Novel passive implantable atrial defibrillator using transcutaneous radiofrequency energy transmission successfully cardioverts atrial fibrillation.
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.


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, 1.54+/-0.02 J). The PIAD waveform had a higher cardioversion success rate than a truncated, 70% tilt monophasic exponential pulse (100 V, 100% versus 78.0+/-7.57%; P=0.001). There were no postshock complications.


CONCLUSIONS
Considering these animal results, this method is promising for cardioverting AF in symptomatic patients.
Manoharan
Ganesh
G
Regional Medical Cardiology Centre, Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, UK.
Evans
Noel
N
Kidwai
Bakthiar
B
Allen
Desmond
D
Anderson
John
J
Adgey
Jennifer
J
D000818:Animals; D001281:Atrial Fibrillation / Q000628:therapy*; D017147:Defibrillators, Implantable / Q000009:adverse effects; D004553:Electric Conductivity; D004554:Electric Countershock / Q000295:instrumentation; D004735:Energy Transfer; D005471:Fluoroscopy; D006321:Heart / Q000000981:diagnostic imaging; D012756:Sheep; D012867:Skin