Some high school students feel like they lug their backpacks around everywhere. Stan Larkin actually did, but stuffed inside wasn’t a slew of textbooks — it was his heart.

Twenty-five-year-old Larkin lived for 555 days without a human heart in his chest. Instead, a device called a SynCardia Freedom Total Artificial Heart, which he carried in that book bag, allowed him to lead a normal life. He even played pickup basketball, hauling his 13.5-pound artificial heart around the court with him.

Last month, he finally received the heart transplant he’d been waiting on. Now, after nine years of his life hanging in the balance, he’s finally finished recovery, according to Tech Times.

When Larkin was 16 years old, he was playing basketball near his home in Ypsilanti, Mich., when he suddenly collapsed on the court. Doctors diagnosed him with arrhythmogenic right ventricular dysplasia, also known as ARVD, which causes irregular heartbeats and presents immediate risk of sudden cardiac arrest, particularly in athletes. So they installed a defibrillator — a small device that uses electric charges to fix the abnormal heartbeats so long as the patient curbs strenuous activity, such as pickup basketball — in Larkin’s chest.

It worked for a while, but after several years void of sports, it became clear Larkin would require a heart transplant. Defibrillators can suffice when one side of the heart is failing, but Larkin’s ARVD had progressed to bi-ventricular dysplasia, which means both his heart’s ventricles, the part of the organ responsible for pumping blood out of the heart, were increasingly unable to perform their function.

The defibrillator simply wasn’t strong enough, nor was Larkin’s heart. This wasn’t good news — Larkin, whose blood type is O-positive, i.e. the most common, was behind hundreds of others waiting on a new heart.

The young father of three was going to die.

“My heart kept getting weaker and weaker,” Larkin told the Ann Arbor News. “I was waiting on a heart transplant, but doctors said I wouldn’t make it to transplant.”

Jonathan Haft, a cardiac surgeon at the University of Michigan Hospital thought there might be one more option — maybe Larkin could live for a while without a heart entirely, at least without an entirely human one.

Michigan man, Stan Larkin, survived on an artificial heart for 18 months before undergoing a successful heart transplant in May 2016. (Reuters)

On Nov. 7, 2014, they hooked him up to “Big Blue,” a blue and massive 418-pound machine that’s meant as a stopgap for patients waiting for a transplant. To put it in extreme layman’s terms, it’s a self-regulating air pump. It works by pumping compressed air through two tubes that are attached to two cone-like valves that completely replace both ventricles. The hefty machine regulates this airflow. The downside is that “Big Blue” is the size of a washing machine, so patients such as Larkin are essentially bedridden in the hospital where the machine resides.

He was alive, but he wasn’t living.

Until Christmas of 2014.

In June of that year, the FDA had approved a portable version of “Big Blue.” Also made by SynCardia Systems Inc., the device called the Freedom portable driver is a far cry from its elder brother. For one thing, it only weighs 13.5 pounds, making it more than 400 pounds lighter than Big Blue while performing the exact same function, according to a press release from the University of Michigan Health System.

It can be plugged into a wall outlet or even a car jack, but it also comes with two batteries so patients aren’t chained to one place. In fact, it fits snugly into a SynCardia-made backpack or shoulder bag and comes equipped with a display panel showing that patient’s beats per minute, fill volume and cardiac output.

“Now that he has this artificial heart, and his circulation is maintained with this mechanical pump, he is otherwise completely healthy,” Haft told the Ann Arbor News in January 2015. “He’s very active, very functional, and I expect that over time he’s going to get stronger and stronger.”

“It was kind of stressful at the beginning, because I had to get used to the noise. It was a lot of noise 24/7, the heartbeat,” Larkin told CTV on Thursday. “As I got used to the noise, I could finally go to sleep. After that, I had to get used to carrying three extra bags with me, everywhere I went. I had to have all this stuff every time I moved.”

He couldn’t hold his daughters, nor could he relax in a normal shower — instead, he was forced to take extremely careful baths, due to the electrical nature of, well, his heart. But he could leave the hospital, and he even played in some basketball games. When he finally received his heart transplant last month, he had lived for 555 days without a human heart.

“I enjoyed the backpack,” he said at a news conference in late May after receiving his new heart via transplant. “It brought my life back.”

At the same conference, Haft joked, “He just really thrived on the device. In fact, the device, the Freedom driver, I think had to be exchanged about 10 times while he was at home, because this thing wasn’t built for pickup basketball.”

While Larkin’s story ended happily, it doesn’t for everyone with ARVD. It’s a genetic disorder, and quickly after Larkin was diagnosed, so was his younger brother Domonique. He also used the Freedom portable device, albeit for a much shorter time — only four days — before receiving a transplant. Like his older brother, Domonique also had three children, but lost two — at least one to ARVD.

Reflecting on his children, his own life and his older brother’s struggles, Domonique told Ann Arbor News, “Obstacles come along in life, but it’s best to stay positive and don’t give up. When you’re in a fight like this, that’s the best thing you can do. Always be thankful and blessed to have the life you live. Don’t take the little things for granted.”

As for Larkin, he’s ready to get back to playing basketball with his new, transplanted human heart.

“I’ll probably run a few pickup games, but not right away,” he said. “I haven’t taken a shot yet without the backpack hooked up. I just want to put the heart to use.”