CET ECG Artifact Troubleshooting 2 — Questions and Answers
Question 1: A patient is shivering during an ECG recording, producing irregular, high-frequency baseline noise. What is the most appropriate first action?
- Apply more electrode gel
- Cover the patient with a warm blanket and wait (Correct answer)
- Increase the paper speed to 50 mm/s
- Switch to a single-channel recorder
Correct answer: Cover the patient with a warm blanket and wait
Shivering causes muscle artifact; warming the patient reduces involuntary muscle activity and resolves the artifact.
Question 2: Which ECG lead is most susceptible to respiratory artifact due to its electrode placement along the thoracic axis?
- Lead I
- Lead aVR
- Lead aVF
- Lead II (Correct answer)
Correct answer: Lead II
Lead II, with electrodes on the right arm and left leg, aligns with the craniocaudal thoracic axis most affected by diaphragmatic movement during breathing.
Question 3: An ECG shows intermittent sharp spikes at irregular intervals unrelated to the cardiac cycle. What is the most likely cause?
- 60 Hz AC interference
- Loose electrode connection (Correct answer)
- Patient movement artifact
- Respiratory baseline wander
Correct answer: Loose electrode connection
Intermittent sharp spikes that occur randomly are a hallmark of a loose or intermittently connected electrode.
Question 4: When troubleshooting AC interference on an ECG, which action should be performed LAST?
- Reapply electrodes with fresh gel
- Move the patient away from electrical equipment
- Ensure all lead wires are untangled
- Engage the ECG machine's built-in 60 Hz notch filter as a permanent solution (Correct answer)
Correct answer: Engage the ECG machine's built-in 60 Hz notch filter as a permanent solution
The notch filter should be a last resort because it can distort ST segments and T-wave morphology, potentially masking clinically relevant changes.
Question 5: A technician notices the ECG baseline drifts upward when the patient inhales and downward when the patient exhales. This pattern is best described as:
- Somatic muscle artifact
- Respiratory baseline wander (Correct answer)
- AC electromagnetic interference
- Electrode polarization artifact
Correct answer: Respiratory baseline wander
Cyclical baseline movement synchronized with breathing is classic respiratory baseline wander caused by impedance changes as the chest wall expands and contracts.
Question 6: Which skin preparation step has the greatest impact on reducing electrode impedance and minimizing artifact?
- Clipping or shaving excess hair at electrode sites (Correct answer)
- Warming electrode gel before application
- Placing electrodes over bony prominences
- Using disposable electrodes instead of reusable ones
Correct answer: Clipping or shaving excess hair at electrode sites
Removing hair ensures full electrode-to-skin contact, which is the primary determinant of low impedance and high signal quality.
Question 7: On a 12-lead ECG, artifact appears only in leads V1–V4 but all limb leads are clean. What is the most likely source?
- Right arm electrode is loose
- One or more precordial electrodes have poor skin contact (Correct answer)
- The patient has atrial flutter
- The ECG machine's amplifier is malfunctioning
Correct answer: One or more precordial electrodes have poor skin contact
Artifact isolated to contiguous precordial leads points to a problem at one or more chest electrode sites, since limb leads are unaffected.
CET ECG Artifact Troubleshooting 2
A patient is shivering during an ECG recording, producing irregular, high-frequency baseline noise.
What is the most appropriate first action?