BRONX, N.Y. (CBS 2) – They call him Ironman.

But he’s not Robert Downey, Jr. and he’s not on the big screen.

He’s a 7-year-old boy from the Bronx who just underwent a heart transplant last week, CBS 2’s Cindy Hsu reports.

“He’s got a little black thing on his chest and his rockets,” Jayson Mejias said, describing the super hero he’s been nicknamed after.

Mejias was a perfectly healthy little boy up until a few months ago when he was sacked with low energy and an unusual swelling near the eye.

“Basically, Jayson was a very hyper kid and then all of a sudden he was very low on energy, sleeping a lot, not eating very well,” his mother Anlu Gautreau said.

His mother brought him to the Children’s Hospital at Monterfiore where he was put on a five month waiting list for a heart. While he waited, doctors hooked him up to what’s called a Berlin Heart. With all the tubes and apparatus, he received the nickname Ironman.

Dr. Jacqueline Lamour said diagnosing heart failure in children is initially very difficult.

“Most children will present with cough and be treated for viral infections or pneumonia,” Dr. Lamour said.

Doctors don’t know what caused his heart to give out, but his parents said they’re just thankful their little Ironman is getting stronger.

“I just wanted to thank the donor family for the precious gift. I’m very grateful. My family’s very grateful. And my son now is able to be a normal boy because of them,” Gautreau said.

The little boy, who said he’s actually most like Captain America, wants to be a police officer when he grows up.

Doctors said Mejias will be released from the hospital next week and be back to school within two months.

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