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Osborn waves in hypothermia induced by baclofen overdose

Nishith K Singh¹, Anushree Agarwal¹, Laura Salazar¹, Joseph Q Henkle²

¹ Southern Illinois University School of Medicine, Internal Medicine, 701 N 1st Street, Springfield, Illinois 62794, USA
² Southern Illinois University School of Medicine, Internal Medicine, Division of Pulmonary and Critical Care, 701 N 1st Street, Springfield, Illinois 62794, USA

Correspondence to:
Nishith Singh, nishith_singh2007{at}yahoo.com

A 25-year-old male smoker with a history of depressive symptoms was brought to our emergency department in stuporous condition. He had allegedly ingested 720 mg of baclofen and about 30 mg of alprazolam in an attempt to commit suicide. Upon arrival in the unit (day 1), he was comatose with absent brain stem reflexes, mechanically ventilated, hypothermic with an oral temperature of 34.2°C (93.56° F) and hypotensive. A 12-lead electrocardiogram (ECG) showed regular sinus rhythm with a rate of 64 bpm, normal QRS, a QTc of 411 ms and intermittent Mobitz type II heart block. Osborn waves like J-point deflections secondary to hypothermia were identified most prominently in lead II (fig 1). Patient’s vitals and sensorium normalised over the next 24 h with supportive measures. A repeat 12-lead ECG on day 2 showed the disappearance of Osborn waves (figs 1 and 2).

View this figure (162K): in this window | in a new window | PowerPoint for Teaching   Figure 1 Resting 12-lead ECG tracing showing J-point deflection on day 1 that disappeared by day 2 with normalisation of temperature.

 

View this figure (173K): in this window | in a new window | PowerPoint for Teaching   Figure 2 A close-up of the Osborn waves in lead II.

 

J point wave was first described by Tomaszewski in 1938¹ but named after JJ Osborn (1953) who reported² systemic descriptions from his work in animal models of experimental hypothermia. It is classically defined as a dome or hump-shaped deflection seen at the R-ST junction (J point) and is also known as "camel-hump sign", "late delta wave", "hathook junction", "hypothermic wave", "J point wave", "K wave" or "H wave". It is most commonly described in hypothermia but can also be seen in hypercalcaemia, subarachnoid haemorrhage, cardiopulmonary arrest from oversedation and vasospatic angina among other.³ The wave is thought to be an ECG manifestation of increased ventricular transmural voltage gradient that is possible in many of these conditions.³ The waves regress with rewarming and are considered by many experts to be of arrhythmogenic potential.

Competing interests: none.

Patient consent: Patient/guardian consent was obtained for publication.

1. Tomaszewski, W. Changements électrocardiographiques observés chez un homme mort de froit. Arch Mal Coeur 1938; 31: 525–8.
2. Osborn, JJ. Experimental hypothermia: respiratory and blood pH changes in relation to cardiac function. Am J Physiol 1953; 175: 389–98.[Free Full Text]
3. Hurst, JW. Naming of the waves in the ECG, with a brief account of their genesis. Circulation 1998; 98: 1937–42.[Free Full Text]

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