Left axis deviation

Left axis deviation (LAD) is a condition in which the electrical axis of the heart is deviated to the left. This is typically identified on an electrocardiogram (ECG) and is characterized by an axis that is more negative than -30 degrees.

Left axis dev (CardioNetworks ECGpedia)

RBBB with first degree AV block

Causes

Left axis deviation can be caused by a variety of conditions, including:

• Left ventricular hypertrophy
• Left bundle branch block
• Inferior myocardial infarction
• Wolff-Parkinson-White syndrome
• Congenital heart disease

Diagnosis

The diagnosis of left axis deviation is made using an electrocardiogram. The electrical axis is determined by analyzing the QRS complex in the limb leads. In left axis deviation, the QRS complex is predominantly negative in lead II and positive in lead I.

Clinical Significance

Left axis deviation itself is not a disease but rather a sign that may indicate underlying cardiac pathology. It is important for clinicians to evaluate the patient for potential causes of LAD and to assess the overall clinical context.

Management

Management of left axis deviation involves addressing the underlying cause. For example, if LAD is due to left ventricular hypertrophy, treatment may focus on managing hypertension or other contributing factors.

Related Pages

• Electrocardiogram
• Cardiac axis
• Left ventricular hypertrophy
• Bundle branch block

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