What type of leads are aVL, aVR, and aVF considered?

The leads aVL, aVR, and aVF are classified as unipolar leads. Unipolar leads measure the electrical activity at a single electrode site in relation to a reference point that is created by averaging the electrical activity from the other electrodes. Each of these leads tracks the electrical signals in a specific plane of the heart, providing a unique view of cardiac electrical activity.

The aVL lead, for instance, looks at the left arm's potential with the reference point averaging the other limbs, while aVR and aVF do similar measurements from the right arm and the left leg respectively. This characteristic of measuring from one active electrode against a composite reference differentiates unipolar leads from bipolar leads, which measure the difference between two active electrodes. Precordial leads, on the other hand, are specific leads placed on the chest that are also unipolar but are not what aVL, aVR, and aVF are referring to.

Thus, the classification of aVL, aVR, and aVF as unipolar leads is based on their design and how they capture and interpret the heart's electrical signals in relation to a calculated ground reference rather than between two points.