摘要To the Editor:Moderator band (MB) is a part of the septomarginal trabeculation,which not only supports the anterior papillary muscle (APM) of the tricuspid valve but also connects it to the free wall.Nevertheless,with the advent of intracardiac echocardiography (ICE),electrophysiologists are now aware of the arrhythmogenic role of MB besides its mechanical function.MB-originated ventricular tachycardia or ventricular fibrillation (VT/VF) is a kind of idiopathic malignant arrhythmia in the absence of structural heart disease,which is frequently triggered by a premature ventricular contraction (PVC) from the same site.[1] As the mechanism of this kind of arrhythmia is not well illustrated,previous research has reported the involvement of the Purkinje system of the right ventricle (RV),although catheter radiofrequency (RF) ablation delivered to the site displaying Purkinje potential showed limited efficacy.[2,3] Herein,we present a case ofMB-originated VT/VF in a 29-year-old woman in whom ablation based on the anatomical substrate (free wall and septum insertions of MB) proved successfully.