Types of ECG artifacts and their causes
ECG artifacts are non-cardiac signals recorded by the monitoring system. Major types:
Motion artifact: caused by patient movement, shivering, seizure activity, or CPR. Can resemble VF, VT, or asystole. Key feature: underlying QRS complexes may be visible within the artifact waveform if looked for carefully. The clinical gold standard: a patient who is responsive and has a palpable pulse cannot be in VF regardless of what the monitor shows.
Baseline wander: low-frequency (< 1 Hz) oscillation of the entire waveform, causing the baseline to drift up and down rhythmically. Caused by patient breathing, lead movement, or loose lead attachment. Makes ST-segment interpretation difficult — the apparent ST elevation or depression may be baseline drift, not true ischemia.
60-Hz interference: regular high-frequency noise (60 cycles/second in North America) that creates a 'hairy' appearance on the waveform. Caused by electrical equipment proximity, poor skin contact, or broken lead wires. Eliminate by improving skin preparation or removing nearby electrical devices.
The cardinal rule: assess the patient, not the monitor
The most dangerous clinical error in telemetry nursing is acting on monitor data without clinical correlation. Motion artifact can perfectly mimic VF, VT, asystole, or complete heart block. Electrical interference can simulate tachyarrhythmias.
Clinical assessment protocol for any alarming rhythm: (1) Look at the patient — are they awake? Talking? (2) Check for pulse — brachial (infants), carotid (adults). (3) Check SpO₂ — active pulse oximetry waveform confirms cardiac output. (4) Check blood pressure — NIBP or arterial line. (5) Look at the monitor AFTER confirming clinical status.
Artifact identification clues: (a) Normal QRS complexes visible within the 'arrhythmia' at the expected rate — suggests the underlying rhythm is intact and the abnormal waveform is superimposed artifact. (b) Sudden onset and sudden resolution corresponding to patient movement. (c) The 'arrhythmia' corresponds to when the patient moved, coughed, shivered, or was touched.