Respiratory sinus arrhythmia from two coupled pacemakers

We reproduce global features of respiratory sinus arrhythmia (RSA), a promi nent source of heart rate variability, from two signals coupled in alternat e fashion so dominance periodically switches back and forth between them. W e consider two different possibilities for this coupling and illustrate our method with numerical simulations that we contrast with the corresponding results from real data. We interpret our findings within the context of the two-pacemaker model of the heartbeat, an alternative to the sin.-le-pace m aker mechanism of pulse generation in the orthodox conduction model. (C) 20 01 Elsevier Science Ireland Ltd. All rights reserved.