Using spectral analysis of the continuous time series signal before and
during lactate and placebo infusions, the authors studied heart rate
variability in six patients with panic disorder and nine normal comparison
subjects. The decrease in high-frequency (0.20-0.50 Hz) power and the
increase in sympathovagal ratios (mid-frequency [0.07- 0.15 Hz] to
high-frequency powers) after the administration of intravenous sodium
lactate were significantly greater in the patients than in the normal
subjects after correction of the values for the amount of lactate infused.
This result suggests an exaggerated cardiac vagal withdrawal in patients
with panic disorder during lactate infusions.