Did you know that...? The heart continues to beat even when it is outside the body
As long as the heart muscle receives oxygen and nutrients, it will continue to contract on its own, without any connection to the central nervous system.
When a person dies, their heart does not stop working immediately or definitively, and it is precisely this that makes heart transplants possible. After the removal of the organ from a donor, the medical team traditionally has 4 to 6 hours to implant it in the recipient, keeping it cold to slow its metabolism. After that time window, the risk that the heart will fail after the transplant increases dramatically.
A body with its own autonomy
All this is possible because the heart does not need the brain to beat. The key is the sinoatrial node, a group of cells located in the right atrium that functions as a natural pacemaker. This node generates electrical impulses automatically and rhythmically, between 60 and 100 times per minute, thanks to a property called cardiac automatism.
As long as the cardiac muscle receives oxygen and nutrients, it will continue contracting by itself, without connection to the central nervous system. That is why, once it has been implanted in the recipient and blood flow has been restored, the donor’s heart usually starts beating again by itself, without the need for any external stimulus.
Avances en trasplantes de corazón
Moreover, with the new ex vivo perfusion machines, known as heart in a box, the organ is kept beating and oxygenated outside the body, which has made it possible to extend that time window and save hearts that previously would have been discarded because of the distance between donor and recipient.
In laboratories, pig hearts have been kept beating for more than an hour connected to perfusion machines that mimic the body’s environment, which makes it possible to study cardiovascular diseases and test new treatments without the need to intervene in living beings.
This advance has been especially important for donation after circulatory death, that is, after a definitive failure of circulation, and not due to brain death. In these cases, there is a brief period, called warm ischaemia, between the cessation of circulation and the moment when the heart once again receives oxygen through perfusion techniques.
The shorter this period is, the better the cardiac tissue is preserved. Thanks to these protocols, this type of donation could increase the availability of hearts for transplant in our country by up to 10%.
