Augmented limb leads

The potential difference between the reference electrode and an exploring electrode constitutes the augmented lead. The three exploring electrodes are the right arm (R), the left arm (L), and the left leg (F). The electrical signals for the unipolar leads are "augmented" by disconnecting the exploring electrode from the reference electrode. Since the reference electrode has zero potential, the augmented potential represents only that measured by the three electrodes. The three augmented leads are designated aVR, aVL, and aVF. An impulse directed toward a limb lead records a positive or upright deflection in that lead.