
An Implantable Cardioverter Defibrillator (ICD) is a small, battery powered, pager size device.
Once the ICD is implanted, the leads monitor the heart rate. If the ICD detects ventricular tachycardia or fibrillation, it sends out a controlled burst of impulses (called "overdrive" pacing). If this does not work, the ICD "shocks" the heart
to restore a normal rhythm. ICDs are very effective in preventing sudden deaths and can be implanted with a low rate of complications.
A defibrillator is made up of two parts: