12-Lead 12-Lead ElectrocardiographyElectrocardiography

a comprehensive course

Adam Thompson, EMT-P, A.S.Adam Thompson, EMT-P, A.S.

STE-Mimics

Part 2

Left Bundle Branch BlockLeft Bundle Branch Block

• LBBB may also mimic a STEMILBBB may also mimic a STEMI– Delayed conduction due to a block of both the Left Delayed conduction due to a block of both the Left

Anterior Fascicle & Left Posterior Fascicle.Anterior Fascicle & Left Posterior Fascicle.– Atrial rhythm with QRS duration > 120 ms and Atrial rhythm with QRS duration > 120 ms and

negatively deflected QRS complex in V1.negatively deflected QRS complex in V1.– May cause ST-elevation due to T-Wave May cause ST-elevation due to T-Wave

discordance. discordance.

LBBB ResearchLBBB Research

• The evidence shows that there is no correlation between a new LBBB and ACS despite what was previously believed. – Am J Emerg Med 2009;27:916-921.

STE due to LBBBSTE due to LBBB

• Like LVH, STE may be caused by the T wave Like LVH, STE may be caused by the T wave discordance normally found with a LBBB.discordance normally found with a LBBB.

• Acute Myocardial Infarction can still be Acute Myocardial Infarction can still be diagnosed in the presence of LBBB.diagnosed in the presence of LBBB.– This is not a commonly known fact, and many This is not a commonly known fact, and many

texts teach that an AMI can not be identified in the texts teach that an AMI can not be identified in the presence of LBBBpresence of LBBB

LBBB

LBBB

LBBB

LBBB

LBBB

T-Wave Discordance

The EndThe End

• More in the next lessonMore in the next lesson