A 20-year-old male rescued from accidental drowning was resuscitated and hospitalized. The first ECG (Fig. 1) was taken at body temperature 29.9°C. Striking features are, as well as the TU fusion, the Osborn waves (arrow) recognizable in every ECG lead and typical of hypothermia. They are named after John J. Osborn, who reported this ECG finding in a 1953 publication on experimental hypothermia in dog hearts [1]. The electrical phenomenon demonstrable in the 12-lead ECG, also known as the J wave, is caused by the effect of superposition of the differing morphology, induced by hypothermia, of the action potentials between endocardium and epicardium [2]. This sign was no longer found in the patient at a temperature of 37°C (Fig. 2)
