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Left Bundle Branch Block - LBBB

  • Right ventricle depolarizes before the Left ventricle
  • QRS is wide, > 0.12 secs due to two R waves
  • QRS is negative in V1
  • No Q wave in I, AVL, V5, V6
  • Broad monomorphic R waves in lead I and V6 with no Q waves
  • Broad monomorphic S waves in lead I, may have small r wave
  • Depressed ST segment with T wave inversion in V6

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Ministry of Health and Long-Term Care
5700 Yonge Street, 6th Floor
Toronto, ON M2M 4K5