Beaming Kit Matthews has every reason to smile after getting a new heart, 15 years after his dad had the same life-saving transplant.
The four-year-old was close to death when he got the new organ last month.
He and dad Joe, 34, both had enlarged hearts. Joe said: “Kit looks the picture of health and is doing so well.
“We are so thrilled. To be given this amazing gift has been the best thing we could ever have hoped for. We just can’t thank the family of his donor enough, for being brave enough to donate their loved one’s organ.
“It has given Kit a new chance at life and we will never forget that.”
Kit was surviving on a mechanical Berlin heart machine, which pumps blood around the body, when a donor was found after an agonising wait.
Dad Joe, of Retford, Notts, knew exactly what his son was going through. The Sunday Mirror first revealed Kit and Joe’s story in May.
Joe was studying in California in 2006 when he began suffering breathlessness. His heart was slowing to nothing so Joe had a defibrillator fitted, but it failed.
During the operation to restart it, his heart stopped for five minutes and he was declared clinically dead but a transplant saved his life.
Doctors told Joe to take it easy but the adrenalin junkie ran a first marathon a year later, competed in the World Transplant Games in Australia in 2009 and is Britain’s fastest man on his second heart, completing the 100m in 11.40 seconds.
Joe added: “I’m an example of how good life can be after receiving the most amazing gift.
“What’s the point of being given a second chance if you don’t make the most of it?”
Kit and brother Monty, two, will be tested to see if the heart problem is a genetic or a devastating coincidence.
Joe went on: “It was a million to one chance when it happened to me all those years ago. I had never imagined that it would happen to Kit too. I was devastated.”
Kit’s condition emerged after Joe’s wife Hannah, 32, took him to hospital in April after he went off food and had no energy.
He was transferred from Doncaster to Newcastle’s Freeman Hospital where he spent nearly four months until a donor heart was found.
In the UK, all adults have to opt out of organ donation following the introduction of Max and Keira’s Law.
The regulations are named after Max Johnson, 12, who campaigned with the Mirror to change the law, and his heart donor Keira Ball, who died aged nine.
But the rules do not apply to under-18s and parents still have to give permission for their child’s organs to be used.
Joe, a traffic manager supervisor, said: “It’s such a tremendous gift and we know another family had to lose their child for ours to live.
“I have one heart hero to thank for my transplant – and now a second for my son’s.”