Left axis deviation

In <a href="/facts/Electrocardiography/YpVswJ0W">electrocardiography</a>, left axis deviation (LAD) is a condition wherein the <a href="/facts/Cardiac_axis/YpVswJ0W">mean electrical axis</a> of <a href="/facts/Ventricle_(heart)/FCzV1xm7">ventricular</a> contraction of the heart lies in a frontal plane direction between −30° and −90°. This is reflected by a <a href="/facts/QRS_complex/Pehk2szJ">QRS complex</a> positive in lead I and negative in leads aVF and II.
There are several potential causes of LAD. Some of the causes include normal variation, <a href="/facts/Ventricular_hypertrophy/YNcQhDVE">thickened left ventricle</a>, <a href="/facts/Electrical_conduction_system_of_the_heart/AouErvDx">conduction</a> defects, inferior wall myocardial infarction, <a href="/facts/Pre-excitation_syndrome/L27LeXkq">pre-excitation</a> syndrome, ventricular ectopic rhythms, <a href="/facts/Congenital_heart_defect/QsuPPC2Y">congenital heart disease</a>, <a href="/facts/Hyperkalemia/epfvUg5w">high potassium levels</a>, <a href="/facts/Emphysema/ud3oXGCr">emphysema</a>, mechanical shift, and <a href="/facts/Cardiac_pacing/b90Qt8ND">paced rhythm</a>.
Symptoms and treatment of left axis deviation depend on the underlying cause.

Left axis deviation open-in-new

Left axis deviation