An AED works by analyzing the heart’s rhythm and sending a shock to the heart to restore a normal rhythm if needed. The defibrillator is used to help people experiencing sudden cardiac arrest (SCA).

The heart’s electrical system controls its rate and rhythm. If the electrical system malfunctions, it can cause the heart to beat with great irregularity, also referred to as an arrhythmia or Ventricular Fibrillation (VF). Should the heart suddenly stop pumping blood, a person will enter sudden cardiac arrest.

AEDs analyze the heart’s rhythm through sticky pads with sensors called electrodes or electrode pads. They are attached to the chest of someone experiencing sudden cardiac arrest. The electrodes send information about the person’s heart rhythm to a computer in the AED machine. The AED analyzes the heart rhythm to find out whether an electric shock is needed. A shock is then delivered through the electrodes if required.

The following video provides more details on how an AED works and how to use an AED.