AEMCA Practice Exam

What characterizes a right bundle branch block on an ECG?

1. A wide QRS with peaked R wave in an upward direction

2. Normal QRS duration with ST elevation

3. A narrow QRS with a delta wave

4. Abnormal T wave inversion

The correct answer is: A wide QRS with peaked R wave in an upward direction

A right bundle branch block (RBBB) is characterized by a wide QRS complex on an electrocardiogram (ECG) due to delayed conduction through the right bundle branch of the heart's conduction system. The QRS duration is typically greater than 120 milliseconds. The morphology of the QRS complex reflects this delay, leading to the observation of a prominent, peaked R wave in the upward direction in leads V1 and V2. This distinct pattern occurs because the electrical impulse takes longer to travel through the right ventricle, resulting in a characteristic appearance of the QRS segment on the ECG. Other options describe features that do not align with the typical findings seen in a right bundle branch block. For instance, normal QRS duration with ST elevation does not reflect the conduction delay characteristic of RBBB. A narrow QRS complex with a delta wave is associated with Wolff-Parkinson-White syndrome, indicating a different conduction issue. Abnormal T wave inversion can occur due to various conditions but is not exclusive to right bundle branch block, making it an inappropriate choice to characterize RBBB.