Patent ID: 7248919

Claim:
A method including: detecting ventricular heart contractions over a time period; detecting atrial heart contractions over the time period; if any ventricular heart contraction is not preceded by a corresponding atrial contraction, then deeming that ventricular heart contraction a premature ventricular contraction (PVC); replacing the PVC with a substitute R-wave at that time which the R-wave would have occurred had the PVC not occurred; obtaining a time-domain first signal representing time intervals between the detected ventricular heart contractions, wherein the detected ventricular heart contractions include any substitute R-waves generated as a result of a PVC; filtering the first signal to obtain a time-domain second signal including frequency components substantially in a first frequency band, wherein the second signal is influenced by both sympathetic and parasympathetic components of an autonomic nervous system; filtering the first signal to obtain a time-domain third signal including frequency components substantially in a second frequency band, wherein the third signal is influenced by the parasympathetic component of the autonomic nervous system and not substantially influenced by the sympathetic component of the autonomic nervous system; obtaining a time domain variance of each of the second and third signals; and providing an indication associated with a balance between the sympathetic and parasympathetic components of the autonomic nervous system based on a ratio between the time-domain variances of the second and third signals.