Woody Luke Duff was diagnosed with a small hole in his heart 32 weeks into mother Elaine's pregnancy when his parents decided to have a 3D scan, and the operation was carried out when he was six months old.
Duff, now an ambassador for Heart Children Ireland, admitted he broke down when he and his wife were told the news by doctors.
He told the Irish Independent: "We weren't even supposed to have it, we just decided to go in and get one of those 3D scans just to get a photo of him. It was a bizarre day, an upsetting day."
The couple were informed that one per cent of children did not survive surgery, but Woody, who was operated upon at Great Ormond Street Hospital in London, did pull through after a four-hour procedure.
Duff said: "No doubt the longest four hours of my life. We brought him up to the anaesthetic room. He wanted to be in our arms. You more or less have your son in a headlock as you see him drift off.
"That was possibly the hardest thing I'll ever have to do, myself and my wife.
"You think it's nothing, four hours, but it was the longest time in my life because you convince yourself he's not going to come out."
Woody has made a full recovery and could yet follow his father into football.
Duff said: "He's fully fit. I'm trying to get him kicking balls already. If he doesn't want to kick a ball at all, I'll forgive him."