ECG rhythms Monitor pitfalls
Sinus rhythm with artifact ECG
Sinus rhythm with motion and muscle artifact. Narrow QRS complexes keep a regular rhythm under baseline wander and muscle noise.
A 30-second recording of the heart model, played in real time. Run live starts the engine itself with this rhythm.
Computed by the TracingsMD heart model (Junkers engine): simulated for education, not a patient recording and not for diagnosis.
Measured on this recording
| Ventricular rate | 78/min |
|---|---|
| PR | Not assessable in this rhythm |
| QRS | 84 ms |
| QT | Not assessable in this rhythm |
| QTc (Bazett) | Not assessable in this rhythm |
| QTc (Fridericia) | Not assessable in this rhythm |
What it is
Signal on the ECG that does not come from the heart: patient movement, shivering or muscle tremor, poor electrode contact, or electrical interference. Artifact can mimic ventricular fibrillation, ventricular tachycardia or atrial fibrillation, or, when a lead comes loose, asystole or a pause, while the real rhythm continues underneath. On this recording a regular sinus rhythm keeps its narrow QRS complexes under baseline wander and muscle noise.
How to read this strip
| Rate | 60–100/min. |
|---|---|
| Rhythm | Regular QRS complexes under the noise. |
| P waves | Partly hidden by noise. |
| PR | Hard to measure through the noise. |
| QRS | Narrow. |
| QT | Not reliably measurable. |
Common sources
- Movement: shivering, rigors, tremor, seizures, brushing teeth, scratching, chest physiotherapy.
- Muscle activity (EMG noise) in a tense or cold patient.
- Poor electrode contact: dried gel, hair, sweat, loose or badly placed electrodes, damaged cables.
- Electrical interference from nearby equipment or the mains supply (50 or 60 Hz).
- Breathing and changes in body position, which move the baseline slowly.
What to consider
- Look at the patient first: a person who is awake, talking or has a pulse is not in VF or pulseless VT, but an awake patient can still be in VT with a pulse, so confirm the QRS complexes.
- Check another signal: a steady pulse oximeter or arterial line waveform at the expected rate supports artifact.
- Find the QRS complexes marching through the noise at the expected rate, and compare other leads: artifact often looks different from lead to lead, while a true arrhythmia changes the rhythm in all of them.
- Fix the signal: clip hair, clean and dry the skin, apply fresh electrodes over bone rather than muscle, secure the cables, and reduce shivering or movement.
- Do not dismiss an alarm because artifact is common: if the patient is unresponsive or has no pulse, follow the cardiac arrest algorithm.
- Artifact read as an arrhythmia can lead to unneeded tests, drugs, shocks or procedures.
Key point
Before calling VF, look at the patient: if the patient is talking, find the QRS complexes marching through the noise.
Not to be confused with
- Ventricular fibrillation — The patient is awake and talking, and regular QRS complexes march through the noise. VF has no QRS complexes.
- Atrial fibrillation — The QRS complexes are regular. Noise on the baseline is not fibrillatory activity.
- Torsades de pointes — Torsades has fast wide complexes that twist in height. Here normal narrow complexes are visible.