The wavefront also experiences a marked delay between its progression through the low right atrium and its arrival at the His location, during which it traverses the region of slow conduction in the isthmus. Moreover, CS activation occurs from the proximal to the distal sites, with the distal CS exhibiting a significantly delayed activation. Via catheter electrograms, the wavefront is initially detected by the proximal CS catheter, followed by the His catheter, and subsequently by the poles of the multipolar catheter located in the high, lateral, and low right atrium. On surface electrocardiogram (ECG) recordings, the P waves exhibit a sawtooth inverted pattern in the inferior leads, an inverted pattern in the high lateral leads, and an upright pattern in V1. A line of functional block can be observed along the crista terminals, precisely at the point where the ascending and descending signals collide. The electrical activity then flows back through the slow conduction zone between the tricuspid valve annulus and the CS. The signal is funneled into the narrow isthmus channel between the tricuspid valve annulus and the inferior vena cava, the cavotricuspid isthmus. There it travels between the tricuspid valve and the crista terminalis. The signal then crosses the roof of the right atrium and descends inferiorly and laterally. It then moves upwards towards the interatrial septum and depolarizes the posterior right atrium. The electrical activity propagates via a slow conduction zone between the tricuspid valve annulus and the coronary sinus (CS). This dysrhythmia is a macroreentrant counterclockwise circuit within the right atrium. Typical atrial flutter involves a circuit spanning the cavotricuspid isthmus (CTI).Ĭounterclockwise CTI-dependent Atrial FlutterĬounterclockwise CTI-dependent AFL is the most common atrial flutter variant. Atrial flutter may be classified as typical or atypical.

Atrial flutter ablation endoscopy