Maternal cerebral hemodynamics in pregnancy-related hypertension. A prospective transcranial Doppler study

To compare maternal cerebral hemodynamics, as assessed by transcranial Doppler studies, with the clinical and radiological findings in different types of pregnancy-related hypertension and to determine their pathophysiology.

A prospective study of 66 consecutive pregnant women with hypertensive disorders (eclampsia, n = 3; pre-eclampsia, n = 41; isolated hemolysis, elevated liver enzymes, and low platelet count (HELLP)-syndrome, n = 12; pre-eclampsia superimposed on chronic hypertension, n = 5; chronic hypertension, n = 5) and 21 women with uncomplicated pregnancies. Mean blood flow velocities (Vmean) were assessed serially by means of transcranial Doppler in all basal arteries and correlated with changes in mean arterial blood pressure (MABP) and the clinical course.

Patients with the pre-eclampsia/eclampsia syndrome showed significantly elevated Vmean values as compared to controls. In the course of the illness Vmean over the whole length of all insonated basal arteries rose simultaneously. The three eclamptic patients showed the highest Vmean values (156, 182, 192 cm/s, respectively), of the middle cerebral artery (MCA) while MABP was 135, 135, and 150 mmHg, respectively. In pre-eclamptic patients the maximal Vmean MCA ranged from 80 (67, 93) to 145 (114, 151) cm/s [median (25th, 75th percentile)] depending on the severity of clinical presentation. In patients with isolated HELLP-syndrome changes in Vmean were either mild (5/12 cases) or absent (7/12 cases).

Considerable differences in cerebral hemodynamics were observed in the various types of pregnancy-related hypertensive disorders examined in this study. Our findings in patients with pre-eclampsia/eclampsia syndrome suggest a breakdown of autoregulation with hyperperfusion and vasogenic edema being the most probable pathophysiological mechanism.