A 65-yr-old woman undergoing repair of an aortic dissection developed the above electrocardiogram at 24°C. J waves, or Osborn waves (electrocardiogram lead II, speed 25 mm/s), are abnormal positive deflections of the electrocardiogram that occur at the J point or the junction between the QRS complex and the ST segment. J-point elevations may be observed in patients with hypothermia (generally less than 32°C), subarachnoid hemorrhage, vasospastic angina, and Brugada Syndrome. The wave amplitude correlates to the severity of the hypothermia, which prolongs repolarization leading to phase 2 reentry and the potential for ventricular fibrillation. Osborn waves represent the electrocardiographic changes created by the differences between epicardial and endocardial potassium channel currents. Supplemental Digital Content (http://links.lww.com/ALN/C540; electrocardiogram lead II, speed 25 mm/s) demonstrates Osborn waves and development of ventricular fibrillation.

When caring for patients with...

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