ECG - LBBB

ECG - LBBB

• • QRS >120 msec = Complete

  • QRS 100 - 119 msec = Incomplete

  • LAD = -30° to -90°

  • Check in lead I, aVL, V5, V6 (lateral leads)

    • Tall wide slurred monophasic or notched R wave with VAT (intrinsicoid deflection) >40 msec in I & V6

    • ST segment depression and T wave inversion directed opposite to the RSR' pattern in the respective leads. These ST-T changes are called secondary ST-T changes i.e., secondary to the conduction disturbance (in contrast to the primary ST-T changes due to ischemia and/or drugs affecting the myocardium)

  • Check in V1 - V3

    • ST elevation

    • T elevation

    • rS or QS pattern: initial r wave followed by deep S wave or deep wide QS only.

Very important: For left bundle branch block, the ECG is often unreliable for identifying infarct.