Heart disease doesn't affect just the old. Jack Doherty, now 4, was in his mother's womb when an ultrasound revealed something might be wrong with his heart.

Two surgeries later, Jack is doing fine, and yesterday he participated in this year's American Heart Association Heart Walk — his third — to demonstrate that the $2.2 million raised will help people of all ages.

Jack didn't walk the entire 3.2 miles, however. He spent most of the walk in his comfortable stroller, where he could eye his medal and, when people with microphones got too loud, put his fingers in his ears.

He first covered his ears during the warm-ups, as an enthusiastic woman shouted commands to the crowd, which filled a good part of the west bleachers at Qwest Field. He kept them covered during the fireworks that signaled the start of the walk.

At yesterday's Seattle Heart Walk, one of several across the country, some 12,000 participants raised more money than at any other — except perhaps Detroit. At the walk's end yesterday, Seattle was still ahead, said JJ McKay, senior vice president of the American Heart Association. He said it will take days to tally the final figures.

Jack got out of his stroller briefly as he and his family headed north on the lower level of the Alaskan Way Viaduct, the first leg of the walk. But then he tripped and fell and ended up on Dad's shoulders.

Jack really had already done his part. He and his family, who live in Edmonds, raised nearly $8,000 in his honor to go to heart research and education.

After a third surgery scheduled for next spring, Jack's problem — a congenital defect in the right side of the heart — will be fixed. That likely will be the last operation he'll need, his parents said.

His doctors have redirected his blood past the right side of his heart straight to the pulmonary artery so it will get enough oxygen.

The Doherty family knows it was past research that allowed their son to live. Dan Doherty, Jack's father, said his aunt had a child who died at birth 50 years ago because he was a "blue baby" — a sign of unoxygenated blood.

Jack's whole family walked yesterday — dad Dan, mom Kathy, and sisters Taylor, 9, and Riley, 6.

They passed other families on the route, some with children who, like Jack, wore a red cap to signify they, too, are heart-disease survivors.

According to the American Heart Association, heart disease is the No. 2 cause of death for children younger than 15.

One group wore shirts with a smiling photo of Ryan King, who died at 16 while playing soccer, never knowing he had an enlarged heart.

Another group was the family of Garrett Hilyer, 5, from Anacortes. Garrett, like Jack, has had two heart surgeries.

They were among the youngest wearing the red hats of survival.

The oldest? McKay says there were several over 90.

Linda Shaw: 206-464-2359 or lshaw@seattletimes.com