Multichannel time-variant spectral and cross-spectral parameters for the evaluation of cardiovascular variability signals before syncope

A beat-to-beat time-variant estimation of spectral (LF, HF and LF/HF ratio) and cross-spectral (phase and coherence functions) parameters is used to evaluate neural mechanisms of cardiovascular regulation before episodes of vaso-vagal syncope. The beat-to-beat parameters are obtained through a recursive identification of a bivariate model, which describe the mutual interactions between Heart Rate (HR) and Arterial Blood Pressure (ABP) variabilities. The obtained results evidence changes in neural regulation mechanisms, at level of both sinus node and vessels, in the epochs preceding syncope. Such changes may be linked to the successive haemodynamic alterations which lead to the syncopal event