Electrocardiographic Characteristics of Repetitive Monomorphic Right Ventricular Tachycardia Originating Near the His‐Bundle

Abstract

Introduction: Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His‐bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His‐bundle in comparison with right ventricular outflow tract (RVOT)‐VT/VPCs. Methods and Results: Ninety RV‐VT/VPC patients underwent catheter mapping and radiofrequency ablation. ECG variables were compared between VT/VPCs originating from the RVOT and near the His‐bundle. Ten patients had foci near the His‐bundle (HIS group), with the His‐bundle local ventricular electrogram preceding the QRS onset by 15–35 msec (mean: 22 msec) and His‐bundle pacing produced a nearly identical ECG to clinical VT/VPCs. The HIS group R wave amplitude in the inferior leads (lead III: 1.0 ± 0.6 mV) was significantly lower than that of the RVOT group (1.7 ± 0.4 mV, P < 0.05). An R wave in aVL was present in 6 of 10 HIS group patients, while almost all RVOT group patients had a QS pattern in aVL. Lead I in HIS group exhibited significantly taller R wave amplitudes than RVOT group. HIS group QRS duration in the inferior leads was shorter than that of the RVOT group. Eight of 10 HIS group patients exhibited a QS pattern in lead V1 compared to 14 of 81 RVOT group patients. HIS group had larger R wave amplitudes in leads V5 and V6 than RVOT group. Conclusion: VT/VPCs originating near the His‐bundle have distinctive ECG characteristics. Knowledge of the characteristic QRS morphology may facilitate catheter mapping and successful ablation.