Topic Reviews A-Z
Save
Left Anterior Fascicular Block
A left anterior fascicular block (LAFB) also known as a left anterior hemiblock (LAHB) occurs when the anterior fascicle of the left bundle branch is no longer able to conduct action potentials.
The criteria to diagnose a LAFB is as follows:
- Left axis deviation of at least -450
- The presence of a qR complex in lead I and a rS complex in lead III.
- Usually a rS complex in lead II and aVF as well (not always).
A LAFB can occur simultaneously with a right bundle branch block. This is referred to as a bifascicular block.
Note that the presence of a qR complex in the inferior leads makes concomitant diagnosis of an old inferior myocardial infarction impossible in the setting of a LAFB.
Insert Images: LAFB1.jpg, LAFB2.jpg, LAFB3.jpg, BifascicularBlock1.jpg
Left anterior fascicular block.
Left anterior fascicular block.
Left anterior fascicular block.