Data compression of cardiac electrical signals using scanning

Abstract

A method and apparatus for storing a representation of a cardiac signal by compressing the data using scan correlation and temporal data compression techniques. The method and apparatus sense cardiac signals when the heart is functioning in a known cardiac state, then characterize this known state by storing a temporally compressed template of time sequence samples. The method and apparatus may perform testing for multiple different cardiac states and store templates associated with each state. Subsequently when the heart is functioning in an unknown cardiac state, the method and apparatus monitor cardiac signals by temporally compressing samples and scan correlating these samples with the previously stored templates to derive correlation coefficients. These correlation coefficients are a basis for identifying and classifying cardiac signal waveforms. For waveforms which correlate highly with a particular template, analysis of the timing of the maximum correlation coefficient provides a fiducial time which designates the time relationship of waveforms within different cardiac cycles. The method and apparatus store information in the form of templates, fiducial timing markers, and waveform occurrence counts. This data provides the information necessary to subsequently reproduce a long-term signal record.