If the size of the wall of the left ventricle increases large voltages are recorded in the leads overlying the hypertrophied left ventricle.
Leads I, aVL, V5 and V6 will record the largest voltages in the form of tall R waves as the wave of depolarisation moves towards them.
Leads V1 and V2 will increase their NEGATIVE voltage as the wave of depolarisation moves away from them.
Sokolov-Lyon criteria for Left ventricular hypertrophy:
S wave in V1
R wave height in V5 or V6 is greater than or equal to 35 mm
There are other criteria for diagnosis LVH on ECG (1. R wave in aVL greater than or equal to 11mm, 2. R wave in V or V greater than 27mm)
Repolarisation changes in the form of ST depression and asymmetrical T wave inversion are often present in te left hear leads, although the reasons for these changes are not entirely clear.