Now, he has one, and he could be back home in time for Christmas.

"He has so much energy now," his mother, Victoria Kenny, said.

"It's beautiful to watch him run from one side of the room to the other.

"Even just being able to pick him up again - without worrying about bumping cords or kinking cannula tubes - is so wonderful."

Jack was seven months old when he was diagnosed with dilated cardiomyopathy - a condition that leaves the heart's main pumping chamber enlarged and weakened.

But his condition had been successfully managed by medication until a bout of influenza "tipped him over the edge".

Jack was flown from John Hunter Children's Hospital to Sydney's Westmead, and then to the Royal Children's Hospital in Melbourne - home to the National Paediatric Heart Transplant Centre.

Ever since, Jack has had to live within a two-metre radius of a machine that kept his blood pumping via a "Berlin heart".

In that time, his baby sister - seven-month-old Chloe - was also born.

Being so far from home and their normal life, anxiously waiting for a perfect match, was tough.

Mrs Kenny said the first few weeks were an "emotional roller coaster".

"Initially they thought Jack's heart had shown signs of improvement, so they dangled the idea of possibly taking him off the Berlin heart," she said.

"The doctors thought we might be able to go back to managing him with medication.

"But after further investigation, it was a bit too complicated, and it would create too many uncertainties, so a transplant was still going to be the best option.

"We were a bit deflated after that. We had home in our sights, and we had an exit strategy, essentially.

"We were ... almost at breaking point. We couldn't get our heads around the fact we were back to that eternal waiting game - living this daily groundhog day with no end in sight."

But a week later, at 6am, the phone rang.

"I thought it was so strange the hospital was calling me at that time," Mrs Kenny said.

"Then I heard the head nurse of transplant's voice and she said, 'Hello Victoria, this is the call you've been waiting for. We have found a heart for Jack'.

"We got the call at 6am, he was in surgery by 8.30, and his new heart took its first beat at 1.15pm."

Jack had been "kicking goals" ever since.

"At first it was so surreal to see him without the pump. There was no noise in the room. He was just back to being Jack."

One by one, Jack shed the different cords, tubes and wires that had kept him going since his arrival at the hospital.

"He's Jack: Unleashed. And he's off," Mrs Kenny laughed.

Jack needed to stay in Melbourne after his release from hospital for follow-up appointments, and biopsies to ensure there are no signs of rejection.

"We are on track to be home by Christmas," Mrs Kenny said.

"The thought of that brings tears to my eyes. It's going to be a pretty special summer, I think.

"It's going to be so much fun watching him explore and reacquaint himself with the world. We have been in Melbourne for so long, but we haven't been able to do many things.

"We'd like to take him to the zoo to see his first actual giraffe. He will probably lose his mind. But even just to let him go down a slide again - those simple things you really take for granted until you can't do them any more."

Mrs Kenny said they would be eternally grateful to Jack's "guardian angel" - his heart donor.

Throughout this journey, the family have been torn between desperation and despair, knowing their gain would be someone else's loss.

"The fact that in their hardest hour they thought of another family's future... It is just the most beautiful and selfless gift that anyone can give, really," Mrs Kenny said.

"We have a chance to write them a letter in about a year's time to say thank you. Obviously there is no obligation for them to reply, but it is something we really want to do.

"We will think of them every day."

Mrs Kenny urged people to talk to their loved ones about organ donation.

"Something we have become quite aware of is that even if you are an organ donor, your family has the ability to override that at the final moment. You need to make sure you have spoken to them specifically about your wishes," she said.

"When you think about organ donation, you never really think about kids, the thought of a child needing an organ is painful to think about.

"But these kids don't have a choice but to wait for a second chance at life.

"I'm going to do my darndest to advocate for an opt-out registry so we can help end the wait."

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