QRS axis is the direction in which the mean QRS current flows. The normal axis points mostly downward and to the left because the more muscular left ventricle generates a stronger depolarizing current that overwhelms that generated by the less bulky right.

How do you find the QRS axis?

The most efficient way to estimate axis is to look at LEAD I and LEAD aVF. A positive QRS in Lead I puts the axis in roughly the same direction as lead I. A positive QRS in Lead aVF similarly aligns the axis with lead aVF. Combining both coloured areas – the quadrant of overlap determines the axis.

What does cardiac axis mean?

The electrical heart axis is an average of all depolarizations in the heart. The depolarization wave begins in the right atrium and proceeds to the left and right ventricle.