A new parameter in the nonlinear dynamics of the heart: The Higher Reconstruction Step

Nonlinear dynamics has been playing an outstanding role in the study of heart in the last decades. It brought many parameters that improved the diagnostic methods, as the Correlation Dimension or Lyapunov Exponents. In this work we propose a new of these parameters, The Higher Reconstruction Step (HRS), an extension of the Time Lag obtained from the Autocorrelation Function (ACF). We collected R-R time series from two groups of men: one group with a cardiac chagasic disease (24 individuals) and a second one of healthy people (21 individuals). Typical values of HRS are in the range 1-5, but there are some outliers. After removing the outliers greater than 50 (or greater than 10) the HRS is significantly smaller in the healthy group, with p <; 0.01 in a t-test for the supine position.