Which EKG lead is most useful for detecting a right bundle branch block?

The lead that is most useful for detecting a right bundle branch block (RBBB) is Lead V1. This is due to its position on the chest being close to the right side of the heart, where the right bundle branch is anatomically located. When RBBB occurs, it typically shows distinctive changes in the EKG morphology in Lead V1, such as a broad, slurred S wave along with a prominent R wave, which indicates delayed depolarization of the right ventricle.

Analyzing the EKG in Lead V1 allows for the visualization of these characteristic patterns that confirm the presence of RBBB. The other leads, while they can provide valuable information regarding the overall heart rhythm and function, do not have the same specificity for identifying changes associated with right bundle branch block that Lead V1 provides.