What is indicated by a positive deflection in lead aVF?

A positive deflection in lead aVF indicates that the electrical activity of the heart is moving towards the left leg, which is the position of the electrode for lead aVF. The aVF lead is oriented to capture the electrical impulses traveling from the upper part of the heart toward the lower part, specifically the inferior wall.

When a positive deflection is observed, it means that the net electrical activity is directed toward the positive electrode positioned at the left leg. This positive wave indicates that the majority of the heart's electrical activity is heading in the direction of the electrode placement, which correlates with the normal movement of electrical impulses during depolarization of the heart ventricles.

This positive deflection is a crucial aspect of interpreting an ECG, as it helps healthcare providers assess the heart's orientation and identify potential abnormalities based on the direction of electrical flow.