Right bundle branch block

In right bundle branch block (RBBB) a block in the right bundle branch causes the right ventricle to depolarise later than the left. This causes certain characteristic ECG features.

Etiology

See bundle branch block.

In addition to the above mentioned etiologies, RBBB is associated with lung pathologies like pulmonary hypertension, embolism, or COPD. This is because these pathologies often put strain on the right ventricle and the right bundle branch.

Clinical features

The characteristic ECG features include:

• Wide QRS (> 120 ms)
• RSR’ pattern in leads V1, V2 (forming an “M” or “rabbit ears” shape)
• Wider S wave than R wave in leads I, V5, V6

The first R in leads V1 and V2 correspond to the depolarisation of the left ventricle, while the second R (the R’) in the “rabbit ears” is delayed and corresponds to the depolarisation of the right ventricle, which occurs after the depolarisation wave has spread from the left ventricle to the myocardium to the right ventricle.