Defibrillators are small computer devices used to treat heart rate and heart rhythm abnormalities in patients who suffer from heart diseases. The devices are designed to be surgically implanted in the chest area and monitor cardiac function. Defibrillators can detect a heartbeat that is either too fast (tachycardia) or too slow (bradycardia), and delivers an electrical impulse or a series of shocks to various parts of the heart to restart normal function.