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Left axis deviation

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Title: Left axis deviation  
Author: World Heritage Encyclopedia
Language: English
Subject: Right axis deviation, Hexaxial reference system, Cardiac dysrhythmia, Right atrial enlargement, Intraventricular block
Collection: Cardiac Dysrhythmia
Publisher: World Heritage Encyclopedia

Left axis deviation

The hexaxial reference system is a diagram that is used to determine the heart's electrical axis in the frontal plane.

Left axis deviation (LAD) is a condition whereby the mean electrical axis of ventricular contraction of the heart lies in a frontal plane direction between −30° and −90°. This is reflected by a QRS complex positive in lead I and negative in leads aVF and II.[1]


Common causes of LAD include left ventricular hypertrophy (LVH), left anterior fascicular block (or hemiblock) and inferior myocardial infarction.[2][3] Less commonly LAD may be a normal variant, particularly in obese or stocky individuals, or it may be associated with Wolff–Parkinson–White syndrome or an ostium primum atrial septal defect.

LVH is generally recognised as a cause of LAD,[2][3][4] although some sources claim that LVH does not cause LAD.[1][5]

See also


  1. ^ a b
  2. ^ a b
  3. ^ a b
  4. ^
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