High-resolution determination of the R-R interval.

A preprocessor is described that determines the time interval between successive R waves of the electrocardiogram with an error of less than 0.2 ms. It accomplishes this by sepearting in hardware the function of determining the approximate location of the R wave from the function of localizing with great accuracy the peak of the wave form. With this device it is possible to detect abnormal heart rate patterns characterized by exceedingly small beat-to-beat variability. The approach may be useful for other bioelectric signals.