Different Patterns of Interatrial Conduction in Clockwise and Counterclockwise Atrial Flutter

Abstract

Background-The terms counterclockwise (CC) and clockwise (C) atrial flutter (Afl) are used to describe right atrial activation around the tricuspid valve in the left anterior oblique view. The manner in which the left atrium is activated, as reflected by coronary sinus (CS) recordings, has not been systematically evaluated. Methods and Results-Nine patients with both CC and C Afl underwent electrophysiological study with CS recordings during both rhythms with the use of a decapolar catheter with the tip placed in the distal CS. Patterns of CS activation during each type of Afl as well as during during sinus rhythm were categorized into 1 of 3 patterns: sequential proximal-to-distal, sequential distal-to-proximal, and fused, indicating activation from different directions. In 7 of 9 patients, the pattern of CS activation in CC Afl and C Afl differed, with a proximal-to-distal pattern in CC Afl and a fused pattern in C Afl. In 2 patients, pacing the high right atrial septum near the presumed site of Bachmann's bundle in sinus rhythm showed a similar fused pattern of CS activation. Conclusions-These results demonstrate different patterns of CS activation in CC Afl and C Afl in the majority of patients and are consistent with a model in which the left atrium is activated predominantly over Bachmann's bundle during C Afl and over the CS os in CC Afl. These findings may have implications for maintenance of Afl, interpretation of flutter wave morphology on surface ECG, and left atrial mechanical function in

Noninvasive Characterization of Intra-Atrial Reentrant Tachyarrhythmias After Surgical Repair of Congenital Heart Diseases

“…Therefore, the most significant difference between CTI-AFL and Incision-AT in the surface ECG is determined by whether the reentry circuit includes the atrial septum or the left atrium. These findings are consistent with previous clinical [23][24][25] and experimental 26 studies showing that septal and/or left atrial activation produces the characteristic Fl-wave morphology in the inferior and precordial leads.…”

Characteristics of Cavotricuspid Isthmus–Dependent Atrial Flutter After Left Atrial Ablation of Atrial Fibrillation

“…This is consistent with interatrial conduction over the musculature of the coronary sinus, as previously described in patients who had not undergone LA ablation. 11,12 In patients with clockwise atrial flutter, the earliest LA activation was at the anterosuperior region, consistent with conduction over Bachmann's bundle. 11,12 One might speculate that interatrial conduction would be altered by extensive LA ablation.…”

Lower Loop Reentry as a Mechanism of Clockwise Right Atrial Flutter

“…This allows the bulk of the intra-atrial septum to be activated in the craniocaudal direction and the left atrium to be activated in a manner similar to that in clockwise typical AFL. 9,11,12 Further studies are needed to define the role of slow conduction in determining the exact reentrant circuitry during clockwise right AFL.…”