USE OF LAPLACE TRANSFORM ANALYSIS TO DESCRIBE THE EFFECT OF PLACENTALEMBOLIZATION ON UMBILICAL ARTERIAL DOPPLER WAVE-FORMS IN FETAL SHEEP

This is the first study to investigate changes in umbilical arterial D oppler shift waveforms caused by placental embolisation in fetal lambs described by a Laplace transform analysis method. The complete maximu m velocity envelope of the waveform was quantified mathematically by t he coefficients of the Laplace transform. The changes in the dominant coefficient were significantly correlated with changes in umbilico-pla cental vascular resistance. The Doppler shift waveforms reproduced tho se seen clinically in some growth-retarded pregnancies and were acquir ed in a clinically realistic manner. Increasing vascular resistance tw o fold in this experiment appeared to produce more consistent changes in the dominant coefficient of the Laplace transform than in the pulsa tility index. Both analysis techniques correlated with umbilico-placen tal vascular resistance and these correlations were not significantly different from each other.