Catheter ablation of ventricular tachycardia originating from the diverticulum of the right ventricular outflow tract

Abstract

Ventricular tachyarrhythmias from the right ventricular outflow tract (RVOT) are well recognized.1 In most cases, such arrhythmias are idiopathic because of the presence of a structurally normal heart. However, this ‘normal heart’ can sometimes be due to the early stage of heart disease or minor abnormalities that cannot be detected by routine examination. We report one case with ventricular tachycardia (VT) originating from the diverticulum of the RVOT. The electrocardiographic and electrophysiological characteristics, mapping and ablation strategies, and detailed images are described in this report. A 62-year-old man with a repetitive monomorphic VT with a typical RVOT origin morphology for 19 years was referred for catheter ablation. The echocardiogram did not suggest any evidence of structural heart disease and revealed a normal left ventricular ejection fraction. The oral administration of amiodarone was initially effective, but the patient was referred for an electrophysiological assessment and catheter ablation because of the side effects of amiodarone and reoccurrence of syncope. Ambulatory monitoring did not reveal any large burden of premature ventricular contractions. The 12-lead electrocardiogram (ECG) during the VT demonstrated a left bundle branch block (LBBB) and inferior axis morphology with a late QRS transition in the precordial lead, V4. The QRS complexes had a tall positive component without a notch in the inferior leads and a Qr pattern in lead I ( Figure 1A ). Figure 1 ( A ) Left panel: the 12-lead electrocardiogram of clinical ventricular tachycardia. Right panel: perfect pace mapping was obtained with an almost 11/12 match to clinical ventricular tachycardia morphology from the target site in the diverticulum. ( B ) The local fragmented, low-voltage electrograms at the earliest site which preceded the onset of QRS during ventricular tachycardia by 23 ms was recorded at the same site. ECG, electrocardiogram; VT, ventricular tachycardia. An electrophysiological study was performed under a fasting state …