A minimal model for the respiratory sinus arrhythmia

The cardiac and respiratory rhythms in humans are knownto be coupled by severalmechanisms. In particular, the first rhythm is deeply modulated by the second. In this report we propose a simple operationalmodel for heart rate variability which, taking such modulation into account, reproduces the main features of some experimental sequences of RR intervals recorded from healthy subjects in the resting condition. Also, peer analysis of the model performance allows us to answer the question whether the observed behaviour should be ascribed to phase synchronisation of the heart beating to the respiratory rhythm. Lastly, the changes of the model activity brought about by changing its relevant parameters are analysed and discussed.