Left axis deviation

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

In electrocardiography, left axis deviation (LAD) is a condition wherein 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]

There are several potential causes of LAD. Some of the causes include normal variation, thickened left ventricle, conduction defects, inferior wall myocardial infarction, pre-excitation syndrome, ventricular ectopic rhythms, congenital heart disease, high potassium levels, emphysema, mechanical shift, and paced rhythm.[2]

Symptoms and treatment of left axis deviation depend on the underlying cause.

  1. ^ Jenkins, Dean (1996). "The electrical axis at a glance". www.ecglibrary.com. Retrieved 2016-11-12.
  2. ^ Kashou, Anthony H.; Basit, Hajira; Chhabra, Lovely (2021), "Electrical Right and Left Axis Deviation", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 29262101, retrieved 2021-07-26