Internal cardioversion uses a device called an implantable cardioverter defibrillator (ICD). ICDs have two parts: a pulse generator and electrodes (wires). The generator is implanted under the skin, like a pacemaker. The wires connect the generator to the heart. If the heart starts beating incorrectly, the defibrillator will sense it and send an electrical shock to the heart, which returns the beat to normal. The generator battery usually lasts for 5 to 8 years.
An ICD is normally used for treating ventricular tachycardia or ventricular fibrillation. The severity of these arrhythmias can cause sudden death because of the dangerously fast heart rate. Less often, internal cardioversion is used to treat atrial (upper heart chamber) arrhythmias.
Before an internal defibrillator is used to perform internal cardioversion[/COLOR], your cardiologist or other health care provider will make sure the electric shock does not make your arrhythmia worse. Once set, the ICD works the same way an external defibrillator would.