Each child had already undergone at least three open-heart surgeries.

They’d endured countless hours in doctors’ offices and hospitals after being born with a serious heart condition.

But this fall the kids tried a new, very different tactic to boost their wellness: They joined a choir. Fourteen children from ages 8 to 16 with a condition called single ventricle circulation, or “Fontan” circulation, met once a week for two months to learn singing and breathing techniques and practice songs for a winter concert at Northwestern University. Researchers at Lurie Children’s Hospital and Northwestern’s Bienen School of Music created the group to assess the health benefits of singing in a choir for children living with the heart condition.

Children with Fontan circulation are born missing a chamber of the heart that normally pumps blood to the lungs. In the past, such children often didn’t live long past birth. Now, doctors can treat it by performing a series of surgeries — the first of which takes place just weeks after birth and the last of which, the Fontan operation, is often performed before kindergarten.

Though the surgeries save the children’s lives, the patients still may need heart transplants as adults. As kids, they often face limitations such as shortness of breath, reduced endurance and other potential complications.

Researchers wondered if they could ease some of those symptoms — and improve the kids’ wellbeing — by teaching them breathing and singing techniques as part of a choir.

“Singing has been shown to be of value in adults with COPD, asthma and some children with cystic fibrosis, but it’s never been employed in children with heart disease, particularly this single ventricle form of heart disease, which is the group of patients most likely to benefit from this,” said Dr. Andrew Pelech, a professor of pediatrics and pediatric cardiologist at Lurie and the principal investigator on the project.

“We’re hoping to improve their exercise capacity, their confidence,” Pelech said.

For eight weeks, the children worked with instructors and singing coaches from the Northwestern music school. Before the lessons started, researchers evaluated the kids’ breathing mechanics, conducted exercise assessments and asked them to fill out wellness questionnaires. At the end of the eight weeks, they repeated the testing.

Pelech said he and others are still evaluating the results to see whether the experience improved their cardiorespiratory health. If it did improve their health, it’s possible that similar programs might be adopted by hospitals across the country.

But even without official results, some of the social and emotional effects were clear, said those who ran the study and participated in it.

“There were a lot of quiet voices in the beginning, and there were a lot of loud, self-confident voices in the end,” said Michelle Steltzer, a pediatric nurse practitioner at Lurie Children’s Heart Center who focuses on single ventricle care and helped organize and facilitate the group.

“Most of these kids had never met another individual with Fontan physiology. Bringing these 14 kids together and seeing somebody like them, that is really a powerful connection that you can’t really … quantify the value of,” said Steltzer, whose older brother had the condition.

Livia Legg of Libertyville said her son Aiden Legg’s confidence grew as the weeks passed and he learned more about breathing and singing techniques.

Before the experience, Aiden Legg, 12, had never expressed much interest in singing. But soon, he was volunteering to lead songs, his mom said. Aiden’s 17-year-old sister Ava Legg looked over at him in church one day, after the study had started, and noticed him doing something he’d never done before: singing along.

“We had never heard his singing voice until the study,” Livia Legg said.

The study also gave him a sense of community, his mom said.

“I met a lot of new people with the same condition as mine,” Aiden Legg said, noting that he came to enjoy singing. “It felt pretty good. It felt like I wasn’t alone with my heart condition anymore.”

The sessions culminated in a concert in early December at the Ryan Center for the Musical Arts at Northwestern — the same lakefront building where the kids had been practicing for two months. The researchers wanted to conduct the study away from the hospital and medical buildings to give the kids a different experience, said Sarah Bartolome, an associate professor of music education at Northwestern and a principal investigator on the study.

In front of family, friends and those who had helped run the study, the children performed a gospel song, a tongue twister, the song “Lovely Day,” and “This is Me” from “The Greatest Showman.”

They also sang Bruno Mars’ “Count on Me.”

“If you ever find yourself stuck in the middle of the sea, I’ll sail the world to find you,” they chorused. “If you ever find yourself lost in the dark and you can’t see, I’ll be the light to guide you. We find out what we’re made of when we are called to help our friends in need.”

The song captured the spirit of the group, Bartolome said.

“These families have all endured some form of medical trauma,” Bartolome said. “They have a shared lived experience of that, so I think (it’s) the idea of count of me, we’re a community, I’m here for you and you’re here for me and we can count on each other.”

Mary Nomellini of Winnetka said it was “healing” to watch her 13-year-old daughter, also named Mary, perform with a group of children who’d faced similar challenges.

Jennifer Weil of Hinsdale said it was tough not to cry as she watched her 11-year-old daughter Alex Weil sing with the other kids.

“They looked so proud of the work that they had done, and I think for them to see a huge audience of people clapping and cheering and supporting them was, I think at least for me and Alex, a really huge validation as to how important these kids are,” Weil said.

The Weils wanted to participate because their family has benefited from decades of research, and joining the study seemed like a good way to give back, Jennifer Weil said.

Plus, Alex Weil had always enjoyed singing, and she liked the idea of singing with kids who all had similar experiences.

“I loved getting to meet kids that were just like me, and I think it was an amazing experience,” Alex Weil said. “Even though we all came from different places and were all completely different, we all had one thing in common, and we all were connected.”