Table 3.
All parameter.23 HRV features were extracted from each phase.
| Domain | Parameter | Description |
|---|---|---|
| Time |
HRV_MeanNN | The mean of the RR intervals. |
| HRV_SDNN | The standard deviation of the RR intervals. | |
| HRV_SDANN1 | The standard deviation of average RR intervals extracted from 1-min segments of time series data. | |
| HRV_RMSSD | The square root of the mean of the squared successive differences between adjacent RR intervals. It is equivalent (although on another scale) to SD1, and therefore it is redundant to report correlations with both. | |
| HRV_SDSD | The standard deviation of the successive differences between RR intervals. | |
| HRV_CVNN | The standard deviation of the RR intervals (SDNN) divided by the mean of the RR intervals (MeanNN). | |
| HRV_CVSD | The root mean square of successive differences divided by the mean of the RR intervals (MeanNN). | |
| HRV_MedianNN | The median of the RR intervals. | |
| HRV_MadNN | The median absolute deviation of the RR intervals. | |
| HRV_MCVNN | The median absolute deviation of the RR intervals (MadNN) divided by the median of the RR intervals (MedianNN). | |
| HRV_IQRNN | The interquartile range (IQR) of the RR intervals. | |
| HRV_pNN50 | The proportion of RR intervals greater than 50 ms, out of the total number of RR intervals. | |
| HRV_pNN20 | The proportion of RR intervals greater than 20 ms, out of the total number of RR intervals. | |
| HRV_HTI | The HRV triangular index, measuring the total number of RR intervals divided by the height of the RR intervals histogram. | |
| HRV_TINN |
A geometrical parameter of the HRV, or more specifically, the baseline width of the RR intervals distribution obtained by triangular interpolation, where the error of least squares determines the triangle. It is an approximation of the RR interval distribution. |
|
| Frequency | HRV_VLF | The spectral power of very low frequencies (by default, .0033 to .04 Hz). |
| HRV_LF | The spectral power of low frequencies (by default, .04 to .15 Hz). | |
| HRV_HF | The spectral power of high frequencies (by default, .15 to .4 Hz). | |
| HRV_VHF | The spectral power of very high frequencies (by default, .4 to .5 Hz). | |
| HRV_LFHF | The ratio obtained by dividing the LF power by the HF power. | |
| HRV_LFn | The normalized LF, obtained by dividing the LF power by the total power. | |
| HRV_HFn | The normalized HF, obtained by dividing the HF power by the total power. | |
| HRV_LnHF | The log transformed HF. |