To re-examine the standard pNN50 heart rate variability (HRV) statistic by determining how other thresholds compare with the commonly adopted 50 ms threshold in distinguishing physiological and pathological groups.
Margret and H A Rey Institute for Nonlinear Dynamics in Physiology and Medicine, Cardiovascular Division, Harvard Medical School/Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
