Maternal Brachial Arterial Waveforms in Gestational Hypertension: Analysis Using a Laplace Transform Technique.

> Objective: A pilot study was designed to investigate whether maternal brachial arterial Doppler shift waveforms analyzed using a Laplace transform analysis technique could distinguish women with gestational hypertension and preeclampsia from women who remained normotensive during their pregnancy. Methods: We examined 50 pregnant women in total. They were divided into two groups. The first was a group of 21 normotensive women, and the second was a group of 29 women with gestational hypertension or preeclampsia, not on medication at the time of study. A Doppler shift waveform of the right and left brachial artery was obtained and analyzed using the conventional parameters of resistance index (RI) and pulsatility index (PI) and Laplace transform analysis. Results: The systolic and diastolic blood pressures and the mean arterial blood pressure at presentation were significantly higher in group 2 as expected. The results of the Laplace transform parameters showed significant differences in the resonant frequency, real pole, c coefficient, and alpha between the two groups. There was no difference in the PI between the two groups, but the differences in RI just reached significance. The Laplace transform parameters in the group with gestational hypertension were consistent with peripheral vasoconstriction, which has been suggested as part of the hemodynamic abnormalities in this condition. Conclusion: Analysis of maternal brachial arterial Doppler shift waveforms by Laplace transform analysis detects differences between normotensive and hypertensive patients. These differences may also reflect some of the hemodynamic changes occurring in gestational hypertension.