IPFM heart-timing reconstruction and TVIPFM modulation¶
What it does¶
This method reconstructs uniformly sampled instantaneous heart rate from discrete beat or pulse occurrence times. It can also estimate dimensionless TVIPFM modulation relative to a slowly changing mean rate.
When to use it¶
Use it when an interval sequence must be converted into a uniformly sampled heart-rate or modulation signal for spectral or multivariate analysis.
Canonical ID: hrv.ipfm
Inputs¶
| Name | Meaning | Type | Unit | Requirements |
|---|---|---|---|---|
tn |
Strictly increasing beat or pulse occurrence times. | real vector | s | minimum length: 2; no NaN; finite |
fs |
Sampling frequency of the uniform output grid. | real scalar | Hz | greater than: 0; no NaN; finite |
Parameters¶
| Name | Meaning | Type | Unit | Default | Requirements |
|---|---|---|---|---|---|
spline_order |
Order of the B-spline used to interpolate cumulative event count. | integer scalar | 1 | 14 |
minimum: 2 |
Outputs¶
| Name | Meaning | Type | Unit |
|---|---|---|---|
ihr |
Uniformly sampled instantaneous heart rate. | real vector | Hz |
m |
Optional dimensionless TVIPFM modulation relative to the time-varying mean rate. | real vector | 1 |
How it works¶
A high-order B-spline interpolates cumulative event count after adding virtual boundary events for numerical stability. Its derivative gives instantaneous rate on the requested uniform grid. When modulation is requested, a zero-phase low-pass estimate of mean rate is removed and used to normalize the residual.
The default spline order and boundary extension are empirical numerical choices. The 0.03 Hz separation used by TVIPFM is supported by the cited method literature.
Interpretation and limitations¶
Event times must already be ordered, finite, and physiologically meaningful. High-order interpolation can overshoot on pathological timing patterns. The modulation output is model-based and should not be interpreted as a direct autonomic measurement.
References¶
- Javier Mateo and Pablo Laguna (2000). Improved Heart Rate Variability Signal Analysis from the Beat Occurrence Times According to the IPFM Model. IEEE Transactions on Biomedical Engineering. doi:10.1109/10.855925
- Javier Mateo and Pablo Laguna (2003). Analysis of Heart Rate Variability in the Presence of Ectopic Beats Using the Heart Timing Signal. IEEE Transactions on Biomedical Engineering. doi:10.1109/TBME.2003.808831
- Raquel Bailón et al. (2011). The Integral Pulse Frequency Modulation Model With Time-Varying Threshold: Application to Heart Rate Variability Analysis During Exercise Stress Testing. IEEE Transactions on Biomedical Engineering. doi:10.1109/TBME.2010.2095011
- Leif Sörnmo, Raquel Bailón, Pablo Laguna (2024). Spectral Analysis of Heart Rate Variability in Time-Varying Conditions and in the Presence of Confounding Factors. IEEE Reviews in Biomedical Engineering. doi:10.1109/RBME.2022.3220636