There are many types of defibrillators including: * Automated external defibrillator (AED), also called a fully automated defibrillator, which performs all of the functions needed for defibrillation on an internal computer. The operator applies pads to the chest and side of a person suffering v-fib, assures that all people are clear from the patient and then usually pushes a button to deliver the shock when prompted by the system. * Manual defibrillator, which requires the operator to assess the need for defibrillation, select an energy level, charge the machine and deliver the shock. * Automatic implanted cardioverter defibrillator, which is surgically implanted into patients who are at risk for sudden cardiac death caused by arrhythmia and automatically detects and treats arr