Frequency-domain HRV metrics¶
What it does¶
This method integrates conventional LF and HF powers or, alternatively, respiration-related and respiration-unrelated spectra obtained after orthogonal subspace projection.
When to use it¶
Use conventional mode to summarize an HRV spectrum in standard frequency bands. Use respiration-separated mode only when the supplied spectra represent the related and residual components of a compatible OSP analysis.
Canonical ID: hrv.fdmetrics
Inputs¶
| Name | Meaning | Type | Unit | Requirements |
|---|---|---|---|---|
pxx |
Power spectral density used by the conventional LF/HF mode. | real vector | caller-defined power/Hz | minimum: 0; minimum length: 1; NaN allowed; finite |
related_pxx |
Spectrum of the HRV component linearly related to respiration. | real vector | 1/Hz | minimum: 0; minimum length: 1; NaN allowed; finite |
unrelated_pxx |
Spectrum of the residual HRV component not represented by respiration. | real vector | 1/Hz | minimum: 0; minimum length: 1; NaN allowed; finite |
f |
Strictly increasing frequency grid shared by the supplied spectrum or spectra. | real vector | Hz | minimum: 0; minimum length: 1; no NaN; finite |
Parameters¶
| Name | Meaning | Type | Unit | Default | Requirements |
|---|---|---|---|---|---|
limit_hf |
Whether conventional HF integration stops at the represented 0.4 Hz boundary. | boolean | dimensionless | yes | not specified |
Outputs¶
| Name | Meaning | Type | Unit |
|---|---|---|---|
hf |
Integrated conventional high-frequency power. | real scalar | caller-defined power |
lf |
Integrated conventional low-frequency power. | real scalar | caller-defined power |
lfn |
Low-frequency power normalized by the combined LF and HF power. | real scalar | 1 |
lfhf |
Ratio between conventional low-frequency and high-frequency power. | real scalar | 1 |
urlf |
Respiration-unrelated low-frequency power. | real scalar | 1 |
re |
Respiration-related power over the represented analysis range. | real scalar | 1 |
r |
Normalized respiration-unrelated LF index. | real scalar | 1 |
How it works¶
Band samples are selected directly from the supplied frequency grid and integrated without interpolating new spectral points. The represented grid therefore determines the effective band coverage. Respiration-separated mode reports unrelated LF power, related power, and a bounded normalized index.
Interpretation and limitations¶
LF and HF powers are descriptive and should not be treated as pure sympathetic or parasympathetic measures. Spectral estimation, detrending, record length, stationarity, artifacts, and respiratory conditions can dominate interpretation. Partial frequency coverage should be reported explicitly.
References¶
- Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology (1996). Heart rate variability: standards of measurement, physiological interpretation and clinical use. European Heart Journal.
- Carolina Varon et al. (2019). Unconstrained Estimation of HRV Indices After Removing Respiratory Influences From Heart Rate. IEEE Journal of Biomedical and Health Informatics. doi:10.1109/JBHI.2018.2884644
- Binbin Liu et al. (2019). An improved method to evaluate heart rate variability based on time-variant cardiorespiratory relation. Journal of Applied Physiology. doi:10.1152/japplphysiol.00125.2019