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Intermediate Technical IVT

LBBB

Also written as: LBBB — Left Bundle Branch Block

Left bundle branch block, a conduction abnormality affecting electrical activation of the left ventricle.

Full Definition

Left bundle branch block (LBBB) is an electrocardiographic finding indicating delayed or absent conduction through the left bundle branch of the cardiac conduction system. This results in asynchronous activation of the left ventricle, with characteristic QRS widening (≥120 ms) and specific morphological changes on the ECG. LBBB can significantly affect cardiac imaging interpretation, causing mechanical dyssynchrony that may be mistaken for regional wall motion abnormalities and can complicate the assessment of ischemia and viability.

Usage

Usage note: Consider impact on imaging interpretation and specify if new or pre-existing when clinically relevant.

In Context

  • "The presence of LBBB made assessment of regional wall motion challenging on echocardiography." — imaging interpretation note
  • "New LBBB in the setting of chest pain raised concern for proximal LAD occlusion." — emergency department evaluation

Also known as

left bundle branch block

Contrasted with

RBBB normal conduction

Don't confuse with

RBBB IVCD WPW

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