Abstract 16048: High Frequency Ganglionated Plexus Stimulation in Man Does Not Influence Local Atrial or Pulmonary Vein Activation Patterns
Introduction Ectopic beats from the pulmonary veins (PV) trigger atrial fibrillation (AF) and are modulated by autonomic stimulation. Ganglionated plexus (GP) are conglomerations of atrial nerves and can be activated by high frequency pacing. The mechanism through which GP stimulation results in PV ectopy is currently incompletely understood.
Hypothesis We hypothesize that GP stimulation changes activation patterns in the atrium and PVs, thereby facilitating PV ectopy.
Methods GPs were stimulated during thoracoscopic surgery for AF. A stepwise stimulation protocol consisted of stimulation (16 Hz) with 1, 2, 5, 10 and 25mA output of the right and left GPs. Simultaneously, electrograms were recorded epicardially from the PV or atrium with a multielectrode (48 electrodes, 6x8 pattern, interelectrode distance 0,5mm). Activation maps were created from sinus beats before and after GP stimulation. As a measure of autonomous modulation, we used change in heart rate and AV conduction.
Results We studied 23 patients. A total of 56 recordings were analysed. Predominantly low-output recordings were available (1mA n=24, 2mA n=20, 5mA n=7, 10mA n-=3, 25mA n=2), because AF was frequently induced through capture of the atrium at high output. PV and atrial electrogram morphology remained unchanged after GP stimulation. Local atrial and PV activation patterns and conduction times were unaffected by GP stimulation (Figure 1). There was a trend toward increased in PQ-interval of (186±32ms vs 189±34ms, p=0,072), and a significant atrial cycle length increase (948±130ms vs 975±142ms, p=0,022) indicating a vagal effect on the SA and AV-node.
Conclusion Low output GP stimulation causes a vagal response but does not result in local changes in activation pattern or conduction time in the atrium or PV's. Therefore, the mechanism of GP stimulation on the induction of AF most likely results from triggered firing from the PVs rather than (micro) re-entry or changes in the local electrogram.
- © 2011 by American Heart Association, Inc.