An implantable cardioverter defibrillator (ICD) (also known as automatic implantable cardioverter defibrillator (AICD) is an electronic device implanted just under the skin of the upper chest, similar to a
pacemaker. It is about the size of a pager and performs several functions. It monitors your heart rhythm continuously. Upon detection of a dangerous rhythm (ventricular tachycardia (VT) and
ventricular fibrillation (VF)), the device will either pace or deliver a shock to terminate the dangerous rhythm. The ICD protects patients at risk from premature deaths due to life threatening heart rhythm. It can also pace the heart when the rate is too slow.