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 Poincaré plot (Pp) analysis extended up to 20
^th
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 2
^nd
and 5
^th
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.