Analysis of Phase Interactions between Oscillatory Processes in Human Cardiovascular System
The phase interactions between heart rate variability (HRV), respiration, forearm skin blood flow oscillations (with laser Doppler flowmetry) and finger-pad tissue blood volume oscillations (with photoplethysmography) in healthy subjects at rest were analyzed. The degree of synchronization between phases of analyzed signals was estimated with the value of wavelet phase coherence function. High phase synchronization between tissue blood volume oscillations and skin blood flow ones was found in low frequency band (0.0095-0.1 Hz) and at frequency of the heart rate (~1 Hz). At frequency of respiration (~ 0.3 Hz) there are differences in phase synchronization between peripheral hemodynamic oscillations (blood volume and blood flow) and heart rate variability or respiration. High phase synchronization was found between finger-pad blood volume oscillations and heart rate variability or respiration. On the contrary, low phase synchronization was observed between forearm skin blood flow oscillations and heart rate variability or respiration.