What is the definition or description of: implantable cardioverter defibrillator?

Heart rhythm device: An implantable cardioverter defibrillator, or icd, is a small device that can automatically detect abnormally fast heart rhythms and stop them with a rapid pulse of paced beats or a shock. It monitors the heart rate and delivers the treatment through special wires, or leads, that may be attached to the inside or outside of the heart or placed under the skin. Most icds also have pacemaker function.