Right Bundle Branch Block (RBBB)

Right Bundle Branch Block (RBBB)

In RBBB, activation of the right ventricle is delayed as depolarisation has to spread across the septum from the left ventricle.

  • The left ventricle is activated normally, meaning that the early part of the QRS complex is unchanged.
  • The delayed right ventricular activation produces a secondary R wave (R’) in the right precordial leads (V1-3) and a wide, slurred S wave in the lateral leads.
  • Delayed activation of the right ventricle also gives rise to secondary repolarization abnormalities, with ST depression and T wave inversion in the right precordial leads.
  • In isolated RBBB the cardiac axis is unchanged, as left ventricular activation proceeds normally via the left bundle branch.
ECG Strip Right Bundle Branch Block RBBB

ECG changes in RBBB

Diagnostic Criteria
  • Broad QRS > 120 ms
  • RSR’ pattern in V1-3 (‘M-shaped’ QRS complex)
  • Wide, slurred S wave in the lateral leads (I, aVL, V5-6)
ECG Right Bundle Branch Block RBBB 2
Associated Features

ST depression and T wave inversion in the right precordial leads (V1-3)

Variations

Sometimes rather than an RSR’ pattern in V1, there may be a broad monophasic R wave or a qR complex.

ECG Right Bundle Branch Block RBBB V1 RSR Complex
Typical RSR’ pattern (‘M’-shaped QRS) in V1

ECG Right Bundle Branch Block RBBB Lead I wide S
Wide slurred S wave in lead I

ECG Right Bundle Branch Block RBBB T wave inversion
Typical pattern of T-wave inversion in V1-3 with RBBB

Causes of Right Bundle Branch Block


ECG Examples of Right Bundle Branch Block

Example 1
ECG Right Bundle Branch Block RBBB 6

Example 2
ECG Right Bundle Branch Block RBBB 5

Example 3
ECG Right Bundle Branch Block RBBB 3

Example 4
ECG RBBB LAD

Incomplete RBBB

ECG Incomplete RBBB Normal Pediatric 2 year old
  • Incomplete RBBB is defined as an RSR’ pattern in V1-3 with QRS duration < 120ms.
  • It is a normal variant, commonly seen in children (of no clinical significance).

Differential Diagnosis of RBBB

ECG Brugada Tyope 1 RBBB mimic 2
  • An RSR’ pattern in V1-3 may also be caused by Brugada syndrome — an ECG pattern associated with malignant ventricular arrhythmias.

Related Topics


LITFL Further Reading


Advanced Reading


ECG LIBRARY 700

ECG LIBRARY

Electrocardiogram

Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

2 Comments

  1. Quick question for clarification: For a it to be classified as an RSR pattern the S wave needs to be a negative deflection below the isoelectric line right?

    So how can the ecg example under “variations” be called a RSR pattern. Isnt it more indicative of a rR pattern?

    Keep up the good work – you guys are lifesavers

  2. How about in rsR’ where r wave is greater than the R” wave (Lead V1 and V2). opposite above. is it still called RBBB

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