Subcutaneous defibrillators constitute new tools at the disposal of interventional cardiologists - arrhythmiologists regarding the prevention and treatment of sudden death. They are an evolution of transvenous defibrillators that have been implanted, for at least 30 years, for either primary (i.e. patients who have not yet experienced a life-threatening arrhythmia but are at increased risk) or secondary (patients who have survived a malignant arrhythmia in the past) prevention.

Defibrillators are small computers similar to pacemakers. They consist of a generator and electrodes and have the ability to recognize dangerous arrhythmias and restore them by administering electrical energy (shock). An advantage of intravenous defibrillators is the ability to reverse a malignant arrhythmia by delivering rapid pacing (antitachycardia pacing).

The subcutaneous defibrillator consists of an electrode that is placed subcutaneously (not in contact with the heart but just under the skin) along the sternum, while the generator is placed through an incision in the left axilla. This results in avoiding complications like pneumothorax and endocarditis. The operation can be done either under general anesthesia or under deep sedation (intoxication).

Therefore, the subcutaneous defibrillator has an absolute indication for implantation in patients, where there is no possibility of placing the classical transvenous defibrillator and they do not need pacing, such as patients with occlusion of the veins of the upper limbs as well as in other categories of patients:

• pediatric patients
• young patients with acquired genetic syndromes such as patients with long QT or Brugada syndrome
• patients with a history of endocarditis
• patients with an increased risk of infection of the defibrillator device or its electrodes (e.g. chronic hemopurifying patients, immunocompetent patients, undergoing chemotherapy due to malignancy)

Post-operative course and follow-up do not differ from usual practice. The next day the patient is discharged while the post-operative pain is treated with mild painkillers.

This photo shows an x-ray of a patient with a subcutaneous defibrillator implanted at Paleo Faliro Medical Center.