What is the main use of the V3 lead in an ECG?

The V3 lead in an ECG primarily serves to visualize the anterior wall of the left ventricle. This lead is positioned between the V2 and V4 leads on the chest wall, ideally located to pick up electrical activity and changes in the anterior portion of the heart. The anterior wall is particularly important to monitor, as it can provide insights into conditions such as anterior myocardial infarction, which is critical for patient management and treatment decisions.

The placement of the V3 lead, along with its relationships to the adjacent leads, allows it to capture a view of the heart's electrical activity from a particular perspective focused on the anterior heart. This position enhances the diagnostic capability regarding issues that may arise specifically in that region, making it invaluable during the interpretation of an ECG.