A defibrillator is used to treat cardiac dysrhythmias. Specifically it helps for ventricular fibrillation (VF).
A defibrillator delivers a dose of electric current to the heart.
Manual external defibrillator
Manual external defibrillators are used by healthcare professionals. They are used in conjunction with an electrocardiogram to diagnose the cardiac rhythm and then manually determine the voltage and timing for the electrical shock.
Automated external defibrillator (AED)
Automated external defibrillators are designed for use by laypersons. AEDs contain technology for analysis of heart rhythms. As a result, it does not require a trained health provider to determine whether or not a rhythm is shockable.
Manual internal defibrillator
Manual internal defibrillators deliver the shock through paddles placed directly on the heart. They are mostly used in the operating room and, in rare circumstances, in the emergency room during an open heart procedure.