The 15-year-old baseball player stood on the pitcher's mound, with two players on base and a big hitter coming up to bat.

As he threw the baseball into his glove, thinking about his next pitch, everything went black as the electrical signals in his heart shorted out.

Genetic testing later revealed the boy - who survived - had a heart defect triggered by surges of adrenaline, recounted Dr. Joey Barnett, a scientist at Vanderbilt focused on pediatric heart disease, at a luncheon at Memorial Hospital on Monday. Barnett, whose research into pediatric heart disease is funded by the American Heart Association, was speaking at the heart association's research luncheon.

The boy's mother rushed to the field and administered CPR for 13 minutes before someone arrived with a defibrillator to shock his heart back into beating, Barnett said.

The story illustrates the crucial needs for earlier diagnosis of cardiovascular diseases in children before disaster strikes, and more research funding into cures, Barnett said.

Scientists and doctors have developed effective treatments for cardiovascular problems, such as implantable defibrillators, he said. The problem is figuring out who needs the $35,000 device before near-death experiences, he said.

"We need genetic tests to help us identify which children are at risks so that we can use this therapy we already have and get it to the people who need it the most," he said.

Cardiovascular disease, including congenital heart defects, is the second-leading killer of people under age 21, second only to accidents, Barnett said.

He hopes within his lifetime scientists will be able to grow an implantable heart valve from stem cells.

"We're not going to have a heart valve tomorrow but today, we can use genetic information to predict who's going to respond to a drug," he said.

Lori Hammon, clinical educator at Memorial, said the luncheon gave her high hopes for future treatments of heart disease, for both children and adults.

Her husband had a heart attack 15 years ago, and doctors discovered the left side of his heart wasn't working properly, she said. Ever since he's been living healthier and sticking to his medicine regimen in hopes that he might qualify for stem cell therapies that have yet to be developed, she said.

"You never know what's around the corner with scientific investigation," she said.