The long march: from monofractals to endogenous multifractality in heart rate variability analysis

The paper presents a methodological critique of the literature on heart rate variability in the context of nonlinear dynamics and time series analysis. The concomitant developments in nonlinear dynamic analysis and cardiology, together with the gradual shift from the monofractal approach to multifractality are evaluated. It is argued that despite its seminal contributions to the under-standing of heart rate variability, the literature has often been plagued by a lack of appropriate synthesis of nonlinear dynamics with time series statistics on the one hand, and the misinterpretation of time and frequency domain analyses on the other. Furthermore, several open questions for future research are identified.