Parameter | Definition |
SDNN | Standard deviation of all RR intervals |
SDNNi | Mean of the SD of all RR intervals for all five minute segments |
rMSSD | Square root of the mean of the sum of squares of differences between adjacent RR intervals |
pNN50 | Percentage of differences between adjacent RR intervals that are greater than 50 msec |
VLF | Very low frequency index (0.004–0.04 Hz) (msec) |
LF | Low frequency index (0.04–0.15 Hz) (msec) |
HF | High frequency index (0.15–0.4 Hz) (msec) |
LF:HF | Ratio of LF to HF |
SD, standard deviation.