Chronic atrioventricular nodal vagal stimulation: first evidence for long-term ventricular rate control in canine atrial fibrillation model.
BACKGROUND
We have previously demonstrated that selective atrioventricular nodal (AVN) vagal stimulation (AVN-VS) can be used to control ventricular rate during atrial fibrillation (AF) in acute experiments. However, it is not known whether this approach could provide a long-term treatment in conscious animals. Thus, this study reports the first observations on the long-term efficacy and safety of this novel approach to control ventricular rate during AF in chronically instrumented dogs.


RESULTS
In 18 dogs, custom-made bipolar patch electrodes were sutured to the epicardial AVN fat pad for delivery of selective AVN-VS by a subcutaneously implanted nerve stimulator (pulse width 100 micros or 1 ms, frequency 20 or 160 Hz, amplitude 6 to 10 V). Fast-rate right atrial pacing (600 bpm) was used to induce and maintain AF. ECG, blood pressure, and body temperature were monitored telemetrically. One week after the induction of AF, AVN-VS was delivered and maintained for at least 5 weeks. It was found that AVN-VS had a consistent effect on ventricular rate slowing (on average 45+/-13 bpm) over the entire period of observation. Echocardiography showed improvement of cardiac indices with ventricular rate slowing. AVN-VS was well tolerated by the animals, causing no signs of distress or discomfort.


CONCLUSIONS
Beneficial long-term ventricular rate slowing during AF can be achieved by implantation of a nerve stimulator attached to the epicardial AVN fat pad. This novel concept is an attractive alternative to other methods of rate control and may be applicable in a selected group of patients.
Zhang
Youhua
Y
Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Yamada
Hirotsugu
H
Bibevski
Steve
S
Zhuang
Shaowei
S
Mowrey
Kent A
KA
Wallick
Don W
DW
Oh
Seil
S
Mazgalev
Todor N
TN
D000818:Animals; D001281:Atrial Fibrillation / Q000628:therapy*; D001283:Atrioventricular Node / Q000294:innervation*; D004195:Disease Models, Animal; D004285:Dogs; D004599:Electric Stimulation Therapy / Q000379:methods*; D013686:Telemetry; D014630:Vagus Nerve / Q000502:physiology*; D016276:Ventricular Function