Heart rate variability effects of an agonist or antagonists of the β-adrenoceptor assessed with scatterplot and sequence analysis

There is evidence that the processes regulating heart rate variations reflect non-linear complexity and show ‘chaotic’ determinism. Data analyses using non-linear methods may therefore reveal patterns not apparent with conventional statistical approaches. We have consequently investigated two non-linear methods, the Poincare plot (scatterplot) and cardiac sequence (quadrant) analysis, and compared these with standard time-domain summary statistics, during a normal volunteer investigation of an agonist and antagonists of the cardiac β-adrenoceptor.