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.