U.S. doctors have transplanted a pig heart into a patient in a last-ditch effort to save his life — a first for medical science.

Doctors at the University of Maryland School of Medicine said Monday the patient is doing well three days after surgery.

The patient is 57-year-old David Bennett, a Maryland handyman too sick to get a human heart.

Bennett said before the surgery: “I want to live. I know it’s a shot in the dark, but it’s my last choice.”

Friday’s surgery showed for the first time that a gene-edited animal heart can function in the human body without immediate rejection.

According to USA TODAY, Bennett is breathing on his own without a ventilator. However, he reportedly is still on an ECMO machine that helps pump blood through his body. USA Today says doctors plan to slowly wean him off the machine.

"This was a breakthrough surgery and brings us one step closer to solving the organ shortage crisis. There are simply not enough donor human hearts available to meet the long list of potential recipients,” said Bartley P. Griffith, MD, who surgically transplanted the pig heart into Bennett.

According to the University of Maryland Medical Center, more than 100,000 Americans are currently waiting for an organ transplant, and more than 6,000 patients die each year before receiving a transplant.

A recent medical breakthrough could help people get organ transplants faster.

“This is really the first attempt to move this into the clinical realm,” Dr. Robert Montgomery, the director of the NYU Langone Transplant Institute, said.

Dr. Montgomery and the rest of the team at NYU Langone Health recently completed the first investigational transplant of a genetically engineered pig kidney, to a human body.

“We had a genetically-edited pig kidney and a recently deceased human whose family essentially donated her body to participate in this test to see if this pig kidney would work,” he explained.

It’s a process known as xenotransplantation.

“There have been attempts at trying to advance xenotransplantation using animal organs for human use for about 50 years,” Dr. Montgomery explained. He said the process for making this surgery possible started about four years ago. They completed the surgery at the end of September. Doctors kept the donor on a ventilator. For 54 hours after the surgery, they monitored the donor to watch the kidney’s function and check for signs of rejection.

“We’ve been sort of stuck in the preclinical animal studies for a very long period of time and this really gives us the confidence because the kidney worked so well and it wasn't rejected. It gives us the confidence that we can now move to a living human trial. I think that is going to happen in the next year or two,” Dr. Montgomery said. “What this will do is really allow, I think, anyone who needs a transplant to be able to get it. And not have to wait for years and maybe get too sick or die before they get it.”

There are 106,713 patients currently on the national waitlist, according to statistics from the Organ Procurement and Transplantation Network data pulled by the United Network for Organ Sharing on October 20, 2021. About 90,259 are in need of a kidney transplant.

“The 90,000 people on the list, that's really just a fraction of people who need a kidney,” said Dr. Michelle Josephson, a professor of medicine at the University of Chicago. Josephson is also a part of the American Society of Nephrology.

“If you look over time it has increased, and you say well why has it increased? I think the numbers increased one because we’re just not keeping up with demand...the other is that as we’ve gotten more knowledgeable about how to manage transplant recipients, we’re more willing to offer transplantation as a viable option to more people with perhaps more diseases and co-morbidities than we once felt capable or comfortable doing,” Dr. Josephson said.

Dr. Joseph Vassalotti with the National Kidney Foundation said that waitlist could take years.

“In parts of the country it might only be one year to wait for a deceased donor kidney. And in other parts of the country it might be 10 years, so there are some differences based on your blood type and where you live,” he said.

The possibility of xenotransplantation to help reduce wait times doesn’t come without controversy.

“There are barriers, people worried about the possibility of taking an infection from the animal world and bringing it into humans, so that's one big concern. There's been also concern that there's specific antibodies that humans might have against pig kidneys,” Dr. Josephson said.

Dr. Montgomery said he worked with a team of more than 100 people to manage those concerns.

“Everything that we did was really vetted through ethicists, through legal experts, religious experts,” he explained.

And it will be a while before this type of transplant is available to the public.

“It’s probably going to be several years before we can have large-scale clinical trials— to see this forward,” Dr. Vassalotti said.

Barbarita Acosta, or affectionately nicknamed Barbie, is celebrating her first birthday this weekend. The infant already overcame extraordinary medical odds.

Barbie was born with neonatal lupus, a rare condition that attacked her heart. At just five days old she received a pacemaker. But after a few weeks, doctors said she needed to find a heart donor.

“They told us that very same day that by the end of the night she would be life-lifted out of there,” mother Angel Moreno said. “So, we came home and packed up as soon as we can. And we just got in the car and followed the helicopter. Tried to beat it there.”

Barbie spent more than 200 days at Lucile Packard Children’s Hospital Stanford.

“Barbie was born with a condition called neonatal lupus, which is a condition in which the mother has antibodies that can attack the baby while she is still in the mother’s womb,” Dr. Seth Hollander said. “Her condition is quite rare. Only about 1% of women will have these antibodies. And only about 2% of women with these antibodies have this kind of effect on the baby.”

Dr. Hollander is the medical director of Pediatric Heart Transplantation.

“About 500 heart transplants are performed in the country each year in children. However, among children under the age of one year are the hardest to find matches for,” he explained. “And infants waiting for heart transplants are the most likely group to pass away while waiting for a donor organ.”

Dr. Hollander said roughly 25% of infants waiting for a heart transplant will die while waiting.

"We are very grateful for whoever that anonymous donor family is for providing such a wonderful gift and a second chance for this little girl,” he said.

Barbie’s heart surgery happened in September when she was a little over six months old.

“It literally brought me to my knees. I was crying,” Moreno said. “We only had so long — I believe it was four hours — to make a decision if we wanted the heart or not. So, it was a really hard decision because there were so many good and bads to both sides of saying yes or no to accepting the heart.”

And COVID-19 protections complicated an already dire road.

“Oh man it was really scary because nobody could really be there to support us,” Moreno explained. “There was actually a long period of time where dad was not allowed to come into the hospital because they were only letting one parent in.”

Barbie’s surgery was a success. And she went home to Sacramento, California, just before Thanksgiving.

Dr. Hollander added Barbie's future is very bright. She has no transplant rejection and is catching up on her developmental milestones.

He expects the heart to last for several decades, allowing Barbie to grow up pretty much like a normal kid.

“When I look at her it’s really hard to believe she’s had a heart transplant because she acts so much like a baby,” Moreno said.

“It’s amazing to know that when we first found out, we weren’t sure if we were going to have a baby, to now, we’re celebrating her first birthday coming up. So, that’s really great.”