Assessment of Baroreflex Mechanism by Joint Analysis of Arterial Blood Pressure and Heart Rate

Baroreflex is an important mechanism for controlling arterial blood pressure (BP). The effectiveness of the baroreflex action is very important diagnostic indicator of cardiovascular system regulatory mechanisms. To assess the effectiveness of baroreflex action, it is necessary to analyze the relationship between the systemic hemodynamics, and in particular, between the signals of beat-to-beat values of blood pressure and heart rate (HR). The paper proposes an algorithm for the joint analysis of these signals. The purpose of the algorithm is the allocation of signal sections with predominantly in-phase and antiphase relationships. The algorithm is based on the window Fourier transform analysis and window calculation of the correlation coefficient, wherein window width is determined from the standard frequency ranges of the cardiac rhythm. Spectral and spectral-temporal analysis is used for generalized qualitative assessment of the interdependence between the signals of beat-to-beat BP values and heart rate. To test the algorithm, we performed synchronous recording of BP and heart rate for 300 s in healthy subjects under conditions of calm wakefulness with eyes closed. The results of their analysis with proposed algorithm are presented.