NONLINEAR PREDICTIVE INTERPOLATION - A NEW METHOD FOR THE CORRECTION OF ECTOPIC BEATS FOR HEART-RATE-VARIABILITY ANALYSIS

Heart rate variability (HRV) analysis is a technique that uses the bea t-to-beat variations in RR intervals as a measure of the level of acti vity of the autonomic nervous system. However, the presence of ectopic beats can alter measures of HRV by introducing mathematical artifact and thus, prevent accurate determinations of HRV. Simple exclusion of those portions of data that contain ectopy from analysis inappropriate because (1) it can lead to a substantial reduction in the amount of d ata available for analysis and (2) if the presence (and frequency) of ectopic beats is correlated with specific alterations in autonomic ton e, then the utilization of only ectopy-free data for analysis will lea d to bias in the measures. For this reason, methods for the correction of ectopic beats have been devised and applied in the determination o f HRV. The authors therefore propose a new method for the correction o f ectopic beats: nonlinear predictive interpolation. Using the fact th at beat-to-beat changes in heart rate occur in a deterministic fashion as the only assumption, the author apply the methods of chaos theory in order to locate ectopy-free portions of the RR interval sequence th at describe trajectories in phase space that are locally similar to th at of the ectopy-containing segments. The authors then determine which of these trajectories most closely approximates that of a particular ectopy-containing segment, and use it to determine replacement RR inte rvals for the ectopic beats.