This ECG displays the classic features of hypothermia: bradycardia, Osborn waves and shivering artefact.
Definitions
- Hypothermia is defined as a core body temperature of < 35 degrees centigrade
- Mild hypothermia is 32-35 degrees
- Moderate hypothermia is 29-32 degrees
- Severe hypothermia is < 29 degrees
ECG Changes in Hypothermia
Hypothermia may produce the following ECG abnormalities:
- Bradyarrhythmias (see below)
- Osborne Waves (= J waves)
- Prolonged PR, QRS and QT intervals
- Shivering artefact
- Ventricular ectopics
- Cardiac arrest due to VT, VF or asystole
Bradyarrhythmias
Patients with hypothermia may manifest a variety of bradyarrhythmias, including:
- Sinus bradycardia (may be marked)
- Atrial fibrillation with slow ventricular response
- Slow junctional rhythms
- Varying degrees of AV block (1st-3rd)
Marked sinus bradycardia (30bpm) secondary to hypothermia
Atrial fibrillation with slow ventricular response due to hypothermia
Osborn Waves
- The Osborn wave (J wave) is a positive deflection at the J point (negative in aVR and V1).
- It is usually most prominent in the precordial leads.
- The height of the Osborn wave is roughly proportional to the degree of hypothermia.
Typical Osborn waves
Subtle Osborn waves in mild hypothermia (temp 32.5 degrees C)
J waves in moderate hypothermia (30 degrees C)
Marked Osborn waves in severe hypothermia
QT Prolongation
- Marked QT prolongation may occur with hypothermia and resolves with rewarming.
Prolonged QTc (620ms) due to severe hypothermia
Shivering Artefact
- Shivering artefact is seen as a “fuzziness” of the ECG baseline.
- It is not specific to hypothermia and may be seen with other conditions associated with tremor (e.g. Parkinson’s disease).
Shivering artefact in a patient with hypothermia (note also the Osborn waves)
Related Topics
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 Reference Sites on the WEB – the best of the rest
References
- Cameron P, Jelinek G, Kelly AM, Murray L, Brown AFT. Textbook of Adult Emergency Medicine. Elsevier 2009.
- Hampton, JR. The ECG in Practice (5th edition), Churchill Livingstone 2008.
- Slovis C, Jenkins R. ABC of clinical electrocardiography: Conditions not primarily affecting the heart. BMJ. 2002 Jun 1;324(7349):1320-3. Review. PMID: 12039829. Full text.
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008.
- Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.
Author Credits
About Edward Burns
Great cases of hypothermia! Exquisite Osborne waves. May I use any of these ECGs for local teaching purposes? -- THANK YOU -- Ken Grauer, MD
Glad they’re of help Ken -- all of LITFL’s resources are creative commons license and designed to be re-used for medical education. So feel free.
Chris