Know thou LBBB

The Law of Discordance

In a normal LBBB the ST segments should be isoelectric or go be in the opposite (discordant) direction from the dominant part of the QRS

So typically in V1 the QRS is mainly negative and the ST segment in elevated. This is normal for LBBB

In V6 the QRS is mainly positive and the ST segment is down. This is normal for LBBB

Modified Sgarbossa Criteria for diagnosing STEMI in the presence of a

LBBB

If there is concordant ST changes (ST segments in the same direction as the dominant part of the QRS) or a discordant ST elevation of greater than 1/4 of the amplitude of the S wave.

A: Concordant STE ≥ 1mm (in any lead) = Most specific for MI

B: Concordant STD ≥ 1mm in V1, V2, or V3 = Specific for MI

C: Discordant STE > 0.25 S

All this applies to Ventricular paced

rhythms

If in doubt get a second opinion

Overnight email concerning ECGs to your boss then phone them for an interpretation

Documentation

Time read

Your interpretation

Time frame for repeat ECGs if needed

Your name legibly