In the standard lead layout, which leads occupy the first column?

In the standard lead layout, which leads occupy the first column?

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

Answer: (A)

In a standard 12-lead ECG layout, the first column is reserved for the limb leads—the Einthoven leads I, II, and III. These three leads are derived from the limb electrodes and view the heart in the frontal plane, so they’re shown as a vertical stack in the first column. The next column contains the augmented limb leads aVR, aVL, and aVF, and the remaining columns hold the chest leads V1–V3 in one column and V4–V6 in the last column. This arrangement places the limb leads in the first column, with the chest leads in the later columns.