Doctors expect Océane McKenzie to enjoy a healthy, normal childhood with her two older brothers. (CBC)

A baby's heart was repaired while she was still in the womb, which doctors at Toronto's Mount Sinai Hospital and the Hospital for Sick Children called a first in Canada.

Océane McKenzie had a severe narrowing of the left ventricle of the heart. If not fixed, the left side of the heart would not function.

A team of doctors expanded the baby's aortic valve using a balloon catheter inserted through the mother's abdomen 31 weeks into the pregnancy. The procedure helped to reverse the baby's heart failure before birth.

"I think the result is a very nice result," Dr. Edgar Jaeggi, head of the fetal cardiac program at Sick Kids, said Friday.

Without the in utero procedure, Océane would have needed three surgeries after birth, and faced a shortened lifespan and long-term complications.

"Knowing that it had never been done successfully, it wasn't a reassuring feeling," recalled mother Vicki McKenzie.

"But at the time, that's what we felt was the only option to give her the best chance at being able to survive and recover."

When she becomes an adult, "we might need to replace the valve, but definitely this baby has probably a normal life expectancy," Jaeggi said.

The procedure allowed Océane to remain safely in utero for another month until she was born on April 15.

"Any procedure you can do to a fetus in utero allows the baby to remain in the best intensive care unit that there is," said Dr. Greg Ryan of Mount Sinai Hospital.

"It allows the baby to become more mature, so if this baby was delivered early, it faced … all of the complications of prematurity."

Valve repair

Dr. Edgar Jaeggi and his team used a balloon catheter to expand a baby's aortic valve while she was still in the womb. (CBC)

As soon as the balloon catheter was put into place using ultrasound imaging or echocardiography, the valve started moving and opening up, Jaeggi explained.

Two more interventions were done — at birth and a few weeks later. Océane's heart function normalized three weeks after birth.

Since the valve itself is abnormally formed, it could become stiffer and need replacing in young adulthood, Jaeggi said.

Doctors have to carefully select a small minority of patients with the syndrome who are at the right stage to benefit from the procedure.

The team of Canadian doctors attempted the procedure on two other much earlier fetuses. Neither survived.

"We have learned that what was a theoretical possibility is an actual possibility," said Ryan.

"And we've not only seen that we can not just fix the valve, but we've seen that the left ventricle can recover. That's what we were hoping would happen, but we were not entirely certain that it would happen until we saw it."

The in utero surgery has been performed several times in the U.S.

The McKenzie family is now saving all the photos and clippings for a special scrapbook.