Novel Passive Implantable Atrial Defibrillator Using Transcutaneous Radiofrequency Energy Transmission Successfully Cardioverts Atrial Fibrillation

Abstract

Background-Conventional methods for cardioversion of atrial fibrillation (AF) to sinus rhythm have numerous difficulties. A novel method for cardioversion using the passive implantable atrial defibrillator (PIAD) was tested in acute animal models. This device does not have a battery or a capacitor to store energy and is activated by transferring RF energy across the skin from an external transmitter to the subcutaneously implanted defibrillator. On activation, a novel monophasic shock waveform with 5% tilt is delivered to the heart via 2 intracardiac defibrillation leads. Methods and Results-Cardioversion attempts with the device were assessed in 2 phases: a feasibility and efficacy study and randomized comparison against standard waveforms. Defibrillation leads were placed transvenously into the distal coronary sinus and the right atrial appendage. These were connected to the subcutaneously implanted PIAD. Sustained AF was induced by rapid atrial pacing. The transmitter coil was placed on the skin overlying the defibrillator, and defibrillation synchronized to the R wave was attempted. The method was found to be efficacious at very low voltage and energy, with 100% cardioversion success observed for 10-ms 100-V shocks (mean energy, 1.54Ϯ0.02 J). The PIAD waveform had a higher cardioversion success rate than a truncated, 70% tilt monophasic exponential pulse (100 V, 100% versus 78.0Ϯ7.57%; Pϭ0.001). There were no postshock complications. Conclusions-Considering these animal results, this method is promising for cardioverting AF in symptomatic patients.

Theory and practice of defibrillation: (1) Atrial fibrillation and DC conversion

“…The role of implantable devices is still under investigation. Hybrid devices that maintain sinus rhythm by multisite atrial pacing and facilitate recurrent internal direct current cardioversion by the delivery of radiofrequency energy 20 have potential for some patients with AF.…”

A Pilot Study of a Low‐Tilt Biphasic Waveform for Transvenous Cardioversion of Atrial Fibrillation: Improved Efficacy Compared with Conventional Capacitor‐Based Waveforms in Patients

“…Various waveform parameters have been studied in order to increase success. We have previously shown that low-tilt monophasic 3,4 and biphasic 5 waveforms are more successful than conventional higher tilt capacitorbased waveforms for the cardioversion of AF in the laboratory. The aim of this pilot study was to investigate if the low-tilt biphasic waveform was more successful and could be delivered safely in patients with persistent and induced AF.…”

Comparing the Efficacy and Safety of a Novel Monophasic Waveform Delivered by the Passive Implantable Atrial Defibrillator With Biphasic Waveforms in Cardioversion of Atrial Fibrillation

“…1 The Ventritex HVSO2 defibrillator (160 F; Ventritex) generated the 3 biphasic waveforms (6 ms in each phase; Figure 1a). A custom-made capacitor-resistance device added to the output circuit enabled waveform rounding.…”

“…U sing an external radio-frequency energy transmitter to transfer energy transcutaneously to the passive implantable atrial defibrillator (PIAD), we recently reported transvenous atrial defibrillation success of 100% at 100 V (1.54Ϯ0.02 J) and pulse width of 10 ms. 1 The PIAD (without a capacitor or a battery), delivering a novel monophasic waveform (slow rising and falling times, a negligible tilt, and rounded leading and trailing edges; Figure 1a), was more efficacious than the standard or rounded monophasic waveforms. 1 Nevertheless, compared with standard monophasic waveforms, biphasic waveforms have improved efficacy in atrial fibrillation (AF) cardioversion, with a reduction in defibrillation threshold.…”

“…1 Nevertheless, compared with standard monophasic waveforms, biphasic waveforms have improved efficacy in atrial fibrillation (AF) cardioversion, with a reduction in defibrillation threshold. 2 The aims of this study of cardioversion of AF were to compare the efficacy of the PIAD waveform against 3 biphasic waveforms at varying voltage settings in pigs ( Figure 1a).…”