Two parts of this system are placed inside the body. The defibrillator is a small metal case that contains electronics and a battery. It is similar to a pacemaker in that it is designed to correct arrhythmias. But while a pacemaker increases a slow heart rate, a defibrillator detects and corrects fast and slow heart rates.
Leads are specialized, thin, insulated wires that are attached to the defibrillator.
The third part, the programmer, is kept in a hospital or clinic. A doctor or nurse uses this specialized computer to monitor and change the instructions of the implanted defibrillator. Different therapies are used to reset the heart rhythm back to normal. However, a defibrillation system does not cure or prevent the arrhythmia. Instead, the system stops the arrhythmia and stores information for the doctor to evaluate later.