Pediatric heart transplant of an inappropriate blood type has been shown to be as effective as the traditional approach

A pediatric cardiac transplant procedure initiated by Canadian doctors – once impossible – has been shown to be at least as effective as the traditional approach, according to a newly published study in Lancet Health for Children & Young People.

ABO-inappropriate heart transplantation was developed in the mid-1990s, after a Canadian transplant team led by Lori West realized that babies under the age of two have uncommon immune systems that would allow them to adopt to save lives for the deprived hearts from donors with inappropriate blood types.

“It is very important to see that it has not only helped these sick children to recover more quickly, but also to live so long, without being denied more. , and better disease outcomes, as children who received an equal blood group heart rate, ”said lead researcher Simon Urschel, associate professor of pediatrics in the Faculty of Medicine & Dentistry of the University of Alberta, director of pediatric cardiac referral at Stollery Children’s Hospital and a member of the Women and Children’s Health Research Institute (WCHRI).

ABO-inappropriate heart transplants are now routinely performed in Canada and some other countries, but not everywhere. That should change thanks to these new survey results, Urschel said.

“For example, Eurotransplant (the body responsible for transplantation in eight European countries) still considers it a low-risk option to be used with caution,” he said. “That anxiety may be relieved in those last places that were willing to do it, now that we’ve shown it’s safe.”

About 50 percent of the population is born with type O blood, 35 percent is type A and 15 percent has type B or AB blood. Anyone can accept organs from a donor with type O blood, but adult type O patients can only get type O organs. The development of ABO-inappropriate pediatric heart transplantation meant that twice as many organs would be available for type O babies born with heart problems.

Urschel and his team analyzed data from more than 2,200 child transplant recipients in Canada, the United Kingdom and the United States from 1999 to 2018. The records came from the Pediatric Heart Transplant Association, a collaborative record. international research which collects data from 58 transmission centers. . As a result there were more than 11,000 patient studies, the largest study of its kind.

Three hundred and sixty-four of the children received inappropriate ABO referrals, and 1,842 received ABO-like hearts. “We wanted to compare apples and apples, so the kids were matched with traits like the underlying disease and the age at which they underwent surgery,” Urschel said.

The researchers found that the survival rate was the same between the two groups, as well as the rates of severe and malignant organ rejection and the risk of developing leukemia after transplantation. They also examined the levels of bacterial, viral, and fungal infections after transfusion, which were of potentially higher concern among those who received ABO-inappropriate transplants.

“Interestingly, we found that fewer of the diseases we were concerned about in the ABO patients were unresponsive,” Urschel said.

Earlier work by the Urschel research team showed that waiting times for these patients were significantly shortened, with the average time for referral being around 50 percent shorter thanks to the new referral method. customary.

“It is easier and faster to find a heart for these patients, which is crucial because they are very ill, often on mechanical heart support devices or on air vents in intensive care units,” he said. “This allows them to not only survive, but stay healthier and in better condition before and after transplant. “

The advanced pediatric heart surgeons who started it all in 1996 – West and Ivan Rebeyka – updated their approach after being hired to join the U of A faculty, with the help of members other relationships such as Urschel. The work of Urschel and West has received funding from the Stollery Children’s Foundation through WCHRI.

The “rule” that ABO-like donors were required to establish was established for elderly patients and has never been revisited from the perspective of infant immunologic immaturity, said West, now Chair of Research Canada (Series 1) in Cardiac Transplantation, and director of the Alberta Transplantation. Canadian Donation and Referral Research Institute and Program.

“This, combined with very high mortality for babies on our referral waiting list, is why we established the first ABO-inappropriate referral protocol,” she said.

“Rehabilitation has always been about pushing risk limits to offer reasonable options to patients who would otherwise have no choice.”

Urschel will continue his work to understand the apparatus in infant immune systems that allows them to accept hearts that are incompatible with blood, hoping that one day they can apply what they have learned to recipients. help older referrals. He is also involved in projects to improve the quality of life of young transplant patients and their families.

“The real need is a real lesson in the need for scientific vigor to guide our activity of clinical protocols, not just blind adoption of previously accepted rules,” West said.

The fact that heart transplant recipients can now live a normal life is the belief of both West and Rebeyka, who have a clinical faculty position with the U Cardiovascular Research Center of A, said Urschel, who is still providing clinical care for adolescents and young people. adult patients who received ABO-inappropriate transplants as infants.

“It’s just amazing to see them, knowing that they were once so ill in the intensive care unit that they probably wouldn’t do it until the next day,” Urschel said.