J wave (Osborn wave)
Also calledOsborn wave · J deflection · camel-hump sign · hypothermic hump
Definition
A notch, often of large amplitude, at the J point (the junction of the QRS complex and the ST segment), at the very end of the QRS complex. It arises from a transmural voltage gradient, caused by a notch in the action potential of the epicardium but not the endocardium. Prominent J waves are classically seen with hypothermia, where they tend to grow as body temperature falls, and also with hypercalcemia, in the early repolarization pattern and in the J-wave syndromes. In hypothermia the J wave is most often tallest in V4, then V3, whereas in early repolarization it appears in the inferior and lateral leads.
Clinical noteWithin one patient the hypothermic J wave grows as temperature falls, but its size on a single admission ECG tracks core temperature only moderately; a similar J-point pattern is also common in healthy people as early repolarization, so context matters.
Sources
- Antzelevitch C, Yan GX, Ackerman MJ, et al. J-wave syndromes expert consensus conference report: emerging concepts and gaps in knowledge. Heart Rhythm. 2016;13(10):e295-e324. doi.org/10.1016/j.hrthm.2016.05.024
- Omar HR, Camporesi EM. The correlation between the amplitude of Osborn wave and core body temperature. Eur Heart J Acute Cardiovasc Care. 2015;4(4):373-377. doi.org/10.1177/2048872614552057
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.