Effects of peripheral cardiac autonomic nerve stimulation on time
and frequency domain measures of heart rate variability.
Bailey, J. Russell, David M. Fitzgerald, Robert J. Applegate.
The Bowman Gray School of Medicine, Wake Forest University, Section
of Cardiology, Winston-Salem, NC
APStracts 2:0501H, 1995.
Heart rate variability is used to assess cardiac autonomic tone. We
sought to determine the relationship of graded direct stimulation of
efferent cardiac autonomic nerves on heart rate variability in an
anesthetized canine model. Time and frequency domain variables were
measured at denervated baseline, and during electrical stimulation of
the vagi and ansae subclaviae over a wide range of frequencies. Both
vagal and ansae stimuli produced significant changes in heart rate
which correlated with the intensity of stimulation. Vagal stimulation
resulted in small increases in time domain indices of heart rate
variability and in the power spectrum from 0.04 to 0.40 Hz, but with
no correlation between stimulus intensity and changes in these
indices. By contrast, ansae stimulation had no effect on time or
frequency domain measures. In the absence of central modulation of
autonomic outflow, indices of heart rate variability reflect the
presence of vagal input, but do not correlate with the level of vagal
tone, and are unaffected by changes in mean sympathetic tone.
Received 23 June 1995; accepted in final form 9 October 1995.
APS Manuscript Number H576-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95