Subcutaneous implantable cardiac defibrillators: indications and limitations.

The implantable cardioverter defibrillator is today an indisputable evidence-based treatment for cardiac sudden death both in primary and secondary prevention. However, trans-venous cardioverter defibrillator implantation still carries a not negligible risk of complications both acutely and during follow-up. Trans-venous endocardial lead is the weak link of implantable cardioverter defibrillator (ICD) technology being the source of most mechanical complications on vessels and heart structures and exposed to infection, malfunction and recalls. A totally subcutaneous defibrillation lead has recently been introduced in clinical practice. With the subcutaneous pulse generator forms a defibrillation system that leaves the vessels and the heart completely "untouched." Subcutaneous ICD has proven to be safe and effective in many clinical trials. Patients without pacing indications and at higher risk of complications from trans-venous lead implantation represent the perfect candidates to S-ICD technology. However, with technical improvement, it is reasonable to expect a further expansion of indications.