International journal of psychophysiology : official journal of the International Organization of Psychophysiology
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Int J Psychophysiol · Nov 2018
Poincaré plot indices as measures of sympathetic cardiac regulation: Responses to psychological stress and associations with pre-ejection period.
The Poincaré plot is a visual representation of the R-R time series within a Cartesian plane constructed by plotting each R-R interval as a function of the previous one. The plot can be characterized by parameters that quantify the standard deviation (SD) of short- and long-term R-R interval variability (SD1 and SD2, respectively). Claims regarding the use of Poincaré plot analysis as an alternative to conventional time-domain and spectral analytic measures of parasympathetic contributions to heart rate variability (HRV) have been evaluated somewhat extensively. ⋯ Following cessation of task performance, all HRV and impedance measures returned to baseline levels, signaling resumption of parasympathetic dominance. Bivariate associations linking SD2 and the SD1/SD2 ratio to PEP were observed; however, these were not large in magnitude, were exceeded in size by associations between the Poincaré metrics and conventional HRV markers of parasympathetic cardiac influences, and were eliminated when the latter were controlled statistically. These observations challenge the proposal that the Poincaré SD2 and SD1/SD2 metrics are suitable markers of sympathetic cardiac regulation in research concerned with mental and physical health.