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Electrocardiographic Changes Caused by Severe Accidental Hypothermia

Published:October 27, 2015DOI:https://doi.org/10.1053/j.jvca.2015.07.019
      To the Editor:
      Hypothermia is defined as a core body temperature≤35°C.
      • Brown D.J.
      • Brugger H.
      • Boyd J.
      • et al.
      Accidental hypothermia.
      Severe accidental hypothermia (core body temperature≤28°C) is a condition associated with significant morbidity and mortality.
      • Brown D.J.
      • Brugger H.
      • Boyd J.
      • et al.
      Accidental hypothermia.
      • Kosinski S.
      • Darocha T.
      • Galazkowski R.
      • et al.
      Accidental hypothermia in Poland—Estimation of prevalence, diagnostic methods and treatment.
      • Darocha T.
      • Kosinski S.
      • Jarosz A.
      • et al.
      Severe Accidental Hypothermia Center.
      • Zafren K.
      • Giesbrecht G.G.
      • Danzl D.F.
      • et al.
      Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia.
      In July 2013, the Severe Accidental Hypothermia Center was founded in the John Paul II Hospital in Cracow.
      • Darocha T.
      • Kosinski S.
      • Jarosz A.
      • et al.
      Severe Accidental Hypothermia Center.
      The Center is dedicated to invasive treatment of patients from the Lesser Poland (Małopolska) province (area of 15,100 square km, population of 3.3 million).
      Hypothermia is well known to induce characteristic electrocardiographic changes.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      A drop in body temperature below 32°C causes slowing of heart conductance and results in significant sinus bradycardia and prolongation of the PR interval, QRS complex, QT interval, and QTc interval.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      • Surawicz B.
      • Childers R.
      • Deal B.J.
      • et al.
      AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part III: Intraventricular conduction disturbances. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
      • Rautaharju P.M.
      • Surawicz B.
      • Gettes L.S.
      • et al.
      AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part IV: The ST segment, T and U waves, and the QT interval. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
      Atrial fibrillation (AF) commonly develops with temperatures below 29°C.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      Ventricular fibrillation (VF) usually is observed when core temperature reaches the values below 28°C.
      • Soar J.
      • Perkins G.D.
      • Abbas G.
      • et al.
      European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
      Osborn waves (J-waves) typically are seen in approximately 80% of patients with core temperature below 30°C.
      • Higuchi S.
      • Takahashi T.
      • Kabeya Y.
      • et al.
      J waves in accidental hypothermia.
      There are several reports describing the effects of mild therapeutic hypothermia on the circulatory system
      • Lebiedz P.
      • Meiners J.
      • Samol A.
      • et al.
      Electrocardiographic changes during therapeutic hypothermia.
      • Khan J.N.
      • Prasad N.
      • Glancy J.M.
      QTc prolongation during therapeutic hypothermia: Are we giving it the attention it deserves?.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      and only a few reports concerning the electrocardiogram (ECG) in severe accidental hypothermia.
      • De Souza D.
      • Perez Riera A.R.
      • Bombing M.T.
      • et al.
      Electrocardiographic changes by accidental hypothermia in an urban and tropical region.
      We prospectively assessed 19 patients (16 male, aged 29-84 years) who were reported to the Severe Accidental Hypothermia Center due to severe accidental hypothermia (core esophageal temperature 16.9°C-29°C, median temperature 25.6°C). Cardiac arrest was present in 9 patients at admission (7 male, aged 29-78 years, core esophageal temperature 16.9°C-24.1°C, median temperature 23.2°C). Ventricular fibrillation occurred in 7 patients and asystole in 2 patients.
      In 10 patients in cardiogenic shock without cardiac arrest (9 male, aged 48-84 years, core esophageal temperature 24.5°C-29°C, median temperature 26.2°C), a standard 12-lead ECG was performed within 5 minutes after their admission to the emergency room. Electrocardiograms were analyzed and interpreted by 2 experienced cardiologists. In all patients, on admission arterial blood was collected for arterial blood gas analysis. Demographic and clinical data of the patients are presented in Table 1. Nine patients in cardiogenic shock without cardiac arrest at admission fulfilled the extracorporeal rewarming criteria, and in them, arteriovenous extracorporeal membrane oxygenation (ECMO) was implanted. In one patient noninvasive rewarming was performed. Three patients died during ECMO rewarming. In 7 patients, cardiorespiratory stability and full neurologic recovery were achieved at discharge from the intensive care unit (Glasgow Coma Scale 15, Cerebral Performance Category 1). Results of analysis of 12-lead electrocardiograms are summarized in Table 2. The leading cardiac rhythms were the following: sinus bradycardia (45-58 bpm) in 6 patients, atrial fibrillation with slow ventricular response in 3 patients, and junctional rhythm in 1 patient. All patients had significantly prolonged PR (220-260 ms), QT (580-820 ms), and QTc (513-763 ms) intervals. QRS duration also was increased (110-180 ms) in the whole study group. All patients had very low P-wave amplitude (0.1 mV). T-waves were negative in 6 patients and flattened (amplitude 0.1 mV) in 3 patients. Typical J-waves (Osborn waves) were recorded in 3 patients with the lowest esophageal core temperatures (24.5, 24.7, and 26.2°C). Analysis of arterial blood samples collected on admission showed metabolic acidosis and elevated lactate levels in all patients. Three patients had significant hypokalemia (potassium level below 3.0 mmol/L); in 7 patients, potassium level was within normal range (3.5-4.3 mmol/L).
      Table 1Patient Clinical Data
      No.Sex/ Age (years)Accident DateCore Esophageal Temperature (°C)Admission BP (mmHg)Type of RewarmingPre-rewarming Catecholamine SupportGCS on Hospital ArrivalClinical Status at Discharge from ICU
      1M/483 Jan 201524.580/50Invasive: arterio-venous ECMOYes6Fully recovered GCS 15, CPC 1
      2M/6029 Nov 201426.260/40Invasive: arterio-venous ECMOYes3Fully recovered GCS 15, CPC 1
      3M/5513 Dec 201426.280/55Invasive: arterio-venous ECMOYes3Fully recovered GCS 15, CPC 1
      4M/501 Nov 201429160/100NoninvasiveNo7Fully recovered GCS 15, CPC 1
      5M/5615 Nov 201327.280/40Invasive: arterio-venous ECMOYes3Fully recovered GCS 15, CPC 1
      6M/6327 Dec 20142870/40Invasive: arterio-venous ECMOYes3Fully recovered GCS 15, CPC 1
      7M/5417 Apr 201424.780/50Invasive: arterio-venous ECMOYes7Fully recovered GCS 15, CPC 1
      8F/8422 Mar 20152860/40Invasive: arterio-venous ECMOYes3Died
      9M/5328 Dec 201426.650/30Invasive: arterio-venous ECMOYes3Died
      10M/632 Apr 201525.680/60Invasive: arterio-venous ECMOYes3Died
      Abbreviations: BP, blood pressure; GCS, Glasgow Coma Scale; ICU, intensive care unit; M, male; ECMO, extracorporeal membrane oxygenation; CPC, Cerebral Performance Category; F, female; No., number.
      Table 2Analysis of Admission Electrocardiograms in Patients Without Cardiac Arrest
      NumberHeart RhythmHR (bpm)PR (ms)QRS (ms)QT (ms)QTc (ms) (by Bazett formula)ST-T abnormalitiesJ-wave/maximum amplitude (mV)
      1sinus50250120700639negative T-waves in II, III, aVF, V3-V5present/0.5
      2sinus45260180620537negative T-waves in I, aVL, V2-V5absent
      3sinus58240130620610negative T-waves in V5-V6present/0.2
      4atrial fibrillation40180780660flattened T-wavesabsent
      5sinus52240160820763negative T-waves in aVLabsent
      6sinus45220130620537noneabsent
      7atrial fibrillation50extracorporeal membrane oxygenation180640640flattened T-wavespresent/0.4
      8junctional47110580513flattened T-wavesabsent
      9atrial fibrillation45140800708negative T-waves in aVF, ST depression 1-2 mm in V3-V5absent
      10sinus47260130620549ST elevation of 2 mm in I, II, aVF, V2-V5, negative T-waves in I, II, aVFabsent
      Abbreviations: HR, heart rate; bpm, beats per minute.
      The effects of hypothermia on the cardiac conduction system have been described in multiple animal experiments and human observational studies.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      • Rolfast C.L.
      • Lust E.J.
      de Cock CC: Electrocardiographic changes in therapeutic hypothermia.
      The typical ECG features of hypothermia include the following: sinus bradycardia, atrial fibrillation with slow ventricular response, prolongation of PR and QT/QTc intervals, widening of P-waves, QRS complex and T-waves.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      • Surawicz B.
      • Childers R.
      • Deal B.J.
      • et al.
      AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part III: Intraventricular conduction disturbances. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
      • Rautaharju P.M.
      • Surawicz B.
      • Gettes L.S.
      • et al.
      AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part IV: The ST segment, T and U waves, and the QT interval. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
      Hypothermia causes reduction in the diastolic depolarization rate of the sinoatrial node P-cells as well as decrease of resting potential with marked prolongation of the action potential and refractory period (slowing repolarization).
      • Khan J.N.
      • Prasad N.
      • Glancy J.M.
      QTc prolongation during therapeutic hypothermia: Are we giving it the attention it deserves?.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      Atrial fibrillation occurs predominantly in moderate hypothermia (up to 50%-60% of cases).
      • Rolfast C.L.
      • Lust E.J.
      de Cock CC: Electrocardiographic changes in therapeutic hypothermia.
      In hypothermia, QT/QTc interval prolongation is secondary to both J-wave presence and slowing of ventricular repolarization (a result of an exaggerated outward potassium current).
      • Khan J.N.
      • Prasad N.
      • Glancy J.M.
      QTc prolongation during therapeutic hypothermia: Are we giving it the attention it deserves?.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      The T-wave changes (T-wave inversion or flattening) are related directly to the degree of hypothermia and inversely proportional to J-wave amplitude.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      • Khan J.N.
      • Prasad N.
      • Glancy J.M.
      QTc prolongation during therapeutic hypothermia: Are we giving it the attention it deserves?.
      In this study, the basic cardiac rhythms were sinus bradycardia (6 patients), atrial fibrillation with slow ventricular response (3 patients), and junctional rhythm (1 patient). All patients had severely prolonged PR, QT/QTc intervals, widened QRS complex, and lowered P-wave amplitude. T-waves changes (inversion or flattening) were noted in 8 patients.
      The most notable ECG abnormality in patients with hypothermia is the J-wave, also known as the Osborn wave.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      It has been described as a positive deflection at the terminal part of the QRS complex (“camel hump” or “hump-like deflection”). However, J-waves are not pathognomonic for hypothermia and also may occur in some normothermic conditions, such as hypercalcemia, brain injuries, intoxication by tricyclic antidepressants, early repolarization syndromes, Brugada disease/syndrome, right ventricular arrhythmogenic dysplasia, or Prinzmetal’s angina.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      • Rautaharju P.M.
      • Surawicz B.
      • Gettes L.S.
      • et al.
      AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part IV: The ST segment, T and U waves, and the QT interval. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
      The presence of J-waves then is associated with higher incidence of ventricular fibrillation and sudden cardiac death.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      In patients with hypothermia, the amplitude of the J-wave is inversely related to the core body temperature.
      • Omar H.R.
      • Camporesi E.M.
      The correlation between the amplitude of Osborn wave and core body temperature.
      Many animal studies failed to show any correlation between Osborn waves and pH or electrolyte levels.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      • Yan G.X.
      • Antzelevitch C.
      Cellular basis for the electrocardiographic J wave.
      Osborn waves typically are seen in approximately 80% of patients with core temperature below 30°C.
      • Doshi H.H.
      • Giudici M.C.
      The EKG in hypothermia and hyperthermia.
      • Osborn J.J.
      Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
      Experimental research proved that the electrophysiologic background for J-waves is an increase in the epicardial potassium current relative to the endocardial current, secondary to hypothermia.
      • Yan G.X.
      • Antzelevitch C.
      Cellular basis for the electrocardiographic J wave.
      In this study group, typical Osborn waves were recorded in 3 patients with the lowest esophageal core temperatures. In all cases, J-waves were accompanied by T-wave changes (inversion or flattening). There was no correlation between J-wave presence and arterial gas analysis.
      Severe accidental hypothermia causes typical and characteristic changes on ECG: sinus bradycardia, prolongation of PR and QT/QTc intervals, widening of QRS complex, and T-wave changes. These changes also were observed in this population. Osborn waves occurred in only 30% of patients with severe accidental hypothermia and seem to depend on the core body temperature.

      References

        • Brown D.J.
        • Brugger H.
        • Boyd J.
        • et al.
        Accidental hypothermia.
        N Engl J Med. 2012; 367: 1930-1938
        • Kosinski S.
        • Darocha T.
        • Galazkowski R.
        • et al.
        Accidental hypothermia in Poland—Estimation of prevalence, diagnostic methods and treatment.
        Scand J Trauma Resusc Emerg Med. 2015; 23: 13
        • Darocha T.
        • Kosinski S.
        • Jarosz A.
        • et al.
        Severe Accidental Hypothermia Center.
        Eur J Emerg Med. 2015; 22: 288-291
        • Zafren K.
        • Giesbrecht G.G.
        • Danzl D.F.
        • et al.
        Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia.
        Wilderness Environ Med. 2014; 25: 425-445
        • Doshi H.H.
        • Giudici M.C.
        The EKG in hypothermia and hyperthermia.
        J Electrocardiol. 2015; 48: 203-209
        • Surawicz B.
        • Childers R.
        • Deal B.J.
        • et al.
        AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part III: Intraventricular conduction disturbances. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
        J Am Coll Cardiol. 2009; 53: 976-981
        • Rautaharju P.M.
        • Surawicz B.
        • Gettes L.S.
        • et al.
        AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part IV: The ST segment, T and U waves, and the QT interval. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology.
        J Am Coll Cardiol. 2003; 53: 982-991
        • Soar J.
        • Perkins G.D.
        • Abbas G.
        • et al.
        European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.
        Resuscitation. 2010; 81: 1400-1433
        • Higuchi S.
        • Takahashi T.
        • Kabeya Y.
        • et al.
        J waves in accidental hypothermia.
        Circ J. 2014; 78: 128-134
        • Lebiedz P.
        • Meiners J.
        • Samol A.
        • et al.
        Electrocardiographic changes during therapeutic hypothermia.
        Resuscitation. 2012; 83: 602-606
        • Khan J.N.
        • Prasad N.
        • Glancy J.M.
        QTc prolongation during therapeutic hypothermia: Are we giving it the attention it deserves?.
        Europace. 2010; 12: 266-270
        • Osborn J.J.
        Experimental hypothermia: Respiratory and blood pH changes in relation to cardiac function.
        Am J Physiol. 1953; 175: 389-398
        • De Souza D.
        • Perez Riera A.R.
        • Bombing M.T.
        • et al.
        Electrocardiographic changes by accidental hypothermia in an urban and tropical region.
        J Electrocardiol. 2007; 40: 47-52
        • Rolfast C.L.
        • Lust E.J.
        de Cock CC: Electrocardiographic changes in therapeutic hypothermia.
        Crit Care. 2012; 16: R100
        • Omar H.R.
        • Camporesi E.M.
        The correlation between the amplitude of Osborn wave and core body temperature.
        Eur Heart J Acute Cardiovasc Care:?>. 2014 Sep 29; ([Epub ahead of print])
        • Yan G.X.
        • Antzelevitch C.
        Cellular basis for the electrocardiographic J wave.
        Circulation. 1996; 93: 372-379