Cardiac Axis

Cardiac axis

Cardiac axis describes the overall direction of electrical spread within the heart.
In a healthy individual the axis should spread from 11 o’clock to 5 o’clock.
To determine the cardiac axis you need to look at leads I,II and III.

Normal cardiac axis

In normal cardiac axis:

    Lead II has the most positive deflection compared to Leads I and III

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Right axis deviation

In right axis deviation:

     Lead III has the most positive deflection and Lead I should be negative

     This is commonly seen in individuals with right ventricular hypertrophy

Left axis deviation

In left axis deviation:

     Lead I has the most positive deflection

     Leads II and III are negative

     Left axis deviation is seen in individuals with heart conduction defects