It took a few days for 24-year-old Stan Larkin to get used to the sound of his new heartbeat, but now he barely even notices it.

The pumping sounds similar to a horse's quick gallop across a cold, hard trail, and can be heard from several feet away. He gets questions about it on a regular basis, and each time he calmly answers.

"It's called a Freedom driver. My heart was too weak to pump blood through my body so I got a Total Artificial Heart and the driver pumps the blood," he explained.

Stan, of Ypsilanti, wears the 13.5-pound Freedom portable driver in a backpack and hauls it around with him 24 hours a day, seven days a week. The backpack is literally what keeps Stan alive.

Stan's condition

During a game of basketball eight years ago, when he was just 16, Stan suddenly blacked out and collapsed. It was the first fainting spell he ever experienced, but it was enough for doctors to run a series of tests on his heart.

He was diagnosed with the inherited heart condition arrhythmogenic right ventricular dysplasia, or ARVD, a disease that causes irregular heart rhythms and one doctors at Johns Hopkins Medicine say is a leading cause of sudden death among young athletes.

Doctors didn't know how strong Stan's heart was, so they gave him a defibrillator, which would administer electric shocks to his heart to correct the abnormal beating.

"It changed a lot for me," he said. "I couldn't play sports anymore and I really couldn't do anything. They just didn't know how strong my heart was."

The defibrillator did its job and kept Stan's heart beating at a regular rate as long as he kept up his end of the bargain and limited his activities, which he did.

In April 2012, things began to go downhill. Stan's body began retaining fluids at an alarming rate, and doctors said he would eventually need a heart transplant in order to live.

His ARVD had progressed into bi-ventricular dysplasia, meaning that neither of his heart's two large chambers that collect and pump blood to his lungs and body functioned like they were supposed to function.

"My heart kept getting weaker and weaker. I was waiting on a heart transplant, but doctors said I wouldn't make it to transplant," Stan said.

Having one of the most common blood types, O-positive, Stan was behind hundreds of people on the donor list for a new heart. Doctors sought out a temporary option for Stan and chose to outfit him with a Total Artificial Heart.

Getting an artificial heart

Stan was admitted to the University of Michigan Hospital on Oct. 11, 2014, so doctors could run a series of physiological tests on him to make sure he was qualified as a candidate for the Total Artificial Heart.

Jonathan Haft, a cardiac surgeon at U-M Hospital, worked with Stan throughout the process in order to make sure this was the best option.

"We felt like the best option for him would've been heart transplantation, but we also felt that his condition was changing very quickly and we did not think he would survive long enough until a suitable heart was identified for him," Haft said.

"He was dying of shock. His heart was not pumping enough blood around to maintain health of all of his vital organs and without urgent intervention he would not have survived."

Stan received his pneumatic Total Artificial Heart on Nov. 7, 2014. Haft said that this particular device is the best way to provide support for someone like Stan who has severe failure in both sides of the heart, with the goal of bridging the patient to heart transplantation.

With the Total Artificial Heart, there are two tubes that exit the body, and those two tubes have to be connected to a machine that can deliver compressed air into the ventricles to allow blood to be pumped through the body. The compressor is powered by an electronic system, which controls the movement of air in and out through those tubes into the device.

In Stan's case, his tubes were connected to a compressor called Big Blue: a 418-pound machine with very limited mobility.

"Big Blue is the device we've used for years with the artificial heart. It's very big, and clearly someone cannot go home with that size device," Haft said.

So from Oct. 11 until Dec. 23, Stan lived at the hospital. He spent Halloween, Thanksgiving, and his 24th birthday hooked up to Big Blue, unable to go home and live life as most other 24 year olds do.

Unplugging from Big Blue

Christmas was special for Stan. It was really the first time he was able to see his entire family, including his three young children, outside of the walls of his hospital room since October.

"It was a really good time. I got to play with my kids, watch them open presents. I got to just spend time with my family, so it was just a good time," he said.

Stan was discharged from U-M Hospital on Dec. 23 after doctors approved him for what's called the Freedom portable driver. It does the same thing Big Blue does - deliver compressed air into the tubes that exit his body in order to pump blood from his heart throughout his body - except it's portable.

The FDA approved the Freedom portable driver June 26, and Stan made history by becoming U-M Hospital's first Total Artificial Heart patient to be discharged using the device. Doctors at U-M also said he's the first patient in the Midwest to be discharged on the Freedom driver.

"Until recently, patients would have to stay in the hospital until they had their heart transplant. The equipment that is outside the body, which powers the device and controls the device, was not suitable for discharge. Recently they've introduced new technology that allows these patients to go home," Haft said.

"Now that he has this artificial heart, and his circulation is maintained with this mechanical pump, he is otherwise completely healthy. He's very active, very functional, and I expect that over time he's going to get stronger and stronger."

Freedom works with the Total Artificial Heart by using a portable power source that comes with two on-board batteries, which are backed up by an internal backup source. In addition to the Freedom driver, Stan also has two back-up drivers and six batteries in case of a malfunction.

The Freedom driver provides patients like Stan with virtually unlimited mobility, although he said that there are still some limitations.

"I can't pick up my kids, I can't get in the shower and I can't drive," he said. "It hurts a little that I can't actually hold my kids because I'm getting stronger, but I can't really lift anything. We play together all the time," he said.

Haft said that the staff had done a number of Total Artificial Heart replacements, which take about half a day to implant, but he was very excited about Stan's unprecedented step in being able to get discharged.

"We're very excited that Mr. Larkin (got to) go home. ... Certainly I think it's not only going to be good for his rehabilitation, but good for his mind and for his spirit as well," Haft said.

"With the introduction of this new technology, it allows this new possibility for us which is important as patients wait for transplant and you never know when an organ is going to become available."

It's a family thing



After it was discovered that Stan had ARVD in 2007, doctors urged everyone in his immediate family to get tested for the disease. Because the condition is hereditary, doctors believed that one of Stan's siblings or parents could also be a carrier of the trait and it would only be a matter of time before that person would also need medical attention.

Doctors were right.

Stan's younger brother Domonique Larkin - younger by just 358 days - was also diagnosed with ARVD just weeks after Stan's diagnosis, and he also had to get a defibrillator implanted.

Domonique, 23, initially had a hard time dealing with the reality of his condition.

"At first I had a hard time coping with it. I was in denial. I was wondering why I had to go through it, and I didn't really believe something was wrong with me," Domonique said.

"I was still playing sports and everything until a few years down the line when I started having my own episodes and my defibrillator started acting up and I started going into cardiac arrest. That got me scared, and I knew I had to take it seriously because I knew I didn't want to go into cardiac arrest again. It was a real wakeup."

Like his older brother Stan, Domonique's heart began to weaken over time, and he also had to get a Total Artificial Heart on Dec. 11, 2014. Coincidentally, the same Big Blue machine that kept his brother alive is also pumping blood through his body and preserving his life.

"(It's) a familial cardiomyopathy, so it's something that's genetic," Haft said.

"(Domonique's) not quite been moved along to be on the Freedom driver, but I'm hopeful that, in the near future, we'll be able to send his brother home on the same device."

Domonique has lost two of his three children - one at 8 months old from a heart condition, and another who was born nearly three months early and died two months later.

He said that the deaths of his children, coupled with his and his brother's heart conditions, have taught him to cherish life and live it abundantly.

"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," he said.

Still awaiting transplants

Both Domonique and Stan know that the Total Artificial Heart, Big Blue and the Freedom portable driver are all temporary bridges until hearts become available for transplant.

They also know that their blood types knock them far down on the list to receive a heart when one becomes available.

In the meantime, Domonique is potentially days away from joining his brother at home, as he might be a suitable candidate for the Freedom portable driver.

Until that day comes, Domonique said the two will continue to do what they've done for each other since their teenage days.

"We're always here for one another. This whole thing drew us a lot closer. It became that we understood what was going on with each other's condition more than anybody else," Domonique said.

"We've always had to look out for each other and deal with each other's episodes, no matter who was around. It made our bond close. I felt the safest when he was was around, and I can't wait to go home and be with my family and just sleep in my own bed again."

Haft said that the artificial heart and the portable driver create opportunities for heart transplant patients that haven't existed in the past, and he's hopeful that it will be a stepping stone for people in Domonique's and Stan's position.

"We do still intend to transplant him, but this device is going to provide us with a bigger window of opportunity so that he can wait until that perfect heart becomes available for him.

Stan said he's not concerned about how long it will take before he gets a transplant, but he's confident it will eventually happen.

"It could take two months or it could take two years. Honestly, it could take longer. But I'm just glad to be able to be home with my kids and family," he said.

"You can't really worry about what's going to happen tomorrow because you could get so caught up that you miss what's going on today. I have to live for today because tomorrow isn't promised."

Jeremy Allen is the University of Michigan reporter for The Ann Arbor News. Follow him on twitter at @JeremyAllenA2. Contact him at 810-247-4625 or jallen42@mlive.com. Find other University of Michigan-related stories here on MLive.com.