Introduction
Conventional transvenous pacemaker has been an effective therapy in patients with symptomatic bradycardia. However, implantation-related complications are not uncommon, including electrode dislocation, electrode fracture, venous thrombosis, tricuspid regurgitation, and, in particular, infection that usually requires a complete removal of the entire pacemaker system.1, 2 The leadless pacemaker, on the other hand, overcomes these complications and its safety and efficacy have been reported in previous clinical studies3-5. However, there is uncertainty over the implantation site for the leadless pacemaker due to patients’ heart anatomical variations and operators’ experience and preference. Previous studies have shown that mid-septal implantation of MicraTM leadless pacemaker has advantages in terms of surgical safety and narrower paced QRS duration than implantation at the right ventricular (RV) apex where the procedure is more prone to causing cardiac perforation and RV apical pacing generates the widest QRS duration.6 Previous clinical investigations of transvenous lead implantation have found that mid-septal implantation of the transvenous lead, when compared with the apical placement, significantly reduces the incidence of pericardial tamponade and myocardial perforation (52% vs. 33%, respectively).7, 8 However, there have been limited reports of clinical investigations on mid-septal deployment of MicraTM leadless pacemakers.
Recently, the technique of right ventriculography via contrast injection under fluoroscopy has been used to place the pacing lead tip in the RV septum.9 The present study aimed to explore the technique of right ventriculography to locate a site in the RV mid-septum for deployment of a MicraTM leadless pacemaker. The study objective was to assess the feasibility and safety of right ventriculography in guiding the mid-septal implantation of MicraTM leadless pacemakers in comparison with that without right ventriculography. Post-implantation, computed tomography (CT) scan was conducted to confirm the accuracy of the site of MicraTM leadless pacemaker in the RV mid-septal region. In addition, the study compared electrical characteristics of pacing by MicraTM leadless pacemaker in septal locations.