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Figure 1 The 12-lead surface electrocardiograms of atypical right atrial flutters. (A) Single-loop re-entry. The flutter waves are positive in leads II, III, aVF and positive in lead V₁. (B) Type I figure-of-eight re-entry. The flutter waves are positive in leads II, III, aVF and biphasic in lead V₁. (C) Type II figure-of-eight re-entry. The flutter waves are negative in leads II, III, aVF and positive in lead V₁.