Validation of a Time Coherent Enhanced Averaging Technique for the Analysis of the Fetal Electrocardiographic Waveform

Abstract

The objective of this study was to determine the accuracy of time coherent enhanced averaging (TCEA) as a technique of fetal electrocardiogram (ECG) waveform isolation. Four 130 day fetal lambs from mixed breed ewes were chronically cannulated. Comparisons between the raw ECG waveforms and waveforms isolated by TCEA were made following administration of a hypoxic gas mixture to the ewe or 1.6 μg isoprenaline intravenously to the fetus. The TCEA technique accurately detected rapid morphological changes associated with hypoxic bradycardia and isoprenaline induced tachycardia. Corruption of potentials and time constants due to the averaging process was minimal. P and T wave heights were the most affected with variable attenuation depending on the heart rate. Maximal attenuation was P wave 0.89 ± raw signal and T wave 0.85 ± raw signal. In conclusion, TCEA is a reliable technique for fetal ECG waveform isolation and analysis.