HRV parameter (unit) | Definition |
---|---|
aRR (s) | Average width of the RR interval |
STD (s) | Standard deviation of all RR intervals |
avHR (beats/minute) | Average of the instantaneous heart rate (HR) |
sdHR (beats/minute) | Standard deviation of the instantaneous HR |
RMSSD (s) | Root mean square of differences between adjacent RR intervals |
NN50 (count) | Number of consecutive RR intervals differing by more than 50Â ms |
pNN50 (%) | Number and percentage of consecutive RR intervals differing by more than 50Â ms |
Triangular index | Total number of all RR intervals divided by the height of the histogram of intervals |
TINN | Baseline width of a triangle fit into the RR interval histogram using a least squares |
LF power (ms2) | Power in low frequency range 0.04-0.15Â Hz |
HF power (ms2) | Power in high frequency range 0.15-0.40Â Hz |
Total power (ms2) | Total power estimated from RR intervals |
LF norm (n.u.) | LF power in normalized units: LF/(Total power-VLF) × 100 |
HF norm (n.u.) | HF power in normalized units: HF/(Total power-VLF) × 100 |
LF/HF | Ratio of LF power to HF power |