Poincare' plots in analysis of heart rate variability

The Poincar plot is a scattergram which is constructed by plotting each RR interval against the previous one. This scattergram may be analysed quantitatively by fitting an ellipse to the plot shape. SD1 (instantaneous beat-to-beat variability of the data) determines the width of the ellipse, SD2 (continuous beat-to-beat variability of the data) determines the length of the ellipse. So1/SD2 ratio is the measure of the heart activity. We also visually examined the differences in the shape of scattergrams. We analysed two groups of patients: test group A (n = 35) -diabetic children with diabetes type 1 and late vascular complications and control group B (n = 50) - healthy children. For each patient 24 hour Holter ECG was recorded. We concluded that we can qualitatively and quantitatively study the heart rate variability (HRV) from the shape of Poincare plot.