A positive deflection on a unipolar EGM indicates the wavefront is moving toward which electrode?

• A. Toward Anode
• B. Toward Cathode
• C. Perpendicular
• D. Unknown

Answer: (A)

In a unipolar EGM, the deflection polarity tells you where the activation wavefront is headed relative to the recording electrode. When the wavefront moves toward the recording electrode, current flows into that electrode and its potential rises relative to the distant reference, producing a positive deflection. Since the recording electrode acts as the anode in this setup, a positive deflection indicates the wavefront is moving toward the anode. If the wavefront were moving away, the deflection would be negative toward the reference. Perpendicular motion doesn’t uniquely define direction, so the positive deflection most specifically points to the wavefront approaching the anode.