Heart Rate Variability: A View from Chaos Theory

This text brings together original research by the authors on the nonlinear characteristics of heart rate variability. Results are presented of the Group of Complex Systems at the Physicochemical Research Institute of the National University of La Plata, Argentina. We show nonlinear measures that are related to a predominance of sympathetic activity. They can be clinically useful in the follow up of cardiac arrhythmias, and Chagas Disease.