Which of the following is NOT one of the limb leads in a 12 lead EKG?

Which of the following is NOT one of the limb leads in a 12 lead EKG?

• A. I
• B. II
• C. V4
• D. aVR

Answer: (C)

In a standard 12-lead EKG, the limb leads consist of leads I, II, III, aVR, aVL, and aVF. Among these, lead V4 is classified as one of the precordial (chest) leads, not a limb lead. The limb leads are crucial for providing information on the heart's electrical activity as seen from different angles in the frontal plane, while the precordial leads, including V4, provide views from the horizontal plane and are positioned on the chest wall.

Understanding the distinction between limb and precordial leads is fundamental for EKG interpretation. The limb leads focus on the heart's activity relative to the arms and legs, while the precordial leads assess the anterior, lateral, and inferior aspects of the heart. Hence, V4's classification as a precordial lead makes it the correct choice for the question about which one is not a limb lead.