Objective: A new generation of leadless cardiac pacemakers effectively overcomes the main limitations of conventional devices, but only offer single-chamber pacing, although dual-chamber or multisite pacing is highly desirable for most patients. The combination of several leadless pacemakers could facilitate a leadless multisite pacemaker but requires an energy-efficient wireless communication for device synchronization. This work investigates the characteristics of conductive intracardiac communication between leadless pacemakers to provide a basis for future designs of leadless multisite pacemaker systems. Methods: Signal propagation and impedance behavior of blood and heart tissue were examined by in vitro and in vivo measurements on domestic pig hearts and by finite-element simulations in the frequency range of 1 kHz-1 MHz. Results: A better signal transmission was obtained for frequencies higher than 10 kHz. The influence of a variety of practical parameters on signal transmission could be identified. A larger distance between pacemakers increases signal attenuation. A better signal transmission is obtained through larger inter-electrode distances and a larger electrode surface area. Furthermore, the influence of pacemaker encapsulation and relative device orientation was assessed. Conclusion: This study suggests that conductive intracardiac communication is well suited to be incorporated in leadless pacemakers. It potentially offers very low power consumption using low communication frequencies. Significance: The presented technique enables highly desired leadless multisite pacing in near future.
