An automated external defibrillator (AED) is a portable device used to restore normal heart rhythm to patients in cardiac arrest by delivering an electrical shock to a patient thought the chest wall. Cardiac arrest is an abrupt loss of the heart function. This occurrs mainly because of ventricular fibrillation.
A built-in computer checks a victim's heart rhythm through adhesive electrodes. The MCU calculates whether defibrillation is needed and a recorded voice indicates whether to press the shock button on the AED. This shock momentarily stuns the heart and stops all activity giving the heart an opportunity to resume beating effectively.
The charge is generated by high-voltage generation circuits from energy stored in a capacitor bank in the control box. The capacitor bank can hold up to 7 kV of electricity. The shock delivered from this system can range from 30 to 400 joules.