In the recent issue of the New England Journal of Medicine, several articles discuss different aspects of heart transplantation. One interesting aspect is about reversing the irreversible – donating hearts after cardiac death.
It used to be that organ donation can only occur after cardiac death, e.g. after a donor’s heart has completely stopped. Organs such as kidneys can then be transplanted from the donor to the recipient. However, this posed a challenge for heart transplant since the donor’s heart is dead and has irreversibly stopped, and is therefore not viable for transplantation anymore.
In recent years, the concept of brain death came up – irreversible loss of brain functioning. This opened new possibilities for organ donation – especially heart donation. However, the heart remains to be the main source of vital signs and cardiac death is still one of the most common way of defining clinical death. There are, however, some recent reports of hearts from “dead” donors that were successfully transplanted and restarted in recipients bodies. This sparked some ethical as well as clinical questions.
According to Robert M. Veatch, professor of medical ethics at the Kennedy Institute of Ethics, Georgetown University
“…when can death be pronounced on the basis of loss of heart function? Death must be permanent. Clinicians sometimes carelessly speak about patients who experience “clinical death” only to be “brought back to life” by means of cardiopulmonary resuscitation.
Where do we actually draw the line between life and death, be it cardiac death or brain death?
A 1993 protocol for the procurement of organs from adults by the University of Pittsburgh Medical Center defines cardiac death when the heart has stopped for 120 seconds, on the basis of the claim that autoresuscitation had never occurred after that period.
There are, however, varying opinions as to how long should one wait before cardiac death is declared. It is possible to restart a heart physiologically by means of external stimulation even beyond the period of 120 seconds. Some experts believe in waiting for 10 minutes or longer. Others would go for 5 minutes.
To put things into perspective, let’s look at some statistics on heart transplant from the American Heart Association:
- 2,192 heart transplants were performed in the US in 2006; 2,125 in 2005.
- In the US, 74.2% of heart transplant patients are male; 68.4% are white; 20.0% are aged 35 to 49 and 55.3% are aged 5 to 64.
- As of June 15, 2007, the five-year survival rate was 72.3% for male heart transplant recipients and 67.6% for females.
Clearly, heart transplant have saved thousands of lives since the first successful procedure was performed in 1968. However, if more lives were to be saved, the definition of life and death have to be resolved.
Next in this series: pediatric heart transplants
Photo credit: bizior