Effects of the auricular electrical stimulation on heart rate variability assessed in phase space: Pilot study

The electrical punctual stimulation (P-Stim) of the vagal nerve in the ear is a new stimulation technique for pain relief therapy. A few studies exist regarding the effects of the P-Stim, considering mainly subjective pain relief. In this pilot study we assess objectively the vagal effects of the P-Stim by the appropriate heart rate variability analysis reflecting vagal activity of the autonomous nerve system. In particular, the variability was investigated in the phase space by the recurrence quantification analysis. The results have shown a more deterministic and less divergent heart rhythm not only during the stimulation period but also afterwards, which indicates temporally sustainable effects of the P-Stim.