An automatic implantable cardiac defibrillator is a device capable of detecting a dangerous heart rhythm and applying an electrical shock to the heart in order to convert the rhythm back to normal. This device is implanted under the skin under local anesthesia, much like a pacemaker, in patients who have a predisposition to dangerous arrhythmias that could cause loss of consciousness. Following implantation, the device is checked at regular intervals several times a year, on an outpatient basis.