Leadless Cardiac Devices-Pacemakers and Implantable Cardioverter-Defibrillators

Since the initial introduction of pacemakers and defibrillators, the rapid growth in microcircuit and battery technology has increased the longevity demands and exposed the vulnerabilities of transvenous leads. Over a half of century later, leadless pacemaker and defibrillation systems are just reaching the clinical arena. Despite the remarkable advantages of leadless pacing systems, the data are still quite limited and broad implementation of these technologies need to occur in a cautious and deliberate fashion as the peri-procedural risks remains high. Two of the three systems, Nanostim(TM) (St. Jude Medical) and Micra Transcatheter Pacing System (Medtronic Inc.), have shown the greatest applicability, although they are currently only limited to single chamber pacing and procedural risks are modest. The WiCS(TM)-LV system (EBR Systems, Inc.) is anatomically limited and benefits a small subset of patients. Leadless implantable cardioverter-defibrillator (ICD) therapy, the subcutaneous ICD (S-ICD, Cameron Health/Boston Scientific), has demonstrated encouraging short-term safety and efficacy data supporting its use. Since its introduction, modifications to the implant procedure, pre-screening of patients, and programming of the devices have reduced procedural-related complications and inappropriate shocks. The S-ICD is a promising technology, but it is premature to conclude that it will supplant conventional ICDs. At this current time, the S-ICD may benefit select patients, such as those with recurrent bacteremia, vascular access limitations, and who may be prone to transvenous lead failure.