What is the correct placement for V3 in a 12-Lead ECG?

In the context of placing leads for a 12-Lead ECG, the correct placement for V3 is indeed halfway between V4 and V2. This positioning is essential for obtaining an accurate representation of the heart's electrical activity from the anterior and lateral aspects.

To understand this placement, it’s helpful to consider the general layout of the precordial leads. V2 is positioned at the left sternal border in the 4th intercostal space, while V4 is located at the midclavicular line in the 5th intercostal space. By placing V3 directly between these two points, it captures the electrical activity occurring in the anterior wall of the heart, which is critical for diagnosing conditions such as anterior myocardial infarctions.

The rationale for V3's placement being centered between V2 and V4 allows for an optimal view of the anterior wall, ensuring that the interlead differences provide a full picture of the heart's electrical conduction and potential ischemic changes. This strategic positioning aids healthcare providers in making informed decisions based on the ECG interpretation.