Both cardioversion and defibrillation deliver an electrical shock to the heart. The shock can restore a normal heartbeat. Both types of treatment are used in people who have abnormal heartbeats or heart rhythms, called arrhythmias.
Cardioversion is a lower-energy shock delivered to the heart which can stop a very fast arrhythmia.
Defibrillation is a high-energy shock delivered to the heart. This type of treatment is needed when a person has a very fast and chaotic arrhythmia in the heart’s lower chambers (ventricles).
The concept behind cardioversion and defibrillation is the same. Both types of treatment stop all electrical activity in the heart. When the heart resumes beating, any problems with the electrical system should be corrected.