Where is V4 placed?

• A. Fourth intercostal space along the left sternal border
• B. Fifth intercostal space along the left anterior axillary line
• C. Midclavicular line, fifth intercostal space
• D. Fifth intercostal space along the midline

Answer: (C)

V4 sits at the left chest in the fifth intercostal space along the midclavicular line. This apex location is chosen because it provides a clear view of the electrical activity of the left ventricle when used with the other precordial leads, giving a complementary perspective to V1–V3 and V5–V6 in a standard 12-lead ECG. The other described positions correspond to other leads: one is the left sternal border in the fourth space, another is the left anterior axillary line in the fifth space, and the midline fifth space isn’t used for a standard chest lead.