Is the normal heartbeat chaotic or homeostatic?
Limits to the usefulness of homeostasis as a guiding physiological principle are revealed by new mechanisms derived from study of nonlinear systems that generate a type of variability called chaos.  Loss of complex physiological variability may occur in certain pathological conditions including heart rate dynamics before sudden death and with aging.
Goldberger
A L
AL
Harvard Medical School, Boston, MA 02215.
D016757:Death, Sudden, Cardiac; D017709:Fractals; D006329:Heart Conduction System / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D017711:Nonlinear Dynamics