Which leads occupy the second column in the standard layout?

Which leads occupy the second column in the standard layout?

• A. aVR, aVL, and aVF
• B. I, II, and III
• C. V1, V2, V3
• D. V4, V5, V6

Answer: (A)

The second column in the standard 12-lead ECG layout contains the augmented limb leads: aVR, aVL, and aVF. These leads are derived from the limb electrodes and are grouped together in the middle column, reflecting their common origin as limb-derived projections. The other groups sit in the other columns: the standard limb leads I, II, and III are found in the first column, while the chest (precordial) leads V1 through V6 appear in the right-hand column. So, the middle column is specifically those augmented limb leads.