Automatic Implantable Cardioverter-Defibrillator (AICD) is a device intended to convert life threatening rhythms of the heart which may cause sudden cardiac death also known as cardiac arrest, to a sinus (normal) rhythm.

Sudden cardiac death is the cause of 50% of all cardiac related deaths. When a life threatening rapid or slow rhythm is sensed by the device, an electric discharge of about 25 to 30 joules is sent through a pair of electrodes; one is sent to the pacemaker and the other to the apex of the right ventricle. Many of these devices hold a memory so the rhythm which induced the AICD may be recorded for later analysis.