Comparability of nonlinear measures of heart rate variability between long- and short-term electrocardiographic recordings

The short-term scaling exponent (alpha (1)) obtained by using the detrended fluctuation analysis technique and approximate entropy and several convent ional measures of heart rate variability were determined from 24-hour, 10-m inute resting state, and 10-minute ambulatory RR interval data in 30 health y subjects and in 30 postinfarction patients. The comparisons of the values derived from long- and short-term RR interval data showed that 10-minute e lectrocardiographic recordings are sufficient to obtain representative indi vidual data about alpha (1) but not about approximate entropy.