systole.hrv.poincare#
- systole.hrv.poincare(rr: Union[List, ndarray], input_type: str = 'rr_ms') Tuple[float, float][source]#
Compute SD1 and SD2 from the Poincaré nonlinear method for heart rate variability.
- Parameters
- rr
R-R interval time-series, peaks or peaks index vectors. The default expected vector is R-R intervals in milliseconds. Other data format can be provided by specifying the “input_type” (can be “rr_s”, “peaks” or “peaks_idx”).
- input_type
The type of input provided. Can be “peaks”, “peaks_idx”, “rr_ms” or “rr_s”. Defaults to “rr_ms”.
- Returns
- sd1
The standard deviation of the points perpendicular to the identity line. This metric is thought to be influenced mainly by the respiratory sinus arythmia (RSA) and reflect short-term heart rate variability.
- sd2
The standard deviation of the points along the identity line. This metric is thought to reflect the long-term heart rate variability.
See also
Notes
The Poincare plot is a commonly used nonlinear method that is based on the graphical representation of the correlation between lagged successive RR intervals (the \(\RR_{n}\) intervals are plotted as a function of the \(\RR_{n+1}\)) intervals. The shape of the resulting plot is then analyzed and two metrics are extracted, representing the standard deviation of the distribution perpendicular to the identity line (SD1) and along the identity line (SD2).
SD1, which corresponds to the standard deviation of the points perpendicular to the identity line, reflects short-term variability and is thought to be caused by respiratory sinus arrhythmia (RSA). SD2, on the other side, the standard deviation along the identity line, corresponds to the long-term heart rate variability.
References
- 1
- 2
M. Brennan, M. Palaniswami, and P. Kamen. Do existing measures of Poincaré plot geometry reflect nonlinear features of heart rate variability. IEEE Trans Biomed Eng, 48(11):1342–1347, 2001.