Current flowing toward a positive electrode on an ECG trace produces which type of deflection?

Current flowing toward a positive electrode on an ECG trace produces which type of deflection?

• A. Upright deflection
• B. Inverted deflection
• C. Isoelectric line
• D. Downward deflection

Answer: (A)

In an ECG, the deflection on a lead depends on the direction of the depolarization wave relative to the positive electrode of that lead. When the wavefront moves toward the recording positive electrode, the recorded signal is positive, producing an upright (positive) deflection above the baseline. If depolarization moves away from the positive electrode, the deflection would be downward, and if the wave is perpendicular to the lead axis, the trace sits on the isoelectric line. So, moving toward the positive electrode yields an upright deflection.