Evaluation of Autonomic Nervous System Function Using Heart Rate Variability Analysis During Transient Heart Rate Reduction Caused by Acupuncture

Abstract

Human studies have demonstrated that heart rate (HR) decreases during acupuncture stimulation, and pharmacologic studies have shown that this autonomic nervous system (ANS) response is parasympathetic-dominant. It has become clear that significant changes occur in the ANS after acupuncture, based on HR variability (HRV). However, it is inconclusive, according to HRV analysis, if acupuncture induces a significant change in autonomic function during stimulation. The aim of this study was to investigate ANS function using HRV analysis during HR reduction induced by manual acupuncture stimulation to the muscles. In this study, electrocardiograms of 25 adult men were analyzed. After resting for 20 minutes, participants underwent 15-20-mm deep acupuncture stimulation at the (LI 10) point at 1 Hz for 2 minutes. Instantaneous HR was recorded. The index of parasympathetic nervous activity high-frequency (HF) normalized units (HFnu) and the ratio of sympathovagal balance (low frequency [LF]/HF) were calculated by HRV analysis. HR during acupuncture was significantly lower, compared to HR both before and after acupuncture. HFnu during acupuncture were significantly higher, compared to HFnu both before and after acupuncture. The LF/HF ratio during acupuncture was significantly lower, compared to the ratio before acupuncture, and remained low after acupuncture, compared to before acupuncture. Acupuncture stimulation to the muscle can effectively reduce HR, increase HFnu, and decrease LF/HF that depends on autonomic regulation of both sympathovagal balances.

Changes in Blood Circulation of the Tendons and Heart Rate Variability During and After Acupuncture

“…26 Several studies showed that the LF/HF ratio decreased significantly during and after acupuncture stimulation, which indicates that acupuncture inhibits activity in the SNS and has an opposite effect on the PNS. 9,27,28 Furthermore, pharmacologic studies showed that HR reduction induced by acupuncture stimulation led to inhibition of the SNS function and enhancement of the PNS function as mentioned earlier. 7,10 In the present study, however, such a decrease in the LF/HF ratio was not noted during acupuncture and the recovery period.…”

“…in the Achilles tendon, using HRV analysis with respect to acupoint specificity. Furthermore, as Uchida et al 9 stated, a limitation of HRV analysis has to be pointed out with regard to using this kind of analysis to determine the state of the ANS. It is, thus, necessary to investigate the effect of the ANS on the change in tendon blood circulation caused by acupuncture stimulation with other techniques (e.g., a pharmacologic method).…”

“…Previous studies demonstrated a transient decline in heart rate (HR) during acupuncture. [7][8][9] According to the findings of pharmacologic studies, 7,10 reduction of the HR associated with acupuncture stimulation was due to inhibition of the sympathetic nervous system and activation of the parasympathetic nervous system. One of current authors' previous studies showed that the amount of increase in the blood volume of the non-acupuncture-treated (contralateral) tendon was highly correlated with that of the acupuncture-treated tendon during the last phase of the recovery period.…”

“…In the present study, a needle was inserted into the Achilles tendon, whereas a needle was inserted into a very specific acupuncture point in the previous studies. [7][8][9]12,14 Given the decrease of HR, in any case, involvement of autonomic reflexes is not totally deniable for THb changes in the acupunctured tendons. However, THb for the treated tendons increased during acupuncture with up-and-down manipulation (Acu-2), whereas THb for the nontreated (contralateral) tendons did not increase (Fig.…”

“…Several studies showed that HR decreased during and after acupuncture. [7][8][9]12,14 For example, Uchida et al 9 reported that HR during 2 minutes of acupuncture stimulation (needle moved vertically at a frequency of 1 Hz) was significantly lower than before and after acupuncture. Yet, other researchers showed that HR did not change during acupuncture stimulation and then significantly decreased after stimulation.…”