MDs to restart hearts of recently dead
Doctors in Canada are preparing to restart the hearts of the recently declared dead, a move experts say will lead to a desperately needed new source of donor hearts.
But that raises an ethically fraught question: How can you be dead if your heart is still beating?
The technique involves taking hearts from organ donors whose hearts have stopped, and restarting them in one of two ways: outside the body, or inside the body of the dead donor.
The plan is to proceed cautiously at first in Canada, and revive hearts inside a portable device, a “heart-in-a-box,” perfusion machine that looks much like a miniature ICU. Blood collected from the donor is pumped through an oxygenator and into the heart. The disembodied organ can be kept alive inside the sterile rig, beating and “breathing,” somewhat spookily, for up to 12 hours, before it’s transplanted. It’s an approach already being used in Australia and the U.K.
The British doctors, however, have gone further: In a carefully choreographed sequence, after life support is withdrawn from an organ donor, after the heart stops beating and doctors wait the obligatory five minutes before declaring death — convinced there is no pulse, no heartbeat, no chance of the heart spontaneously restarting on its own — the body is taken to the operating room. Surgeons cut into the sternum, clamp the main arteries supplying blood to the brain and connect the body to a machine that takes over the work of the heart and the lungs. The machine is called ECMO, or extracorporeal membrane oxygenation. It was famously used to save lives in the SARS outbreak in 2003.
Once connected to ECMO, a large incision is made through the abdominal wall, to gain access to the abdominal cavity. Blood is re-circulated to the thorax and abdomen, and the heart “revived.” The dead person now has a beating heart.
Over a period of about 20 minutes, the heart is weaned off the machine, until it’s pumping on its own, inside the corpse. Once surgeons are satisfied the organ is healthy enough for transplant, the resurrected heart is injected with a cooling solution, extracted from the donor body and then put inside the portable perfusion device for transport to the transplant hospital, where the heart is restarted once again — this time inside the body of the recipient.
Known as normothermic regional perfusion, the procedure has created a stir in the U.K., where it is restricted to a handful of hospitals.
Now, a conference of experts formed by the Canadian Blood Services and Trillium Gift of Life Network in Ontario is developing expert guidance to determine the conditions under which that type of “donation” could be done here.
Donor hearts are usually only ever taken from people declared brain-stem dead. They’re medically and legally dead, but their hearts are still beating. But there’s a stark shortage of hearts from brain-dead donors.
In this case, the hearts would come from “circulatory death” donors — people who don’t meet criteria for brain death, but whose hearts have stopped beating.
They usually involve people on life support with such a bleak prognosis their family decides they would rather be dead. Life support is withdrawn, and, once the heart stops beating, organ procurement can begin. Approved at a 2006 conference of experts, DCD donors now account for 25 percent of all donations in Canada. It’s led to a dramatic increase in donor kidneys, livers and even lungs.
The only people who haven’t benefited are people waiting for a new heart. That’s because after life support is withdrawn, the heart contracts vigorously, and is slowly starved of oxygen and blood. The cells of the muscle begin to die off, blood pressure drops, and the heart goes into cardiac arrest. The heart, unlike other organs, is exquisitely sensitive to warm ischemia time — time without blood flow and oxygen.
In order to use a heart from a DCD donor, it has to travel back, quickly, the way it came.
“The thing that people need to get their heads around is that, in order to do DCD hearts — heart transplants after the heart has stopped beating — the heart has to start beating again,” said Dr. Sam Shemie, a McGill University critical-care doctor and medical advisor for deceased donations for the Canadian Blood Services.
“It can either beat again outside the body, in this perfusion system, or it can beat again inside the body,” Shemie said.
“And the question is, because it’s a more complicated procedure, because there are biological realities and there are ethical issues, the question will be for Canada going forward, and I don’t have the answer for you now, can we do normothermic regional perfusion in Canada for DCD hearts? And, if so, how to do it consistent with existing practices and the medical, ethical and legal safeguards that should be in place.”
Even for doctors, the concept isn’t easy to process. Intuitively, there seem to be huge contradictions: If death is defined as irreversible cessation of circulatory and respiratory function, and that circulation is restored, how can the person still be truly dead? If ECMO restarts the heart, are you biologically alive?
American bioethicist and pediatrician Dr. Robert Truog has noted that just because a heart won’t restart on its own doesn’t mean that it cannot be restarted, and that people are twisting themselves into pretzels over the permanence determination. What matters most, he and others have argued, is circulation to the brain.
However, if you “reanimate” the heart, is there even a remote chance you might reanimate the brain, even if the major vessels are clamped, cut and tied off?
“We need to be certain that there is no brain perfusion following the resumption of circulation in the donor body,” said Dr. Andrew Healey, a critical-care physician and chief medical officer of donation at Trillium Gift of Life Network.
“We also need to be certain that we have accepted that resuming circulation in the body does not invalidate the determination of death,” Healey said. “And the critical-care community, in the large part, would accept that, I think. But more work is to be done before this can occur in Ontario.”