Table 1.
HRV parameters and their physiological association
| Parameter | Abbreviation | Physiological association |
|---|---|---|
| Time domain | ||
| Standard deviation of NN intervals | SDNN | Overall HRV, sympathetic and parasympathetic innervation |
| Root mean square of successive difference between NN intervals | RMSSD | Short-term HRV, primarily parasympathetic innervation |
| Frequency domain | ||
| Total power | TP | Total HRV (as the band encompasses all frequencies) |
| High frequency | HF | Parasympathetic control |
| Ratio high frequency and total power | HF/TP | Parasympathetic control |
| Intermediate frequency | IntF | Sympathetic and parasympathetic arm of the ANS |
| Low frequency | LF | Sympathetic and parasympathetic arm of the ANS |
| Very low frequency | VLF | Sympathetic control |
| Ratio very low frequency and high frequency | VLF/HF | Sympatho-vagal balance |
| Ratio very low frequency and low frequency | VLF/LF | Sympatho-vagal balance |
| Ratio low frequency and high frequency | LF/HF | Sympatho-vagal balance |
(ANS autonomic nervous system, NN normal-to-normal)