Dual-Chamber Pacing from a Single Leadless Device: Preclinical Implant and Retrieval Feasibility Study.

BACKGROUND: 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. OBJECTIVE: To demonstrate the feasibility of single device leadless dual-chamber pacing (DDD) in an ovine model by assessing implant safety, chronic electrical performance, and chronic device retrieval. METHODS: Twelve 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. RESULTS: Device implantation was successful in all twelve sheep, with no major complications through 6-months. At 6-months, the mean capture threshold was 0.6±0.2V@0.24ms at 402±80Ω for atrial pacing and 1.2±0.2V@0.24ms at 531±258Ω for ventricular pacing. Average P-wave and R-wave amplitudes were 2.2±1.0mV and 4.9±3.7mV, respectively. All six 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 5/6 achieving dual-chamber capture on the first attempt. CONCLUSION: This study demonstrates the proof-of-concept and feasibility of fully leadless DDD pacing via a single device implanted in the TOK, including chronic pacing efficacy, and successful retrieval through 6-months.