Microvascular remodelling in preeclampsia: quantifying capillary rarefaction accurately and independently predicts preeclampsia

Nailfold Video Capillaroscopy in Pregnant Women With and Without Cardiovascular Risk Factors

Objective

To evaluate microvasculature in pregnant women with and without cardiovascular risk factors.

Design

Cross-sectional, observational study.

Population

Women were recruited at the outpatient clinic for high risk prenatal care. Out of a total of 345 women assessed at first and/or second and/or third trimester, 169 women without and 176 with cardiovascular risk factors were included.

Methods

Nailfold video capillaroscopy (NVC) measurements were performed at magnification of 200x at all fingers except thumbs. Images were stored for offline measurement of capillary density (CDe) and capillary diameters (CDi). Maternal anthropometrics, obstetric, and medical history were used for categorization in low and high cardiovascular risk. Comparison between groups and trimesters, with respect to pregnancy outcome, was performed using linear mixed model analysis.

Results

Women with a high risk cardiovascular profile show higher CDe, regardless of pregnancy outcome. CDi drops during pregnancy, with lowest CDi in third trimester in patients with preeclampsia. Capillary bed (CB), as a composite of CDe and CDi, is stable during pregnancy in women with low risk cardiovascular profile. In women with high risk cardiovascular profile, CB drops from the first to the second trimester, regardless of pregnancy outcome. Only in women with pre-eclampsia, the CB is lower in the third trimester as compared to the first trimester.

There is an inverse association between CDe and mean arterial pressure (MAP) in women with high cardiovascular risk and pre-eclampsia.

Conclusion

Microcirculation is altered during the course of pregnancy and microcirculatory behavior is different in patients with low and high cardiovascular risk profile, as well as in patients with preeclampsia.

Research on the influence of prenatal exercises on anthropometric and vascular parameters in pregnant women

Introduction/Objective. The frequency of a sedentary lifestyle during pregnancy increases. This contributes to gestational weight gain and has a negative impact on health. This study researched the impact of prenatal exercise on gestational weight gain, blood pressure, and microcirculation in pregnant women who exercised and those who did not exercise. Methods. The study included seventy pregnant women with a normal pregnancy, who attended a psychophysical preparation program for childbirth for eight weeks. The control group (n=35) attended theoretical classes on childbirth, and the experimental group (n=35) attended prenatal exercises as well. Gestational weight gain, blood pressure, and nailfold capillary density were determined and compared between the two groups. Results. Gestational weight gain of 19.94 kg in non-exercising pregnant women was significantly greater than the gestational weight gain of 11.65 kg in pregnant women who exercised. Pregnant women who did not exercise had an increase in systolic (by 15.56 mmHg) and diastolic pressure (by 16.08 mmHg), which is significantly higher compared to pregnant women who exercised. In this group, systolic pressure increased by 2.5 mmHg, while diastolic did not change. A significant difference in the nailfold capillary density at the end of the prenatal program has not been determined. Conclusion. Prenatal exercise of moderate-intensity has a positive effect on gestational weight gain and the level of blood pressure in pregnant women. The nailfold capillary density has not differed significantly after the prenatal program in pregnant women who have exercised and in those who have not.

The Nine Month Stress Test: Pregnancy and Exercise - Similarities and Interactions

Of all physiological systems, the cardiovascular system takes on the most profound adaptation in pregnancy to support fetal growth and development. The adaptations that arise are systemic and involve structural and functional changes that can be observed at the cerebral, central, peripheral, and microvascular beds. This includes, although is not limited to increased heart rate, stroke volume and cardiac output with negligible change to blood pressure, reductions in vascular resistance and cerebral blood flow velocity, systemic artery enlargement, enhanced endothelial function. All of this takes place to accommodate blood volume expansion and ensure adequate fetal and maternal oxygen delivery. In some instances, the demand placed on the vasculature can manifest as cardiovascular maladaptation and thus, cardiovascular complications can arise. Exercise is recommended in pregnancy because of its powerful ability to reduce the incidence and severity of cardiovascular complications in pregnancy. However, the mechanism by which it acts is poorly understood. The first aim of this review is to describe the systemic adaptations that take place in pregnancy. Secondly, this review aims to describe the influence of exercise on these systemic adaptations. It is anticipated that this review can comprehensively capture the extent of knowledge in this area while identifying areas that warrant further investigation.

Prediction models for preeclampsia: A systematic review

BACKGROUND

Preeclampsia is a disease specific to pregnancy that can cause severe maternal and foetal morbidity and mortality. Early identification of women at higher risk for preeclampsia could potentially aid early prevention and treatment. Although a plethora of preeclampsia prediction models have been developed in recent years, individualised prediction of preeclampsia is rarely used in clinical practice.

OBJECTIVES

The objective of this systematic review was to provide an overview of studies on preeclampsia prediction.

STUDY DESIGN

Relevant research papers were identified through a MEDLINE search up to 1 January 2017. Prognostic studies on the prediction of preeclampsia or preeclampsia-related disorders were included. Quality screening was performed with the Quality in Prognostic Studies (QUIPS) tool.

RESULTS

Sixty-eight prediction models from 70 studies with 425,125 participants were selected for further review. The number of participants varied and the gestational age at prediction varied widely across studies. The most frequently used predictors were medical history, body mass index, blood pressure, parity, uterine artery pulsatility index, and maternal age. The type of predictor (maternal characteristics, ultrasound markers and/or biomarkers) was not clearly associated with model discrimination. Few prediction studies were internally (4%) or externally (6%) validated.

CONCLUSIONS

To date, multiple and widely varying models for preeclampsia prediction have been developed, some yielding promising results. The high degree of between-study heterogeneity impedes selection of the best model, or an aggregated analysis of prognostic models. Before multivariable preeclampsia prediction can be clinically implemented universally, further validation and calibration of well-performing prediction models is needed.

Sidestream Dark Field Imaging of the Microcirculation to Assess Preeclampsia Microvascular Dysfunction

Background

Development of predictive models of preeclampsia has only yielded modest results. We hypothesized that impaired indices of microcirculatory function could be detected using sidestream dark field imaging. The objective of this study was to examine microvascular function in women at high risk for preeclampsia at mid-gestation.

Methods

Women between 16 and 22 weeks of gestation were screened for eligibility. Patients were recruited if they met eligibility criteria indicating high risk for preeclampsia. Investigators performed non-invasive sidestream dark field imaging of the sublingual microcirculation. Images were analyzed to determine microcirculatory parameters (microvascular flow index, perfused vessel density, total vessel density, and proportion of perfused vessels). After delivery, charts were reviewed to determine if they developed gestational hypertension, preeclampsia or severe preeclampsia.

Results

Twelve of 66 participants (18.2%) developed preeclampsia or severe preeclampsia during the course of their pregnancy. Microvascular flow index was not significantly different between participants with normal pregnancies and participants with preeclampsia or severe preeclampsia (2.75 ± 0.38 vs. 2.80 ± 0.34, respectively; P = 0.459). Similarly, there were no significant differences between groups in the remaining microcirculatory parameters.

Conclusions

Sidestream dark field imaging of the sublingual microcirculation may remain an appropriate tool to identify women at risk for preeclampsia, albeit later in pregnancy.

Capillaroscopy in pregnancy

INTRODUCTION

In pregnancy, the circulatory system undergoes profound adaptation to meet the requirements in blood supply for the mother and the foetus. With the development of new techniques, research of the microcirculatory changes becomes available. This expert review gives an overview of the current evidence in the field of capillaroscopy. The aim of this review is to summarize the available techniques in the assessment of the microcirculation during pregnancy. Areas covered: A literature search was done, using the strategy: (microcirculation OR capillary OR capillaries OR capillaroscopy) AND pregnancy AND (density OR diameter OR count OR number). All articles were screened and all English articles were considered, when containing information regarding imaging of capillaries. Only structural parameters were considered, functional parameters (e.g. flow velocity) were not considered. Reference search was undertaken after reading full text articles. Articles from reference search underwent same selection criteria as in the primary search. Expert commentary: With growing insight in microcirculatory changes in hypertensive pregnancy conditions, the field of capillaroscopy will become more important in future. The technique is feasible and easy to use in clinical practice as well as in research setting. The first step, necessary to perform further research in this field in future, is to get consensus in technique to perform capillaroscopy and in methods to quantitatively and qualitatively describe the observed changes in microvasculature.

The influence of prenatal exercise and pre-eclampsia on maternal vascular function

During healthy pregnancy, the cardiovascular system undergoes diverse adaptations to support adequate transfer of oxygen and nutrients from mother to fetus. In order to accommodate the large expansion of blood volume and associated cardiac output, the structure, mechanics, and function of the arteries are altered. Specifically, in healthy pregnancy there is a remodeling of arteries (increased angiogenesis and vasodilation), a generalized reduction in arterial stiffness (increased compliance), and an enhanced endothelial function. The development of pregnancy complications, specifically pre-eclampsia, is associated with poor placentation (decreased angiogenesis), increased arterial stiffness, and vascular dysfunction (reduced endothelial function). Many of the positive adaptations that occur in healthy pregnancy are enhanced in response to chronic exercise. Specifically, placental angiogenesis and endothelial function have been shown to improve to a greater extent in women who are active during their pregnancy compared with those who are not. Prenatal exercise may be important in helping to reduce the risk of vascular dysfunction in pregnancy. However, our knowledge of the vascular adaptations resulting from maternal exercise is limited. This review highlights maternal vascular adaptations occurring during healthy pregnancy, and contrasts the vascular maladaptation associated with pre-eclampsia. Finally, we discuss the role of prenatal exercise on vascular function in the potential prevention of vascular complications associated with pre-eclampsia.

Effects of non-supervised low intensity aerobic excise training on the microvascular endothelial function of patients with type 1 diabetes: a non-pharmacological interventional study

Background

The aim of the present study was to evaluate changes in microvascular density and reactivity in patients with type 1 diabetes (T1D) resulting from low intensity chronic exercise training.

Methods

This study included 22 (34 ± 7 years) consecutive outpatients with T1D and disease duration > 6 years. We used intravital video-microscopy to measure basal skin capillary density and capillary recruitment using post-occlusive reactive hyperemia (PORH) in the dorsum of the fingers. Endothelium-dependent and -independent vasodilation of the skin microcirculation was evaluated in the forearm with a laser Doppler flow monitoring (LDF) system in combination with acetylcholine and sodium nitroprusside iontophoresis, PORH and local thermal hyperemia.

Results

The basal mean capillary density (MCD) after exercise training was significantly higher than before exercise (134 ± 25 vs. 119 ± 19 capillaries/mm², respectively; P = 0.0013). MCD during PORH was also higher after exercise (140 ± 26 vs. 121 ± 24 capillaries/mm², respectively; P < 0.0001). Endothelium-dependent capillary recruitment during PORH was also significantly higher after exercise (140 ± 26 vs. 134 ± 25 capillaries/mm², respectively; P < 0.0012). There were no significant changes in skin microvascular reactivity after exercise as investigated using LDF.

Conclusions

Our results showed that low intensity aerobic exercise, performed four times per week for 12 weeks by patients with T1D, induces significant increases in microvascular density and endothelial-dependent capillary reactivity.

Trial registration

ClinicalTrials.gov NCT02441504. Registered 7 May 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0191-9) contains supplementary material, which is available to authorized users.

Reduced uterine perfusion pressure decreases functional capillary density in skeletal muscle

The purpose of this study was to examine the functional and structural capillary density in the reduced uterine perfusion pressure (RUPP) model, which when performed during pregnancy is an established animal model of preeclampsia. We hypothesized that the RUPP model would be associated with capillary rarefaction and impaired capillary perfusion, which would be more pronounced in the pregnant state. Female Sprague-Dawley rats (n = 32) were randomized to nonpregnancy (Nonpregnant) or breeding (Pregnant) at 12 wk of age and again to RUPP or SHAM surgeries on gestational day (GD) 14 (or equivalent age in nonpregnant rats). On GD 20 (or equivalent), capillary structure and perfusion of the extensor digitorum longus were imaged using digital intravital video microscopy. Functional videos were analyzed by a blinded observer to measure capillary density, expressed as capillaries per millimeter intersecting three staggered reference lines (200 μm). Flow was scored as the percentage of capillaries having 1) continuous, 2) intermittent, or 3) stopped flow. Total capillary density was not different between groups. There was a main effect of RUPP surgery resulting in decreased continuous flow vessels (P < 0.01) and increased stopped flow (P < 0.01), which was driven by differences between pregnant animals (Continuous flow: pregnant SHAM 80.1 ± 7.8% vs. pregnant RUPP 67.8 ± 11.2%, P < 0.05) (Stopped flow: pregnant SHAM 8.7 ± 3.2% vs. pregnant RUPP 17.9 ± 5.7%, P < 0.01). Our results demonstrate that the RUPP surgery is associated with a decrease in functional capillary density in skeletal muscle that is more pronounced in the pregnant state, which may contribute to the vascular pathophysiology observed in preeclampsia.

Large scale aggregate microarray analysis reveals three distinct molecular subclasses of human preeclampsia

Background

Preeclampsia (PE) is a life-threatening hypertensive pathology of pregnancy affecting 3–5% of all pregnancies. To date, PE has no cure, early detection markers, or effective treatments short of the removal of what is thought to be the causative organ, the placenta, which may necessitate a preterm delivery. Additionally, numerous small placental microarray studies attempting to identify “PE-specific” genes have yielded inconsistent results. We therefore hypothesize that preeclampsia is a multifactorial disease encompassing several pathology subclasses, and that large cohort placental gene expression analysis will reveal these groups.

Results

To address our hypothesis, we utilized known bioinformatic methods to aggregate 7 microarray data sets across multiple platforms in order to generate a large data set of 173 patient samples, including 77 with preeclampsia. Unsupervised clustering of these patient samples revealed three distinct molecular subclasses of PE. This included a “canonical” PE subclass demonstrating elevated expression of known PE markers and genes associated with poor oxygenation and increased secretion, as well as two other subclasses potentially representing a poor maternal response to pregnancy and an immunological presentation of preeclampsia.

Conclusion

Our analysis sheds new light on the heterogeneity of PE patients, and offers up additional avenues for future investigation. Hopefully, our subclassification of preeclampsia based on molecular diversity will finally lead to the development of robust diagnostics and patient-based treatments for this disorder.