title: ECG features and proarrhythmic potentials of therapeutic hypothermia.
abstract: Hypothermia can induce ECG J waves. Recent studies suggest that J waves may be associated with ventricular fibrillation (VF) in patients with structurally normal hearts. However, little is known about the ECG features, clinical significance or arrhythmogenic potentials of therapeutic hypothermia (TH)-induced J waves.
  
  
  
  We analysed ECGs from 240 patients who underwent TH at six major university hospitals in Korea between August 2010 and December 2013. The prevalence, amplitudes and distributions of the J waves and the development of malignant arrhythmia were analysed.
  
  
  
  The average patient body temperature was 33.5±1.0°C during TH. J waves were observed in 98 patients (40.8%). They were newly developed in 91 cases, and pre-existing J waves were augmented in seven patients. J waves during TH were primarily observed in leads II, III, aVF and V4-6. The average amplitude of the J waves was 0.239±0.152 mV. There were four VF events during TH. These events occurred in three patients who were finally diagnosed with Brugada syndrome, idiopathic VF or early repolarisation syndrome, respectively, and in one patient with non-cardiac aetiology (asphyxia).
  
  
  
  J waves were recorded in about 40% of the patients who received TH. They were most frequently observed in the inferior limb leads or lateral precordial leads. Life-threatening VF occurred only rarely (1.7%) during TH and were mainly observed in patients with primary arrhythmic disorder. Although a causal relationship between TH-induced J waves and VF remains unknown, administering TH to this potentially susceptible, high-risk population may require careful attention.
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Woo Seok
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Gi-Byoung
authors.initials: GB
authors.lastname: Nam
authors.affiliation: Division of Cardiology, Department of Internal Medicine, College of Medicine, Seoul St Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Uk
authors.initials: U
authors.lastname: Jo
authors.affiliation: Department of Emergency Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Won Young
authors.initials: WY
authors.lastname: Kim
authors.affiliation: Division of Cardiology, Department of Internal Medicine, College of Medicine, Seoul St Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Yong-Seog
authors.initials: YS
authors.lastname: Oh
authors.affiliation: Department of Emergency Medicine, College of Medicine, Seoul St Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Kyu Nam
authors.initials: KN
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Guang-Won
authors.initials: GW
authors.lastname: Seo
authors.affiliation: Department of Internal Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Ki-Hun
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Eun-Sun
authors.initials: ES
authors.lastname: Jin
authors.affiliation: Division of Cardiology, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Korea.
authors.forename: Kyoung-Suk
authors.initials: KS
authors.lastname: Rhee
authors.affiliation: Division of Cardiology, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Korea.
authors.forename: Laeyoung
authors.initials: L
authors.lastname: Jung
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Pusan National University Yangsan Hospital, Busan, Korea.
authors.forename: Ki-Won
authors.initials: KW
authors.lastname: Hwang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, College of Medicine, Incheon St Mary's Hospital, The Catholic University of Korea, Seoul, Korea.
authors.forename: Yoo Ri
authors.initials: YR
authors.lastname: Kim
authors.affiliation: Division of Cardiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Chang Hee
authors.initials: CH
authors.lastname: Kwon
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kee-Joon
authors.initials: KJ
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine, Heart Institute, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: You-Ho
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001833:Body Temperature Regulation; D053840:Brugada Syndrome / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006323:Heart Arrest / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006785:Hospitals, University; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D056910:Republic of Korea; D012151:Resuscitation / Q000009:adverse effects* / Q000379:methods; D012307:Risk Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology