Intracardiac and surface ECG tracings during radiofrequency catheter ablation of the right bundle branch in a patient with BBRVT

Shown are five surface ECG leads (I, II, aVF, V1, V6) and intracardiac recordings from the His bundle region (HBE2-3,1-2), the right ventricular apex (RVA3-4), and a mapping catheter (USER1) positioned distal to the His catheter along the RV septum. Application of radiofrequency (RF) energy to the tip of the mapping catheter causes two accelerated beats with a typical left bundle branch block (LBBB) morphology (black arrow), likely from heating and activating the right bundle branch. After these beats, complete right bundle branch block (RBBB) is present (red arrow), as evidenced by the change in QRS morphology, particularly in lead V1. Following right bundle branch ablation, the HV interval increased to 105 milliseconds, though no infranodal A-V block was noted. Right bundle branch reentrant tachycardia was no longer inducible. A permanent pacemaker was placed because of the markedly prolonged HV interval.