Minimally invasive percutaneous epicardial placement of a prototype miniature pacemaker with a leadlet under direct visualization: A feasibility study in an infant porcine model

Background: Pacemaker implantation in infants is limited to epicardial lead placement and an abdominal generator pocket. We propose a minimally invasive solution using a prototype miniature pacemaker with a steroid-eluting leadlet that can affix against the epicardium under thoracoscopy. Objective: The purpose of this study was to evaluate the safety and feasibility of acute implantation of a prototype miniature pacemaker in an infant porcine model. Methods: A self-anchoring 2-channel access port was inserted into a 1-cm incision left of the subxiphoid space. A rigid thoracoscope with variable viewing angle was inserted through the main channel to visualize the heart under insufflation. An 18-G needle through the second channel accessed the pericardial space, which was secured with a 7-F sheath. The leadlet was affixed against the epicardium using a distal helical side-biting electrode. The sheath, thoracoscope, and port were removed, and the pacemaker was tucked into the incision. Ventricular sensing, lead impedances, and capture thresholds were measured. Results: Twelve piglets (weight 4.8 ± 1.9 kg) had successful device implantation. The median time from incision to leadlet fixation was 21 minutes (interquartile range [IQR] 18–31 minutes). The median lead impedance was 510 Ω (IQR 495–620 Ω). The median R-wave amplitude was 5.7 mV (IQR 4.2–7.0 mV). The median capture threshold was 1.63 V (IQR 1.32–2.97 V) at 0.4 ms pulse width and 1.50 V (IQR 1.16–2.38 V) at 1.0 ms pulse width. There were no complications. Conclusion: Minimally invasive epicardial placement of a prototype miniature pacemaker under thoracoscopy was safe and avoided open chest surgery and creation of an abdominal generator pocket.