β-adrenoceptor Modulation and Heart Rate Variability—The Value of Scatterplot Measures of Compactness

This article compares different methods of scatterplot analysis to assess the optimal methodology. The scatterplot (Poincare plot) is a nonlinear heart rate variability method where a “return map” is constructed by plotting each current cycle against the previous beat (RR vs. RRn−1). Geometric analysis of the scatterplot allows short-term and long-term heart rate variability (HRV) to be assessed. A three-dimensional construct is also possible, where the third axis represents the density of values, at any given RR vs. RRn−1 intersection. Topological methods of analysis can compute the density distribution function or compactness of a dataset. Scatterplots that otherwise appear very similar in the two-dimensional plot may be clearly differentiated using this approach. Correct characterization may improve the ability of scatterplot analysis to predict outcomes in cardiovascular disease.