Right Bundle Branch Block in Right Ventricular Apical Pacing

Right ventricular (RV) apical pacing results in left bundle branch block pattern with left axis deviation in electrocardiogram (ECG). Appearance of right bundle branch block (RBBB) pattern on electrocardiogram after RV apical pacing commonly denotes septal perforation or coronary sinus pacing. 59 year old male underwent permanent pacemaker implantation (VVI) for symptomatic complete heart block with tined pacing lead fixed in right ventricular apex. 12 lead ECG showed RBBB pattern after implantation, despite the lead in RV apex. Some of the mechanisms proposed are incorrect lead placement, left ventricle getting activated first through anomalous pathways, pacing stimulus travelling through right bundle to atrioventricular node retrogradely and down the left bundle branch and lastly diseased right ventricular conduction system leading the pacing stimulus to penetrate left ventricular conduction system early.