Comparison of non-stationarity heart rate variability in healthy volunteers and patients with impaired autonomic control of blood circulation

The method of analyzing heart rate variability is used to study the work of autonomic control of blood circulation. Changes in heart rate variability may indicate pathologies of autonomic control of blood circulation. We used methods to analyze heart rate non-stationarity. The goal of our work to study the possibility of analyzing the non-stationarity of heart rate variability to screen the type of dysfunction of the autonomic control of blood circulation. We analyzed four groups of subjects: healthy volunteers, patients with arterial hypertension, patients with chronic heart failure and patients with denervated hearts. We analyzed the sequence of RR-intervals and calculated four indices the non-stationarity of heart rate variability for each subject: standard deviation of the sequence of RR-intervals; time until the first zero value of the autocorrelation coefficient of the sequence of RR-intervals; the criterion for the difference between one-dimensional distributions of a sequence of RR-intervals; Euclidean distance between vectors of coefficients of the regression equation the sequences of RR-intervals. We obtained results indicating that the compared methods of analyzing non-stationarity demonstrate correlated results and complement each other, providing different information about the baroreflex control of heart rhythm.