Abstract 15236: Subcutaneous Nerve Activity and Heart Rate Acceleration in Ambulatory Dogs
The skin is well innervated by sympathetic nerves. We hypothesize that subcutaneous nerve activity (SCNA) is a good measure of sympathetic tone in ambulatory dogs. We performed sterile surgery to implant a radiotransmitter in 7 ambulatory dogs to record left stellate ganglion nerve activity (SGNA), left thoracic vagal nerve activity (VNA) and SCNA from two widely spaced bipolar electrodes in the subcutaneous space of the left thorax. The nerve activities were integrated over 1-min intervals for 24 hrs. Figure shows typical examples of SGNA, SCNA associated with heart rate (HR) acceleration. There is a significant positive correlation between SGNA and SCNA, with r values of 0.70 (95% confidence interval, CI 0.61 to 0.84) in these 7 dogs (p < 0.05 for each dog). The r value between SCNA and heart rate (0.74, 95% CI 0.68 to 0.80) is significantly (p=0.007) higher than the r value between SGNA and heart rate (0.56, 95% CI 0.45 to 0.67). We also analyzed 10 episodes per dog in which heart rate exceeded 150 bpm. We found that both SGNA and SCNA invariably preceded these tachycardia episodes. There is a strong indication of circadian variation of both SCNA and SGNA in all dogs studied, but VNA did not show a significant circadian variation. Crosstalk between electrodes was ruled out because SGNA, VNA and SCNA bursts occurred at different times. We conclude that it is feasible to continuously assess sympathetic tone by recording nerve activities from subcutaneous space in ambulatory dogs. The SCNA more effectively predicts heart rate acceleration than SGNA.
- © 2013 by American Heart Association, Inc.