An Implantable Cardioverter Defibrillator (ICD) is a battery-powered device placed under your skin. It is connected to your heart by one or more wires (leads) and keeps track of your heartbeat. It is important to realise that ICDs have the ability to pace the heart just like a pacemaker when the heart rate is too slow.
In addition the ICD has the ability to stop fast, potentially lethal arrhythmias arising in the lower chambers of the heart called ventricular tachycardia (VT) or ventricular fibrillation.
The ICD stops these ventricular arrhythmias either by “overdriving” the fast rate or by delivering a small shock directly into the heart thus resetting the rhythm.
The ICD is implanted in exactly the same way as a pacemaker. This is done under local anaesthetic and with sedation. Recovery after the implant is very quick with patients feeling only minimal discomfort for a few days.
At the implant the electrophysiologist may feel that the shock function of the device must be tested. This will be done under deep sedation with the patient asleep. This is often omitted given the high success of the device.