This is a type of cardiac device that is implanted into the body and acts as a defibrillator to restore rhythm to the heartbeat. It does this by performing cardioversion on the heart in which electrical currents are used to restore the correct rhythm to the heart. It is important to remember that the heartbeat and rhythm is because of a synchronous contraction of the heart muscles. These muscles receive electrical impulses which signal contraction, and if this system fails, especially in the case of the ventricles, sudden death can result.