Which conduction abnormality is described by Right Bundle Branch Block?

• A. Atrioventricular block
• B. Right Bundle Branch Block
• C. Left bundle branch block
• D. Atrial flutter

Answer: (B)

The concept being tested is recognizing a specific intraventricular conduction abnormality. In Right Bundle Branch Block, the pathway that normally conducts the electrical impulse to the right ventricle is impaired. This causes delayed activation of the right ventricle while the left ventricle activates normally, leading to a characteristic pattern on the ECG: a widened QRS complex (greater than 120 ms) with a typical rhythm of an RSR' in the right precordial lead (often V1) and a broad, often slurred S wave in the lateral leads (I, V6).

This pattern distinguishes it from other conduction or rhythm issues. An atrioventricular block involves impaired conduction at the AV node or below, often with a changing PR interval or dropped beats. A left bundle branch block presents with a different ECG pattern in the lateral leads and a broad QRS as well but with opposite dispersion of the activation. Atrial flutter is an atrial rhythm disturbance with sawtooth flutter waves, not a block in the ventricular conduction pathways.

So the description points to a block in the right bundle branch, i.e., Right Bundle Branch Block.