Man lived without a heart for 555 days carrying around an artificial one in a backpack

A man who lived without a heart for 555 days was kept alive by the grey backpack he carried everywhere with him.

You'd often put a laptop or maybe a notebook in a backpack - but a replacement heart? Well, that's an interesting one.

While waiting for a human heart transplant, Stan Larkin lived over a year without the organ at all.

It certainly wasn't noticeable to passers-by either, as the Michigan resident very much appeared to be a typical young and healthy adult.

Stan Larkin lived 555 days without a heart. (CNN)

But a grey backpack Stan carried around everywhere, which may have looked so innocent, was actually keeping him alive.

Stan didn't let this slow him down, however, and enjoyed taking his three young children to the park, and even managed to play basketball with the backpack on.

Inside of the bag was the power source for an artificial heart pumping in his chest.

Stan's real heart was removed from his body in November 2014, subsequently being replaced by a device that meant he didn't have to stay in hospital while waiting for a transplant.

His heart transplant finally arrived in May 2016 and had the procedure done at the University of Michigan Frankel Cardiovascular Center.

"Most people would be scared to go so long with [an artificial heart], but I just want to tell them that you have to go through the fear, because it helps you,” he told CNN shortly after the operation.

"I’m going home so fast after the transplant because it helped me stay healthy before the transplant.”

He had to wait a while for a heart transplant. (Getty Stock Photo)

Unfortunately those waiting for a transplant make have to wait years for the necessary treatment, according to Dr. Billy Cohn, a cardiovascular surgeon.

“Many of these patients have hearts that are so weak, the kidneys, liver and other critical organs will fail while they are waiting,” he said.

"Many of these patients would die without some form of support."

Stan needed the transplant due to a genetic form of heart disease called familial cardiomyopathy.

The Michigan man didn't even realize that his heart was suffering until 2007, when he collapsed during a basketball game without warning.

Familial cardiomyopathy is 'a heart disorder characterized by a heart that is enlarged in diameter and weak in pumping function,' according to the Division of Cardiology.

Dr. Jonathan Haft, the surgeon who operated on Stan, said the type of cardiomyopathy seen in Stan causes arrhythmias and failure on both sides of the heart.