BOSTON -- Transplanting organs from those who suffer cardiac death, rather than the widely accepted standard of brain death, could sharply increase the supply, said a surgeon here.
BOSTON, July 25 -- Transplanting organs from those who suffer cardiac death, rather than the widely accepted standard of brain death, could sharply increase the supply, said a surgeon here.
Donors after cardiac death, also called "non-heart-beating donors," are those considered to be dead according to circulatory-respiratory criteria specified in the Uniform Determination of Death Act.
Irreversible circulatory-respiratory failure differs from breath death in that it implies but is not definitive of brain death. Brain death, defined as total and irreversible cessation of all brain activity, including in the brain stem, is the other accepted definition of clinical death.
Surgeon Anthony D'Alessandro, M.D., executive director of the University of Wisconsin organ procurement organization, said at the World Transplant Congress the donor pool could deepen by perhaps 25% if the circulatory-respiratory criteria were more commonly applied.
Current attempts to expand the supply of donor organs include the use of living donors for kidneys and livers, use of organs from older donors, or in the case of livers accepting donations from people who are positive for viral infections or have hypernatremia at the time of organ procurement.
In donation after cardiac death, after the wishes of the patient and family have been verified, the attending physician would terminate all life support, making the declaration of death only after waiting at least five minutes after the heart has stopped beating, to ensure that no spontaneous recovery of heart beat (auto-resuscitation) is possible. Dr. D'Alessandro noted that there has never been a documented case of a heart resuming beating after two minutes.
No member of the organ procurement team would be present at the time of death, and none are involved in the decision to end life support, he emphasized.
Although there is some compromise involved, organs harvested from donors after cardiac death can in many cases function similarly to those taken from brain-dead donors, Dr. D'Alessandro said.
"There is some mild damage that does occur to the organs in those situations," he commented, "but it's to the point where a lot has changed in terms of the preservation of organs, the care of patients, the medications we use after transplantation, such that warm time and the damage that occurs from it can be minimized, and organ function can occur in a way that's very similar to when patients donate organs in the brain-dead setting,"
Last November, investigators from Baylor in Houston reported at the annual meeting of the American Association for the Study of Liver Diseases that one-year survival and one-year graft survival were significantly but acceptably lower when 342 patients who received livers from donors after cardiac death were compared with matched controls who received organs from donors whose hearts were still beating, but were in circulatory collapse.
At the World Transplant Congress, several groups reported their experience with donation after cardiac death - some with follow-up as long as six years.
In one such study, Mary Eng, M.D., and colleagues of the University of Washington at Seattle evaluated outcomes retrospectively in 169 patients who received liver transplants from heart-beating donors, compared with 24 who received organs donated after cardiac death. They found that there were no significant differences in primary non-function of the graft, or in hepatic artery or portal venous infectious complications.
Additionally, they found that while there was a higher percentage of biliary complications in the patients who received organs from donors after cardiac death, the difference was not statistically significant,
Patients with grafts from donors who suffered cardiac death did, however, have an increased rate of ischemic cholangiopathy, which occurred in 12.5% of patients vs. 2.4% of those in the heart-beating donor group (P=0.04)
There were no significant differences in rates of rejection or short- term patient and graft survival, the investigators reported.
From Japan, where for cultural reasons more than 97% of kidney donations from deceased donors come from donations after cardiac death, Masayoshi Miura, M.D., and colleagues of the Hokkaido University Graduate School of Medicine in Sapporo, reported on marginal donors. That is, they met the expanded criteria for donation and were over age 50, yet their kidneys could still be successfully transplanted after cardiac death as long as warm ischemic time and total ischemic time were kept to a minimum.
And in another study slated for a poster presentation later in the week, Dr. D'Alessandro and colleagues reported that beta-islet cells harvested from donors after cardiac death were not inferior to islets from brain dead donors in in vitro studies, offering the potential to expand the pool of pancreases from which recoverable islet cells can be harvested.
Although whole pancreas transplants are still uncommon, there has been "excellent" long-term success with pancreases harvested from donors after cardiac death, Dr. D'Alessandro said.