Wandering baseline refers to which of the following?

• A. A stable line at baseline
• B. An ECG artifact caused by electrical interference
• C. The line that marks P wave location
• D. Shift on the ECG tracing from the baseline or center of the paper

Answer: (D)

Wandering baseline is the drift of the isoelectric line—the flat baseline of an ECG—that moves up or down during the recording instead of staying constant. This drift is usually caused by factors at the skin-electrode interface, such as poor skin prep, loose or defective leads, or movement and respiration. Because the baseline isn’t stable, it becomes hard to accurately measure segments and intervals, and the tracing can look like abnormal findings even when the heart rhythm is normal. This is different from an electrical interference artifact, which appears as noise or spikes on the trace, and it’s not about where the P waves occur. To prevent wandering baseline, ensure clean skin, proper electrode adhesion, secure leads, and minimal movement during recording.