ECG ECG Artifacts and Troubleshooting 2 — Questions and Answers
Question 1: If lead aVR shows a positive deflection in all waveforms, what should the technician check?
- Paper speed
- Right arm and left arm electrode reversal (Correct answer)
- Precordial lead placement
- Machine calibration
Correct answer: Right arm and left arm electrode reversal
Lead aVR normally shows predominantly negative deflections; if it appears positive, right arm (RA) and left arm (LA) electrode reversal is the most likely cause.
Question 2: A nearly flat (isoelectric) tracing in lead I suggests which electrode problem?
- Precordial lead misplacement
- Right arm and left arm electrode reversal or disconnection (Correct answer)
- V1 electrode misplacement
- Low battery
Correct answer: Right arm and left arm electrode reversal or disconnection
Lead I measures the potential difference between RA and LA; if both electrodes are on the same limb or disconnected, lead I will appear flat or isoelectric.
Question 3: Which step should be taken first when all leads simultaneously show poor quality?
- Replace the ECG machine
- Check the right leg (RL) ground electrode connection (Correct answer)
- Move to a different room
- Increase amplifier gain
Correct answer: Check the right leg (RL) ground electrode connection
The right leg (RL) electrode serves as the ground reference for all leads; a loose or disconnected RL electrode degrades every lead simultaneously.
Question 4: Respiratory artifact causes the ECG baseline to undulate at approximately:
- 60 Hz
- The patient's respiratory rate (12–20 cycles/min) (Correct answer)
- The patient's heart rate
- 1 Hz
Correct answer: The patient's respiratory rate (12–20 cycles/min)
Respiratory artifact cycles at the patient's breathing rate (typically 12–20 breaths/min), producing slow, rhythmic baseline shifts synchronized with respiration.
Question 5: When precordial electrodes are placed too high on the chest, which leads are most affected?
- Limb leads I, II, III
- Precordial leads V1–V4 (Correct answer)
- Only aVR and aVL
- Only lead III
Correct answer: Precordial leads V1–V4
Precordial leads V1–V4 are most sensitive to vertical misplacement because they overlie the upper heart; high placement alters R-wave progression and ST morphology.
Question 6: What is the correct action when a patient's diaphoresis (sweating) causes electrodes to slip?
- Record the ECG immediately before more slipping occurs
- Dry the skin thoroughly and use additional securing tape before reattaching (Correct answer)
- Switch to gel-free electrodes only
- Abandon the ECG
Correct answer: Dry the skin thoroughly and use additional securing tape before reattaching
Drying the skin thoroughly and securing electrodes with additional tape or cloth stabilizes electrode contact in diaphoretic patients, improving signal quality.
ECG ECG Artifacts and Troubleshooting 2
If lead aVR shows a positive deflection in all waveforms, what should the technician check?