The heart has a natural pacemaker that sends electrical pulses through the heart, regulating the beat and moving blood throughout the body. When the electrical system of the heart is disrupted, a person is said to have an arrhythmia (irregular heart beat), and more than half of all cardiac deaths are sudden deaths — the abrupt loss of heart function.
An implantable cardioverter defibrillator (ICD) is designed to quickly detect a life-threatening arrhythmia and prevent sudden cardiac death. The ICD is placed within the body to recognize rapid arrhythmias and correct them with an electronic shock. An ICD consists of a pulse generator and a capacitor that can shock the heart, a circuit that tells the ICD when to discharge, and electrodes placed in the heart to sense the rhythm and deliver a shock to the heart muscle. All ICDs also have a built-in pacemaker, which also allows the device to correct heartbeats that are too slow. In this case, the pacemaker in the ICD will send a low electrical pulse to the heart to “remind” it to beat.
An ICD runs on batteries that last for five to seven years, and during regular clinic visits, a physician can determine when the device is running low and needs to be replaced.
