ECG Motion Artefacts

ECG Motion Artefacts Overview

• 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

• Fever (rigors)
• Hypothermia (shivering)
• Cardiopulmonary resuscitation (chest compressions)
• A non-compliant, mobile, talkative patient (= the most common cause)!

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!

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Yellow Belt online course: Become an ECG expert. Medmastery
• Wiesbauer F, Kühn P. ECG Blue Belt online course: Learn to diagnose any rhythm problem. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.

Textbooks

• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Hampton J. The ECG Made Practical 7e, 2019
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography 1e, 2009
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Mattu A, Brady W. ECG’s for the Emergency Physician Part I 1e, 2003 and Part II
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004

LITFL Further Reading

• ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
• ECG A to Z by diagnosis – ECG interpretation in clinical context
• ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
• 100 ECG Quiz – Self-assessment tool for examination practice
• ECG Reference SITES and BOOKS – the best of the rest