Abstract 12655: Cardiac Pacing Alters Neural Information Processing in the Intrinsic Cardiac Nervous System
Introduction: Cardiac pacing is an established therapy; however, it may have detrimental effects on cardiac neurohumoral control. We investigated the effects of pacing on the intrinsic cardiac nervous system (ICNS), an important coordinator of regional cardiac function.
Methods: Activity from intrinsic cardiac (IC) neurons in the ventral interventricular ganglionated plexus (VIV GP) was recorded using a linear microelectrode array in 5 normal pigs. Changes in IC activity were evaluated in response to epicardial pacing (current: 6 mA; pulse width: 2 ms) at 10% above resting heart rate at the following sites: (1) right atrial appendage (RAA), (2) right ventricular (RV) apex, and (3) left ventricular (LV) posterolateral wall.
Results: A total of 72 IC neurons were identified. The proportion of neurons responding to pacing was 23% at RAA, 27% at RV apex, and 27% at LV posterolateral wall. Pacing at each site caused significant activation (p < 0.01), significant suppression (p < 0.01), or no change in firing rate of different subsets of neurons. Of all sites, the largest change in firing rate from basal activity was at the LV posterolateral wall, with a significant increase of 1.38 Hz (p < 0.01) in neurons activated by pacing and a significant decrease of 0.63 Hz (p < 0.01) in those suppressed by pacing (Figure 1). There was also a significant difference in basal activity between neurons activated by pacing versus those suppressed by pacing (p < 0.01).
Conclusions: Our results suggest that pacing has a site-dependent effect on the ICNS. We observed effects with both atrial and ventricular pacing and that LV posterolateral pacing has the greatest impact on neural activity in the VIV GP. Also, neurons with low levels of basal activity tended to be activated by pacing, and those with high levels of basal activity tended to be suppressed, indicating a state-dependent effect. Modulation of information processing in the ICNS may provide the link between pacing and neuroendocrine activation.
Author Disclosures: P.S. Rajendran: None. M. Vaseghi: None. J. Armour: None. J.L. Ardell: Research Grant; Significant; Cyberonics. Consultant/Advisory Board; Significant; Cyberonics. K. Shivkumar: None.
- © 2014 by American Heart Association, Inc.