Stochastic analysis of heart rate variability and its relation to echocardiography parameters in hypertrophic cardiomyopathy patients

Abstract

The heart rate variability of 10 healthy males (age 26 − 4/+ 3 y) and 49 patients with hypertrophic cardiomyopathy (HCM) (25 males, 24 females, age 29.5 − 11.5/+ 10.5 y) was studied. We applied Kramers–Moyal expansion to extract the drift and diffusion terms of the Langevin equation for the RR interval time series. These terms may be used for a stochastic reconstruction of the time series and for description of the properties of heart rate variability. New parameters characterizing the diffusion term are proposed: the coefficients of the linear fit to the left (LCF) and right (RCF) branch of the dependence of the diffusion term on the rescaled heart rate. Relations of the new parameters to classical echocardiography parameters were studied. Using the relation between the difference LCF–RCF and the left ventricular systolic diameter, the HCM patients studied were divided into three groups. In addition, comparison of the properties of the heart rate variability in the HCM group with that obtained for the healthy young men showed that the parameter LCF–RCF may be treated as a measure of the effect of HCM on heart rate variability and may have diagnostic value.