ECG changes to know

Question 1

What are ECG changes in Left Bundle Branch Block?

Answer 1

Broad QRS complex (over 120ms)

Dominant S wave in V1

Broad monophasic R wave in lateral leads: I, aVL, V5-6

No Q waves in lateral leads

Prolonged R wave (over 60ms) in leads V5-6

Question 2

What are ECG changes in Right Bundle Branch Block?

Answer 2

Broad QRS complex (over 120ms)

RSR’ pattern in V1-3

Wide slurred S wave in lateral leads (I, aVL, V5-6)