Heart rate variability and preoperative anxiety.

Power spectral analysis of heart rate variability has been used to gain some understanding of the activity of the autonomic nervous system. In this study various indices of heart rate variability were related to the degree of preoperative anxiety experienced by 32 patients presenting for day case surgery. It was found that there was no correlation between anxiety and mean heart rate, or between anxiety and the spectral power in the mid frequency band (0.05-0.15 Hz). However, there was an increase in the relative power of the higher frequency band (0.15-0.5 Hz) with increasing anxiety levels (Spearman correlation r = 0.4034). This suggests that preoperative anxiety may often be associated with a relative vagal predominance in the sympathovagal balance.