Correlation dimension analysis of heart rate variability in patients with dilated cardiomyopathy
A correlation dimension analysis of heart rate variability (HRV) was applied to a group of 55 patients with dilated cardiomyopathy (DCM) and 55 healthy subjects as controls. The 24-h RR time series for each subject was divided into segments of 10,000 beats to determine the correlation dimension (CD) per segment. A study of the influence of the time delay (lag) in the calculation of CD was performed. Good discrimination between both groups (p<0.005) was obtained with lag values of 5 or greater. CD values of DCM patients (8.41.9) were significantly lower than CD values for controls (9.51.9). An analysis of CD values of HRV showed that for healthy people, CD night values (10.61.8) were significant greater than CD day values (9.21.9), revealing a circadian rhythm. In DCM patients, this circadian rhythm was lost and there were no differences between CD values in day (8.82.4) and night (8.92.1).
correlation dimension heart rate variability dilated cardiomyopathy circadian rhythms non-linear analysis