Left Posterior Fascicular Block - ECG

Left posterior fascicular block (LPFB) is also known as left posterior hemiblock (LPHB). In contrast to LAFB, LPFB is a rare finding. It is typical with negative QRS amplitude in lead I and positive QRS amplitudes in leads II and III. The ECG axis is deviated to the right (vertically).

 

Left Posterior Fascicular Block - ECGThis is a classic left posterior fascicular block – we see negative QRS amplitude in I (blue) and positive QRS in II and III (red). Leads aVL and aVF (red ellipse) suggest vertical deviation of ECG axis.
 

LPFB does not have a great significance when it is an incidental finding. Sometimes it may accompany myocardial infarction and it is emphasized that LPFB may be present in right ventricular overload.

 

Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Contact: jiri.stefanek@seznam.cz
 Sources: basic text sources