He's up and walking just days after having a heart transplant at Morgan Stanley Children's Hospital.
"I'm here making sure my heart is gonna be ok when I leave," said Mordecai.
Now 7 years old, or 7 and a quarter as he likes to say, Mordecai was born with a condition that caused his heart to be enlarged, stiff and weak.
"I felt ok but every time I was running I had to run for a certain time and then stop to breathe," he adds.
Pediatric Cardiologist Dr. Linda Addonizio says Mordecai defied the odds but ultimately needed a new heart.
"The left ventricle is very, very large and it's barely moving, from the time he was born the question was if he was going to survive," said Dr. Linda Addonizio.
The morning of Valentine's Day, the phone rang.
"I had a gut feeling and it was them," said Grace Mendez, Mordecai's mother.
Mordecai had transplant surgery that afternoon and said it wasn't exactly a typical Valentine's Day.
"This time I got a new heart," he said.
But to him, the whole thing was really no big deal.
His new heart is snappy and strong. He'll have to be on medication for the rest of his life to prevent his body from rejecting the heart, but his doctor says now the sky's the limit.
And the survival rates for kids with heart transplants keep getting better and better.
There are children who have lived into their 20's, beyond that is unknown territory doctors have only been doing heart transplants in children since the 1980's.
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