Mechanism of the effects of sodium channel blockade on the arrhythmogenic substrate of Brugada syndrome.

Background: The mechanisms by which sodium channel blockade and high-rate pacing modify electrogram (EGM) substrates of Brugada syndrome (BrS) have not been elucidated.

Objective: The purpose of this study was to determine the effect of ajmaline and high pacing rate on the BrS substrates.

Methods: Thirty-two patients with BrS (mean age 40 ± 12 years) and frequent ventricular fibrillation episodes underwent right ventricular outflow tract substrate electroanatomical and electrocardiographic imaging (ECGI) mapping before and after ajmaline administration and during high-rate atrial pacing.

Mapping and Ablation of Ventricular Fibrillation Associated With Early Repolarization Syndrome.

Background: We conducted a multicenter study to evaluate mapping and ablation of ventricular fibrillation (VF) substrates or VF triggers in early repolarization syndromes (ERS) or J-wave syndrome (JWS).

Methods: We studied 52 patients with ERS (4 women; median age, 35 years) with recurrent VF episodes. Body surface electrocardiographic imaging and endocardial and epicardial electroanatomical mapping of both ventricles were performed during sinus rhythm and VF for localization of triggers, substrates, and drivers.