Final answer:
The V4 lead of a 12-lead ECG should be placed at the fifth intercostal space at the mid-clavicular line, just to the left of the sternum and in line with the middle of the clavicle.
Step-by-step explanation:
The V4 lead should be placed at the fifth intercostal space (which is the space between the ribs), at the mid-clavicular line. This is typically located just to the left of the sternum (breastbone) and in alignment with the middle of the clavicle (collarbone). Correct positioning of the V4 electrode, as with other electrodes in a 12-lead ECG, is crucial for obtaining an accurate representation of the heart's electrical activity. By ensuring proper placement, the resulting electrocardiogram can effectively assist in diagnosing various cardiac conditions.