Modelling the dynamics of angles of human R-R intervals

Heart rate variability (HRV) data from young healthy humans is expanded int o two components, namely, the angles and radii of a map of R-R intervals. I t is shown that. for most subjects at rest breathing spontaneously, the map of successive angles reveals a highly deterministic structure after the fr equency range below similar to0.05 Hz has been filtered out. However, no ob vious low-dimensional structure is found in the map of successive radii. A recently proposed model describing the map of angles for a periodic self-os cillator under external periodic and quasiperiodic forcing is successfully applied to model the dynamics of such angles.