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YPSILANTI, Mich.- Stan Larkin was diagnosed with arrhythmogenic right ventricular dysplasia (ARVD), which causes irregular heartbeats and puts the patient at a highly increased risk of cardiac arrest, at the age of 16 after he collapsed during a basketball game.

Doctors installed a defibrillator in Larkin’s chest to regulate his abnormal heartbeat.

After several years with the device and avoiding any strenuous activity, his condition worsened, spreading to both sides of the heart.

It became clear Larkin would need a heart transplant.

Having an o-positive blood type, the most common, put Larkin behind hundreds on the transplant list. Doctors said he wouldn’t survive long enough for his name to be chosen.

That’s when Jonathan Haft, a cardiac surgeon at the University of Michigan Hospital, suggested that maybe Stan Larkin could live without a heart entirely.

A human heart, anyway.

On Nov. 7, 2014, they hooked him up to a massive 418-pound machine that’s meant as a stopgap for patients waiting for a transplant. This means it pumped air into valves in his chest that replaced the ventricles.

This machine kept him in the hospital, completely bedridden, but alive.

Christmas of 2014 Larkin received a recently approved technology. It was a portable version of the massive machine that had been keeping him alive.

The portable device is called a SynCardia Freedom Total Artificial Heart, which Larkin carried in a book bag on his back.

Life wasn’t totally normal with the device, but he could leave the hospital, and he even played in some basketball games.

Larkin finally received a heart transplant last month.

He had lived for 555 days without a human heart.