J Waves in Accidental Hypothermia

Abstract

128HIGUCHI S et al. Circulation JournalOfficial Journal of the Japanese Circulation Society http://www. j-circ.or.jp he J wave, also known as the Osborn wave, 1 is a positive deflection at the terminal part of the QRS complex. Although J waves are often observed in hypothermic patients, 2 few reports have revealed the relationship between the presence of J waves and body temperature (BT). The exact BT at which J waves develop in clinical settings has not yet been determined.The J wave is noted not only in hypothermia but also in some nonhypothermic conditions such as Brugada and early repolarization syndromes. The presence of J waves in such syndromes is related to the occurrence of ventricular fibrillation (VF), leading to sudden death. However, whether hypothermic patients with J waves are susceptible to fatal ventricular arrhythmia or ventricular tachycardia (VT)/VF remains undetermined. Indeed, some previous reports have shown that the incidence of VT/VF is unexpectedly low in hypothermic patients with J waves, varying from 0% to 2%. 3-5 The augmentation of J waves following a long R-R interval is reported to be a marker for VF 6,7 because the heterogeneity of membrane potentials is expressed as augmentation of J waves and can induce VF due to phase 2 reentry. 8 A previous report demonstrated that VF developed after sudden augmentation of J waves in idiopathic VF, which was induced following a long coupling interval. 6 Such an event in hypothermic patients would serve as a warning sign for identifying patients at high risk of developing VF.In the present study, we sought to clarify the relationship between the incidence of J waves and BT, as well as the clinical implications of J waves in patients with accidental hypothermia. We also attempted to determine the augmentation of J waves following a long R-R interval in patients with atrial fibrillation (AF). Methods Study DesignWe studied 64 consecutive patients who were admitted to hospital for accidental hypothermia between 2002 and 2012. Of these, 63 were homeless people admitted during the winter. The remaining patient was not homeless, but succumbed to hypothermia in a cold house because of depression. We reviewed all the patients' medical records to evaluate clinical characteristics such as age, sex, vital signs, cause of hypothermia, ECG findings, and laboratory data on admission. Hypothermia was defined as a rectal temperature <35.0°C.

Low room temperature can trigger ventricular fibrillation in J wave syndromes

“…Higuchi et al 12 reported the prevalence of J waves and the relationship between the body temperature and J-wave amplitude in 61 patients with accidental hypothermia. They also examined the augmentation of J waves following variable RR intervals in such patients with atrial fibrillation, and found that J waves are augmented after a relatively short RR interval.…”

Appearance of J wave in the inferolateral leads and ventricular fibrillation provoked by mild hypothermia in a patient with Brugada syndrome

“…Furthermore, J waves appeared at mild hypothermia (34°C), which was reported to be a marginal temperature for their development in the clinical setting 24 . Even at mild hypothermia, the amplitude of J waves in the inferolateral leads became augmented, leading to the development of VPCs.…”

Accidental hypothermia-induced electrical storm successfully treated with isoproterenol

“…On the contrary, in our case, the magnitude of J waves decreased after a long R-R interval in the same manner as that observed in a previous study of patients with hypothermia. 9 Previous studies have demonstrated that ISP, a betaadrenergic stimulant, is very effective at suppressing electrical storms related to BrS and ERS. ISP increases the I Ca current and restores the dome of the epicardial AP.…”