Left Bundle Branch Block

Left Bundle Branch Block

ECG Quiz 33Features of left bundle branch block are evident. The QRS is widened, measuring around 160 milliseconds. M shaped pattern is seen in lateral leads I, V5 and V6. Broad negative complexes are seen in V1, V2 and V3. ST depression and T wave inversion are noted in the lateral leads I, aVL, V5 and V6. S waves are very deep in leads V1 to V4. An R wave in V1 and upright T wave in V5 may be a subtle evidence of underlying coronary artery disease in LBBB. There is also left axis deviation in this ECG.