Step 6: Inspect QRS complexes for ventricular hypertrophy or low voltage

In the setting of Left Ventricular Hypertrophy (LVH), the left ventricle enlarges and so the leads oriented to the left ventricle (V5, V6, aVL) will "see" more electrical activity moving towards them. As well, the leads oriented away from the left ventricle (V1, V2) will "see" more activity moving away from them. In LVH therefore, leads V5, V6 and aVL will have tall R waves, while leads V1 and V2 will have deep S waves. (The arrow in the diagram on the right shows the direction of the net electrical activity in LVH.)

V1 or V2

V5, V6 or aVL

The voltage criteria for LVH are satisfied if the sum of the amplitude of the deepest S wave in V1 or V2, and the amplitude of the tallest R wave in V5 or V6, is equal to or greater than 35 mm (3.5 mV). The voltage criteria are also satisfied if the amplitude of the R wave in lead aVL is equal to or greater than 12 mm (1.2mV).