Pacemakers are small battery operated devices which are inserted under the skin and underlying tissue below the collar bone. The procedure is done in a cathlab (operating theater) and takes about an hour. Pacemakers help when slow heart rhythms pose symptoms.
Implantable cardiac defibrillator (ICD) has all functions of a pacemaker, but in addition can also give shock in a life threatening arrhythmia conditions and potentially save a patient. This type of device is inserted if it is deemed that the patient is at high risk of developing life threatening arrhythmia.