Which lead location requires proper placement at the mid-axillary line?

The correct lead location that requires proper placement at the mid-axillary line is V5. V5 is one of the precordial leads used in an electrocardiogram (ECG or EKG) to provide important information about the heart's electrical activity. For accurate readings, V5 is specifically placed on the left side of the chest, at the level of the fifth intercostal space, in line with the mid-axillary line. This placement allows for optimal visualization of the heart's left lateral wall, which is crucial for detecting any pathological changes occurring in that area.

In contrast, other leads have different placement guidelines. For instance, V4 is positioned at the fifth intercostal space at the left midclavicular line, while V1 and V2 are placed at the right and left sides of the sternum, respectively, at different intercostal spaces. Knowing the proper placement for each lead is vital for obtaining accurate and meaningful results from an ECG.