Mismatched Hearts Save Babies' Lives
Due to the fact that infant hearts are so rare, doctors have gotten creative with the way that they approach the organ transplant.
Connor Geddes was 13 days old when surgeons gave him a new heart that didn’t match his blood type — deliberately.
Connor, now 11 months old and thriving, is one of several dozen babies around the world to have received mismatched hearts, part of a slowly growing movement to increase these tiniest patients’ survival by taking advantage of a lag in their immune systems.
Now the nation’s transplant network is expanding that effort, saying youngsters may be candidates for an incompatible heart up to age 2.
It’s the first step in a new push by the United Network for Organ Sharing to decrease the number of children who die awaiting an organ transplant, a toll particularly high for infants and toddlers.
A babies’ immune systems must learn to recognize and attack an organ of a different blood type, a process that’s turning out to be more gradual than scientists long thought.
Transplant a heart before the baby starts making antibodies that will attack a mismatched organ, and he or she survives as well as babies given matching hearts, says Dr. Lori West, the Canadian surgeon who pioneered incompatible transplants in Toronto in the late 1990s.
But given the scarcity of tiny hearts, the mismatch option was good news. In 2005, the last count available, 45 children under age 2 died while awaiting a new heart. As of last month, 74 youngsters under 2 were on the waiting list.
About one in 5,000 children are born with a heart defect so bad that they’ll need a transplant in the first year or two of life. Yet few babies die of conditions that allow their hearts to be donated.
Those babies still need immune-suppressing drugs for life — blood type is just one form of organ rejection.
Until recently some transplant centers were reluctant to perform mismatch heart surgeries. There was a concern whether children really fare well years after getting a mismatched heart, or if rejection just sets in later.
Now that Dr. West has patients that have survived a decade with the transplant, the worry is starting to fade.
Knowing that the procedure cannot be performed on adults, no one knows what the cutoff age is.
Babies begin producing antibodies to different blood types between 5 months and 2½ years of age — it varies widely from child to child, says West, now at the University of Alberta’s Stollery Children’s Hospital. Only a few of the 90 or so mismatched heart transplants performed worldwide have occurred past a child’s first birthday, the oldest in a 30-month-old in Britain.
Still, age is just a rough marker for antibody production, West stresses. Blood tests to check antibodies are the real key.
Hence the new U.S. policy, adopted last fall and to go into effect later this year. It expands use of mismatched hearts up to age 2, as long as antibody tests show the toddlers are candidates.
For now, many transplant centers are like Webber’s, trying their first mismatched transplants in babies before working up to toddlers.
Last March, Connor Geddes of Erie, Pa., became Pittsburgh’s first of five such transplants. His heart’s left side was too small to pump. Doctors said Connor wouldn’t live long enough to await a heart that matched his Type A blood, but they had a heart from a Type B donor available.
Eleven months later, Connor shows no sign of rejection and happily totters after his older brothers. His tracheotomy tube — from lungs weakened by heart-pumping machines while he awaited the transplant — is to be removed soon, and the scar on his chest is barely visible.
SOURCE:MSNBC
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