What does an EKG with a "pseudo RBBB" indicate?

A "pseudo RBBB" (pseudo Right Bundle Branch Block) refers to a situation where there is an appearance on the EKG that resembles right bundle branch block patterns, but it is actually caused by other factors, not a true conduction delay in the right bundle branch itself. This phenomenon often occurs in cases where the left ventricle is hypertrophied or when there is an imbalance in the conduction through the left side of the heart, which can mimic the characteristics of a right bundle branch block.

When interpreting EKGs, it is crucial to differentiate between true bundle branch blocks and patterns that mimic them, such as a pseudo RBBB. This type of block usually points to changes in the heart that may not align with the common clinical significance associated with right bundle branch block specifically but instead suggest alterations in conduction pathways.

The presence of a pseudo RBBB suggests atypical right bundle branch block, highlighting that while the EKG looks characteristic of a right bundle branch block, the underlying cause and clinical implications might differ. This is an important consideration because it influences the further diagnostic and clinical management of the patient.