An AICD stands for an Automatic Implantable Cardioverter Defibrillator. It's a specialized device implanted in the chest or abdomen to monitor and regulate abnormal heart rhythms, particularly life-threatening arrhythmias such as ventricular tachycardia (VT) and ventricular fibrillation (VF).

An AICD is similar in function to a pacemaker but has the added capability to deliver an electrical shock (defibrillation) to the heart if it detects a dangerously fast or chaotic rhythm. This shock restores normal heart rhythm and can be life-saving in cases of sudden cardiac arrest.

The components of an AICD include a pulse generator and leads (thin wires) connected to the heart. The pulse generator continuously monitors the heart's electrical activity, and if it detects an abnormal rhythm, it can deliver pacing pulses to restore normal rhythm. If a life-threatening arrhythmia such as VT or VF occurs, the AICD delivers a high-energy shock to the heart to terminate the arrhythmia and restore normal heart rhythm.

AICD implantation is typically performed under local anesthesia, and the procedure is minimally invasive. After implantation, the AICD is programmed to meet the individual needs of the patient, and regular follow-up appointments are scheduled to monitor its function and adjust settings as needed.