Jennica Clasby says her daughter was only 3 years old when she first complained that her heart hurt.

It was a strange thing to hear from a toddler, but decided to take her daughter Brooklyn to the hospital anyway. After listening to her heart, doctors immediately sent Brooklyn for an echo-cardiogram and within hours she was rushed to a children's hospital in Denver more than 100 miles from their home in Pueblo.

“Here we thought we had a healthy 3 year old at that point and the next she really had to fight for her life,” said Jennica.

Doctors discovered that Brooklyn's heart was failing and she was diagnosed with pulmonary hypertension. The disease affects the way blood is pumped out of the heart and through the lungs.

In a healthy body, blood is pumped from the right side of the heart to the lungs. Then that oxygen rich blood returns to the left side of the heart where it is pumped around the body. The arteries in Brooklyn's lungs are constricted leaving one side of her heart working harder than the other, which can lead to heart failure.

Medications can help but so does location.

“Her doctor at that point said, you know I really think you should look at moving to sea level,” said Jennica.

Brooklyn's family began to look for a new home and settled on Western Washington, where the low elevation makes the air richer in oxygen, taking pressure off her heart. Their new home put the family close to Seattle Children's, a hospital capable of treating Brooklyn where she was placed under the care of Dr. Delphine Yung.

“She did get a little bit better. We adjusted her medications, and she did well for a couple of years, and then she started to get worse again. The pressures were going up; heart failure was coming back,” said Yung.

Desperate to save Brooklyn's life, her doctor talked about the possibility of a lung transplant. It was a risky option with a low success rate.

But that's when Yung found an alternative, a surgery only performed a handful of times. Yung had been following research from France where doctors had re-created an old surgery technique called the Potts shunt. The surgery dating back to the 1940s and connects the aorta to the pulmonary artery and was developed for kids who didn't have enough pulmonary blood flow.

Dr. Jonathan Chen, Chief of Pediatric Cardiovascular Surgery at Seattle Children's, explains how this old technique had a new twist.

“The idea of these surgeons was to use the Potts Shunt for the reverse problem when the pressure is too high in the pulmonary arteries and the shunt can off load that into the aorta,” said Chen. The idea of the shunt is to divert de-oxygenated blood down the descending aorta so that the heart doesn't have to work as hard.

On September 11, 2014, Brooklyn went into surgery, a day Brooklyn remembers well.

“I was really nervous and then after I remember I wouldn't smile for any pictures until my nurse took me outside for a walk. She took me outside and that’s the first time that I smiled,” said Brooklyn.

As her condition began to improve, Brooklyn passed another big milestone: her intravenous or IV line surgically implanted in her since she was three to deliver medication was removed. That meant for the first time in years, Brooklyn could take a bath without worry or even better jump in a pool. She says her doctors and nurses threw her a party.

“They brought me in presents and it was like swimming suits and goggles and underwater toys and then after that, me, my nurse, my doctor, and my parents all went swimming in the hospital swimming pool,” said Brooklyn.

Fast forward three years and Brooklyn has no problem keeping up with friends now. In fact, her mom says she can't slow her daughter down.

“You would never know that she has this really rare disease, I think she looks like any other healthy 10-year-old,” said Jennica.

Brooklyn's doctors say while Brooklyn still struggles for air that her body will adapt to lower oxygen levels. Because this new version of the old surgery has only been around for a few years, doctors don't have any evidence on longevity but say in theory the shunt will continue to work as she grows