(Circulation. 2000;101:e233.)
© 2000 American Heart Association, Inc.
Circulation Electronic Pages |
From the Cardiology Division, Department of Medicine, Bronx Lebanon Hospital Center, Bronx, NY.
Correspondence to Imad A. Alhaddad, MD, Division of Cardiology, Department of Medicine, Bronx Lebanon Hospital Center, 1650 Grand Concourse, Bronx, New York, NY 10457. E-mail alhaddad@pol.net
| Introduction |
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Hypothermia, defined as core body temperature <95°F, is associated with ECG changes of diagnostic and prognostic importance. In the initial stages of hypothermia, a sinus tachycardia develops as part of the general stress reaction. As the temperature drops below 90°F, a sinus bradycardia supervenes, associated with progressive prolongation of the PR interval, QRS complex, and QT interval. With temperature approaching 86°F, atrial ectopic activity is often noted and can progress to atrial fibrillation. At this level of hypothermia, 80% of patients have Osborn waves that consist of an extra deflection at the end of the QRS complex.
Osborn waves, also known as J waves, camel-hump waves, and hypothermic waves, are best seen the inferior and lateral precordial leads. They become more prominent as the body temperature drops, and they regress gradually with rewarming.
With temperature <86°F, a progressive widening of the QRS complex
increases
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