Different Effects of Acupuncture at Shenmen (HT7)-Tongli (HT5) and Shenmen-Neiguan (PC6) Points on Heart Rate Variability in Healthy Subjects

Point combinations are commonly used in acupuncture to produce synergistic effects to enhance therapeutic benefits. Shenmen (HT7) and Tongli (HT5) are located on the heart meridian, while Neiguan (PC6) lies on the pericardium meridian. These acupoints lie close together and are all closely related to heart function. Heart rate variability (HRV) analysis is a simple noninvasive technique used to evaluate the function of the autonomic nervous system. The present study sought to investigate the differences in HRV among patients stimulated at HT7 alone; HT7 and HT5; and HT7 and PC 6. We designed a crossover clinical study and recruited a total of 20 healthy volunteers. All subjects received 4 experimental sessions that included sham acupuncture (SA); verum acupuncture at HT7; verum acupuncture at HT7+HT5; and verum acupuncture at HT7+PC6. HRV analysis was recorded before, during, and after each acupuncture session. Results indicated that the lnLF and lnVariance components of HRV were lower at 20 min post acupuncture in the HT7 and HT7+HT5 sessions than in the SA session; no similar results were noted in the HT7+PC6 session. Both acupuncture at HT7 alone and at HT7+HT5 produce similar effects on the lnLF and lnVariance components of HRV. The effects of acupuncture at HT7 may be counteracted by adding PC6, suggesting that HT7 and PC6 may have antagonistic effects on sympathovagal balance. In order to enhance the efficacy of point combinations, the points selected should not lie close together along the same meridian and also should not lie close along neighboring meridians.