What Is Left Axis Deviation?

Left axis deviation is a condition in which the electrical axis of the heart's ventricular depolarization is abnormally positioned between negative 30 and negative 90, which suggests an underlying anatomical or physiological condition is affecting the electrical conduction system of the heart. Common causes of left axis deviation include an old or recent myocardial infarction, paced rhythms, emphysema, hyperkalemia, and right-sided accessory pathways, such as Wolff-Parkinson-White syndrome, among other causes, according to ECG Library.