Effect of acupuncture on cardiac output

Abstract

Background We have been investigating the effect of acupuncture on peripheral circulation. Because it must be measured using a catheter, examination of cardiac output is invasive, and so there are few reports about the influence of acupuncture on cardiac output in humans. In addition, inserting a catheter endovascularly may cause vasoconstriction that could influence hemodynamics. Therefore, we observed cardiac output during acupuncture with an impedance cardiac output flowmeter. Methods Thirty healthy volunteers (mean age: 30±8 years; 20 men and 10 women) were enrolled. Using an impedance cardiac output flowmeter (Dash3000, Omron Healthcare Co., Ltd.), the heart rate, systolic blood pressure, diastolic blood pressure, stroke volume and cardiac index were measured. Each subject rested in the supine position for 10 min, and then acupuncture needles (disposable stainless steel needles; 1.6 mm×40 mm) were inserted bilaterally at LR-3 on the instep and manual stimulation was done for 18 s. Measurements were obtained at rest, during stimulation, and 30, 60 and 180 s after stimulation. Statistical analysis was performed with SPSS software (version 16.0, SPSS Japan Inc., Tokyo, Japan). The percent changes of each variable were calculated and compared by repeated measures ANOVA with a post hoc Dunnett's test. Measurements were performed for 6 s, and then the mean values were calculated. The subjects were instructed to breathe once every 6 s during the examination. Results The heart rate decreased significantly after stimulation compared with the resting value (mean±SD: 65.0±8.2% vs. 62.2±7.4%, p=0.001). There was no significant change in cardiac index. Systolic blood pressure decreased significantly at 180 s after stimulation compared with the resting value (115.4±9.8% vs. 113.3±10.0%, p=0.04) but diastolic blood pressure did not change significantly. Conclusions Acupuncture did not have an effect on the cardiac index but decreased the heart rate. It is possible that parasympathetic sympathetic nerve activity due to acupuncture stimulation may decrease the heart rate.