In an ECG what are the precordial leads positive with respect to?

In an ECG, the precordial leads (V1 to V6) are positive with respect to a common reference point, which is typically the center of the heart or the Wilson central terminal (a theoretical point derived from the average of the limb electrodes). Each precordial lead measures the electrical activity of the heart in a specific plane and direction, providing insight into the heart's electrical conduction and potential abnormalities. The positive orientation of these leads allows for the assessment of various cardiac conditions by highlighting specific areas of the heart.