Which chest lead placement is at the 5th intercostal space along the midaxillary line?

• A. V4 placement
• B. V6 placement
• C. V5 placement
• D. V3 placement

Answer: (B)

Chest lead placement on the precordial set is designed to view the heart from different angles in the transverse plane. The 5th intercostal space is the space between the fifth and sixth ribs, and the midaxillary line runs down the side of the chest under the armpit. Placing a chest lead at that spot captures electrical activity from the lateral aspect of the left ventricle, which is why this location corresponds to V6. The other placements are at different landmarks along the chest wall (midclavicular line for V4, anterior axillary line for V5, and between V2 and V4 for V3), so they don’t sit on the midaxillary line at the same horizontal level.