Journal of cardiovascular electrophysiology
-
J. Cardiovasc. Electrophysiol. · Jul 1996
Clinical TrialEffect of graded increases in parasympathetic tone on heart rate variability.
Time-and frequency-domain measurements of heart rate variability have been used as indices of parasympathetic tone. However, studies of the effect of parasympathetic stimulation on these indices in humans have yielded conflicting results. ⋯ These findings suggest that the respiratory variation in "parasympathetic effect" typically observed at the sinus node can be either increased or decreased by parasympathetic stimulation, depending on the initial level of parasympathetic tone and the intensity of stimulation. This resolves the previously conflicting data. Thus, evaluation of parasympathetic tone using heart rate variability techniques should be cautiously undertaken.