Jim Barnes/ Dallas Morning News

Andy Miller doesn't think there's anything he can't do.

"I'm going to play football," the Garland 7-year-old says.

That causes the head of his mother, Jodie, to slump.

"He's going to play football," she murmurs Jodie and her husband, Derek Miller, say one of the toughest parts about life since Andy's heart transplant surgery is letting their son live a normal childhood. And that will be even tougher this fall when Andy tries a new sport.

Almost three years ago, Andy Miller underwent transplant surgery. On Friday, he competed for the third straight year in the Texas Rangers Organ Donor Game outside Ameriquest Field in Arlington.

It was hard for the Millers to imagine Andy on a football or baseball field three years ago. An active sportsman up to that point, Andy suddenly started to become exhausted after a long run. Before long, he could hardly manage to stand and dribble a basketball.

Doctors discovered he had an enlarged heart, one almost the size of an adult's in a 4-year-old's chest. Medication could help him for a while, but the only long-term solution was a transplant.

He received his transplant on Dec. 26, 2001, after a grandmother donated the heart of her grandson, who had died with the rest of his family in a fire in Tennessee.

Within days, Andy wanted to run again.

The Organ Donor Game has become a Miller tradition. Two years ago, Andy stole the show from NBA center Greg Ostertag, who was involved with the game because he donated a kidney to his sister.

Andy charged in front of Ostertag to catch a fly ball. Ostertag, a Duncanville native, then asked Andy to run the bases for him during his next at-bat.

"When Andy came up to bat, Ostertag asked if he could run the bases for Andy," Derek Miller said. "Andy just looked at him and said, 'No.' He takes it all so seriously."

Though he will have to take medication for the rest of his life, the transplant will not place any restrictions on Andy. His parents have noticed that he has become more introverted. He once showed off the scar on his chest but has shied away from it in the last year, they said.

Derek Miller said he doesn't worry about Andy's health as much these days.

He's more concerned with Andy's baseball team.

"He's playing for the beloved Yankees," Derek said. "It's the Evil Empire."

A Rangers fan, Derek may not wear with pride his Yankees cap as the team's coach, but he said he is overjoyed to be spending time with his son on the diamond.

After the surgery, the Millers sent a paper heart to the grandmother, thanking her for donating her grandson's organs. Pam Silvestri of the Southwest Transplant Alliance told the Millers she received a response from the woman.

"She said she keeps the heart on her nightstand," Jodie Miller said. "Any time she wonders whether she did the right thing, she just takes a look at it and thinks about Andy."