive Viagra. George Walen is a 1-year-old who had a congenital diaphragmatic hernia, which shifted all his internal organs upward at birth, putting tremendous pressure on the heart and lungs. While surgery has fixed the herniation, his lungs continue to struggle. Viagra seems to be helping.
Viagra is not without risks for babies. If the drug levels are raised too high, babies can have a general blood pressure drop that can be life threatening. And no one knows what the long-term effects of Viagra could be. Current studies are underway to answer these questions.
But the fact remains that Hartley is much better. He may soon go home.
"He's a charmer," said his dad, James. "We figure this will make for great stories when he's a teen-ager. He can laugh about how Viagra saved him as a baby."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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