Nonlinear neurodynamics model of heart rate variability, multifractality and chaos

A neural feedback-control model was developed to simulate the nonlinear dynamics of heart rate variability (HRV). The model consists of central integration of baroreceptor and chemoreceptor afferents, cardiac regulation by vagal and sympathetic efferents, acute baroreflex resetting and vagosympathetic interaction. Model simulations of HRV data from normal subjects showed that: 1) nonlinear multivariate feedbacks comprising nonadditive vagal and sympathetic influences on heart rate, baroreflex resetting and presynaptic modulation of vagosympathetic outflow contributed to the chaos-like multifractal behavior of HRV; and 2) such intrinsic chaotic behavior may be masked by random disturbances resulting from physical or behavioral activities particularly during daytime.