Clockwise flutter

ECG: Tachycardia at 130 bpm with wide QRS, right delay, left axis; carotid massage slows the nodal conduction and allows demonstrating a fast, regular and monomorphic atrial activity of 260 bpm; the morphology does not correspond to that of a counterclockwise common flutter; the atrial depolarization wave is positive and broad in the inferior leads with a visible notch in leads II, III but also in aVR; atrial activity is negative in V1 and positive in V6; it is therefore an atrial clockwise flutter of the right atrium with an initial 2:1 conduction with a right bundle branch block and a left anterior fascicular block;

Comments: 10% of patients with common flutter episodes also experience clockwise flutter episodes, the right atrial reentry circuit being the same but rotating in the other direction (clockwise). The anatomical and functional constraints are identical to the common flutter although the activation is reversed, cranio-caudal in the septum, caudo-cephalic in the anterior wall. While the incidence of this type of flutter is relatively low, it can be induced by pacing in the electrophysiology room in 50% of patients with a common flutter.

On the electrocardiogram, we find a monomorphic and rapid pattern (tachycardia cycle identical to that of the common flutter) of atrial activity. Some characteristic elements allow establishing the diagnosis:

• In the inferior leads II, III, aVF: a predominantly positive, wide wave with a notch in the positive portion in lead II (positive flutter pattern inferiorly) is frequently found; the pattern can be less characteristic with negative atrial activity recalling the pattern of the common flutter
• The atrial depolarization wave is often negative, of low amplitude, with a notch in aVL
• Lead V1 also often displays a characteristic pattern, with a wide negative bifid activation; a notch can also be evidenced in the middle of the negative deflection of the flutter wave
• There is a transition in the precordium between the negative activity in V1 and the positive activity in V6.

Take-home message: The clockwise right atrial flutter pattern includes: 1) an atrial rate usually between 250 and 300 bpm, 2) a positive atrial activation with a notch in the inferior leads, 3) a weak voltage pattern in aVL, 4) a positive component in V6 and negative component in V1.