Hypothermia electrocardiogram

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Hypothermia is characterized on the EKG by sinus bradycardia, PR prolongation, QT prolongation, QRS prolongation and Osborn waves.

Electrocardiographic Findings

  • Osborn waves may appear on the ECG for temperatures less tahn 91.4 degrees Fahrenheit (33 degrees Celsius)
  1. There is a slowing of the sinus rate
  2. Prolongation of the PR interval and the QTc
  3. Prolongation of the QRS is often due to the appearance of the J wave
  4. The most typical finding is the appearance of the Osborne J wave, an extra deflection between the QRS complex and the T wave.
    • Consistently found when the temperature falls below 25 degrees Centigrade.
    • More prominent in the left precordial leads
    • Increases in size with decreasing temperature
    • Caused by a current of injury, delayed ventricular depolarization, or early repolarization
  5. About 50 to 60% of these patients develop atrial fibrillation. VF may also occur.

Osborn Waves

Osborn waves are positive deflections occurring at the junction between the QRS complex and the ST segment, where the S point, also known as the J joint, has a myocardial infarction-like elevation.

There is variability in the morphology of Osborn waves as all J wave deflections do not look alike. Some Osborn waves are merely elevations of ST segments in leads V1 and V2, whereas others are of the "spike-and-dome" variety. Given the variability in morphology, a variety of mechanisms may be responsible for the size and shape of J wave deflections.

Shown below is an example of the "spike and dome" variant of the Osborn wave:

An Osborn J wave
An Osborn J wave

Shown below is an Osborn wave in an 81-year-old male with a core temperature 89.5 degrees F (31.94 C):


Electrocardiographic Examples

Examples of Osborn Waves in the Setting of Hypothermia

Shown below is the 12 lead ECG of a patient with a body temperature of 32 degrees Celsius. Note the sinus bradycardia, the prolonged QT interval (QTc is not prolonged) and the Osborn J wave, most prominently in leads V2-V5:


Shown below is An ECG of a patient with a body temperature of 28 degrees Celsius:


Shown below are Osborn J waves due to hypothermia:


Shown below are Osborn J waves due to hypothermia:

References

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