Transplant Procedure Overcomes Blood-Type Incompatibility
More young children could receive life-saving heart transplants in the future, if a procedure performed for the first time at 菠萝视频 becomes accepted practice. Pediatric cardiac surgeons at the recently performed the state鈥檚 first ABO-incompatible heart transplant in a 2-month-old patient.
The procedure鈥攔eserved for children 2 years old and younger who have not yet developed significant levels of anti-ABO antibodies鈥攈elps a transplant recipient tolerate an organ from a donor whose blood type is incompatible.
When patients who have one blood type receive blood from someone with a different blood type, it may cause their immune systems to react. This is called ABO incompatibility. ABO-incompatible transplants are rare in the United States, mostly due to current donor and recipient matching algorithms. But pending changes to the United Network for Organ Sharing (UNOS) protocol are giving 菠萝视频 physicians hope that the practice will become standard treatment.
In the past, children listed as ABO-incompatible for heart transplants were at the 鈥渂ottom of the list鈥� in terms of matching. But recent outcomes showing improved survival rates have sparked growing interest in the technique.
鈥淲e are the only center in the state doing ABO-incompatible heart transplants,鈥� says , associate professor of pediatrics and medical director of the Pediatric Heart Transplant program at Children鈥檚 Hospital. 鈥淣ot every transplant center in the country will be able to perform this procedure. Our patients listed as ABO-incompatible will now have access to organs that previously were not available to them. They will have an improved chance, rather than dying while waiting.鈥�
In 2006, UNOS agreed to allow incompatible organ listing for heart-transplant patients 6 months old and younger. A year later regulations changed to include candidates 2 years old and younger. Now discussions are underway to permit compatible and incompatible heart transplants to be listed equally.
鈥淲e are hoping it will happen in the coming year,鈥� Dodd says. 鈥淢aking this change will further shorten the waitlist time for this patient population as well as improve long-term survival. It will significantly impact the children who come to us for hearts.鈥�
Once UNOS鈥� complex, computerized matching system finds a recipient for an organ, the medical team has a couple of hours to prepare the recipient for transplantation. But for incompatible organs, a few extra steps are required for a successful outcome.
鈥淭his procedure, which is done in the operating room, allows us to modulate the immune system of our patients to allow them to tolerate a transplant from a donor whose blood type is incompatible,鈥� says , assistant professor of cardiac surgery. 鈥淎t the time of their operation, we do an exchange transfusion鈥攚hich means we replace all their native blood volume with blood from our blood bank, minimizing the immunologic response to the transplanted heart causing hyperacute rejection.鈥�
Mettler says the medical team checks the antibodies in the blood before re-perfusing the organ once transplantation is complete to ensure that the levels are low enough to prevent rejection. If the levels are too high, another exchange is done. 鈥淲ith an exchange transfusion and an immature patient鈥檚 immune system, as they age they will develop tolerance of the organ that is from a different blood type,鈥� he explains. 鈥淭he long-term outcomes are equivalent to patients who have received ABO-compatible transplantation.鈥�
For nearly two decades, Canada and some European countries have been performing pediatric ABO-incompatible heart transplants. Dodd said those countries鈥� high mortality rates while waiting for donors prompted them to seek alternative treatment options.
Since pioneering the incompatible transplant, Canada has seen a dramatic decrease in transplant mortality rates: from 58 percent down to 7 percent. Dodd anticipates similar improvements for both 菠萝视频 and other eligible centers nationwide as the practice becomes standard.
The pending UNOS change in criteria also could result in a 20 percent increase in heart transplant volume at 菠萝视频, as few centers in the Southeast perform ABO-incompatible heart transplants. In fact, fewer than 20 facilities offer the procedure nationwide.
鈥淭his is a testament to multiple disciplines collaborating within 菠萝视频,鈥� says Mettler. 鈥淭o be able to perform an equally complex medical and surgical procedure in the most fragile population very early in life is very satisfying. Many areas within the hospital come together to make this work. We hope that being able to offer ABO-incompatible transplants leads to fewer children dying while waiting for an acceptable organ.鈥�