PITTSBURGH (KDKA) – A little girl named Molly is being called a miracle after a breakthrough treatment saved her life, and it is all thanks to the doctors at Children’s Hospital.

It was supposed to be an exciting first day of school for 5-year-old Molly Dunne of Wilmington, Del. Instead, it was the first of day of the fight of her life when her mother got a call that the little girl had collapsed.

“It was her first day of kindergarten, and she left the house and she was fine,” said Kristen Dunne, Molly’s mom. “They called 911 and I got there and she was on the floor. It was very scary.”

At a Wilmington Hospital, Kristen and her husband found out Molly had severe pulmonary hypertension caused by a genetic condition.

They’re fears then turned to Molly’s twin sister Kate and 8-year-old brother, Ryan.

“There’s a genetic condition that Molly has called HHT, hereditary hemorrhagic telangiectasia,” said Kristen. “They believe that is the cause of pulmonary hypertension, and we had my other two children genetically tested and my son has the HHT as well.”

Then, Molly’s situation took a tragic turn, she went into cardiac arrest and suffered brain damage, a machine kept her alive.

“I’ll never forget the look on the doctor’s face when he said, ‘She is very sick and she could die. We want to get her help,’” said Kristen.

On Sept. 29, the day before her sixth birthday, Molly was flown to Children’s Hospital.

Dr. Peter Wearden, a pediatric heart surgeon, and his team came up with an aggressive strategy to keep Molly alive.

“Because she had such astronomically high blood pressure in her lungs, even higher than it was in the rest of her body, her right heart failed,” said Dr. Wearden. “We used a device called the Novalung. It’s basically an oxygenator that has a very low resistance and I was able to connect to her heart.”

“To hear that they’re doing something that hasn’t really been done before was scary, but I had no other options,” said Kristen. “I wanted Molly to be with us still, and that she was given a chance.”

Molly is only the second child in the United States to receive this artificial lung.

“It served twp purposes. One, it replaced her lungs. It was able to do all the gas exchange her lungs would normally do,” said Dr. Wearden. “The other thing was, it lowered the blood pressure the heart was pumping against, so it allowed her heart to recover.”

“It wasn’t easy for them to get the artificial lung,” added Kristen. “They fought to get that for her, and they made it work. They made it happen. I don’t think that could haven’t been done anywhere else.”

After 25 days, the Novalung was removed. Amazingly, for the last two months, Molly has remained stable and is getting stronger every day.

“My husband and I say that children’s hospital saved her life,” said Kristen. “I don’t think there’s enough words to say to them to thank them. How do thank them enough for saving your child.”

Dr. Wearden says Molly will always need treatment for the high blood pressure of her lungs and stay on that for life. Really, time is the medicine for the brain injury, a lot of attention and physical therapy.