Vascular reactivity in patients with preeclampsia and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome

Circulating extracellular vesicles during pregnancy in women with type 1 diabetes: a secondary analysis of the CONCEPTT trial

BACKGROUND

Extracellular vesicles are membrane vesicles that are released into the extracellular environment and accumulate in the circulation in vascular disease. We aimed to quantify circulating extracellular vesicles in pregnant women with type 1 diabetes and to examine associations between extracellular vesicle levels, continuous glucose measures, and pregnancy outcomes.

METHODS

We used plasma samples from the Continuous Glucose Monitoring in Women with Type 1 Diabetes in Pregnancy Trial study and quantified circulating extracellular vesicles by flow cytometry (n = 163). Relationships with clinical variables were assessed by repeated measures correlation. Logistic regression was used to assess associations between elevated extracellular vesicle levels and pregnancy outcomes.

RESULTS

Platelet extracellular vesicle levels were inversely associated with glucose time above range and glycaemic variability measures (P < 0.05). A weak positive association was observed between endothelial extracellular vesicles and mean amplitude of glycemic excursion (P < 0.05). In a univariate logistic regression model, high baseline endothelial extracellular vesicles was associated with increased risk of neonatal intensive care unit (NICU) admission (OR: 2.06, 1.03-4.10), and respiratory distress requiring ventilation (OR: 4.98, 1.04-23.92). After adjusting for HbA1c and blood pressure the relationship for NICU admission persisted and an association with hyperbilirubinemia was seen (OR: 2.56, 1.10-5.94). Elevated platelet extracellular vesicles were associated with an increased risk of NICU admission (OR: 2.18, 1.04-4.57), and hyperbilirubinemia (OR: 2.61, 1.11-6.12) after adjusting for HbA1c and blood pressure.

CONCLUSIONS

High levels of extracellular vesicles in early pregnancy were associated with adverse neonatal outcomes. Assessment of extracellular vesicles may represent a novel approach to personalized care in type 1 diabetes pregnancy.

Preeclampsia Emerging as a Risk Factor of Cardiovascular Disease in Women

The objective of this literature review was to explore the long-term cardiovascular effects of preeclampsia in women. The primary goal was to determine which organs were most commonly affected in this population. Although it was previously believed that preeclampsia is cured after the delivery of the fetus and the placenta current evidence supports an association between preeclampsia and cardiovascular disease later in life, many years after the manifestation of this hypertensive pregnancy related disorder. Therefore preeclampsia may be emerging as a novel cardiovascular risk factor for women, which requires long-term follow up.

Neural control of blood pressure during pregnancy in humans

PURPOSE

Previous microneurographic studies found that muscle sympathetic nerve activity (MSNA) increased in normotensive pregnant women and was even greater in women with gestational hypertension and preeclampsia during the third trimester. It is possible that sympathetic activation during the latter months of normal pregnancy helps return arterial pressure to non-pregnant levels. However, when the increase in sympathetic activity is excessive, hypertension ensues. The key question that must be addressed is whether sympathetic activation develops early during pregnancy and remains high throughout gestation, or whether this sympathetic overactivity only occurs at term, providing the substrate for preeclampsia and other pregnancy-associated cardiovascular complications.

METHODS

This was a literature review of autonomic neural control during pregnancy.

RESULTS

Recent work from our laboratory and other laboratories showed that in healthy women resting MSNA increased in early pregnancy, increased further in late pregnancy, and returned to the pre-pregnancy levels shortly after delivery. We found that women who exhibited excessive sympathetic activation during the first trimester, before any clinical signs and symptoms appeared, developed gestational hypertension at term. We also found that the level of corin, an atrial natriuretic peptide-converting enzyme, was increased in the maternal circulation, especially during late pregnancy, as a homeostatic response to elevated sympathetic activity.

CONCLUSION

These findings provide important insight into the neural mechanisms underlying hypertensive disorders during pregnancy. With this knowledge, early prevention or treatment targeted to the appropriate pathophysiology may be initiated, which may reduce maternal and fetal death or morbidity, as well as cardiovascular risks in women later in life.

Elastic properties of ascending aorta and ventricular-arterial coupling in women with previous pregnancy complicated by HELLP syndrome

OBJECTIVE

To compare the elastic properties of the ascending aorta and ventricular-arterial coupling (VAC) in women with a previous pregnancy complicated by hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, women who experienced preeclampsia, and healthy controls.

METHODS

Women with a history of preeclampsia (n = 60) or HELLP syndrome (n = 49) and matched healthy controls (n = 60) underwent transthoracic echocardiography at 6 months to 4 years after delivery. Aortic M-mode and tissue Doppler imaging (TDI) parameters were measured. Aortic diameters were assessed at end-diastole at four levels: Valsalva sinuses, sinotubular junction, tubular tract, and aortic arch. Aortic compliance, distensibility, stiffness index, Peterson's elastic modulus, pulse-wave velocity, and M-mode strain were calculated using standard formulae. Aortic expansion velocity, early and late diastolic retraction velocities, and peak systolic tissue strain (TDI-ε) were determined. VAC was defined as the ratio between aortic elastance (Ea) and left ventricular end-systolic elastance (Ees). All women were free from cardiovascular risk factors.

RESULTS

Women with a history of HELLP syndrome showed larger aortas than those with previous preeclampsia or controls, probably related to a higher blood pressure. Aortic elastic properties, including Ea, were similar between HELLP and preeclampsia groups, even comparing cases with early-onset preeclampsia and HELLP. In contrast, Ees was more impaired in the HELLP group than in the other two. Consequently, about one-quarter of women who experienced HELLP syndrome had a pathological VAC, whereas only 5% of previously preeclamptic patients did. Multivariate analysis confirmed the association between HELLP syndrome and VAC, whereas other parameters including aortic compliance, distensibility, stiffness index, and elastic modulus are linked only to gestational age at preeclampsia onset, ad also Ea and Ees did.

CONCLUSIONS

We found a significant overlap between the aortic elastic properties in women with a history of preeclampsia and those with a previous HELLP syndrome, suggesting a common pathophysiologic pathway. However, women who experienced HELLP syndrome showed a higher blood pressure than other cases and controls, probably determining larger aortas. In addition, VAC was more altered in the HELLP group than in the others because of a higher Ea and a lower Ees.

Preeclampsia: Novel Mechanisms and Potential Therapeutic Approaches

Preeclampsia is a serious complication of pregnancy where it affects 5–8% of all pregnancies. It increases the morbidity and mortality of both the fetus and pregnant woman, especially in developing countries. It deleteriously affects several vital organs, including the kidneys, liver, brain, and lung. Although, the pathogenesis of preeclampsia has not yet been fully understood, growing evidence suggests that aberrations in the angiogenic factors levels and coagulopathy are responsible for the clinical manifestations of the disease. The common nominator of tissue damage of all these target organs is endothelial injury, which impedes their normal function. At the renal level, glomerular endothelial injury leads to the development of maternal proteinuria. Actually, peripheral vasoconstriction secondary to maternal systemic inflammation and endothelial cell activation is sufficient for the development of preeclampsia-induced hypertension. Similarly, preeclampsia can cause hepatic and neurologic dysfunction due to vascular damage and/or hypertension. Obviously, preeclampsia adversely affects various organs, however it is not yet clear whether pre-eclampsia per se adversely affects various organs or whether it exposes underlying genetic predispositions to cardiovascular disease that manifest in later life. The current review summarizes recent development in the pathogenesis of preeclampsia with special focus on novel diagnostic biomarkers and their relevance to potential therapeutic options for this disease state. Specifically, the review highlights the renal manifestations of the disease with emphasis on the involvement of angiogenic factors in vascular injury and on how restoration of the angiogenic balance affects renal and cardiovascular outcome of Preeclamptic women.

Maternal endothelial function and vascular stiffness after HELLP syndrome: a case-control study

OBJECTIVES

To assess endothelial function and arterial stiffness in women with a previous pregnancy complicated by pre-eclampsia (PE) with hemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome, and to compare these findings to those in women with previous PE but no HELLP and to those in controls with previous uncomplicated pregnancy, in order to investigate the influence of HELLP syndrome on subsequent cardiovascular impairment.

METHODS

In this prospective single-center case-control study, we performed peripheral arterial tonometry (PAT) (using the EndoPAT method) and pulse-wave velocity (PWV) assessment in 109 women who had had a singleton pregnancy complicated by PE with (n = 49) or without (n = 60) HELLP syndrome, as well as in 60 controls with previous uncomplicated pregnancy, between 6 months and 4 years after delivery. The following EndoPAT and PWV indices were compared between groups: reactive hyperemia index (RHI), as an indication of endothelial function, and peripheral and aortic heart-rate-corrected augmentation indices (AIx) standardized for a heart rate of 75 bpm (AIx@75) and carotid-femoral pulse-wave velocity (cfPWV), as indications of arterial stiffness.

RESULTS

PAT and arterial stiffness indices were significantly different between PE cases, with or without previous HELLP, and controls, except for carotid-femoral PWV. There were no significant differences among PE groups: women who had experienced HELLP and those with a history of PE without HELLP showed similar rates of RHI ≤ 1.67 (28.6% vs 18.3%, P = 0.254) and RHI ≤ 2.00 (61.2% vs 41.7%, P = 0.055), peripheral AIx@75 ≥ 17% (38.8% vs 30.0%, P = 0.417), aortic AIx@75 ≥ 35% (29.2% vs 20.0%, P = 0.461) and cfPWV × 0.8 > 9.6 m/s, which occurred in only three women, all in the group without previous HELLP (0% vs 5.0%, P = 0.251). On multivariate regression analysis, HELLP syndrome, intrauterine growth restriction (IUGR) and early-onset PE independently predicted endothelial dysfunction at 6 months to 4 years postpartum, after correcting for uterine artery pulsatility index, birth-weight percentile, and maternal blood pressure, age and body mass index. Women with both previous HELLP and early-onset IUGR had a significantly higher prevalence of endothelial dysfunction (P = 0.001).

CONCLUSION

Similar vascular abnormalities were found in women previously affected by HELLP syndrome and those with previous PE without HELLP. However, a history of HELLP syndrome, IUGR and early-onset PE seems to identify a subgroup of women with a higher risk for future development of endothelial dysfunction. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Using the angiogenic factors sFlt-1 and PlGF with Doppler ultrasound of the uterine artery for confirming preeclampsia

PURPOSE

The aim of this study is to assess the value of the angiogenic factors for diagnosing preeclampsia and predicting the severity of manifestation. A secondary aim is assessing the combination of the uterine artery Doppler with the angiogenic factors for improving the diagnostic power.

METHODS

This is a prospective single center study in a tertiary referral hospital. This study includes 728 individual patients. Inclusion criteria were singleton pregnancies, a referral to the hospital with suspicion of preeclampsia and any one or combination of the following symptoms: headache, upper abdominal pain, edema, and hypertension. Patients with complications that would affect the course of the pregnancy, such as placenta praevia, premature preterm rupture of membranes, breech presentation, and fetal chromosomal or structural anomalies, were excluded from the study. Blood samples collection and uterine artery Doppler ultrasound were performed at time of recruitment. The differences in sFlt-1, PlGF, and their quotient among normal collective and patients with preeclampsia were analyzed. Doppler ultrasound was performed by one of four highly qualified sonographers. Wilcoxon-Mann-Whitney U test, Spearman's rank correlation, receiver operating characteristic curves, Chi-square test, and logistic regression were used in the analysis.

RESULTS

A total of 1003 individual samples for the angiogenic factors were included in the analysis. 584 out of the recruited 728 patients had follow-up data with delivery information at the study hospital. Patients with preeclampsia show a significant increase in sFlt-1, which directly correlate with the increased severity of manifestation (Spearman's ρ 0.49). The sFlt-1 cut-off value of 5424 pg/ml confirms preeclampsia with 83.7 % sensitivity, 68.1 % specificity, and 24 % misclassification rate. Preeclampsia patients also show a significant decrease in PlGF, which negatively correlates with the increased severity of manifestation (Spearman's ρ -0.39). A PlGF cut-off value of 118 pg/ml confirms preeclampsia with 47.6 % sensitivity, 71.4 % specificity, and 27 % misclassification rate. Logistic regression shows that a combination of the quotient from sFlt-1/PlGF with notching and uterine artery PI provides a valid model for diagnosing preeclampsia with a diagnostic power of 74.4 %.

CONCLUSIONS

The study confirms the use of the sFlt-1 and PlGF for diagnosing preeclampsia. It also shows their significance in differentiating between different categories of preeclampsia according to severity. This study shows that the use of angiogenic factors in combination with ultrasound findings provides valid models for confirming preeclampsia.

Severe Preeclampsia With and Without HELLP Differ With Regard to Placental Pathology

The aim of the present study was to evaluate the histopathology in placentas from patients with severe preeclampsia with and without hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome. An additional aim was to compare the prevalence of infants born small for gestational age in the 2 groups. The study is retrospective and includes 178 women who have been diagnosed at the Karolinska University Hospital Huddinge or at the Free University Medical Center between 2000 and 2005 with severe preeclampsia. A total of 96 women had severe preeclampsia without signs of HELLP (preeclampsia group), whereas 82 fulfilled the criteria for having HELLP syndrome (HELLP group). Infarction ( P =0.014), intervillous thrombosis ( P <0.001), and abruption ( P =0.002) were more common in the preeclampsia group than in the HELLP group. There was no statistically significant difference in the frequency of accelerated villous maturation ( P =0.61), decidual arteriopathy ( P =0.27), or chorioamnionitis ( P =0.61). Furthermore, there was a higher mean placental weight, adjusted for gestational age, in the Swedish HELLP material than in the preeclampsia group ( P <0.001). Finally, mothers in the preeclampsia group gave birth significantly more often to small for gestational age babies than mothers suffering from HELLP syndrome ( P <0.001). The histopathologic profile and the range of placental lesions were partly different in the preeclampsia and HELLP patients. Considering the central role that placenta seems to have in preeclampsia, the present result might suggest that different underlying pathogenetic mechanisms and courses can be in play in patients with preeclampsia and HELLP syndrome.

Water immersion in preeclampsia

OBJECTIVE

Preeclampsia is associated with profound vasoconstriction in most organ systems and reduced plasma volume. Because water immersion produces a marked central redistribution of blood volume and suppresses the renin-angiotensin system response and sympathetic activity, we hypothesized that water immersion might be useful in the treatment of preeclampsia.

STUDY DESIGN

The effects of thermoneutral water immersion for 3 hours on central and peripheral hemodynamics were evaluated in 7 preeclamptic patients, 7 normal pregnant control patients, and 7 nonpregnant women. Finger plethysmography was used to determine hemodynamic measurements (cardiac output and total peripheral resistance), and forearm blood flow was measured by strain gauge plethysmography. Postischemic hyperemia was used to determine endothelium-dependent vasodilation. Analysis was by analysis of variance for repeated measurements.

RESULTS

During water immersion cardiac output increased while diastolic blood pressure and heart rate decreased, although systolic blood pressure remained unchanged in each group. Forearm blood flow increased significantly in the normal pregnant and preeclamptic subjects. Total peripheral resistance decreased in all groups, but values in preeclamptic patients remained above those of normotensive pregnant women. Water immersion had no effect on endothelium-dependent vasodilation in the preeclamptic group, and most hemodynamic changes that were observed reversed to baseline within 2 hours of completion of the procedure.

CONCLUSION

Although water immersion results in hemodynamic alterations in a manner that is theoretically therapeutic for women with preeclampsia, the effect was limited and short-lived. In addition water immersion had no effect on endothelium-dependent vasodilation in women with preeclampsia. The therapeutic potential for water immersion in preeclampsia appears to be limited.

Prediction of HELLP syndrome with assessment of maternal dual hepatic blood supply by using Doppler ultrasound

OBJECTIVE

Early structural and functional changes in the systemic vasculature have been proposed to play a major pathogenetic role in HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome. Our objective was to assess whether the evaluation of maternal hepatic blood supply is instructive to the prediction of onset of HELLP syndrome.

DESIGN

Prospective observation study.

POPULATION

Fifty-eight women with severe preeclampsia and 60 healthy pregnant controls at 25-36 weeks gestation.

METHODS

Angle-corrected time-averaged flow velocity and the cross-sectional area of common hepatic artery and portal vein were measured by using Doppler ultrasonography in 58 women with severe preeclampsia and in 60 healthy pregnant controls at 25-36 weeks gestation. Intravascular flow volumes were calculated from the product of the time-averaged velocity and the cross-sectional area. The total liver blood flow was taken as the sum of flow volumes in the hepatic artery and portal vein.

RESULTS

The total liver blood flow decreased significantly to about 40% of control in 9 women with severe preeclampsia who developed HELLP syndrome within 4 days after the examination, but not in 49 women with severe preeclampsia without HELLP syndrome.

CONCLUSION

The results indicated that the decrease in dual hepatic blood supply preceded the onset of HELLP syndrome.

Contribution of endogenous endothelin-1 to basal vascular tone during normal pregnancy and preeclampsia

OBJECTIVE

The aim of this study was to determine the physiologic role for endogenous endothelin in the regulation of vascular tone during normal pregnancy and preeclampsia. The vascular sensitivity to endothelin-1 during pregnancy was studied also.

STUDY DESIGN

Forearm blood flow was measured by venous occlusion plethysmography during intra-arterial infusion of phosphoramidon, an endothelin-converting enzyme inhibitor, for 60 minutes, which was followed by co-infusion with endothelin-1 for 30 minutes. Three groups were studied: healthy nonpregnant women, normal pregnant women, and women with preeclampsia.

RESULTS

There was a significant increase in forearm blood flow in the nonpregnant group after phosphoramidon infusion alone (73%+/-37%; P<.05). Phosphoramidon did not change forearm blood flow in pregnant subjects. Co-infusion with endothelin-1 significantly decreased forearm blood flow in both the nonpregnant and normal pregnant women (53%+/-7% and 40%+/-11%, respectively; P<.01). No response to endothelin-1 was found among women with preeclampsia.

CONCLUSION

The vascular sensitivity to endothelin-1 is not altered during normal pregnancy in contrast to preeclamptic pregnancy, where no effect of endothelin-1 was seen. Reduced endothelin dependence during pregnancy might be one mechanism behind the fall in peripheral vascular resistance.

Postpartum intravenous dexamethasone for severely preeclamptic patients without hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome: a randomized trial

OBJECTIVE

We compared maternal outcomes for patients with severe preeclampsia who were managed postpartum with or without adjunctive intravenous dexamethasone.

METHODS

This study was a randomized, blinded placebo-controlled clinical trial comparing the use of dexamethasone postpartum (10 mg-10 mg-5 mg-5 mg intravenously every 12 hours) with a saline control in patients with severe preeclampsia. The Student t and chi(2) tests were used for data analysis, with P < .05 considered significant.

RESULTS

Data from 157 patients (77 patients receiving dexamethasone, 80 patients receiving placebo) who were treated during 2000-2003 were analyzed. Demographics, diagnostic criteria, baseline laboratory values, and postpartum outcomes were similar between groups. Although dexamethasone-treated patients had fewer returns (6.5% compared with 11.3%) to the labor/delivery/recovery unit for uncontrolled hypertension than control patients, no significant differences were found in blood pressure, antihypertensive requirements, laboratory values, length of hospitalization, interval urine output at 48 hours postpartum, or major maternal morbidity. Two control patients developed hemolysis, elevated liver enzymes, low platelets syndrome.

CONCLUSION

Adjunctive use of intravenous dexamethasone for postpartum patients with severe preeclampsia does not reduce disease severity or duration.

LEVEL OF EVIDENCE

I.

Plasma volume and blood pressure regulation in hypertensive pregnancy

BACKGROUND

Pre-eclampsia is a multisystem disorder, peculiar to and frequent in human pregnancy. It remains a leading cause of maternal and neonatal morbidity and mortality. Hemodynamic disturbances are the most prominent features of the syndrome.

PURPOSE

To provide an overview of plasma volume regulation and blood pressure control mechanisms outside pregnancy, and of the changes in normal pregnancies and in pregnancies complicated by hypertensive disorders. Furthermore, to discuss the rationale of several hemodynamic interventions.

RESULTS

In normal pregnancy, large cardiovascular changes take place. A generalized fall in vascular tone by systemic vasorelaxation causes increased blood volume, heart rate and cardiac output. In the preclinical phase, differences have been observed between normal and hypertensive pregnancies in the function of the autonomic nervous system, cardiac output and plasma volume, the volume remaining at the non-pregnant level. In the clinical phase of pre-eclampsia the typical case picture is one of a vasoconstrictive state with low plasma volume and cardiac output, high blood pressure and systemic vascular resistance in combination with signs of organ damage [proteinuria, hemolysis elevated liver enzymes low platelets (HELLP) syndrome]. Hemodynamic management is necessary in severe disease to prevent maternal complications. Management primarily focuses on pharmacological treatment of blood pressure. Clinicians make educated choices from a limited array of available drugs: beta-receptor antagonists, nifedipine, dihydralazine, methyldopa or ketanserine. Other drugs have restricted use in pregnancy. Management of low circulating volume with plasma expanders remains a subject of controversy.

Pregnancy-induced sympathetic overactivity: a precursor of preeclampsia

BACKGROUND

Preeclampsia has been shown to constitute a state of sympathetic overactivity. However, it remains unclear if the sympathetic activity precedes preeclampsia or represents only a secondary phenomenon. To further investigate this issue, we performed a prospective study in pregnant women considered to be at increased risk for preeclampsia owing to preeclampsia during a preceding pregnancy.

MATERIALS AND METHODS

Twenty-two women with a history of preeclampsia were longitudinally studied on three occasions: twice during pregnancy (M1: 22 +/- 4, M2: 33 +/- 5 weeks) and once postpartum (M3: 26 +/- 6 weeks postpartum). We measured muscle sympathetic nerve activity (MSNA), forearm blood flow, and blood pressure at rest and during reactive hyperaemia after forearm occlusion.

RESULTS

At M1 and M2, none of the subjects was hypertensive, however, muscle sympathetic nerve activity levels were significantly augmented, compared with their postpartum values (M1: 21 +/- 9, M2: 29 +/- 14, M3: 9 +/- 5 bursts min(-1); P < 0.05). Forearm vascular resistance did not significantly change from M1 through M3 (M1: 16 +/- 9, M2: 15 +/- 7, M3: 16 +/- 7 U; P = NS). Gestational muscle sympathetic nerve activity values did not differ significantly among the subjects with subsequent preeclampsia compared with those who remained normotensive [with preeclampsia (n = 6): M1: 21 +/- 5, M2: 27 +/- 6, M3: 7 +/- 4 bursts min(-1); without preeclampsia (n = 16): M1: 21 +/- 11, M2: 30 +/- 16, M3: 9 +/- 6 bursts min(-1); P = NS].

CONCLUSION

Invariably, all women at risk for preeclampisa showed a pregnancy-induced increase in MSNA (pregnancy-induced sympathetic overactivity, PISO), which normalized after delivery. Most importantly, PISO is not necessarily associated with peripheral vasoconstriction and hypertension. Furthermore, only a subset of patients developed preeclampsia later on. Therefore, we hypothesize that PISO constitutes a precursor of preeclampsia which is physiologically compensated for by vasodilating mechanisms, leading to preeclampsia only when they fail.