Asymmetry of Cardiac Interbeat Intervals in Heart Failure

Heart rate (HR) asymmetry is a dynamic phenomenon related to the interplay of dominant regulatory mechanisms of cardiovascular system which operate over different scales of observation. The aim of this work is to examine asymmetry phenomenon in heart failure (HF) patients with sinus rhythm. We computed Guzik's index of heart rate asymmetry related to HR deceleration (Cd) from the Poincare plot (Pp) analysis extended up to 20th order. In the control group asymmetry is maintained over all orders of the Pp. In HF patients with asymmetric properties, Cd is reduced in the range between 2nd and 5th order of the Pp analysis, compared the control subjects. More, this method revealed two clusters of HF patients. In conclusion, proposed new approach can be applied to reveal alterations in the behavior of the cardiovascular control mechanisms in pathological conditions

Multiscale Entropy Analysis: Application to Cardio-Respiratory Coupling

It is known that in pathological conditions, physiological systems develop changes in the multiscale properties of physiological signals. However, in real life, little is known about how changes in the function of one of the two coupled physiological systems induce changes in function of the other one, especially on their multiscale behavior. Hence, in this work we aimed to examine the complexity of cardio-respiratory coupled systems control using multiscale entropy (MSE) analysis of cardiac intervals MSE (RR), respiratory time series MSE (Resp), and synchrony of these rhythms by cross multiscale entropy (CMSE) analysis, in the heart failure (HF) patients and healthy subjects. We analyzed 20 min of synchronously recorded RR intervals and respiratory signal during relaxation in the supine position in 42 heart failure patients and 14 control healthy subjects. Heart failure group was divided into three subgroups, according to the RR interval time series characteristics (atrial fibrillation (HFAF), sinus rhythm (HFSin), and sinus rhythm with ventricular extrasystoles (HFVES)). Compared with healthy control subjects, alterations in respiratory signal properties were observed in patients from the HFSin and HFVES groups. Further, mean MSE curves of RR intervals and respiratory signal were not statistically different only in the HFSin group (p = 0.43). The level of synchrony between these time series was significantly higher in HFSin and HFVES patients than in control subjects and HFAF patients (p lt 0.01). In conclusion, depending on the specific pathologies, primary alterations in the regularity of cardiac rhythm resulted in changes in the regularity of the respiratory rhythm, as well as in the level of their asynchrony