Localized Reentry as a Mechanism of Anterior Left Atrial Flutter

Abstract

Background: Localized reentry is thought to be a mechanism of organized atrial fibrillation (AF) if a temporal activation gradient between the distal and proximal bipoles of ablation catheter is found during left atrial ablation for AF. We report 3 cases of which left atrial flutter (AFL) was caused by localized reentry of anterior left wall. Case: Case 1 is 76 years old male with dilated cardiomyopathy. He was admitted for heart failure and uncommon AFL, and underwent catheter ablation. A temporal activation gradient between the distal and proximal bipoles covering most of AFL cycle length was observed at anterior left atrium, and so mechanism of AFL was considered to be a localized reentry. By the first radiofrequency (RF) application at this site, AFL was shifted to peri-mitral AFL. While we performed modified left anterior linear ablation, AFL was terminated and could not be induced by any pacing. Case 2 is 56 years old female with complete atrioventricular block, and Case 3 is 65 years old male with mitral stenosis. Both patients were admitted for uncommon AFL. In both cases, localized temporal gradients covering most of the flutter cycle length were also observed at anterior left atrium like case 1, and AFL was terminated by single RF application and could no longer be induced. Conclusion: Anterior left atrium wall is an arrythmogenic site where localized reentry often come into being.