The five-year-old “miracle” boy has already been left overjoyed at having an upcoming law named after him, which will send the number of life-saving organ transplants soaring in Northern Ireland.
Keeping a smile on the tough tyke’s face is his 19-day-old brother Cairbre Frances Mac Gabhann.
Born June 29, Cairbre is clear of the congenital cardiac condition that has nearly killed Dáithí – who had his first open-chest surgery at four days old.
He also has to swallow a cocktail of drugs to stay alive and ends up having to be wheeled in a pram when he loses energy as he languishes on the heart transplant waiting list.
His west Belfast parents, Máirtín Mac Gabhann (32) and Seph Ní Mhealláin (26), told the Sunday World they were petrified when doctors used a 20-week scan to check if unborn Cairbre would suffer the same incurable congenital heart defect that has repeatedly almost killed Dáithí.
Ballymurphy-born Irish language teacher Máirtín added: “As soon as I saw Dáithí’s condition on the list of anomalies being checked for, I s**t myself. It was so scary.
“The trauma kicked in and I was sweating buckets – it really frightened me.”
He said about relief washing over the family when the five-month anomaly ultrasound came back clear: “Thankfully it was all good. The new baby’s heart also did really well in a scan after he was born.
“He’s been fine, and his arrival is making Dáithí really happy.
“We’re at our caravan now on holiday after school stopped, and I’m watching Dáithí play, and he’s living life to the fullest, like he always does.”
Despite Cairbre’s arrival giving the family joy, there was a poignant side to his birth.
Máirtín and Seph found out they were expecting again weeks after Máirtín’s mum Frances Smith died aged 55 with kidney cancer.
The baby’s middle name is a tribute to her.
Máirtín added: “As well as losing a mother and nanny, we lost one of the biggest campaigners for our fight to raise awareness about organ donation.”
Dáithí was born on October 21, 2016 with hypoplastic left heart syndrome – a potentially killer defect that means only half the organ works.
His parents have made global headlines since they started their tireless campaign to raise organ donation awareness amid Dáithí’s health nightmare.
As a result of their battle – and their youngster’s death-defying courage and upbeat attitude – Dáithí’s Law will kick in from spring 2023.
It means all adults will be considered potential donors unless they opt out.
Health Minister Robin Swann announced earlier this year the name of the bill was in recognition the unrelenting commitment of Dáithí and his parents.
He added: “As a parent of a child with a congenital heart defect, I know only too well what drives them and what drove them to bring forward this legislation and the support that is necessary.”
Surgeons told Máirtín and Seph that Dáithí had a 10 per cent chance of survival after his first open-heart surgery.
When they asked if the couple wanted to pull the plug on their struggling son’s life support, Máirtín said the request prompted a “miracle moment like you would see in films”.
“As soon as the surgeon offered us the option of withdrawing life support, Dáithí opened his eyes,” he added.
“It’s what I call his ‘miracle moment’. He looked directly at the surgeon, who turned to me and said, ‘Your boy wants to live’.
“It didn’t increase his chances of survival any, but that was when we knew we had a fighter on our hands.”
Dáithí soon suffered a stroke, was stricken with a bowel condition and had more open-heart surgery at 10 days old.
After spending the first five months of his life in intensive care, he improved.
Just after he turned one, he was hit by flu and examinations showed a leaky heart valve ruled him out of more life-saving surgeries.
He has been on the heart transplant waiting list since, and to stay alive he has to take daily doses of a painkiller, heart medication and pills to make him go to the toilet.
Dáithí also recently beat Covid.
Even though Máirtín grew “distressed” watching his sports-obsessed lad grow lethargic as his oxygen levels plummeted, he knew he would pull through.
“Dáithí’s too much of a fighter to let something like that get him, after all he’s been through,” he said.
“I look at him and all I see is resilience – he’s just the strongest wee boy I know.
“With all the medication he’s on he probably feels like s**t every day, but he just gets up and gets on with it.”
Máirtín admitted he has had therapy to deal with the “phenomenal toll” on his mental health of seeing his boy struggle.
He added he tries “not to think about” how it will take the death of another child to save Dáithí’s life.
“That used to get me down, but I can’t control that,” he said.
“Organ donation is a very sensitive topic, and when we started the campaign I used to think about that.
“But people pass away every day, and some of those people are children, and there’s absolutely nothing I can do about that.
“Although it is very sad – and I don’t want anyone to die, and I don’t want any children to die – it has got absolutely nothing to do with me and my family.
“I had a consultant tell me, ‘Other kids dying has nothing to do with you or your family – you are just raising awareness of organ donation when it happens’.”
Dáithí is also asking difficult questions about his unrelenting health fight.
Máirtín said: “He lives a pretty normal life, but when he has to be put in the pram at school when his energy levels run low, he asks why, and his mates are wondering.
“He’s always asking when he will be able to take part in sport like them, and has to be told he’s in the pram because his energy levels aren’t the same.
“He knows what’s going on – he knows he needs a new heart and knows his heart is different and is special, but those things are heartbreaking to hear.
“It’s possible he may have to use a wheelchair when he gets older, but I hope not.
“Hopefully one day when he gets that new heart he’ll be able to do more.”
But Dáithí will have to get “sicker to get better”.
Máirtín said he isn’t top of the transplant list as he appears to be improving with his medication regime.
“Dáithí also asked me the other day if he gets a new heart will he be able to stop taking his medication, and I had to tell him, ‘No, it will be medication for the rest of your life’.
“If he was to get a new heart tomorrow, I would expect his quality of life to improve significantly.
“But there is a shortage of organs in the UK, and they are going to those who need it most – children dying in hospitals, and they will get one before him.
“The toll this takes on your mental health is phenomenal.
“No one day is the same – it is a rollercoaster: you have your up, down and around days.
“But we’re all in this together, and we’re keeping each other sane.
“Nobody in the family is the rock – we’re all the rock at different times.”