What Is Axis on Ecg

The axis of the ECG is the major direction of the overall electrical activity of the heart. It can be normal, leftward (left axis deviation, or LAD), rightward (right axis deviation, or RAD) or indeterminate (northwest axis). The QRS axis is the most important to determine.

What is normal heart axis?

As evident from the figure, the normal heart axis is between –30° and 90°. If the axis is more positive than 90° it is referred to as right axis deviation. If the axis is more negative than –30° it is referred to as left axis deviation.

What causes left axis deviation of the heart?

Some of the causes include normal variation, thickened left ventricle, conduction defects, inferior wall myocardial infarction, pre-excitation syndromes, ventricular ectopic rhythms, congenital heart disease, high potassium levels, emphysema, mechanical shift, and pacemaker-generated rhythm or paced rhythm.