Dual-chamber pacing from a single leadless device: Preclinical implant and retrieval feasibility study

Sequential atrioventricular pacing can be accomplished with separate atrial and ventricular devices. Integration of atrial and ventricular pacing within a single leadless device represents a novel approach to dual-chamber pacing (DDD).

This study aimed to demonstrate the feasibility of single-device, leadless DDD in an ovine model by assessing implant safety, chronic electrical performance, and chronic device retrieval.

12 sheep were implanted with a leadless DDD pacemaker in the triangle of Koch (TOK) via a jugular venous approach. Chronic electrical performance through 6 months was assessed using periodic cardiac monitoring. At 6 months, half of the devices were retrieved using a custom retrieval system, followed by attempted reimplantation of a new leadless DDD device in the TOK.

Device implantation was successful in all 12 sheep, with no major complications through 6 months. At 6 months, the mean capture threshold was 0.6 ± 0.2 V at 0.24 ms at 402 ± 80 Ω for atrial pacing and 1.2 ± 0.2 V at 0.24 ms at 531 ± 258 Ω for ventricular pacing. Average P-wave and R-wave amplitudes were 2.2 ± 1.0 mV and 4.9 ± 3.7 mV, respectively. All 6 leadless pacemakers were successfully retrieved without complication (mean retrieval time 20 ± 3 minutes). All 6 animals were reimplanted with a new device in the TOK, with 5 of 6 achieving dual-chamber capture on the first attempt.

This study demonstrates the proof of concept and feasibility of fully leadless DDD via a single device implanted in the TOK, including chronic pacing efficacy and successful retrieval through 6 months.