Which electrocardiographic finding is classic for right bundle branch block?

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Multiple Choice

Which electrocardiographic finding is classic for right bundle branch block?

A classic sign of right bundle branch block is an RSR' pattern in the right precordial lead V1. This happens because the impulse is delayed reaching the right ventricle, so the left ventricle activates first and the right ventricle depolarizes later, creating a second positive deflection (the R') in V1. The overall QRS is widened (over 120 ms) due to the inte r-ventricular conduction delay. In addition, you may see a broad S wave in the left-sided leads (I, V6) reflecting the altered depolarization direction. Other patterns listed don’t fit RBBB: for example, a Q wave in V1 isn’t the hallmark of this block, ST elevations in inferior leads point to an acute inferior MI, and tall T waves in V5 are not specific for RBBB.

A classic sign of right bundle branch block is an RSR' pattern in the right precordial lead V1. This happens because the impulse is delayed reaching the right ventricle, so the left ventricle activates first and the right ventricle depolarizes later, creating a second positive deflection (the R') in V1. The overall QRS is widened (over 120 ms) due to the inte r-ventricular conduction delay. In addition, you may see a broad S wave in the left-sided leads (I, V6) reflecting the altered depolarization direction.

Other patterns listed don’t fit RBBB: for example, a Q wave in V1 isn’t the hallmark of this block, ST elevations in inferior leads point to an acute inferior MI, and tall T waves in V5 are not specific for RBBB.

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