Introduction
Multiple atrial tachycardias (ATs) in a patient related to spontaneous polytropic atrial scars or radical atrial fibrillation (AF) ablation are usually characterized by multiple mechanisms and require complex ablation procedures.1 Scar-related electrically silent areas (ESAs) and slow conduction to the isthmus are considered two of the main mechanisms of these ATs. Despite targeted ablation of these mechanisms and the use of high-resolution mapping, which provides superior accuracy and understanding of the conduction features, these ATs are associated with high recurrence.1,2 ATs in these patients may be associated with more complex substrates and other potential mechanisms. The phenomenon of a functional block has been used to explain some complex sustained arrhythmias.3 ATs sustained by a functional block line have been seldom reported.4 In the present study, we assessed the characteristics of the electrophysiological mechanism in a series of 8 patients with multiple ATs, and we present the role of the functional block region in this specific category of AT.