This is the process of administering an electric shock to the person in order to allow normal heart rhythm to take place again. There are some people who are able to live again because of this. The longer the time that the heart stops, the more damage that it can cause to the brain. The brain requires constant oxygen that it can get from people’s blood.
The moment that it does not get enough blood, there is a big chance that it will stop and die. Even if the heart resumes its pumping again, things might never be the same for a person who is already declared “brain dead.”