What causes a left axis deviation?

As a medical professional with expertise in cardiology, I can explain that a left axis deviation (LAD) on an electrocardiogram (ECG) is a condition where the electrical impulses of the heart's ventricles are deviating to the left instead of following the normal rightward trajectory. This deviation can be caused by several factors, which include: 1. Left Ventricular Hypertrophy (LVH): This is a common cause where the heart muscle, specifically the left ventricle, becomes thicker. The increased mass can alter the electrical pathway, leading to LAD. 2. Left Anterior Fascicular Block (LAFB): This blockage affects the electrical conduction system of the heart, particularly the left anterior fascicle, which is one of the three bundles that help in the proper sequencing of the heart's contractions. 3. Inferior Myocardial Infarction: An infarction, or heart attack, in the inferior wall of the heart can also result in LAD. The damage to the heart muscle can change the normal direction of electrical impulses. It's important to note that LAD is not a diagnosis in itself but rather a finding that may indicate an underlying heart condition. Further evaluation by a healthcare professional is necessary to determine the cause and appropriate treatment.

Cause. Common causes of LAD include left ventricular hypertrophy (LVH), left anterior fascicular block (or hemiblock) and inferior myocardial infarction.