In addition, any two precordial leads next to one another are considered to be contiguous.

The precordial leads view the heart's electrical activity in the so-called horizontal plane.

Reversal of the limb leads and of the precordial leads.

ST segment depression and T wave inversion in right precordial leads is usually seen in severe RVH such as in pulmonary stenosis and pulmonary hypertension.

Looking at the precordial leads, the r wave usually progresses from showing a rS-type complex in V with an increasing R and a decreasing S wave when moving towards the left side.

Wilson's central terminal paved the way for the development of the augmented limb leads aVR, aVL, aVF and the precordial leads V, V, V, V, V and V.

The current guidelines for the ECG diagnosis of the ST segment elevation type of acute myocardial infarction require at least 1 mm (0.1 mV) of ST segment elevation in the limb leads, and at least 2 mm elevation in the precordial leads.