A software toolkit for nonlinear Heart Rate Variability analysis

This paper presents an extension to the RHRV package that enables nonlinear Heart Rate Variability (HRV) analysis. RHRV is an open source package for the R environment for statistical computing which already has support for a wide variety of time and frequency HRV analysis methods. Now RHRV also provides a phase space reconstruction algorithm that uses the delays method and that deals with the problem of discretization in the RR series. The package provides automatic estimation of both the embedding dimension and the time lag needed for the phase space reconstruction. Functionality to perform nonlinearity tests and nonlinear noise reduction is also provided. A wide variety of nonlinear statistics can be calculated, including largest Lyapunov exponent, correlation dimension, SD1/SD2 of Poincaré plots, detrended fluctuation analysis, approximate entropy and recurrence quantification analysis.