How Does an Automated External Defibrillator Work?

On countless medical TV shows you’ve likely seen the actor/doctor yell, “Clear!” and administer a life-saving shock to the “patient.” This dramatization of defibrillator technology doesn’t tell the whole story. How exactly does a cardiac defibrillator work?

Defibrillation is the delivery of lifesaving electrical energy to the heart during an abnormal rhythm or very rapid erratic beating of the heart known as Ventricular Fibrillation (VF).  Electrodes placed on the victim’s chest to serve as the conduit for delivering a measured electrical shock to the heart to restore natural rhythm.

Automatic external defibrillators, or AEDs, are small computerized devices that analyze heart rhythms and provide the shock needed for defibrillation. Through electrodes placed on a patient’s chest a processor inside the AED analyzes the victim’s heart. The machine will not shock unless it is necessary; AEDs are designed to shock only when VF, a common cause of cardiac arrest, is detected.

After the processor analyzes the heart rhythm and determines a shock is required, an electric current is delivered to the heart through the victim’s chest wall through the adhesive electrode pads. The shock delivered by a cardiac defibrillator interrupts the chaotic rhythm and allows it to return to normal.

HeartSine AEDs can be used by anyone, anytime, or anywhere to administer a lifesaving shock to victims of Sudden Cardiac Arrest (SCA). Audio and visual prompts guide the user step by step through the rescue process.

With CPR alone, the chance of survival after SCA is less than 5 percent; when CPR is combined with the use of a cardiac defibrillator within the first few minutes, the chance of survival can increase dramatically to more than 75 percent.

Having an AED on the premises gives victims of SCA the best chance of survival until paramedics arrive and take over care.