Mismatched Hearts Save Infants

Most any surgeon out of medical school is taught a rule that must never be violated. When transplanting a heart, the heart must be compatible with the patient's blood type. A mismatched heart leads to rapid death.

Every year, people die waiting for that magical matching heart. And precious donated hearts that aren't matched to a patient are simply thrown away.

For one American pediatric cardiologist, the loss of life that flowed from this well-known rule was appalling. So she began to wonder, what would happen if you transplanted a mismatched heart into a dying child? Correspondent Scott Pelley reports.

"They told us he had a severe deformity of the heart, and unless he had either a transplant or three stages of operation, that he would ultimately die," says Angela White. "That was something -- it's hard to swallow … It's just an awful feeling just to see your baby laying there, completely, you know, helpless."

Helpless because the left side of his heart is abnormally small. Keanan's heart wouldn't keep him alive for long so Dr. Glen Van Arsdell started on what would've been a series of three surgeries to repair Keanan's natural heart.

"He'd undergone what we call stage one palliative surgery and that had gone well," says Dr. Van Arsdell. "However, several months later, his heart function deteriorated substantially, so he needed to be transplanted."

But a heart to match Keanan is hard to find. They want the right size and a matching blood type, because the body's immune system will reject a mismatched heart. Antibodies in the blood are always on the lookout to destroy foreign tissue.

Angela knows finding a suitable heart that's just the right size for her son might take weeks or months -- or might not come at all.

"I see numerous kids be prepped for transplant, and each time it hurts a little. You wonder why it can't be you," says Angela. "And rationally, you know, you're seeing older children going in and you can rationalize that that heart's not the right one, it's not gonna fit. But, it still hurts."

"It was a very difficult time. We lost most of the babies that were listed for transplant," says Dr. West. "More than 50 percent of the babies that were listed for transplant perished on the waiting list because there were no organs that could be found that were of suitable size and a compatible blood type."

Most often, it was the blood type mismatch that forced Dr. West to turn down rare infant hearts that otherwise would save the lives of her patients.

"In late 1995, there was an infant waiting and we were offered a heart, and then the blood type was wrong," says West. "And turning down that organ, which I was compelled, really, to do, it became clear to me then, at that moment, that we needed to go back and really examine this whole issue."

The child died, and that reminded West of some experiments she had done six years before. In transplanting organs into mice, she noticed something strange about infant mice. It turned out that baby mice were able to tolerate organs that weren't an exact match.

West suspected that their immune systems were just so immature they didn't recognize the mismatched organs as foreign tissue. It's a long way from man to mouse, but as her patients died, she began to wonder.

That fall, West met Rita and Harry Schroeder. An ultrasound showed that the fetus Rita carried had a malformed heart.

"It was tough. Essentially what they were saying is that the left side of the heart hadn't developed properly. So it wasn't pumping," recalls Harry Schroeder. "So the ultimate outcome of that of course, for that, would be if it didn't work by the time he was born, without serious medical intervention, he would pass away shortly after he was born."

Rita and Harry named their son Caleb. He was put on the waiting list for a new heart, but they couldn't find one to match his "type O" blood.

"We weren't sure how long we would have with him. I mean they projected hours, they projected days," recalls Rita. "So the hospital, the staff there counseled us. And they said take a lot of pictures. You don't know how long you're gonna have him for."

With time running out, West proposed something that would require the approval of the hospital ethics committee. She wanted to try a variation of her mouse experiment on Caleb.

"She says, 'Caleb seems like a prime candidate. He's still in pretty good shape. The heart is fantastic. We think this should work,'" recalls Harry.

The heart they found was the right size, but the wrong blood type. So they transplanted a type "AB" heart into Caleb's type "O" body on the theory that, at less than a month old, his immune system was so immature it hadn't developed the antibodies to attack the foreign heart.

West says her colleagues advised her against the operation. "I said, 'There's no choice. There is no choice for Caleb. He will die. This is why I think it will work," says West. "There is no antibody. Caleb doesn't have antibody. This will work, I believe. It will at least buy us time. And otherwise he's going to die."

That was seven years ago. Today, Caleb can do anything any normal 7-year-old boy can do. This second-grader is quick on his feet and a little better than he should be at this age with a chess piece.

Caleb has never missed a beat. The transplant was a complete success. His type "AB" heart is pumping in his type "O" body. And he still takes routine anti-rejection drugs that all transplant patients take.

But the blood type mismatch has not been a problem. In fact, doctors have discovered something unexpected. Now that Caleb's immune system is mature, it appears to accept all blood types. In theory, for example, he could get a transfusion from anyone.

"It was an enormous leap of faith. And where was the faith? It is in the science," says West. "I can only say this isn't magic. It's not voodoo. These are facts. There are scientific facts there."

Before, Keanan White would have had less than a 50/50 chance of getting a heart in time. But now, with mismatched hearts in use, 93 percent of the babies at the Hospital for Sick Children get the heart they need.

Angela White and her husband, Christopher, waited four months. But 60 Minutes II was there the day they got the call they'd been waiting for. A heart came in from the United States. It's the wrong type — an "AB" heart for Keanan's type "A" blood.

Surgeon Glen Van Arsdell rushed the donor heart back and keeps it on ice until he's ready to sew it into Keanan's chest. But it turns out the blood type isn't the only issue — the heart is larger than they would like and it might not fit.

The heart was big, but Van Arsdell managed to fit it in. "What we do is we try to do size mismatches and we try to do blood type mismatches. Keanan had both. He had size mismatch and he had a type mismatch," says Van Arsdell. "But because we can do that, he has a heart whereas otherwise he wouldn't have a heart today. We lucked out. No question. Keanan lucked out."

It's now routine in Toronto to offer mismatched hearts to any infant under the age of one year or so. Kids much older than that typically have immune systems that are too well developed to accept the blood type mismatch. Just seven days after his transplant, we looked in on Keanan.

"The function of the heart is fine. It's just fine. It's working normally," says West. "He should do well over the years."

And two months later, he was doing even better at home. Keanan is the 16th baby at the Hospital for Sick Children to live with a mismatched heart. The program has never had a blood type rejection.

So far, doctors have done approximately 38 mismatch transplants in Canada, Britain and a few in the United States. But in the United States, it still hasn't caught on widely. That may soon change.

"It can be done. But overcoming that preconceived notion that it can't be done will take years, probably," says West.