Which pattern is used to identify Left Bundle Branch Block (LBBB) on an ECG?

Identifying Left Bundle Branch Block (LBBB) on an ECG is essential for understanding the condition of the heart's electrical conduction system. The specific pattern that indicates LBBB is characterized by a deep S-wave in lead V1.

In the case of LBBB, the electrical impulse is delayed in the left bundle branch, resulting in a distinctive alteration in the ventricular depolarization process. This delay commonly manifests as a prominent and deep S-wave in lead V1. While there may be a tall R-wave in the lateral leads due to the paradoxical repolarization sequence, it is the deep S-wave in V1 that specifically signals LBBB.

This S-wave is significant because it showcases the initial part of the electrical conduction path not being propagated normally, reflecting the dysfunction in the left bundle branch. In summary, recognizing the deep S-wave in lead V1 is crucial for diagnosing LBBB and understanding the underlying issues in cardiac conduction.