The Visually-Evoked Cerebral Blood Flow Response in Women with a Recent History of Preeclampsia and/or Eclampsia

Abstract

Several studies provide evidence for altered cerebral hemodynamics during (pre)eclampsia. Whether (pre)eclampsia has a persistent negative impact on cerebral hemodynamics, possibly contributing to an elevated risk of premature stroke, is unknown. The aims of this study were (i) to refine and apply a control system-based method previously introduced by Rosengarten to quantify the visually-evoked blood flow response of the posterior cerebral artery (PCA); and (ii) to test the hypothesis with this method that cerebral hemodynamics in women with a recent history of (pre)eclampsia is abnormal relative to that in parous controls. Hereto, we recorded cerebral blood flow velocity (CBFV) in the PCA by transcranial Doppler (TCD) sonography during cyclic visual stimulation in 15 former preeclamptics, 13 former eclamptics and 13 controls. The typical CBFV response was fitted with the step response of a second-order-linear model enabling quantification by parameters K (gain), ζ (damping), ω (natural frequency), T v (rate time) and T d (time delay). The method refinement introduced here consisted of response filtering before quantification and of considering the individual instead of group-averaged response patterns. Application of this refinement reduced the fitting errors (1.4 ± 1.2 vs. 3.2 ± 1.8, p < 0.01). Intergroup differences in model parameters were not found. Although statistically not significant, a trend was observed that critical damping (ζ>1) occurred more frequently in the combined group of former patients than in the controls (7 of 28 vs.1 of 13, p = 0.16). Critical damping (ζ>1) reflects an abnormal response, which is either compensated for by a rise in rate time (“intermediate”; ζ>1; T v > 20) or remains uncompensated (“sluggish”; ζ>1; T v < 20). Critical damping increased significantly ( p = 0.039) with (pre-)eclampsia-to-test-interval in the PE+E patients with abnormal responses (ζ>1), suggesting that (pre)eclampsia might induce diminishing cerebral hemodynamic function over time. Based on a system-analytical classification approach, the data of this study provide evidence for individual CBFV responses to be abnormal in former (pre)eclamptics compared with controls. Further study is needed to reveal how the abnormal CBFV response classification reflects cerebrovascular dysfunction. (E-mail: esther.martens@mumc.nl)