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...bljana, Slovenia in cooperation with NASA, Houston, Texas [5,6]. The parameters obtained were the RR, PR, uncorrected and corrected QT (QTc) and JT intervals; P, QRS and T-wave amplitudes; frontal plane QRS and T-wave axes; and ST segment levels. Corrected QT interval was calculated using an exponential formula [7]. For calculating P, QRS and T-wave amplitudes we used a program that calculated average vector amplitude from all 12 leads. B. Advanced ECG parameters derived from signal averaging and from variability analyses. Signal averaging was performed using software developed by the authors [8, 9, 10] to generate results for parameters of: 1) derived 3-dimensional ECG, using the Frank-lead reconstruction technique of Kors et al [11] to derive vectorcardiographic (VCG) parameters including the spatial mean QRS-T angle and spatial ventricular gradient (VG); 2) QRS and T-waveform complexity via singular value decomposition (SVD), to derive parameters such as the principal component analysis (PCA) ratio, intradipolar ratio (IRD) [9] the “relative residuum” [9] and the dipolar and non-dipolar voltages [8] of the QRS and T waveforms; 3) 12-lead high frequency (HF, 150-250 Hz) QRS ECG, from which...

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...after being successfully resuscitated. The introduction of MTH (defined as core body temperature of 32-34°C) in 2002 has revolutionized treatment of comatose survivals after cardiac arrest, increasing survival and improving neurological outcome. Recent studies suggest that MTH might also reduce myocardial damage [1]. Accidental hypothermia has been shown to cause electrocardiographic changes such as increase in RR, PR and QT intervals, appearance of Osborn waves, conduction blocks and various arrhythmias. Although a few studies of standard ECG parameters in MTH have also shown similar changes [2, 3, 4], no study to date has utilized more advanced ECG parameters to more fully characterize the electrophysiological effects of MTH versus normothermia. 2. Methods 2.1. Patients Our study was approved by the Institutional Review Board at the University Medical Centre, Ljubljana, Slovenia, and included comatose patients, older than 16 years, after cardiac arrest treated with MTH at the University Medical Centre, Ljubljana. In all patients, core body temperature was measured by thermistor intravesically. ECG was recorded during MTH and after restoration of normal body temperature. 2.2. Data collecti...