Cardiac Axis — ECG/EKG Terminology

Definition: The average direction of the wave of depolarization through the ventricles.

Key Facts

• Represents average direction of ventricular depolarization in the frontal plane.
• Can shift with chamber enlargement, conduction block, or infarction.
• Axis interpretation uses limb-lead QRS polarity relationships.

ECG Connection: Axis change is an important secondary clue in rhythm and conduction interpretation.

Why It Matters: Trend axis with morphology changes to identify new conduction or structural problems.