Osborn Wave (J Wave) Overview

The Osborn wave (J wave) is a positive deflection seen at the J point in precordial and true limb leads. It is most commonly associated with hypothermia. These changes will appear as a reciprocal, negative deflection in aVR and V1.

The J point in the ECG is the point where the QRS complex joins the ST segment. It represents the approximate end of depolarization and the beginning of repolarization as determined by the surface ECG. There is an overlap of around 10ms.

The J point may deviate from the baseline in early repolarization, epicardial or endocardial ischemia or injury, pericarditis, RBBB, LBBB, RVH, LVH or digitalis effect.

Osborn wave J point on ECG labelled
J point in a) normal; b) J point elevation; c) with Osborn wave (J wave); d) J point depression

Note: The letter J on the ECG defines 2 totally different and unrelated events. The J point is a point in time marking the end of the QRS and the onset of the ST segment present on all ECGs. The J wave is a much less common, slow deflection of uncertain origin originally described in relation to hypothermia.

Osborn Wave Causes

Characteristically seen in hypothermia (typically T < 30C), but they are not pathognomic. Causes of non-hypothermic Osborn waves include:

No definitive physiological cause for the deflection has been described, despite numerous postulates.

Compared to other hypothermia-induced ECG abnormalities (e.g. sinus bradycardia; supraventricular arrhythmias, QT prolongation and AV block), the Osborn wave is thought to be the most specific.


Eponymously associated with John Jay Osborn (1917-2014) following his 1953 ‘current of injury’ description in hypothermic dogs. See below for a deep dive into the eponymous history.

Osborn Wave ECG examples

Example 1

ECG Subtle Osborn wave J wave hypothermia
  • Subtle J waves in mild hypothermia [Temp: 32.5°C (90.5°F)]
  • The height of the J wave is roughly proportional to the degree of hypothermia

Example 2

J waves Osborn Wave hypothermia temp 30°C
  • J waves in moderate hypothermia. [Temp: 30°C (86°F)]

Example 3

J waves Osborn Wave hypothermia temp 30°C
  • J waves in moderate hypothermia. [Temp: 28°C (82.4°F)]

Example 4

Osborn wave temp 26 hypothermia
  • Marked J waves in severe hypothermia [Temp: 26°C (78.8°F)]
  • Note “negative” J waves seen in aVR and V1

Controversy regarding terminology

Occasionally you may encounter other terms used to describe Osborn waves (J waves). Some authors have used the term J wave deflection to describe such a large, prominent deviation of the J point from the baseline. Other terms used previously include the “late delta wave”, “J-point wave”, and the “camel-hump sign of Osborn“.

There is little consensus regarding terminology, nature, and prognostic significance of the J wave. In the setting of hypothermia, this phenomenon is most commonly referred to as an Osborn wave.

Eponymous History of the Osborn Wave

1922 – Kraus described a J-point deflection in hypercalcaemic conditions

1938 – Tomaszewski et al. provided the first description of hypothermic J wave in an accidentally frozen man. He described the J wave as a very slowly inscribed deflection between the QRS complex and the ST segment of the ECG, resembling a “domed T wave.”

…à côté de l’onde R on en voit une autre, ressemblant au T en dôme

Tomaszewski 1938

1943 – Grosse-Brockhoff and Schoedel studied the influence of hypothermia on different organ systems and they produced a specific ventricular conduction disorder, “aufsteigenden S-Schenkel eine deutliche Nachzacke” similar to the J wave in experiments with dogs. They noted that a widening of the secondary deflection on the QRS complex and supraventricular arrhythmias were accompanied by a parallel increase of carbon dioxide in alveolar air during body cooling.

Hypothermia Osborn wave 1943
Rectal temperature: a. 31.5°C; b. 23.5°C
Grosse-Brockhoff and Schoedel 1943

1950 – W.G. Bigelow et al described ECG changes in hypothermic dogs as:

characterised by a doubling of the QRS interval, and lengthening of the QT interval by three to four times. The T-wave is long and irregular, and usually inverted.

Bigelow, 1950

1953 – Osborn studied the effect of hypothermia on the respiratory and cardiac function in dogs. Experimentally-induced hypothermia caused the development of a distinct deflection at the J point on the ECG and resulted in ventricular fibrillation. He called this deflection the ‘current of injury’.

Osborn 1953 current of injury a and b

Fig 4. Electrocardiogram during hypothermia (lead II).
a. Hypothermic dog 7 min. before onset of ventricular fibrillation. Animal showed early alkalosis followed by acidosis. Rectal temp. 23’C, pulse 50.
b. Diagram of ECG shown in A, identifying current of injury. 
Osborn JJ. Am J Physiol. 1953

Osborn considered acidaemia induced by hypothermia as a primary cause of the Osborn wave, because it disappeared if the arterial pH was normalized by hyperventilation during the same degree of cooling. He postulated:

…the ECG changes associated with hypothermia, particularly of the ‘current of injury’ type may not be associated with the low temperature directly, but rather may be more closely associated with faulty elimination of CO2 under hypothermic conditions

Osborn, 1953

1959 – Emslie-Smith et al found differences in the endocardial and epicardial responses of the ventricular myocardium to cold and proposed that a J wave, which is more prominent in epicardial than in endocardial leads, could be reflected in surface leads. They questioned the participation of acidosis in J wave genesis and the ability of this deflection to predict development of ventricular fibrillation.

The characteristic deflection of hypothermia has sometimes been named after Osborn who discussed it in 1953.

Emslie-Smith, 1959

1970 – Fernandez et al described a series of cases of hypothermia and re-warming. They noted the electrocardiographic features of hypothermia to include: bradycardia, nodal rhythm, atrial fibrillation, PR prolongation, second-degree heart block, QT interval prolongation, premature ventricular contractions and the J wave or “camel hump” (a term suggested by W. Procter Harvey, MD)

Rewarming camel hump J deflection 2
Serial lead II electrocardiograms taken during rewarming process. Note loss of muscular tremors, emergence of P waves, increase in heart rate, and gradual diminution of the size of J waves (arrows). Fernandez 1970

1994Patel et al presented eight normothermic patients whose 12-lead ECG demonstrated QRS-ST junction notches similar to those seen in hypothermia. J wave deflections were found in the settings of acute ischaemic events, cocaine use, haloperidol overdose, and left ventricular hypertrophy due to hypertension. They concluded that the Osborn wave is not pathognomonic of hypothermia.

1996 – Yan and Antzelevitch provide the first direct evidence in support of the hypothesis that heterogeneous distribution of a transient outward current-mediated spike-and-dome morphology of the action potential across the ventricular wall underlies the manifestation of the electrocardiographic J wave. The presence of a prominent action potential notch in epicardium but not endocardium is shown to provide a voltage gradient that manifests as a J (Osborn) wave or elevated J-point in the ECG.

Over the years it has been increasingly common for clinicians to label the J-wave deflection seen in hypothermia as an Osborn wave.

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BA MA (Oxon) MBChB (Edin) FACEM FFSEM. Emergency physician, Sir Charles Gairdner Hospital.  Passion for rugby; medical history; medical education; and asynchronous learning #FOAMed evangelist. Co-founder and CTO of Life in the Fast lane | Eponyms | Books | Twitter |

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Adult/Paediatric Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

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