The pattern of Tpeak–Tend and QT interval, and J wave during therapeutic hypothermia

Abstract Background and Purpose The electrocardiogram manifestations of hypothermia include J waves and prolongation of QT intervals. This study described changes in repolarization patterns during therapeutic hypothermia (TH). Methods We measured the QTc and the interval from the peak to the end of the T wave (TpTe) from the V4 and V6 leads in 20 patients with TH. The TpTe was also expressed as a ratio to the duration of QT ([TpTe/QT] × 100%), and to the corrected value for heart rate (TpTe/√RR). Results The QTc became prolonged in all patients during TH. While the TpTe/√RR did not change, the ([TpTe/QTe] × 100%] decreased significantly during TH. The J wave developed during TH in seven patients. With one patient, ventricular fibrillation occurred preceded by an abnormal J wave and prolonged TpTe during TH. Conclusions QTc prolongation without TpTe increase or abnormal J wave may not be arrhythmogenic during TH.