Objectives To discuss the relationship between vagus nerve and heart rate variability (HRV).
Methods 12 healthy rabbits were selected and anaesthetized, ventilation was used to control respiratory parameters, tide volume preset 10 mL/kg, respiratory frequency preset 50 beat per min, carotid compression transducer was used to monitor blood-pressure. ECGs of pre and post vagotomy were collected and analysed.
Results RRI cyclical change pre and post vagotomy coincided with the respiratory cycle. Peak of RRI and respiratory power spectral density post vagotomy were shifted right (0.19 ± 0.02 vs 0.20 ± 0.03, P < 0.01), but they still located at the same frequency. HF post-vagotomy were significantly decreased (0.31 ± 0.21 vs 0.48 ± 0.24, P < 0.01), LF/HF post-vagotomy were significantly increased (0.59 ± 0.47 vs 0.27 ± 0.30, P < 0.01), compared with HF and LF/HF pre-vagotomy.
Conclusions Vagus nerve could affect respiratory sinus arrhythmia (RSA), but it was not the unique pathway attribute to RSA. High frequency power (HF) could reflect the function of vagus, but could not totally represent the tense of vagus nerve.