[Catheter ablation of atrial flutter and fibrillation]

The knowledge of the anatomic and functional bases of common flutter circuits has allowed the definition of an anatomic isthmus, between the inferior vena cava and the tricuspid valve, where radiofrequency application can interrupt the circuit. Some atypical flutter circuits are identical to common flutter circuits, but for an inverted rotation (clockwise), and these can be also ablated in the same isthmus. In cases of flutter (or reentrant tachycardia) due to surgical scars in the atrium, mapping supported with programmed stimulation, can define anatomic isthmuses, where ablation can also interrupt the circuit. There is still no definition of left atrial flutter circuits, that may guide ablation in these cases. Atrial fibrillation ablation is still in its infancy. Some initial experiences have tried to reproduce the division of atrial myocardium as in the maze procedure, and fibrillation was interrupted in a number of patients, submitted to very long procedures. There is still no clear definition of the muscular anatomy of the left atrium, in relation with the fibrillatory process, to guide the design of effective ablation lines. There are also technical problems to produce continuous, transmural ablation lines, that are not arrhythmogenic by themselves. The wide clinical application of ablation to treat atrial fibrillation is still in the distant future.