[Research progress of methods of heart rate variability analysis].

One of the hotspots in the analysis of ECG is heart rate variability (HRV). In the present, the method mostly used for the analysis of HRV signal is linear analysis, and nonlinear analysis seldom used. Research progress of several methods of HRV analysis is presented. Principles and characteristics of using nonlinear analysis for the study of HRV are analyzed in detail. Fractal dimension, complexity and approximate entropy are discussed.