J wave

Causes

They are usually observed in people suffering from hypothermia with a temperature of less than 32 °C (90 °F), though they may also occur in people with very high blood levels of calcium (hypercalcemia), brain injury, vasospastic angina, acute pericarditis, or they could also be a normal variant. Osborn waves on ECG are frequent during targeted temperature management (TTM) after cardiac arrest, particularly in patients treated with 33 °C. Osborn waves are not associated with increased risk of ventricular arrhythmia, and may be considered a benign physiological phenomenon, associated with lower mortality in univariable analyses.

Mechanism

The J wave reflects the transmural gradient of amplitude of the cardiac transient outward K+ current: channels responsible for this current exhibit differential expression across ventricular myocardium, producing a more potent current in the epicardium than the endocardium.

History

The prominent J deflection attributed to hypothermia was first reported in 1938 by Tomaszewski. These waves were then definitively described in 1953 by John J. Osborn (1917–2014) and were named in his honor. Over time, the wave has increasingly been referred to as a J wave, though is still sometimes referred to as the Osborn wave in most part due to Osborn's article in the American Journal of Physiology on experimental hypothermia.

References

References

1. (2005). "Prominent J wave (Osborn wave) with coincidental hypothermia in a 64-year-old woman". Tex Heart Inst J.
2. (2004). "Osborn waves: history and significance". Indian Pacing Electrophysiol J.
3. "ecg_6lead018.html".
4. "THE MERCK MANUAL OF GERIATRICS, Ch. 67, Hyperthermia and Hypothermia, Fig. 67-1".
5. Marx, John. (2010). "Rosen's emergency medicine: concepts and clinical practice 7th edition". Mosby/Elsevier.
6. (July 2018). "Osborn waves following out-of-hospital cardiac arrest—Effect of level of temperature management and risk of arrhythmia and death". Resuscitation.
7. (2014). "Mayo Clinic Electrophysiology Manual". Mayo Clinic Scientific Press/Oxford University Press.
8. Osborn, J. J.. (1953). "Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function". Am J Physiol.
9. (2011). "Osborn waves in a hypothermic patient". Journal of Community Hospital Internal Medicine Perspectives.