How long can a human heart sit in a cooler of ice—thirsty for vein-borne blood, detached from oxygen and lungs—before it becomes useless to the transplant patient who desperately needs it? Not much longer than six hours, and that’s already pushing it, says Dr. Thierry Mesana, chief of cardiac surgery at the Ottawa Heart Institute. “We don’t have so much trouble with anything under four hours,” says Mesana, who has been transplanting hearts for 25 years. “Beyond six hours is certainly too long.”
Those time restrictions lead to some unfortunate limitations for Canadian hospitals holding patients waiting for heart transplants (as of the end of last year, there were 135 of them in Canada). Even when a perfect match becomes available for transplant, it’s sometimes lost due to degradation over time. Mesana says it’s rare to be able to bring hearts to Ottawa from Vancouver, for example, even when a match—by blood type, age, weight—arises. “We basically can’t do it, most of the time,” he explains. If a match doesn’t turn up within a six-hour radius, the heart is lost.