Click on image to view larger version.
Figure 1 Extracting atrial waveform. (A) In this electrocardiogram (ECG) of typical atrial flutter (AFL), the labeled F-wave template is correlated to successive ECG time points, yielding (B) a correlation time series ("filtered atrial waveform"). Peaks (r approximately equal to 1) identify recurrent F waves even if they overlap QRS/T waves. Lead II is shown in panel A to depict sawtooth F waves, but only leads V5 or I (X-axis), aVF (Y-axis), and V1 (Z-axis) were analyzed in this study.