Filtering of surface Laplacian electrocardiograms from humans to produce atrial activation patterns

Four digital filtering techniques were evaluated to improve the signal-to-noise ratio (SNR) of directly obtained Laplacian electrograms (LECG), which were bandpass filtered before analog to digital conversion. The moment of activation (MOA) in the LECG was detected to create isochronal body surface maps, which show activation patterns. Unprocessed atrial LECG activity coincided with P-waves in the Lead II ECG (L2). Partial atrial flutter activation patterns were also constructed. The LECG system promises to reveal underlying cardiac activation patterns, including those of the atria, which are far less prominent than those from the ventricles.