Around 18 months ago the Sydneysider was so desperately unwell that she was on life support in The Children's Hospital at Westmead.

Her enlarged heart had gone into cardiac arrest twice and doctors told her parents that she had just 14 days left.

That was all, just two weeks for a heart to be found. And if one wasn't found, they would recommend turning off the machines that were keeping the then 13-year-old alive.

"We're not overly religious," Scarlett's mother Amanda Kercher-Hack said. "But I just prayed to her guardian angels and I prayed to Saint Mary MacKillop."

Along with her husband Philip Hack and their younger daughter Harper, then aged 10, they prayed. They asked their friends to pray, and word spread and soon they heard that nuns in Italy were also praying for Scarlett.

Mr Hack told his brother - curator, creative director and co-founder of Dazed, Jefferson Hack - about his daughter's fight for survival.

At the time Jefferson just happened to be on holidays with Bono on the private island of Mustique in the Caribbean. Jefferson told Bono, and the lead singer of U2 then sent a personal message to Amanda and Philip telling them he'd be praying for Scarlett.

Australia's consent rate for deceased organ donors is 56 per cent in 2021, and that resulted in consent being given for 421 people following their death.

Scarlett's parents knew their daughter's chances of getting a heart within such a short time frame were remote.

Amanda and Philip first realised something was wrong when Scarlett was 10 years old after she complained of heart palpitations and had difficulty exercising.

She was eventually diagnosed with hypertrophic cardiomyopathy which causes the walls of the heart chamber to thicken. They can become stiff and this reduces the amount of blood taken in and pumped out to the body.

"There is no cure, I suggest you learn CPR."

Those words from Scarlett's paediatric cardiologist left Amanda in shock.

"I didn't even take my husband to the appointment because I didn't think it was going to be anything serious," she said. "I drove home, but I don't remember how I got home."

Scarlett saw specialist after specialist and for the next three years she was well, but at 13 years of age she collapsed in the middle of dance classes when her heart stopped beating.

She had a defibrillator put in, but following a number of fainting episodes her doctors called her in for a stress test. But, she never made it.

"She was on the ward at Westmead and she had all the cardiologists around her and she went into cardiac arrest in front of them all," Amanda said.

Philip was by his daughter's side at the time and watched in terror as she was wheeled away while doctors gave her CPR.

"It was horrific," Amanda said. "While they were wheeling her down, one of the doctors jumped on her bed and straddled Scarlett and was doing chest compressions on her.

"He [Philip] saw it all, he's very traumatised."

Scarlett survived and was put on a heart-lung bypass machine, it was just a few days before Christmas in December 2020.

Six or seven days later she had another cardiac arrest.

She survived again, but her cardiothoracic surgeons Dr Ian Nicholson and Dr Yishay Orr, who Amanda later credits with saving Scarlett's life, had a heartbreaking prognosis.

"He [Dr Nicholson] said you've got two options 'you can let her go, you can turn off [the machine] or we can try for a heart transplant'," Amanda said.

Scarlett was heavily sedated and unable to communicate when her doctors delivered the deadline to her shocked parents.

"They said 'we've got 14 days. If we don't get a heart in 14 days we're going to have to turn off the machine because she won't last beyond that'," Amanda said.

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Eight days later, at 2am, the call finally came through. There was a heart for Scarlett.

"We just hugged and cried and jumped around," Amanda said.

"You've never wanted a phone call more in your life," Amanda explains.

"But of course it's bittersweet because you know that the sheer relief that we've got a chance, means that someone else is having their worst day, and that's not lost on us."

In the 18 months since the transplant, Amanda has written numerous letters, via the Organ and Tissue Authority, to the family of the donor thanking them for giving her daughter a second chance at life.

And while Scarlett is an organ recipient, she's also an organ donor. Her original heart may have been faulty, but its valves were healthy, and they were donated to help save someone else's life.

Scarlett, who is now 15 years old, sat in on this interview with ACM. She's intelligent and thoughtful as she talks about what life is like now.

She has some health complications because she was so sick, but her second chance at life is not lost on her and she has great plans for the future.

"I want to do some travelling around Australia in a van," she said of when she finishes school. "Then I want to move to Canada and get a husky and live there in the woodland part of Canada."

"It's just a lovely place and also they've got free healthcare, and it's good security there, and their gun laws are very tight."

In hospital Scarlett learnt to crochet and has since set up her own Instagram page to sell her oh-so-cute crocheted animals. The sales are raising funds so her dog Scout can be trained to be her service dog. Visit her page at @crochet.cuties_ to check out what's on offer.

Even if you have registered to be an organ donor, families of potential donors are given the final say on whether their loved one's organs are donated.

"One in 10 families will say no," Amanda said. "You don't need your organs here, there's a famous quote 'don't take your organs with you heaven knows we need them here'."

Find out more and register to be a donor at www.donatelife.gov.au/register-donor-today.