🚧 Under construction — VoTechWorks is being built. A free tech program — complimentary, as our commitment to get America working.
voTechWorksGrade 13 · a vocational technology learning center, by urbanicity
newSchoolWorks.com › VoTechWorks › Health & Personal Services › EKG Technician › 12-Lead EKG Acquisition › Lesson 7
HLT-EKGT89-03 · Lesson 7 · 6 clock hours · lab

Recognizing and Eliminating Artifact

Objective. Students will identify the four major artifact types on printed 12-lead tracings and apply the correct corrective intervention to produce a clean, interpretable recording.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Why Artifact Matters

An artifact is any signal on an EKG tracing that does not come from the heart's electrical activity. Artifact can mimic dysrhythmias, obscure true waveforms, and lead a clinician toward an incorrect diagnosis. Your job as an EKG Technician is to recognize artifact before handing the tracing to the provider, eliminate it, and re-acquire a clean, interpretable recording. The NHA CET exam tests artifact recognition directly, and employers depend on you to deliver tracings that are ready for clinical interpretation.

The Four Major Artifact Types

1. Somatic Tremor (Muscle Artifact)

Somatic tremor is caused by voluntary or involuntary skeletal muscle activity. On the tracing it appears as an irregular, chaotic, high-frequency baseline that varies in amplitude. The waveform looks "fuzzy" or "hairy." Common causes include shivering, anxiety, Parkinson's disease, pain, or a patient who cannot hold still.

Corrective actions: Speak calmly and instruct the patient to relax and breathe normally. Offer a blanket if the patient is cold. Position limb electrodes on fleshy areas rather than bony prominences. If tremor is continuous (as with certain neurological conditions), placing limb electrodes more proximally—closer to the torso—can reduce the artifact.

2. AC Interference (60-Cycle Interference)

Alternating current from nearby electrical equipment or poor grounding produces a perfectly uniform, high-frequency oscillation of exactly 60 cycles per second in the United States. On the tracing it looks like a thick, even, fuzzy band—sometimes described as a "sawtooth" pattern—that is remarkably regular compared with somatic tremor.

Corrective actions: Check that all electrode connections are secure and that no lead wires are dangling near power cords, IV pumps, or fluorescent lights. Ask that non-essential electrical equipment be moved away from the patient. Make sure the machine is properly grounded. Check for dry or improperly placed electrodes—poor skin contact is a common gateway for AC interference.

3. Wandering Baseline

The baseline drifts slowly up and down across the tracing, making it difficult to measure the true isoelectric line and ST segment. Causes include patient breathing (most common), poor electrode contact from inadequate skin preparation, excessive electrode gel, or loose electrodes.

Corrective actions: Re-prep the skin—clip body hair if present, clean with an alcohol wipe, allow to dry fully, and apply a fresh electrode with firm pressure. Ask the patient to breathe shallowly and evenly. Make sure the electrode tab is not being pulled by the cable. Check that the electrode has not been placed over a rib or other area that moves dramatically with respiration.

4. Lead Pop / Lead Disconnection

A lead pop appears as a sudden, sharp vertical spike or a flat line in one or more leads, followed by return to the normal signal. A full disconnection produces a flat line or wild high-amplitude excursions in the affected lead(s) only—other leads continue normally. Causes include a loose snap connector, a cracked or broken lead wire, or an electrode that has completely lifted from the skin.

Corrective actions: Check every snap connection from the electrode to the cable. Replace any electrode that has lost contact. Inspect lead wires for visible breaks or damaged insulation. If a wire is cracked or the connector is broken, replace the cable rather than continuing the acquisition.

Systematic Approach to Artifact Identification

When you receive a tracing with artifact, use this sequence:

1. Look at which leads are affected. Artifact in all leads simultaneously usually points to somatic tremor or AC interference. Artifact in only one or two leads points to a local problem—lead pop or a single bad electrode.

2. Examine the character of the artifact. Irregular and chaotic = somatic tremor. Regular and uniform = AC interference. Slow drift = wandering baseline. Sudden spike or flat line = lead pop/disconnection.

3. Correct the cause, not just the symptom. Pressing a filter button on the machine may make the tracing look cleaner on screen but can distort waveform morphology and should not substitute for true artifact elimination.

4. Re-acquire and compare. Print the clean tracing and keep the artifact tracing in the session record if your facility policy requires it.

Safety and Scope-of-Practice Notes

Key terms8

ArtifactAny signal recorded on an EKG tracing that does not originate from the heart's electrical activity; artifact interferes with interpretation.
Somatic TremorArtifact caused by skeletal muscle activity—voluntary or involuntary—that produces an irregular, chaotic, high-frequency disturbance across one or more leads.
AC InterferenceArtifact caused by alternating current from nearby electrical sources, seen as a perfectly uniform 60-cycle-per-second oscillation creating a consistently thick, even band on the tracing.
Wandering BaselineArtifact in which the isoelectric line slowly drifts up and down, most commonly caused by patient breathing or poor electrode-to-skin contact.
Lead PopArtifact appearing as a sudden sharp spike or brief signal loss in one lead, caused by a loose snap connection, lifted electrode, or damaged lead wire.
Isoelectric LineThe flat baseline of an EKG between waveforms, representing no net electrical activity; a stable isoelectric line is required for accurate waveform measurement.
Electrode PrepThe process of cleaning, drying, and sometimes abrading the skin before applying an electrode to maximize conductivity and reduce artifact.
Lead WireThe cable that connects a limb or precordial electrode to the EKG machine; damage to lead wires is a common cause of lead pop artifact.
In class: Sort a set of 16 printed tracing strips into four artifact categories (somatic tremor, AC interference, wandering baseline, lead pop/disconnection) using a reference identification card, then self-check against an answer key. · Deliberately introduce each of the four artifact types on a live EKG acquisition using a manikin or volunteer (e.g., ask the volunteer to shiver, position a lead near an AC source, loosen an electrode) and identify them on the printout. · Apply the correct corrective action for each introduced artifact—patient coaching, repositioning, re-prepping electrode, resolving cable proximity—and re-acquire a clean tracing, comparing before-and-after prints.
Materials: Printed artifact tracing set (16 strips), EKG machine, electrode supplies, artifact identification reference card, answer key, NHA CET exam content outline
Check: Students must correctly identify all four artifact types on a blinded set of 8 test strips (≥7/8 correct) and demonstrate at least one corrective intervention successfully on the live unit as observed by instructor.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

EKG Acquisition and Electrodes
1. A 12-lead tracing shows an irregular, chaotic, high-frequency disturbance that varies in amplitude across all leads. The patient says she is cold. What is the most likely artifact type?
EKG Acquisition and Electrodes
2. You notice a perfectly uniform, thick, even oscillation in all leads of a freshly printed tracing. The pattern does not vary in amplitude or timing. Which corrective action should you try first?
EKG Acquisition and Electrodes
3. A tracing shows the baseline slowly rising and falling with each breath the patient takes. The QRS complexes are present and regular. What artifact is displayed?
EKG Acquisition and Electrodes
4. Lead V3 suddenly shows a sharp vertical spike followed by a return to a normal signal, while all other leads remain clean. The most likely cause is:
EKG Acquisition and Electrodes
5. After identifying somatic tremor artifact, which intervention is most appropriate to attempt before re-acquiring the tracing?
EKG Acquisition and Electrodes
6. Which of the following best describes how to distinguish AC interference from somatic tremor on a printed tracing?
Safety and Professionalism
7. A patient has a known tremor disorder and cannot hold still. After coaching, somatic tremor persists. What is the most appropriate next step within your scope of practice?
EKG Acquisition and Electrodes
8. During a live acquisition you notice that lead II shows a completely flat line while all other leads display normal waveforms. The patient is awake, alert, and feels fine. What is the most likely explanation?
Record this lesson on my transcript. Sign in with your key and enrollment email to record lessons (enroll free if you have no key). This page stays open to read and practise.
← Previous lessonProgram planNext lesson →