Which lead is placed at the anterior axillary line?

The lead that is placed at the anterior axillary line is V5. This lead is positioned at the same horizontal level as V4 but is located at the anterior axillary line, which is a vertical line drawn down from the anterior axillary fold where the pectoralis major muscle is located. Proper placement of V5 is important for accurate assessment of the heart's electrical activity, particularly to capture the lateral wall of the left ventricle in the context of an electrocardiogram (ECG).

Understanding the placement of leads is crucial in the interpretation of ECGs, as each lead provides a different view of the heart's activity. V5's location contributes to its role in defining cardiac events occurring on the lateral wall, hence its specific placement at the anterior axillary line is essential for accurate diagnosis and monitoring.