Study of cardiac arrhythmia using zero-crossing analysis

It has been known for some time that the variability of the R-R intervals in the electrocardiogram yields valuable information concerning the types of arrhythmia which might be present. In this paper, an investigation is made into the application of zero-crossing analysis to the study of such variability. The number of times the R-R interval crosses its mean value over a specified interval of time is counted, and may be associated with a particular characteristic frequency, related to the dominant frequency components of the power spectrum of R-R intervals. Higher order crossing counts may be computed by taking combinations of sum and difference operations on the original time series. The advantage of using zero-crossing analysis over spectral analysis is the computational simplicity of the former. It is demonstrated, by analysing data taken from the MIT-BIH Arrhythmia database, that zero crossing analysis can sometimes be used t distinguish between different arrhythmias, but forethought concerning the number of sum and difference operations to be taken on the original data set is required when computing the higher order crossing counts.