Hypertensive and normal pregnancy: a longitudinal study of blood pressure, distensibility of dorsal hand veins and the ratio of the stable metabolites of thromboxane A2 and prostacyclin in plasma

Efficacy of combined medication of nifedipine and magnesium sulfate on gestational hypertension and the effect on PAPP-A, VEGF, NO, Hcy and vWF

Objective

To investigate the effects of combined medication of nifedipine and magnesium sulfate on the blood pressure, pregnancy-associated plasma protein A (PAPP-A), vascular endothelial growth factor (VEGF), nitric oxide (NO), homocysteine (Hcy) and von Willebrand factor (vWF) in gestational hypertension patients.

Methods

A total of 220 gestational hypertension patients were enrolled as the subjects, and divided into two groups randomly, i.e. the observation group and the control group. In observation group, patients took combined medication of nifedipine and magnesium sulfate, while those in the control group only took magnesium sulfate for treatment. Clinical efficacy, and the changes in blood pressure, PAPP-A, VEGF, NO, Hcy and vWF before and after treatment were compared between two groups.

Results

In the observation group and the control group, total effectiveness rates were 92.7% and 70.9%, respectively (p < 0.05). After treatment, we found significant decreases in PAPP-A, VEGF, NO, Hcy and vWF in patients of two groups, with more significant decreases in the observation group (p < 0.05). Incidence rates of the adverse reactions in two groups were 5.5% and 6.4%, respectively, without any statistically significant differences (p > 0.05). In the observation group, patients had fewer complications (p < 0.05).

Conclusion

Combined medication of magnesium sulfate and nifedipine can decrease the levels of PAPP-A, VEGF, NO, Hcy and vWF in serum as well as the blood pressure of patients with gestational hypertension, with a reduction in incidence rate of complications and improvement in efficacy.

Cytokines, angiogenic, and antiangiogenic factors and bioactive lipids in preeclampsia

Preeclampsia is a low-grade systemic inflammatory condition in which oxidative stress and endothelial dysfunction occurs. Plasma levels of soluble receptor for vascular endothelial growth factor (VEGFR)-1, also known as sFlt1 (soluble fms-like tyrosine kinase 1), an antiangiogenic factor have been reported to be elevated in preeclampsia. It was reported that pregnant mice deficient in catechol-O-methyltransferase (COMT) activity show a preeclampsia-like phenotype due to a deficiency or absence of 2-methoxyoestradiol (2-ME), a natural metabolite of estradiol that is elevated during the third trimester of normal human pregnancy. Additionally, autoantibodies (AT1-AAs) that bind and activate the angiotensin II receptor type 1 a (AT1 receptor) also have a role in preeclampsia. None of these abnormalities are consistently seen in all the patients with preeclampsia and some of them are not specific to pregnancy. Preeclampsia could occur due to an imbalance between pro- and antiangiogenic factors. VEGF, an angiogenic factor, is necessary for the transport of polyunsaturated fatty acids (PUFAs) to endothelial cells. Hence reduced VEGF levels decrease the availability of PUFAs to endothelial cells. This leads to a decrease in the formation of anti-inflammatory and angiogenic factors: lipoxins, resolvins, protectins, and maresins from PUFAs. Lipoxins, resolvins, protectins, maresins, and PUFAs suppress insulin resistance; activation of leukocytes, platelets, and macrophages; production of interleukin-6 and tumor necrosis factor-α; and oxidative stress and endothelial dysfunction; and enhance production of prostacyclin and nitric oxide (NO). Estrogen enhances the formation of lipoxin A4 and NO. PUFAs also augment the production of NO and inhibit the activity of angiotensin-converting enzyme and antagonize the actions of angiotensin II. Thus, PUFAs can prevent activation of angiotensin II receptor type 1 a (AT1 receptor). Patients with preeclampsia have decreased plasma phospholipid concentrations of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), the precursors of lipoxins (from AA), resolvins (from EPA and DHA), and protectins (from DHA) and prostaglandin E1 (PGE1 from DGLA: dihomo-γ-linolenic acid) and prostacyclin (PGI2 derived from AA). Based on these evidences, it is proposed that preeclampsia may occur due to deficiency of PUFAs and their anti-inflammatory products: lipoxins, resolvins, protectins, and maresins.

Blood pressure change in normotensive, gestational hypertensive, preeclamptic, and essential hypertensive pregnancies

We compared patterns of blood pressure (BP) change among normotensive women, women who developed gestational hypertension or preeclampsia, and women who had essential hypertension to examine how distinct these conditions are and whether rates of BP change may help to identify women at risk for hypertensive disorders. We used antenatal clinic BP measurements (median, 14 per woman) of 13016 women from the Avon Longitudinal Study of Parents and Children who had a singleton or twin live birth surviving until ≥ 1 year. Linear spline models were used to describe changes in systolic and diastolic BPs in different periods of pregnancy (8-18, 18-30, 30-36, and ≥ 36 weeks' gestation). Women who had essential hypertension and those who developed gestational hypertension or preeclampsia had higher BP at 8 weeks' gestation (baseline) compared with normotensive women. The decrease in BP until 18 weeks was smaller in gestational hypertensive compared with normotensive pregnancies. BP rose more rapidly from 18 weeks onward in gestational hypertensive and preeclamptic pregnancies and from 30 weeks onward in essential hypertensive compared with normotensive pregnancies. Women who developed preeclampsia had a more rapid increase in BP from 30 weeks onward than those who developed gestational hypertension or had essential hypertension. Our findings indicate notable patterns of BP change that distinguish women with essential hypertension, gestational hypertension, and preeclampsia from each other and from normotensive women, even from early pregnancy. These distinct patterns may be useful for identifying women at risk of developing a hypertensive disorder later in pregnancy.

Prostacyclin/thromboxane early changes in pregnancies that are complicated by preeclampsia

OBJECTIVE

The purpose of this study was to examine 6-keto-prostaglandin F(1)(alpha) and thromboxane B(2) plasma levels throughout normotensive and preeclamptic pregnancies and to analyze the predictive values of these quantifications for the detection of preeclampsia during the second trimester of pregnancy.

STUDY DESIGN

Blood samples were collected from 30 healthy, nonpregnant women and at 4-week intervals from a cohort of nulliparous women who were recruited before 16 weeks of gestation. Preeclampsia developed in 26 patients; 52 normotensive control subjects were matched from the same cohort. The 6-keto-prostaglandin F(1)(alpha) and thromboxane B(2) were assayed by radioimmunoassay. Trends were compared between pregnancy groups and with the nonpregnant women. Predictive values were determined with the second-trimester assessments.

RESULTS

The 6-keto-prostaglandin F(1)(alpha)/thromboxane B(2) ratio decreased throughout pregnancy in women with preeclampsia; there were no significant changes in normotensive women. We found higher thromboxane B(2) levels within the group with preeclampsia during the first gestational trimester (preeclampsia, 188 +/- 17 pg/mL; control, 119 +/- 4.8 pg/mL [mean +/- SEM]; P =.001). During the third trimester, patients with preeclampsia had lower 6-keto-prostaglandin F(1)(alpha) levels than did control subjects (preeclampsia, 191 +/- 9.8 pg/mL; control, 288 +/- 10 pg/mL; P =.001). The 6-keto-prostaglandin F(1)(alpha)/thromboxane B(2) ratio was suitable to calculate predictive values; the best cutoff point and time interval were 3.0 and 22 to 26 weeks of gestation, respectively. Sensitivity, specificity, and positive and negative predictive values were 88%, 97%, 69%, and 99%, respectively; the odds ratio was 14.6 (95% CI, 6.9-30.4).

CONCLUSION

The prostacyclin/thromboxane ratio favored vasoconstriction early in gestation in women in whom preeclampsia developed. A 6-keto-prostaglandin F(1)(alpha)/thromboxane B(2) ratio of <or=3.0 at 22 to 26 weeks of gestation had a high predictive value for the development of preeclampsia.

Maternal thromboxane and prostacyclin levels in relation to fetal birth weight

OBJECTIVE

To analyse whether pregnancies resulting in a small for gestational age neonate are preceded by a prostacyclin deficiency or an imbalance between thromboxane and prostacyclin.

STUDY DESIGN

At five fixed time points during pregnancy, 24-h urine samples were collected for the measurement of thromboxane and prostacyclin metabolites thromboxane-B(2) (TXB(2)) and 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)). In order to study trend differences between pregnancies with appropriate (AGA; n=26) and small for gestational age neonates (SGA; n=17), trend analysis with simple contrasts were accomplished for TXB(2), 6-keto-PGF(1alpha) and the TXB(2)/6-keto-PGF(1alpha) ratio.

RESULTS

Trend analysis showed higher TXB(2) levels and higher TXB(2)/6-keto-PGF(1alpha) ratios in patients with SGA versus AGA newborns. No statistically significant difference in 6-keto-PGF(1alpha) excretion between patients with SGA and AGA newborns was detected.

CONCLUSION

The birth of an SGA neonate is not preceded by prostacyclin deficiency. With ongoing pregnancy an imbalance between thromboxane and prostacyclin becomes more obvious in pregnancies with SGA newborns.

Levels of stable metabolites of prostacyclin and thromboxane A2 and their ratio in normotensive and preeclamptic pregnant women during the antepartum and postpartum periods

OBJECTIVE

To measure the levels of the circulating metabolites of prostacyclin and thromboxane A2 during the antepartum and postpartum periods in severe preeclamptic and eclamptic patients as well as in normotensive pregnant women.

METHODS

6-Keto-prostaglandin F1alpha (6-keto-PGF1alpha) and thromboxane B2 (TxB2) were measured in the plasma of 15 severe preeclamptic, 15 eclamptic, and 15 normotensive pregnant women during the antepartum and postpartum (5th day) periods. At the same time blood pressure measurements were obtained. Kruskal-Wallis, Wilcoxon rank-sum, and Wilcoxon's signed-rank tests were used for statistical analysis.

RESULTS

1) There was no significant difference in the levels of 6-keto-PGF1alpha and TxB2 of the normotensive pregnant women between the antepartum and the postpartum (5th day) periods. 2) In the severe preeclamptic and eclamptic groups, 6-keto-PGF1alpha levels showed significant increase after the delivery (P < 0.01, and P < 0.001, respectively). 3) In the severe preeclamptic and eclamptic groups TxB2 levels showed significant decrease after delivery (P < 0.01, and P < 0.001, respectively). 4) The 6-keto-PGF1alpha/TxB2 ratio both during the antepartum and the postpartum (5th day) periods showed significant differences between the severe preeclamptic and normotensive, and between the eclamptic and normotensive groups (P < 0.001, and P < 0.001 respectively). 5) No correlation was observed between the mean arterial pressure and the antepartum levels of 6-keto-PGF1alpha TxB2 or their ratios.

CONCLUSIONS

Our study was able to demonstrate a significant difference in circulating metabolites of prostacyclin and TxA2 between normotensive pregnant women and those with severe preeclampsia and eclampsia. But no correlation was observed between the blood pressure and the antepartum 6-keto-PGF1alpha, TxB2 levels or their ratios. 6-keto-PGF1alpha levels increased and TxB2 levels decreased in the postpartum period (5th day). However, the 6-keto-PGF1alpha/TxB2 ratio was still low in the severe preeclamptic and eclamptic patients when compared with the control group. This situation shows that the pathophysiologic mechanism does not improve completely within a few days after delivery.

Vasoactive mediators in pregnancy-induced hypertensive disorders: a longitudinal study

OBJECTIVE

The objective of this study was to evaluate the extent to which endothelin and the eicosanoids prostacyclin and thromboxane A2 are involved in the pathophysiology of gestational hypertension and preeclampsia.

STUDY DESIGN

In a longitudinal design, venous blood samples and 24-hour urine specimens were collected from 396 women in each trimester of pregnancy. After delivery of all patients, venous plasma endothelin was assessed in 20 subjects with identified preeclampsia, 48 subjects with gestational hypertension, and 59 normotensive subjects. Urinary excretions of the thromboxane A2 and of the prostacyclin metabolites thromboxane B2 and 6-keto-prostaglandin F1 alpha were assessed in 16 subjects with preeclampsia, 35 subjects with gestational hypertension, and 31 normotensive subjects.

RESULTS

Endothelin levels showed a second-trimester drop in all groups. In all 3 gestational trimesters a high correlation was found between the excretion of thromboxane B2 and that of 6-keto-prostaglandin F1 alpha (P <.001). The overall thromboxane B2 and 6-keto-prostaglandin F1 alpha urinary excretions increased throughout pregnancy and the overall thromboxane B2 /6-keto-prostaglandin F1 alpha ratio decreased. No significant differences in endothelin, thromboxane B2, and 6-keto-prostaglandin F1 alpha excretion levels or in thromboxane B2 /6-keto-prostaglandin F1 alpha ratios were found between women with preeclampsia, gestational hypertension, and normotension. Only in a small group of patients with severe preeclampsia (n = 2) and severe gestational hypertension (n = 2) were increased second-trimester endothelin values and increased thromboxane B2 /6-keto-prostaglandin F1 alpha ratios found.

CONCLUSION

In this longitudinal study we found no evidence for prostacyclin deficiency or increased endothelin levels in preeclampsia. Only women with severe preeclampsia and severe gestational hypertension expressed increased endothelin levels and thromboxane dominance over prostacyclin.

Venous and arterial behavior during normal pregnancy

To assess the contribution of the arterial and venous systems in the hemodynamic changes of normal pregnancy, we studied blood flow, vascular resistance, venous tone, and the viscoelastic properties ("creep") of the upper and lower limbs (using plethysmography), aortic distensibility (using pulse wave velocity measurements), and cardiac dimensions (using echocardiography) in nine healthy women. Studies were longitudinally performed at the first (10-13 wk) and third (33-38 wk) trimesters of pregnancy in comparison with the period between the third and sixth month after delivery. From the first trimester, heart rate significantly increased while systemic blood pressure and limb vascular resistances did not change significantly and aortic distensibility increased (P < 0.05). Lower limb viscoelastic properties decreased at the third trimester (P < 0.05) and venous tone increased from the first trimester (P < 0.01), whereas little changes were observed at the site of upper limbs. The decrease in calf venous tone was significantly correlated with the increase in left ventricular diastolic diameter at the first (P < 0.001) and the third trimester (P < 0.05). The study provides evidence that during normal pregnancy, changes in the arterial and venous sides of the circulation occur independently of pressure alterations. The increase in venous tone, contributing to preload augmentation, and the decrease in aortic stiffness, reducing afterload, both optimize cardiac function until delivery.