Single site radiofrequency catheter ablation of atrial fibrillation: Studies guided by simultaneous multisite mapping in the canine sterile pericarditis model

OBJECTIVES To test the hypothesis that when activation of Bachmann's bundle (BB) is critical to the unstable reentrant circuits that maintain atrial fibrillation (AF) in the sterile pericarditis canine model, a lesion in BE would prevent induction of stable AF. BACKGROUND One mechanism of induced AF in this model is multiple unstable reentrant circuits, which frequently include BE as part of the reentrant pathway. METHODS Simultaneous multisite mapping studies during AF and after ablation of BB Were performed by recording (384 to 396 electrodes) from both atria and the atrial septum during six induced AF episodes in six dogs With sterile pericarditis. Activation maps of AF (mean duration, 24 +/- 28 min) during 12 consecutive 100-ms windows were analyzed. RESULTS During AF, multiple unstable reentrant circuits (mean, 1.2 +/- 0.2 per window; range, 1 to 4) were observed, 68% involving BE. Nonactivation zones (mean duration, 57 +/- 16 ms in the right atrium and 53 +/- 23 ms in the left atrium) observed during AF were reactivated by a wave front most often coming from the atrial septum via BE (right atrium, 62%; left atrium, 67%). After successful radiofrequency catheter ablation of the midportion of BE, AF >5 s was not induced in all dogs. Mapping studies of transient AF (less than or equal to 5 s) induced after ablation showed neither reentrant circuits nor wave fronts activating the right atrium via BE. CONCLUSIONS In this AF model, catheter ablation of BE terminates and prevents the induction of AF by preventing 1) formation of unstable reentrant circuits that involve BE, and 2) activation of the atrial-free walls after a nonactivation period. (C) 2000 by the American College of Cardiology.