Click on image to view larger version.

Figure 1 This figure shows schemas of variable flutter wave morphologies on 12-lead electrocardiograms. The first two waves are monophasic positive (F+) and negative (F–) flutter waves. The third through sixth waves are biphasic flutter waves, consisting of dominant negative with small terminal positive (F–/f+), dominant positive with small terminal negative (F+/f–), small initial negative with dominant terminal positive (f–/F+), and the equal amplitude of negative and positive waves (Isoelectric). Flat polarity is amplitude <0.01 mV and more than –0.01 mV.