Brugada-Like ECG Pattern in Severe Hypothermia
On a cold December morning, a 28-year-old student was rescued after he had fallen into a nearly frozen river. He was admitted to the emergency department with severe hypothermia [28.5°C/83°F]. The examination and laboratory tests of the hemodynamically stable patient revealed no abnormality. The initial ECG exhibited sinus bradycardia, QT-interval prolongation, atrial and ventricular ectopy, and giant J waves in all ECG leads (Figure 1). Furthermore, there was a right bundle-branch block pattern and a saddleback-type ST-segment elevation in the precordial leads, ECG abnormalities suggestive of Brugada syndrome (Figure 2).
After uncomplicated rewarming to a body temperature of 36.8°C/98°F, a follow-up ECG 14 hours after admission revealed that all ECG abnormalities had disappeared (Figure 3). The patient recovered quickly, without any significant arrhythmias, and was discharged 6 days after admission.
It has been well described that severe hypothermia is associated with sinus bradycardia, prolongation of the PQ and QT intervals, progressive widening of the QRS complex, and increased incidence of atrial and ventricular ectopy.1 Furthermore, the inscription of a prominent J wave at the beginning of the ST segment, the so-called Osborn wave, is also a pathognomonic finding in severe hypothermia. However, the Brugada syndrome of idiopathic ventricular fibrillation is also characterized by the appearance of Osborn waves, and it has been identified that an increase of the transmural voltage gradient is the underlying mechanism for the J-point elevation.2 However, apart from Osborn waves, classical Brugada-like ECG changes have thus far not been described in patients with severe hypothermia.
Obviously, there is a link between hypothermia and the Brugada syndrome. In a canine in vivo model, cooling the epicardium of the right ventricular outflow tract resulted in a reproducible generation of a Brugada-like ECG pattern in addition to increased transmural dispersion and increased ventricular arrhythmogenesis.3
The clinical significance of the hypothermia-induced, Brugada-like ECG pattern is as-yet unknown. Given that hypothermia has high mortality and is associated with ventricular arrhythmias,4 the appearance of the Brugada-like ECG pattern during hypothermia may provide evidence for a common underlying cellular arrhythmogenic mechanism of the congenital and the hypothermia-induced acquired form of the Brugada syndrome.