Which leads are classified as unipolar?

The classification of unipolar leads refers to those leads that measure the electrical potential in relation to a single point, typically using a neutral or grounded reference point. In the context of an electrocardiogram (ECG), unipolar leads consist of augmented leads and precordial leads.

The leads aVR, aVL, and aVF are correctly identified as unipolar leads. Each of these leads derives its readings from a central terminal formed by the average of the two limbs not included in the respective lead. For example, aVF references the right arm and left arm to measure electrical activity in the direction of the feet. This approach allows for a more focused measurement of the heart's electrical activity from a specific viewpoint.

Unipolar leads contribute to a comprehensive understanding of the heart's electrical axis and help to identify various cardiac conditions. In contrast, other lead groupings mentioned in the question, such as I, II, and III, are bipolar leads and measure the potential difference between two distinct points rather than from a single point to a reference. Precordial leads (V1, V2, V3) are also technically classified as unipolar because they measure the electrical activity at the chest wall in reference to a zero