Certified Medical Assistant (CMA AAMA)Procedures, Examinations and DiagnosticsHard
During EKG recording, the medical assistant notices fine, regular, rapid spiking artifact across all leads. The patient is calm and electrodes appear properly attached. What is the most likely cause?
- ASomatic tremor from patient movement
- BA wandering baseline from loose electrode contact
- CAlternating current (AC) interference from nearby electrical equipment
- DImproper limb lead reversal
Show answer & explanationAnswer & explanation
Correct answer: C. Alternating current (AC) interference from nearby electrical equipment
AC interference produces a characteristic fine, regular, rapid artifact at 60 Hz caused by nearby electrical devices or improper grounding, distinct from the irregular spikes of somatic tremor or the slow drifting of a wandering baseline.
Why the other options are wrong
- A. Somatic tremor causes irregular, coarse artifact correlating with muscle movement, not fine regular spikes.
- B. A wandering baseline appears as slow up-and-down drifting, not fine rapid spiking.
- D. Lead reversal produces abnormal but not artifactual spiking waveforms.
EKG Artifact Types
Distortions in EKG tracings caused by patient movement, poor electrode contact, or electrical interference rather than true cardiac activity.
- Somatic tremor: irregular, coarse artifact from muscle movement
- Wandering baseline: slow drift from loose electrodes or lotion/oil on skin
- AC interference: fine, regular 60 Hz spikes from nearby electrical equipment
Memory trick: '60 Hz hum = electrical interference drum'