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.

Keywords: Cardiac arrest; Cardiopulmonary resuscitation; Induced mild hypothermia; QT interval.