LAUSR

Introduction Cardiac pacing has been an established therapy for patients with bradyarrhythmias. In conventional pacemakers, leadrelated complications such as venous obstruction, insulation fracture, and lead-related infection are the main concern after pacemaker implantation. Recently leadless pacemaker systems (LPS) were developed and now function to overcome these lead-related complications. The Nanostim LPS (St Jude Medical, St. Paul, MN) can provide pacing for bradyarrhythmias. This system is a pulse generator with built-in battery and electrodes for implantation in the right ventricle. It is well known that in conventional pacing systems the pacing thresholds of implanted leads tend to rise initially owing to tissue injury surrounding the implanted pacing lead. These initially high pacing thresholds tend to attenuate within the first 5–10 minutes after implantation. However, if these high pacing thresholds remain after this period of time, then repositioning of the conventional pacemaker lead may be considered. The behavior of pacing thresholds in LPS is not well documented. We report on 2 patients with LPS in whom pacing thresholds showed differing behavior from conventional pacemaker systems.