Radiofrequency ablation of atrial tachycardia and atrial flutter.

Atrial endocardial mapping defines the activation pattern during regular atrial arrhythmias. The response to pacing (entrainment mapping) yields additional information about the mechanism and location of the circuit. Regarding radiofrequency ablation, the regular atrial tachycardias may be classified in two broad patterns: 1) macroreentrant tachycardias, characterized by circular activation, including typical atrial flutter and reentry around scars, and 2) focal tachycardias, characterized by radial activation from a small myocardial area. Catheter ablation of right atrial macroreentrant circuits and focal tachycardias are now standard procedures. The target for ablation of focal tachycardia is the point of earliest activation, and single application is effective in most cases. Ablation of macroreentrant tachycardias requires identifying a narrow isthmus inside the circuit, and linear ablation is needed in most cases. The goal of radiofrequency ablation for typical atrial flutter is to interrupt conduction across the inferior vena cavatricuspid valve isthmus. The procedure is highly effective and safe, although recurrences of the arrhythmia are not rare. Incisional macroreentrant tachycardias after surgical correction of congenital heart diseases and primary cardiac tumors may also be ablated identifying critical isthmuses in the circuit by a combination of mapping and entrainment techniques. Left atrial macroreentry is much less known and at present more information is needed before catheter ablation becomes a standard procedure.