Atypical atrial flutters

Abstract

Typical atrial flutter is due to a counterclockwise macro-re-entry circuit localized in the right atrium with a surface ECG pattern showing predominantly negative F waves in the inferior leads and positive F waves in V1. Recently it has been proposed to classify atrial flutter on the basis of its cavo-tricuspid isthmus dependence rather than on the ECG pattern. Therefore some atrial flutters are considered typical even if the ECG does not exhibit a typical pattern. This is the case for reverse typical atrial flutter, lower loop re-entry and partial-isthmus-dependent short circuit flutter. The term atypical flutter refers to a non-isthmus dependent flutter. Usually these patients have had previous cardiac surgery with a right or left atriotomy. Flutter involving a spontaneous right atrial scar is not uncommon.

Pre-injection of magnesium sulfate enhances the efficacy of ibutilide for the conversion of typical but not of atypical persistent atrial flutter

“…As electrophysiological testing was not performed to reveal the mechanism of the atrial rhythm, surface electrocardiogram (ECG) -criteria known to be indicating cavotricuspid isthmus-dependent TAF (counterclockwise or clockwise) were applied to distinguish this arrhythmia from AAF [6][7][8].…”

Clinical Prediction of Cavotricuspid Isthmus Dependence in Patients Referred for Catheter Ablation of “Typical” Atrial Flutter

“…Occasional difficulties obtaining the established endpoint of bidirectional conduction block due to anatomical variations (e.g., deep pouches, trabeculations) have been mostly overcome by the use of large or cooled tip ablation electrodes 15–17 . Catheter ablation of anatomically fixed non‐CTI‐dependent AFL has also been reported in smaller series 18,19 …”

Atypical Flutter:

“…Low loop reentry is also interrupted by IVC‐TR ablation and block. For these reasons some authors consider it a form of typical AFL 11 …”

“…Atypical flutter observed in the electrophysiological laboratory during mapping and pacing maneuvers, is often not stable enough to allow full mapping and entrainment of the circuit 2 , 11 , 15 . Interesting mechanistic hypothesis can be built from partial mapping data derived from stable multipole catheters, however, complete understanding of its clinical and pathogenic significance will probably need the application of more sophisticated, nonsequential mapping techniques.…”

“…For these reasons some authors consider it a form of typical AFL. 11 Another interesting variation of the typical flutter mechanism inducible in the laboratory is double wave reentry, an unstable situation after programmed stimulation, in which two wavefronts chase one another in the flutter circuit. 12 Available evidence is based on the study of mul-tiple RA endocardial recordings around the TR, and full activation mapping of this rhythm has not been reported.…”