What are the classic ECG features of right bundle branch block (RBBB)?

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Multiple Choice

What are the classic ECG features of right bundle branch block (RBBB)?

Right bundle branch block causes delayed activation of the right ventricle, which lengthens overall depolarization and widens the QRS to more than 120 ms. The hallmark is an rsR' pattern in the right precordial leads (V1 and often V2), giving an “M-shaped” appearance due to the initial septal activation followed by late RV activation producing a second R’. In the lateral leads (I, aVL, V5–V6) you see wide, often deep S waves, reflecting that the left ventricle completes activation while the right ventricle is still being activated, shifting the overall depolarization vector away from these leads. Together, these features—QRS >120 ms, rsR' in V1–V2, and wide S waves in lateral leads—define the classic ECG pattern of RBBB. The other patterns describe different conditions (for example, a first-degree AV block with prolonged PR but normal QRS, or a narrow QRS with inverted T waves) and do not fit the RBBB pattern.

Right bundle branch block causes delayed activation of the right ventricle, which lengthens overall depolarization and widens the QRS to more than 120 ms. The hallmark is an rsR' pattern in the right precordial leads (V1 and often V2), giving an “M-shaped” appearance due to the initial septal activation followed by late RV activation producing a second R’. In the lateral leads (I, aVL, V5–V6) you see wide, often deep S waves, reflecting that the left ventricle completes activation while the right ventricle is still being activated, shifting the overall depolarization vector away from these leads. Together, these features—QRS >120 ms, rsR' in V1–V2, and wide S waves in lateral leads—define the classic ECG pattern of RBBB. The other patterns describe different conditions (for example, a first-degree AV block with prolonged PR but normal QRS, or a narrow QRS with inverted T waves) and do not fit the RBBB pattern.

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