Inappropriate Shocks due to Subcutaneous Air in a Patient With a Subcutaneous Cardiac Defibrillator
A 56-year-old man with a history of ischemic cardiomyopathy and a transvenous implanted cardiac defibrillator (ICD) for secondary prevention presented with device endocarditis requiring ICD removal and lead extraction. After extended therapy with intravenous antibiotics and resolution of systemic infection, a subcutaneous implantable cardiac defibrillator (S-ICD; Cameron Health/Boston Scientific, San Clemente, CA) was electively implanted with standard technique.1 Specifically, 3 subcutaneous pockets were created, a subaxillary pocket for the generator and 2 parasternal pockets, to which the defibrillator coil was tunneled. After the coil and generator were positioned and sutured and after the fascial layer was closed, sustained ventricular fibrillation was induced. Detection was successful in the primary vector, which involves the pulse generator and proximal parasternal sensing electrode (Figure 1). Sinus rhythm was effectively restored with a submaximal 65-J polarity shock with time to therapy of 13 seconds and impedance of 55 Ω. Device interrogation the next day was unremarkable; the device, per its automatic programming, chose the secondary vector for detection (which involves the pulse generator and distal parasternal sensing electrode; Figure 1). The postoperative course was otherwise uneventful, and the patient was discharged the following day.