Stan Larkin, a 25-year-old Michigan resident, lived 555 days without a human heart transplant. He carried a gray backpack with a power source for an artificial heart pumping in his chest.

In November 2014, Larkin's real heart was removed from his body and replaced with a device that allowed him to stay home instead of in a hospital while waiting for a transplant. Human organs grown in pigs may help transplant patients, and the total artificial heart finally arrived in May 2016.

Larkin recovered from his procedure at the University of Michigan Frankel Cardiovascular Center and returned home the following week. In 2016, there were about 4,000 patients nationwide waiting for human heart transplants, and many of these patients have weak hearts that could cause critical organs to fail while they are waiting.