The cardioverter-defibrillator is a small electronic device, implanted in order to identify life-threatening cardiac arrhythmias and perform appropriate electrical intervention to stop it (anti-arrhythmic stimulation, cardioversion, defibrillation). ICD prevents sudden death and improves the chances of survival in patients at particular risk of ventricular tachycardia and ventricular fibrillation. The method of ICD implantation is similar to the pacemaker implantation. The life of an ICD battery depends on the number and type of device intervention. As in the case of stimulators, all patients with ICD are under permanent specialist outpatient care.