Cameron Bartle was born with half a heart, sitting back to front inside his little chest.
But the Hawke's Bay boy has battled back from four open-heart surgeries - and is looking forward to a fourth birthday his parents feared he would never see.
Cameron first went under the knife five days after his birth on August 22, 2012.
His parents - Rachael and Nick Bartle - were told of the heart problems at Rachael's 19-week antenatal scan.
Further tests revealed the baby boy had an extremely rare heart condition. "In layman's terms, half a heart. Our world just fell apart," his mother told the Herald.
The parents, who had already lost their first-born son, Jamie, as a result of an unexpected complication at birth, were given three possible scenarios: to terminate, to continue but let nature take its course, or to do all they could.
"There was never an option to not continue," said Rachael Bartle.
Cameron was born with hypoplastic right heart syndrome.
About five children a year in New Zealand suffer the condition, but Cameron had complicating factors - his surgeon said it was the only kind she had dealt with in more than 20 years.
The family spent the first nine weeks of Cameron's life in hospital, staying a large portion of that time in the paediatric intensive care unit and the cardiac ward.
"After he was born I didn't get to even hold him till the night before his surgery and it was only really quick because of all the wires," Bartle said.
Cameron had his second surgery at just 15 weeks.
At 3 years and 3 months, he had his third and what was meant to be his last surgery.
However, a complication meant he needed a fourth surgery just days later.
"We got a call in the middle of the night, which was also the anniversary of our first son's death, to say he was in complete renal failure and was quickly going downhill," Bartle said.
"It was super scary."
But after 21 days in the paediatric intensive care unit and four weeks in the heart ward, the family was discharged - just in time for Christmas 2015.
Kirsten Finucane, Director of Paediatric and Congenital Cardiac Surgery at Starship Hospital, said the preschooler had a bit of a "stormy time" getting through his final operation, but was now doing well.
"He now has much better oxygen levels in his blood and this will help his exercise tolerance and his learning capacity as he gets ready to go to school."
It's hoped, barring any unexpected complications, Cameron won't need any more surgery until his mid-20s.
Bartle said she noticed a definite improvement in the past months.
"If you saw him he's just a normal almost four-year-old running around, causing havoc," she said.
"He's quite proud, he's very brave. He tells people, 'I'm a heart-kid, what's your super power?'"
The Bartle family - including Cameron's older brother, Cory - returned to Auckland this weekend to make a guest appearance at a Friends of Starship fundraising event.
Cameron's parents shared their story to about 350 guests at yesterday's Diamonds & Stars Tea Party at The Langham Hotel, which aimed to raise more than $100,000 for Starship's Heart Ward, New Zealand's only national paediatric congenital cardiac service.
Bartle said without the medical expertise at Starship, their cherished boy wouldn't be alive.
"They've been so incredible, without them and all their incredible teams Cameron wouldn't be here," she said.
• To donate to the Starship Foundation, visit: starship.org.nz/donate