Left bundle branch block

Question 1

What is LBBB?

Answer 1

Conduction down from the bundle of his to the left bundle branch is blocked, delaying depolarisation of the left ventricle.

Question 2

How do I recognise LBBB?

Answer 2

• QRS complex greater than 0.12 seconds or 3 small squares.
• Negative QRS complex in V1 With dominant S-Wave
• Positive QRS complex in lateral leads LI, V5 and V6.
• V1 QRS Complex may present with ‘W shape’
• T- wave abnormalities can occur

Question 3

What leads can LBBB be present in

Answer 3

All however should observe LII, V1 > V4

Question 4

Signs and symptoms of LBBB

Answer 4

• Chest pain
• Shortness of breath
• Dyspnoea
• can also present asymptomatic

Question 5

LBBB Significance

Answer 5

Typically associated with myocardial ischemia.

Question 6

How should new onset of LBBB be treated?

Answer 6

Should be treated as tho the patient is having ST elevation myocardial infarction (STEMI).
- Follow local STEMI guidelines

Question 7

What should I check with a patient presenting with LBBB?

Answer 7

Should check if the patient is known to have LBBB as some patents can live willingly and normal lives with LBBB.

Question 8

What is incomplete bundle branch block ?

Answer 8

An incomplete left bundle branch block is a presenting morphology with a QRS duration of <0.12 seconds or 3 small squares.