Cardiac autonomic regulation under hypnosis assessed by heart rate variability: spectral analysis and fractal complexity.
OBJECTIVE
This study examined the effects of hypnosis on autonomic cardiac control. We hypothesized a modification of autonomic modulation of the heart rate with an enhanced vagal tone during hypnosis compared to baseline.


METHODS
In 12 healthy subjects (6 men and 6 women, 22.2 +/- 1.0 years of age) ECG was recorded at baseline and during hypnosis. Heart rate variability parameters were obtained in the frequency domain (LFnu: low frequency normalized units, and HFnu: high frequency normalized units) and from nonlinear analysis methods (detrended fluctuation analysis, DFA).


RESULTS
Compared to the control condition, hypnosis showed a significantly decreased LFnu, a significantly increased HFnu, and a significantly decreased LF/HF. DFA showed a significantly decreased short-range similarity. Heart rate remained unchanged.


CONCLUSIONS
Autonomic cardiac tone is significantly modified during hypnosis by shifting the balance of the sympathovagal interaction toward an enhanced parasympathetic modulation, accompanied by a reduction of the sympathetic tone and a decreased short-range similarity but without a concomitant change in heart rate. Central and secondary autonomous nervous system changes induced by hypnosis are a possible explanation for our results. Another highly probable explanation is given by a variation in the depth of respiration. Hypnosis appears to prevent the autonomic responses expected during neutral stimulation.
Aubert
André E
AE
Laboratory of Experimental Cardiology, University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium. andre.aubert@med.kuleuven.be
Verheyden
Bart
B
Beckers
Frank
F
Tack
Jan
J
Vandenberghe
Joris
J
D001341:Autonomic Nervous System / Q000502:physiology*; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006990:Hypnosis; D016014:Linear Models; D008297:Male; D017711:Nonlinear Dynamics; D012119:Respiration; D055815:Young Adult