Atrial fibrillation after atrial flutter ablation.

Abstract

Listen

Translate article

Typical atrial flutter is caused by a re-entrant circuit confined to the right atrium (RA). It involves the “atrial flutter isthmus” which is a protected narrow isthmus of conduction, bounded on one side by the inferior vena cava, the eustachian ridge and the coronary sinus ostium and by the tricuspid valve annulus on the other. Clinically atrial flutter is frequently associated with atrial fibrillation and the mechanism for this association has yet to be elucidated. Several types of atrial flutter exist. Typical atrial flutter, or counterclockwise atrial flutter is characterized by negative “sawtooth” flutter waves in leads II, III and aVF on the electrocardiogram. In this form of flutter the impulse is conducted counterclockwise up the atrial septum, with epicardial breakthrough superiorly in the right atrium where it then travels down the free wall of the RA to re-enter the atrial septum. Reverse typical atrial flutter, with positive “sawtooth” flutter waves in leads II, III and aVF on an electrocardiogram, is characterized by impulse conduction opposite to that in typical atrial flutter, in the clockwise direction. In incisional atrial flutter, after repair of congenital heart defects, the re-entrant circuit involves areas of block caused by the incision and interestingly often involves the atrial flutter isthmus as well. A left atrial flutter exists but has not been well characterized, and involves a circuit around one or more of the pulmonary veins or the mitral valve annulus [1,2]. Standard treatment for atrial flutter with antiarrhythmics has changed over time. As compared to class IA agents, class I and class III agents have been shown to be more effective and safer in supression of atrial flutter. Despite the availability of these pharmacologic agents, it is difficult to suppress atrial flutter completely with pharmacotherapy even when multiple agents are used and antiarrhythmics are no longer the treatment of choice for typical atrial flutter. Prospective studies comparing catheter ablation and anti-arrhythmic therapy have shown catheter ablation to be associated with a lower recurrence rate of atrial flutter and fibrillation, a lower rehospitalization rate and improved sense of well being [3‐5]. Thus radiofrequency catheter ablation at the ‘atrial flutter isthmus’ is now considered the treatment of choice, with successful ablation occurring in >90% of patients. Successful ablation of atrial flutter is confirmed by the presence of bidirectional conduction block in the flutter isthmus. Recurrence of atrial arrhythmias following successful ablation of atrial flutter is related to ei