Cold winter time
the ECG below was recorded on a on a freezing day in December:
The patient was found unconscious outside and was hypothermic when brought to the ED.
When looking at the baseline of the Tracing you can notice shivering artifacts. Also, there are Osborn waves (also known as J-Waves) - positive deflections seen at the J point in precordial and true limb leads. They most commonly are associated with hypothermia and will appear as a reciprocal, negative deflection in aVR and V1. Osborn waves typically appear at core temperatures of 30°C and below.
As Osborn waves are not specific signs of hypothermia, other causes may include: Hypercalcaemia, acute myocardial infarction, Takotsubo cardiomyopathy, left ventricular hypertrophy from hypertension, normal variant in benign early repolarisation, intracranial hypertension, severe head injury, severe myocarditis, Brugada syndrome or idiopathic VF.
Bradyarrhythmia can also be noticed, which is another ECG feature of hypothermia.
Historical Note: John Jay Osborn (1917-2014) described what is now called Osborn wave within his work ‘current of injury’ 1953 in hypothermic dogs.
A very good summary on Osborn waves can be found at https://litfl.com/osborn-wave-j-wave-ecg-library/
The ECG above was digitized using PMcardioBot.