Radiofrequency ablation of atrial tachycardia and atrial flutter

Atrial endocardial mapping defines the activation pattern during regular at rial arrhythmias. The response to pacing (entrainment mapping) yields addit ional information about the mechanism and location of the circuit. Regarding radiofrequency ablation, the regular atrial tachycardias may be c lassified in two broad patterns: 1) macroreentrant tachycardias, characteri zed by circular activation, including typical atrial flutter and reentry ar ound scars, and 2) focal tachycardias, characterized by radial activation f rom a small myocardial area. Catheter ablation of right atrial macroreentrant circuits and focal tachyca rdias are now standard procedures. The target for ablation of focal tachyca rdia is the point of earliest activation, and single application is effecti ve in most cases. Ablation of macroreentrant tachycardias requires identify ing a narrow isthmus inside the circuit, and linear ablation is needed in m ost cases. The goal of radiofrequency ablation for typical atrial flutter i s to interrupt conduction across the inferior vena cavatricuspid valve isth mus. The procedure is highly effective and safe, although recurrences of th e arrhythmia are not rare. Incisional macroreentrant tachycardias after sur gical correction of congenital heart diseases and primary cardiac tumors ma y also be ablated identifying critical isthmuses in the circuit by a combin ation 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.