Bundle branch block in alternate beats: The role of supernormal and concealed bundle branch conduction

This article reports an example of right bundle branch block occurring on alternate beats in the presence of atrial tachycardia with 2:1 atrioventricular conduction. Analysis of the tracing suggests that the alternate disappearance of right bundle branch block is a manifestation of supernormal bundle branch conduction. The phenomenon is assumed to be caused by retrograde concealed conduction within the bundle branch that is blocked in anterograde direction (the “linking” mechanism).