The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Quantification of regularity in RR-interval time series using approximate entropy, sample entropy, and multi-scale entropy
Author:	Shah, Nirvish
View Online:	njit-etd2005-120 (xii, 105 pages ~ 11.4 MB pdf)
Department:	Department of Biomedical Engineering
Degree:	Master of Science
Program:	Biomedical Engineering
Document Type:	Thesis
Advisory Committee:	Reisman, Stanley S. (Committee chair) Rockland, Ronald H. (Committee member) Alvarez, Tara L. (Committee member)
Date:	2005-08
Keywords:	Heart rate variability Entropy Nonlinear fluctuation
Availability:	Unrestricted
Abstract:	Heart rate variability (HRV) has proven to be a useful noninvasive tool to study the neuronal control of the heart. Recently, nonlinear dynamic methods based on chaos theory and fractal dynamics have been developed to uncover the nonlinear fluctuations in heart rate. Approximate Entropy (ApEn), Sample Entropy (SampEn) and Multi-scale Entropy (MSE) are measures based on chaos theory that quantify the regularity in time series. This study has been designed to examine the ability of these measures to distinguish the RR-interval time series of normal subjects (NSR) from subjects with congestive heart failure (CHF). The study was conducted on the RR-interval data of 44 NSR subjects and 18 CHF subjects. In addition to this, entropy measures of three apparently healthy subjects were calculated during sitting, standing, exercise and paced breathing to determine the change in entropy measures during these conditions. The results showed that ApEn and SampEn measures for 1000 RR-intervals were significantly (P < 0.005) higher for the NSR group than the CHF group. However, no significant difference was observed for these measures calculated for 40,000 RRintervals. MSE analysis revealed that the complexity of the RR-interval time series was significantly higher for the NSR group than the CHF group at all scales but one. SampEn was significantly lower during exercise while there was no significant difference in SampEn for other activities. The results reproduced the findings of others. This study suggests a general decrease in entropy in subjects with congestive heart failure.