Internal Cardiac Defibrillators (ICDs) - An automatic ICD is a device that monitors a person's heart rate. It can be used to monitor and treat tachycardia (when the heart beats too fast), brachycardia (when the heart beats too slowly). They do also act as pacemakers to treat rhythms that are too slow also if needed
The device is programmed to either speed up or slow down the heart, depending on the patient's heart rate. The automatic ICD gives the heart a shock if the patient starts having life-threatening arrhythmias (abnormal heart beat) or an abnormally high heart rate.
There are different kinds of automatic ICD systems, but they all have two parts - electrodes (thin, flexible wires) and a generator. The electrodes, or leads, monitor or sense the heart's electrical activity. The generator is the battery power source. It is a small metal can about 1/2 the size of a deck of cards.
The generator stores information about any arrhythmias the patient may have, and tracks how often a shock is needed.
About the procedure: Typical surgical implantation of an automatic ICD system is done with moderate to deep sedation. The surgery usually takes between 1 and two hours.