New study endorses harvesting hearts after declaration of cardiopulmonary death

There's an Associated Press article in this morning's Dallas Morning News describing a multicenter study involving the transplantation of hearts taken out of donors who were not brain dead but had been declared dead after irreversible cessation of cardiac and circulatory function (DCD/DCCD).

Certain solid organs have been transplanted after DCD for decades. The protocol for harvesting involves the following steps:

• moving the patient to the operating room (usually from an ICU);
• stopping all life-supporting measures;
• waiting for a fixed period of time for the heart to stop beating (usually 60-90 minutes);
• if the heart stops, waiting another period of time (usually 5 minutes) to see if the heart will autoresuscitate;
• if autoresuscitation doesn't occur, death is declared and organ harvesting (usually kidneys, liver, and pancreas).

The DCD procedure was designed to shorten the warm ischemic time from when cardiopulmonary function ceases and the harvested organ can be restored to function in the recipient's body. Even with that innovation, though, hearts were not considered for transplantation because of their extreme fragility.

As described by the AP, however, the results of a multicenter study over a number of years establishes that the six-month survival rate after DCD (94%) was slightly better that the survival rate for heart transplants after brain death (90%). So what has changed? As reported by the AP:

Now doctors can remove those hearts and put them in a machine [a "heart-in-a-box" device invented by TransMedics, the sponsor of the study] that “reanimates” them, pumping through blood and nutrients as they’re transported –- and demonstrating if they work OK before the planned transplant.

I am all for increasing the supply of donor hearts, and this is a very interesting development.  I am wondering, however, how to square the transplantation of a viable heart with the cardiopulmonary criterion of death. The statutory standard of "irreversible cessation of all cardiopulmonary function" will  now need to be understood as “irreversible in the donor’s body but not necessarily in the body of the recipient of the heart.” That begs the question, which has applied to DCD from the beginning, why has cardiopulmonary ceased (because we took away the donor’s life support) and why is the cessation irreversible (because we didn’t try to reverse it). Once we actually try to restore cardiac function (“reanimating” the heart in a “heart-in-a-box” device), some hearts are restored and do at least as well in the recipient’s body as a heart from a brain-dead patient. 

Are we comfortable with this slightly altered version of "irreversible cessation"? Should we be? The so-called "dead donor rule" (DDR) forbids killing a patient for organs or removing organs needed to sustain life from a living patient. So far, we have avoided the slippery slope of removing organs from patients who are almost dead or "as good as dead." How certain are we that this new approach to DCD heart transplantation satisfies the DDR? 

Determination of Brain Death/Death by Neurologic Criteria: The World Brain Death Project

Brain death/death by neurologic criteria (BD/DNC) is described in every jurisdiction in the U.S. as the irreversible cessation of all brain function, including that of the brain stem. The universal acceptance of this seemingly straightforward criterion masks an unsettling reality: "There are inconsistencies in concept, criteria, practice, and documentation of brain death/death by neurologic criteria (BD/DNC) both internationally and within countries." That's the opening salvo by an international, multidisciplinary group that has published its findings and recommendations in an important new paper in JAMA. 

As summarized by the panel: "This report provides recommendations for the minimum clinical standards for determination of brain death/death by neurologic criteria in adults and children with clear guidance for various clinical circumstances. The recommendations have widespread international society endorsement and can serve to guide professional societies and countries in the revision or development of protocols and procedures for determination of brain death/death by neurologic criteria, leading to greater consistency within and between countries."

In the same issue, Dr. Robert Truog at Harvard Medical School and Boston Children's provides a useful editorial on the report. His bottom line: loss of consciousness, loss of spontaneous respiratory drive, and the irreversibility of both conditions are the source of inconsistency and confusion. Research as to all three factors is desperately needed and devilishly difficulty to carry out. And even if that research is performed and is successful in establishing clinical criteria for their determination, much work will remain to be done, e.g.:

Bringing these recommendations to the entire international community will require a 2-pronged approach. First, evidence to support the existing tests needs to be bolstered, and this may require greater use of advanced neurodiagnostic techniques. A key question will be whether the whole-brain biological standard for defining BC/DNC will remain tenable, or whether this concept should be replaced by the values-based brainstem standard. Second, since much of the world does not have access to advanced technologies, the World Brain Death Project will need to focus on development and validation of tests that rely on the clinical examination and widely available diagnostic tools. This will be essential if the capacity for accurately diagnosing BD/DNC is to become accessible to all clinicians around the world.