TODDLER Isaiah Germann loves to pretend he's the Incredible Hulk but, as he lies on an operating table, his life in a surgeon's hands, he looks anything but.
The two-year-old lives on half a heart.
He was born with just one working ventricle, or pumping chamber, rather than the usual two.
His mother Karen Rupapera, 33, says her youngest son's heart defect has not stopped him from playing super heroes like other little boys.
"He's got such a big personality," the mother of two boys says.
"He's into Hulk at the moment. He'll take his shirt off in the lounge room and just wear his shorts and he'll be running around saying 'Hulk smash'."
The Incredible Hulk is nowhere to be found on this day at the Lady Cilento Children's Hospital in Brisbane as Isaiah, weighing just over 12kg, has surgery on his tiny heart, about the size of a plum.
But Superman's here, standing right beside the little boy throughout the open-heart surgery.
That's the name Miss Rupapera has given cardiac surgeon Nelson Alphonso, the man who has operated on Isaiah's heart four times since birth, keeping her little "lionheart" alive.
Normal hearts have two pumping chambers. The right ventricle pumps "blue blood" - oxygen depleted blood - to the lungs to be replenished with oxygen.
Oxygen-rich "red blood" then travels to the left ventricle, which is responsible for pumping it around the body.
The blood returns to the right side of the heart, starting the process all over again.
Collectively, Isaiah's operations have reconfigured his heart and circulatory system so the fully formed right pumping chamber takes over the work of the underdeveloped left ventricle.
In what amounts to changing the body's plumbing, large veins are disconnected from the heart and connected to arteries that supply blood to the lungs.
This allows oxygen-starved blood to go directly to the lungs rather than returning to the right side of the heart.
Isaiah had his first operation at six days old, a day that remains etched in the memory of both his parents.
Dad Josh Germann, 35, says Isaiah's heart stopped soon after the operation as he held his baby's hand. Doctors had to resuscitate his son.
"The machines went off," Miss Rupapera recalls.
"I just walked out. I sat outside for 15 minutes. I came back in and it was fine. Josh was standing there and he was white as a ghost."
Miss Rupapera was unable to hide her tears as she handed Isaiah to his dad for the short walk into theatre last week for his latest surgery.
Mr Germann held Isaiah as he was sedated, needing tissues himself as he left his son in the hands of the medical team.
Doctors first identified problems with Isaiah's heart when he was still in the womb.
His Gold Coast-based parents were given the opportunity to terminate, but declined. It was not an option they were prepared to take.
When Isaiah was born, he was diagnosed as having an "unbalanced atrioventricular septal defect, with co-arctation of the aorta, hypoplastic aortic arch and a small left ventricle".
Miss Rupapera rattles off the words by rote.
"Basically, he functions on half a heart," she explains.
Without complex surgery, he would have died before his first birthday.
With it, he has a chance at a longer life, although his future is unknown.
He may still need a heart transplant one day.
"So many kids like him die but you just don't know," Miss Rupapera says.
"You just have to think positive, just give him a good life, take each day as it comes.
"We don't wrap him up in cotton wool too much. We let him be a kid because if something happened tomorrow, we want to know that he's had a good life and good memories.
"Research is everything. At the moment, the statistics are that there's a possibility we will outlive him. But who knows in 10 years' time what they'll be able to do?"
Watching him run around the hospital before his latest surgery, it's hard to believe Isaiah has serious health issues.
But as he climbs into his mother's arms, she points out the blue tinge to his lips and on the tips of his fingers and toes - evidence of sub-optimal oxygen levels in his blood.
Although he won't turn three for another three months, he understands he has a "broken heart".
"Last night I lay in bed with him and I said: 'You've got to go to hospital tomorrow'," Miss Rupapera says.
"He was like: 'The doctors are going to fix my heart'."
Dr Alphonso, aka Superman, says about 350 to 400 heart operations are performed at the Lady Cilento Children's Hospital annually.
Only about 20 to 30 of the operations are carried out on children, such as Isaiah, born with a single working ventricle.
He says more than 80 per cent of children who have similar surgery to Isaiah live at least to their 20s. Reliable statistics beyond that are not available.
"You'll find a lot of videos on YouTube of people with half a heart who lead a full life," Dr Alphonso says.
"It doesn't necessarily mean that you have to live half a life just because you've got half a heart. Plenty of people do skydiving, for instance."
A week after surgery, Isaiah remains in hospital but his mother points out his beautifully pink lips and finger tips.
"He's doing really well," she says.
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