Maternal cerebral blood flow and glucose metabolism in pregnancies complicated by severe preeclampsia

Cerebral hemodynamics and vasoconstriction in preeclampsia: From diagnosis to resolution

OBJECTIVES

To evaluate maternal cerebral hemodynamics in patients with preeclampsia (PE) from diagnosis to clinical resolution using transcranial Doppler (TCD) and compare these findings with those of healthy pregnant women. Furthermore, we sought to describe the prevalence of vasoconstriction (VC) and related clinical parameters in PE.

STUDY DESIGN

Case-control study including consecutive patients with PE at diagnosis and healthy pregnant women at week 36 of pregnancy. We prospectively collected clinical and neuroimaging data. TCD was repeated at inclusion and on days 1, 7, and 30 postpartum.

MAIN OUTCOME MEASURES

Evolution of intracranial arteries hemodynamics (mean velocities (MV), resistance index). VC diagnosis and related features are described.

RESULTS

A total of 165 patients (80 with PE) underwent 467 TCD procedures. Patients with PE presented higher MAP. Intracranial arteries MV were significantly higher in patients with PE (at diagnosis and days 1 and 7 postpartum) but were normalized by day 30, without correlation with MAP evolution or treatment. VC was present in 32.5% of patients with PE (p < 0.001) and was mainly mild according to the Lindegaard index. Severe PE was associated with VC (50.0% vs. 22.6%; odds ratio 3.484; 95% confidence interval 1.425-8.520; p = 0.014). No other independent risk factors for reversible VC were identified.

CONCLUSIONS

Patients with PE presented significantly higher MV in the anterior circulation compared to healthy controls, which worsened by day 7 and reverted by day 30 after delivery. VC was present in one-third of PE but was mainly mild and asymptomatic. Severe PE was associated with VC development.

What Is the Role of the Maternal Ophthalmic and Cervical Internal Carotid Arteries in Predicting Maternal Adverse Outcomes in Preeclampsia?

OBJECTIVES

We aimed to investigate the efficacy of maternal ophthalmic artery (OA) and cervical internal carotid artery (CICA) in predicting adverse maternal outcomes and gestational age at birth in preeclampsia (PE).

METHODS

The study was performed at the Zeynep Kamil Women and Children's Diseases Training and Research Hospital. Measurements were made in 2 groups consisting of 50 pregnant women with PE and 50 healthy pregnant women. The peak systolic velocity (PSV), end-diastolic velocity, PI, RI, first diastolic peak velocity, systolic/diastolic (S/D) ratio, and peak ratio of the maternal OA were measured by a transorbital Doppler ultrasound (US) scan. The PSV, end-diastolic velocity, PI, RI, and S/D ratio of the CICA were measured. The differences of Doppler indices between groups with P < .05 were considered statistically significant. Cutoff values were calculated, which could be used to predict adverse maternal outcomes and gestational age at birth.

RESULTS

The RI and PI values of the OA were lower, and the first diastolic peak velocity, PSV, and peak ratio values were higher among the PE group. The RI and S/D values of the CICA were significantly lower in the PE group compared to the healthy group. The OA RI was determined to be the strongest US variable in predicting adverse maternal outcomes and gestational age at birth, with a cutoff value of 0.72, 76% sensitivity, and 76% specificity.

CONCLUSIONS

Maternal OA Doppler indices can be used as US markers to predict adverse maternal outcomes.

Placental ischemia-induced increases in brain water content and cerebrovascular permeability: role of TNF-α

Cerebrovascular complications and increased risk of encephalopathies are characteristic of preeclampsia and contribute to 40% of preeclampsia/eclampsia-related deaths. Circulating tumor necrosis factor-α (TNF-α) is elevated in preeclamptic women, and infusion of TNF-α into pregnant rats mimics characteristics of preeclampsia. While this suggests that TNF-α has a mechanistic role to promote preeclampsia, the impact of TNF-α on the cerebral vasculature during pregnancy remains unclear. We tested the hypothesis that TNF-α contributes to cerebrovascular abnormalities during placental ischemia by first infusing TNF-α in pregnant rats (200 ng/day ip, from gestational day 14 to 19) at levels to mimic those reported in preeclamptic women. TNF-α increased mean arterial pressure (MAP, P < 0.05) and brain water content in the anterior cerebrum (P < 0.05); however, TNF-α infusion had no effect on blood-brain barrier (BBB) permeability in the anterior cerebrum or posterior cerebrum. We then assessed the role of endogenous TNF-α in mediating these abnormalities in a model of placental ischemia induced by reducing uterine perfusion pressure followed by treatment with the soluble TNF-α receptor (etanercept, 0.8 mg/kg sc) on gestational day 18. Etanercept reduced placental ischemia-mediated increases in MAP, anterior brain water content (P < 0.05), and BBB permeability (202 ± 44% in placental ischemic rats to 101 ± 28% of normal pregnant rats). Our results indicate that TNF-α mechanistically contributes to cerebral edema by increasing BBB permeability and is an underlying factor in the development of cerebrovascular abnormalities associated with preeclampsia complicated by placental ischemia.

Changes in maternal posterior and anterior cerebral artery flow velocity during pregnancy and postpartum--a longitudinal study

BACKGROUND

To evaluate the normal range of blood flow velocity in the maternal anterior (ACA) and posterior cerebral arteries (PCA) along the normal pregnancy and postpartum period.

METHODS

Transcranial Doppler ultrasound was used to measure the systolic, diastolic, and mean blood velocities in the ACA and PCA during normal gestation. The resistance and pulsatility indices were calculated. Data were analyzed using multilevel modeling, incorporating random effects models, to construct mean and percentile curves.

RESULTS

We performed 355 measurements on 59 patients, which showed that systolic and mean velocity in the ACA decreased, whereas diastolic velocity increased in the PCA during normal pregnancy. Resistance and pulsatility indices in both vessels increased to a maximum in the second trimester, decreased during the third trimester, and increased during the postpartum period.

CONCLUSIONS

This study provides normative data for ACA and PCA velocity and indices during pregnancy and postpartum, demonstrating changes in velocity that suggest a shift of cerebral blood flow from the anterior to the posterior cerebral circulation.