ECG Motion Artefacts

Introduction

• Motion artefact due to tremor or shivering can obscure the waveforms of the ECG or simulate pathology, making ECG interpretation difficult.
• In certain circumstances (e.g. hypothermia), the presence of shivering artefact may actually aid diagnosis.

Causes of Tremor

• Benign Essential Tremor (physiological tremor)
• Parkinson’s Disease (resting tremor)
• Cerebellar disease (intention tremor)
• Alcohol / Benzodiazepine withdrawal
• Anxiety
• Thyrotoxicosis
• Multiple sclerosis
• Drugs: Amphetamines, cocaine, beta-agonists (adrenaline, salbutamol), theophylline, caffeine, lithium.

Other types of motion artefact

ECG Examples

Example 1

Hypothermia:

• This ECG displays the classic features of hypothermia: bradycardia, Osborn waves and shivering artefact.

Example 2

Parkinsonian tremor:

• The irregular baseline in this ECG gives the appearance of atrial fibrillation.
• The slow regular rhythm even suggests the possibility of atrial fibrillation with complete heart block and a junctional escape rhythm.
• However, on closer inspection there are visible P waves in V3 (circled).
• This patient had sinus bradycardia and a resting tremor due to Parkinson’s disease.

Example 3

Chest compressions during CPR:

• The high amplitude oscillations at the start of the rhythm strip are produced by movement artefact due to chest compressions during cardiopulmonary resuscitation.
• The second half of the rhythm strip shows ventricular fibrillation – presumably at this point the resuscitating team have stopped CPR to reassess the rhythm!

Example 4

Precordial thump:

• This ECG demonstrates the movement artefact produced by a precordial thump!

Further Reading

• ECG BASICS — Waves, Intervals, Segments and Clinical Interpretation
• ECG CLINICAL CASES — Your favourite ECG’s placed in clinical context with a challenging Q&A approach
• ECG and Cardiology Eponymous Syndromes — Cheats guide to eponymous emancipation
• ECG Exam Template — a framework for the FACEM part 2 exam.
• ECG Reference Sites on the WEB — the best of the rest

Author Credits