This was a study published by a group from China. Their results are not in agreement with most other studies on Heart Rate Variability and acupuncture as measured by FFT. They found that there was no change in the LF/HF ratio. They did find an increase in the Sample Entropy with acupuncture, which concurs with my findings posted in previous posts. She was not able to answer me how they filtered and checked for artifact in their heart rate tracings, so they might not have done that. That is a key part of the analysis for LF/HFR which may account for their different findings.
Abstract
Acupuncture has been shown to alter the functional status of the autonomic nervous system. The purpose of the present study was to study the effect of acupuncture on heart rate variability, using linear and non-linear methods of analysis. We consecutively recruited 40 patients, including cases of insomnia, stomachache,
diarrhea, dizziness, cervical syndrome, low back pain, gonarthritis, peripheral facial paralysis, post-traumatic organic brain syndrome and urinary retention. Different acupoint prescriptions were used, according to the textbook for Five-years-education of Traditional Chinese Medicine Specialty in Chinese Universities.
Heart rate variability was recorded before, during, and after acupuncture. Acupuncture substantially reduced variability, causing a 41 % reduction in the standard deviation. Using Fourier analysis, variance both in the low (LF) and the high frequency (HF) range were markedly reduced, whereas the LF/HF ratio (an indication of sympatho-vagal balance) was not altered. The heart rate was unchanged. Sample entropy, which is a measure of the complexity of time series, significantly increased (+ 35 %). Thus, acupuncture produced a pattern of changes different from that seen in pathological conditions, where increased variability and reduced complexity is expected.
Key words : acupuncture - fourier analysis - heart rate variability - sample entropy
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