Clockwise flutter

ECG: Irregular ventricular rhythm; evidence of rapid, regular and monomorphic atrial activity of 220 bpm; the morphology does not correspond to that of a counterclockwise common flutter; the atrial depolarization wave is positive, wide in the inferior leads with a visible notch in leads II, III but also in aVR; the atrial activity is negative in V1 and positive in V6; it is therefore a clockwise atrial flutter of the right atrium;

Comments: This tracing shows the characteristics of an atrial flutter of the right atrium with a clockwise rotation. We observe 1) a monomorphic and rapid pattern of atrial activity, 2) in the inferior leads II, III, aVF, a mainly positive, wide wave with a notch in the positive portion in leads II and III, 3) low amplitude atrial depolarization with a notch in aVL, 4) negative atrial activation in V1 and positive in V6;

The electrical pattern is slightly less specific than that of the common counterclockwise flutter with more inter-patient variability. This flutter is also isthmus-dependent and can be effectively treated by ablation. It is therefore necessary to know its electrocardiographic characteristics and to be able to make the differential diagnosis from a left flutter for example, the therapeutic actions being very different.

Take-home message: 10% of patients with common flutter episodes also have clockwise flutter episodes, the right atrial reentry circuit being the same but rotating in the opposite direction (clockwise). It is therefore necessary to know their electrocardiographic characteristics and to make the differential diagnosis with that of a left flutter.