When Jim and Rena Knarr's son Trevor was born, they were overjoyed.

But three weeks later, they received a phone call from a cardiologist, who left a chilling voicemail: Trevor had a heart condition that should have been diagnosed at birth.

"You've got to get him to (Penn State Hershey Children's Hospital)," Rena recalled the doctor saying. "He was missed."

The news was hard for the Knarrs, who live in Newberry Township.

"It's very difficult to take," Jim said. "It's very rough as a parent."

"It just felt like somebody punched you in the stomach," Rena added.

Now their 8-year-old son needs a second heart operation, which has spurred the family to raise money and walk in the second annual Congenital Heart Walk, set for Saturday in Hershey.

Rena Knarr said they want to give back so that no parent has to receive the same phone call.

"I don't want another mom or dad to go through what we went through," she said.

Trevor's heart: Trevor is now in second grade at Commonwealth Connections Academy, a cyber school based out of Harrisburg. He looks like a regular kid and loves to be active, but he's limited to two non-contact sports: swimming and baseball.

That's because he has a heart condition called aortic stenosis.

Trevor has a bicuspid aortic valve, which means his valve has two flaps instead of three, and the stenosis causes his valve not to open fully, decreasing blood flow from the heart. That means his heart has to work harder to pump blood through his body.

When he was 3 years old, he had open heart surgery, and doctors cut out a membrane to make an opening in his valve, Rena Knarr said. The surgery took five hours, she said.

Next round: Although doctors didn't anticipate that Trevor would need another surgery, the membrane they removed has grown back, she said.

Now Trevor is due for his second open heart surgery in June.

When his parents got the news, Trevor said, "That's not bad news — that's good news," Knarr recalled. Her son said the surgery will make him better.

"He has this attitude that's really good," she said. "He's taking it better than I am."

During this procedure, doctors plan to be more aggressive than when Trevor was 3, Knarr said. They will cut more of the heart muscle away to try and permanently rid his heart of the membrane growth, she said.

Trevor's older brother, Jacob, who turns 16 in May, will undergo compatibility testing in the hopes of donating blood to him during the surgery, Knarr said.

The walk: The Congenital Heart Walk is a national event that takes place in 30 different communities across the country.

Money raised at this year's walk in Hershey will benefit both the Adult Congenital Heart Association and The Children's Heart Foundation.

The Knarrs will be participating in the Hershey walk for the first time. They initially set a fundraising goal of $100 but have raised about $1,600 for the team so far, Knarr said.

The Knarrs had kind words for Penn State Hershey Children's Hospital, which is a teaching hospital. Knarr said during Trevor's stay, all the residents loved him because he'd let them listen to his heart.

"This is the year that we decided we'd like to give back," she said.

As for Trevor, he said he's excited to walk with at least a dozen family members for a good cause.

"I feel great when I help other people," he said.

— Reach Mollie Durkin at mdurkin@yorkdispatch.com.