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)
- There is a slowing of the sinus rate
- Prolongation of the PR interval and the QTc
- Prolongation of the QRS is often due to the appearance of the J wave
- 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
- 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:
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:
