[Simulation of coupling behavior of heart rhythms for study of phase synchronization]

Biological systems exhibit numerous rhythmic processes. In the human, rhythms produced by e.g. the cardiac and respiratory systems show signs of synchronisation, reflecting a physiological coupling of the underlying oscillating processes. When examining such rhythms for evidence of coupling, it is difficult to distinguish between epochs of coincidental (numerical) and real (physiological) synchronisation. The objective of this study was to simulate model rhythms in order to examine the conditions under which coupling may be recognised and the influence of noise on this recognition. Different model rhythms with adjustable noise were implemented. The synchronisation between pairs of such rhythms was examined with the help of synchrograms. Functions were used to simulate coupling. The results of the simulation were compared to real fetal-maternal cardiac rhythms. The simulation showed that heart rate variability may be an important factor in distinguishing between coincidental and real synchronisation.