Cardiac Effect of Acupuncture on the Neiguan Point.

Background: The acupuncture on the Neiguan point (PC6) is used in the traditional Chinese medicine to calm the mind and relieve pain. In this study, we assess whether the stimulation of this point through acupuncture influences the heart rate. Methods: A resting 3-lead ECG was evaluated for 71 subjects in sinus rhythm during a 5-phase protocol (rest-sham acupuncture - rest - acupuncture on Neiguan point - rest). After a filtering procedure, the R peaks were detected and the RR intervals computed. The changes in the RR series after stimulation were assessed in both acupuncture phases (sham and on the Neiguan point) as the slope of the RR interval series post stimulation. Results: Comparing the RR changes in the Neiguan point acupuncture with the ones of the sham acupuncture for all subjects, we found a higher slope for the Neiguan point acupuncture (Neiguan: $2.90\pm 11.70vs$ sham: -1.02 $\pm 10.95, p=0.015)$ . This effect disappeared over time: indeed, computing the slopes of RR series further away in time from the acupuncture, a significant difference was not found between the two phases. Conclusion: These results suggest that acupuncture on the Neiguan point has a transient vagal effect on the heart, that should be considered in clinical practice.