Network approach to increments of RR-intervals for visualization of dynamics of cardiac regulation

The transition network for RR-increments is presented in a directed and weighted graph, with vertices representing RR-increments and edges corresponding to the order in a sequence of increments. The adjacency matrix and the transition matrix of this network provide a graphical tool which could be useful in the assessment of cardiac regulation. As an example, the method is applied in detecting differences between diurnal activity and nocturnal rest.