EKG Artifacts and Troubleshooting
Updated October 27, 2026
An artifact is anything on the EKG tracing that doesn’t come from the heart’s electrical activity. Artifacts can hide real rhythms or mimic dangerous ones, so recognizing and fixing them is a big part of EKG Acquisition, the largest domain on the NHA CET exam. Here are the four common types, followed by free practice questions. Always check the patient first: never assume a worrying tracing is only artifact.
The four common artifacts
| Artifact | Looks like | Common causes | Fix |
|---|---|---|---|
| Somatic tremor (muscle) | Jittery, irregular spikes | Shivering, tension, talking, tremors (such as Parkinson’s disease) | Keep the patient warm and relaxed, support the limbs, ask them to lie still and not talk |
| Wandering baseline | The baseline drifts up and down | Poor electrode contact, lotion or sweat on the skin, breathing movement | Clean and dry the skin, reapply electrodes, check the cables |
| AC (60-cycle) interference | Thick, regular, evenly spaced lines | Electrical interference from nearby devices, cables crossing power cords, poor grounding | Unplug nearby equipment if possible, move cables away from cords, check the machine’s grounding |
| Interrupted baseline | Breaks in the tracing, or a flat line | A loose electrode, a broken cable or a lead wire that came off | Reattach electrodes, check and replace damaged cables |
Standard settings
- Paper speed: 25 mm per second
- Standard calibration: 10 mm per millivolt (the calibration mark is 10 small boxes tall)
If the settings are changed, note it on the tracing.
Free practice questions
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A tracing shows thick, regular, evenly spaced lines along the baseline. Which artifact is this?Answer: CAC interference from nearby electrical equipment produces a thick, regular pattern. Move cables away from power cords and unplug nearby devices if possible.
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The baseline slowly drifts up and down. What is a common cause?Answer: AA wandering baseline is often caused by poor electrode contact or breathing movement. Clean and dry the skin and reapply the electrodes.
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A patient who is cold and shivering produces a jittery tracing. Which artifact is this?Answer: DMuscle movement from shivering produces somatic tremor artifact. Warming the patient and helping them relax reduces it.
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The tracing suddenly shows a flat line in one lead while the patient is talking normally. What is the most likely cause?Answer: AA patient who is talking normally has a heartbeat. A flat line in one lead points to a loose electrode, a disconnected lead or a broken cable. Check the patient first, then the connections.
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What is the standard EKG paper speed?Answer: BThe standard paper speed is 25 mm per second. If another speed is used, it must be noted on the tracing.
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What is the standard EKG calibration?Answer: DStandard calibration is 10 mm per millivolt, shown as a calibration mark 10 small boxes tall.
Pass your EKG technician exam on the first try
- All 190 questions on safety and compliance, patient care, EKG acquisition and rhythm analysis
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