A vectorcardiograpbic approacb to understanding the 12-lead electrocardiogram of atrial flutter

We hypothesized that phase relationships of arrial flutter waves nmong diFerent ECG lends could be used to discriminate atrial flutter mechanisms and that vectorcardiography could be used To identlfy such phase relations hips. Twenry-seven ECGs reflecting counterclockwise (CCW) isthmus-dependent (ID) flutter and eight ECGs reflecting clockwise (CW) ID putter were reviewed. Vector analysis identified the following chronologic sequence in the ECGs of 24 of ihe 27 CCW ID flutter vector loops: iso-electric in all leads, trough in [I9 peak in VI, peak in II, and trough in VI. The CW IDflutter ECGs had the reverse sequence in 11 and V1. The phase relationships of hads JI and VI track the CCW and CW activation sequences of ID flutter, even for ECGs not satisfying the prevalent polarity and morphology criteria.