What are the standard leads in a 12-lead ECG?

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

Answer: (B)

The selection encompasses all 12 leads used in a standard 12-lead ECG. This includes the three bipolar limb leads (I, II, III), which measure the electrical activity between pairs of limbs, and the three augmented limb leads (aVR, aVL, aVF), which provide a different perspective of the heart's electrical activity from the limbs. Additionally, it includes the six precordial leads (V1, V2, V3, V4, V5, and V6) that are placed on the chest, allowing for a thorough evaluation of the heart from various angles.

In contrast, the other options lack components necessary for a complete 12-lead ECG. For instance, certain selections may omit critical augmented limb leads, preventing comprehensive monitoring of the heart's activity. By including all necessary leads, the complete set allows for accurate diagnosis of many cardiac conditions.