Background: There is no ideal sedation technique that can be used during transoesophageal echocardiography (TEE), and the data concerning the effects of available sedation techniques on heart rate variability (HRV) are limited.

Aim: To compare the effects of sedation through hypnotherapy with medical sedation achieved by midazolam on HRV.

Methods: We recruited 76 patients with an indication of TEE; the age range was 18–83 years. In Group T there were 26 patients who had the procedure under topical pharyngeal anaesthesia, in Group D there were 23 patients who received midazolam, and in Group H there were 27 patients receiving hypnosis. All patients had an IV access; throughout the procedure heart rate, rhythm electrocardiography, and peripheric O2 saturation were monitored with a non-invasive monitor, and blood pressure measurements were taken every 3 min. Rhythm Holter recordings were obtained from all patients and TEE was performed.

Results: When time domain parameters for HRV were compared in all three groups, the hypnosis group had significant increases in pNN50 and RMSSD compared to Groups D and T (p < 0.05). As concerns frequency domain parameters, there were no significant differences between groups where low frequency (LF) was decreased in hypnosis group and high frequency (HF) was increased (p > 0.05). However, LF/HF was decreased statistically significantly (p < 0.05) when compared with the midazolam group.

Conclusions: Contrary to standard sedation in TEE patients, when hypnosis is used autonomic cardiac tone is modified to a significant extent. Hypnotic sedation achieves this by increasing the parasympathetic activity, decreasing the sympathetic activity, and changing the sympathovagal interaction balance.