The relationship between brachial artery flow-mediated dilatation, high sensitivity C-reactive protein, and uterine artery doppler velocimetry in women with pre-eclampsia

High dietary salt intake attenuates nitric oxide mediated endothelium-dependent vasodilation and increases oxidative stress in pregnancy

OBJECTIVE

This study aimed to investigate the impact of dietary salt intake during normal pregnancy on maternal microvascular and macrovascular endothelium-dependent reactivity and oxidative stress level.

MATERIALS AND METHODS

In this cross-sectional study, based on their 24-h urinary sodium excretion, pregnant women (37-40 weeks of gestation) were divided into three groups: normal salt (<5.75 g/day, N  = 12), high salt (5.75-10.25 g/day, N  = 36), and very high salt (VHS;>10.25 g/day, N  = 17). Forearm skin microvascular reactivity in response to vascular occlusion, local heating (LTH) and iontophoresis of acetylcholine (AChID), as well as brachial artery flow mediated dilation (FMD) were measured. Serum nitric oxide, endocan, 8-iso-prostaglandin F2α (8-iso-PGF2α), thiobarbituric acid reactive substances (TBARS), and ferric-reducing ability of plasma assay were measured as biomarkers of endothelial function/activation and oxidative stress.

RESULTS

Brachial artery FMD, microvascular AChID, and LTH were significantly decreased in VHS compared with NS group, while LTH was also decreased in normal salt compared with high salt group. Nitric oxide was significantly decreased in both high salt and VHS groups compared with normal salt. Endocan, 8-iso-PGF2α, and TBARS were significantly increased in VHS compared with the normal salt group.

CONCLUSION

High dietary salt intake is associated with decreased nitric oxide mediated endothelium-dependent vasodilation in peripheral microcirculation and macrocirculation of healthy pregnant women due to increased oxidative stress.

Comparison of brachial artery flow-mediated dilatation, uterine artery Doppler, and umbilical artery Doppler measurements in obese and normal pregnant women

OBJECTIVE

In this study, we aimed to compare vascular function at trimesters 1, 2, and 3 between obese and normal pregnant women through brachial artery flow-mediated dilatation (FMD), uterine artery Doppler, and umbilical artery Doppler measurements.

METHODS

Pregnant women between the ages of 18 and 40 who presented to our clinic were included. Brachial artery FMD, uterine and umbilical artery Doppler, and clinical parameters of 40 obese pregnant women from each trimester between 11 and 14 weeks, 24 and 28 weeks, 37 and 40 weeks and control pregnant group in the same number and gestational week were examined.

RESULTS

In all three trimesters, the FMD value was lower in obese pregnant women compared to normal women with adequate weight (p < 0.001). In obese pregnant women, lower FMD values were observed in the second trimester compared to other trimesters (p = 0.011) Cut-off value of FMD below 14.35 in obese pregnant women was found to be associated with gestational diabetes mellitus. Uterine artery Doppler in obese pregnant women started to increase from the second trimester compared to normal women with adequate weight.

CONCLUSION

Obese pregnant women have endovascular dysfunction compared to normal pregnant women and this becomes evident from the second trimester.

Cross-modality and in-vivo validation of 4D flow MRI evaluation of uterine artery blood flow in human pregnancy

OBJECTIVES

Clinical assessment of uterine artery (UtA) hemodynamics is currently limited to Doppler ultrasound (US) velocimetry. We have demonstrated previously the feasibility of applying four-dimensional (4D) flow magnetic resonance imaging (MRI) to evaluate UtA hemodynamics during pregnancy, allowing flow quantification of the entire course of the vessel. In this study, we sought to further validate the physiological relevance of 4D flow MRI measurement of UtA blood flow by exploring its association with pregnancy outcome relative to US-based metrics.

METHODS

Recruited into this prospective, cross-sectional study were 87 women with a singleton pregnancy who underwent 4D flow MRI between May 2016 and April 2019 to measure the UtA pulsatility index (MRI-PI) and blood flow rate (MRI-flow, in mL/min). UtA-PI was also measured using US (US-PI). The primary outcome was a composite (COMP) of pre-eclampsia (PE) and/or small-for-gestational-age (SGA) neonate, and secondary outcomes were PE and SGA neonate individually. We assessed the ability of MRI-flow, MRI-PI and US-PI to distinguish between outcomes, and evaluated whether MRI-flow changed as gestation progressed.

RESULTS

Following 4D flow postprocessing and exclusions from the analysis, 74 women had 4D flow MRI data analyzed for both UtAs. Of these, 18 developed a COMP outcome: three developed PE only, 11 had a SGA neonate only and four had both. A comparison of the COMP group vs the no-COMP group found no differences in maternal age, body mass index, nulliparity, gravidity or race. For 66 of the 74 subjects, US data were also available. In these subjects, both median MRI-PI (0.95 vs 0.70; P < 0.01) and median US-PI (0.95 vs 0.73; P < 0.01) were significantly increased in subjects in the COMP group compared with those in the no-COMP group. The UtA blood-flow rate, as measured by MRI, did not increase significantly from the second to the third trimester (median flow (interquartile range (IQR)), 543 (419-698) vs 575 (440-746) mL/min; P = 0.77), but it was significantly lower overall in the COMP compared with the no-COMP group (median flow (IQR), 486 (366-598) vs 624 (457-749) mL/min; P = 0.04). The areas under the receiver-operating-characteristics curves for MRI-flow, MRI-PI and US-PI in predicting COMP were not significantly different (0.694, 0.737 and 0.731, respectively; P = 0.87).

CONCLUSIONS

4D flow MRI can yield physiological measures of UtA blood-flow rate and PI that are associated with adverse pregnancy outcome. This may open up new avenues in the future to expand the potential of this technique as a robust tool with which to evaluate UtA hemodynamics in pregnancy. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

A Systematic Review of Vascular Structure and Function in Pre-eclampsia: Non-invasive Assessment and Mechanistic Links

Hypertensive disorders of pregnancy, such as pre-eclampsia, are known to be independently associated with the development of premature cardiovascular disease (CVD) in women. In pre-eclampsia, the placenta secretes excess anti-angiogenic factors into the maternal circulation, leading to widespread endothelial damage, and inflammation. This endothelial damage is evidenced to persist beyond the acute illness. However, whether it is permanent and responsible for the elevated rates of premature CVD seen in this at-risk group remains unclear. A systematic review of the available literature with respect to vascular structure and function prior to, during and after a pregnancy complicated by pre-eclampsia was performed. Studies non-invasively assessing vascular structure using carotid intima-media thickness (CIMT), retinal microvasculature caliber, CT coronary angiogram, or coronary calcium scores were included. Vascular function was assessed using brachial flow-mediated dilation (FMD), pulse wave analysis (PWA), and peripheral arterial tonometry (PAT). In total 59 articles were included (13 CIMT, 5 CTCA/Ca score, five retinal microvasculature, 27 FMD, 7 PAT, and 14 PWV/PWA), consisting of prospective and retrospective cohort, and case-control studies. Change in vascular structure was evidenced with significant increases in CIMT by 73-180 μm greater than that of non-affected women. This is tempered by other studies reporting resolution of structural changes postpartum, highlighting the need for further research. Accelerated coronary calcification and plaque deposition was identified, with greater rates of increased calcium scores and subclinical coronary artery disease shown by CTCA in women with a history of pre-eclampsia at 30 years postpartum. Impaired endothelial function was consistently reported prior to, during and immediately after pregnancy as evidenced by differences in FMD of 1.7-12.2% less than non-affected women, an increase in PWV by 13.2-26%, and reduced retinal microvascular caliber and arterial elasticity indices. The evidence was less conclusive for the persistence of long-term endothelial dysfunction. Understanding the underlying mechanistic links between pre-eclampsia and CVD is a key step to identifying targeted therapies aimed at "repairing the endothelium" and attenuating risk. This review has highlighted the need for a greater understanding of vascular structure and function following pre-eclampsia through high quality studies with large sample sizes, particularly in the longer postpartum period when clinical CVD disease starts to manifest.

A Systematic Review of Vascular Structure and Function in Pre-eclampsia: Non-invasive Assessment and Mechanistic Links

Hypertensive disorders of pregnancy, such as pre-eclampsia, are known to be independently associated with the development of premature cardiovascular disease (CVD) in women. In pre-eclampsia, the placenta secretes excess anti-angiogenic factors into the maternal circulation, leading to widespread endothelial damage, and inflammation. This endothelial damage is evidenced to persist beyond the acute illness. However, whether it is permanent and responsible for the elevated rates of premature CVD seen in this at-risk group remains unclear. A systematic review of the available literature with respect to vascular structure and function prior to, during and after a pregnancy complicated by pre-eclampsia was performed. Studies non-invasively assessing vascular structure using carotid intima-media thickness (CIMT), retinal microvasculature caliber, CT coronary angiogram, or coronary calcium scores were included. Vascular function was assessed using brachial flow-mediated dilation (FMD), pulse wave analysis (PWA), and peripheral arterial tonometry (PAT). In total 59 articles were included (13 CIMT, 5 CTCA/Ca score, five retinal microvasculature, 27 FMD, 7 PAT, and 14 PWV/PWA), consisting of prospective and retrospective cohort, and case-control studies. Change in vascular structure was evidenced with significant increases in CIMT by 73–180 μm greater than that of non-affected women. This is tempered by other studies reporting resolution of structural changes postpartum, highlighting the need for further research. Accelerated coronary calcification and plaque deposition was identified, with greater rates of increased calcium scores and subclinical coronary artery disease shown by CTCA in women with a history of pre-eclampsia at 30 years postpartum. Impaired endothelial function was consistently reported prior to, during and immediately after pregnancy as evidenced by differences in FMD of 1.7–12.2% less than non-affected women, an increase in PWV by 13.2–26%, and reduced retinal microvascular caliber and arterial elasticity indices. The evidence was less conclusive for the persistence of long-term endothelial dysfunction. Understanding the underlying mechanistic links between pre-eclampsia and CVD is a key step to identifying targeted therapies aimed at “repairing the endothelium” and attenuating risk. This review has highlighted the need for a greater understanding of vascular structure and function following pre-eclampsia through high quality studies with large sample sizes, particularly in the longer postpartum period when clinical CVD disease starts to manifest.

Flow mediated dilatation of Taiwanese women with normal singleton pregnancies

OBJECTIVE

To determine the normal values of flow mediated dilatation (FMD) in Taiwanese women with normal singleton pregnancies for the early detection of preeclampsia.

MATERIALS AND METHODS

Data of women with normal singleton pregnancies seen at the Tri-Service General Hospital and Taiji Clinic between January 2014 and December 2015 were collected and analyzed. FMD was measured using high-resolution ultrasonography of the brachial artery for the assessment of endothelial function at the first and second trimester. The relationship between the FMD values and maternal gestational age was analyzed.

RESULTS

A total of 122 pregnant women were included in the study. Systole FMD values first and second trimester were 9.05 ± 3.72 and 10.93 ± 3.74, respectively; and the diastole were 9.24 ± 3.64 and 11.18 ± 3.93, respectively. FMD and gestational age were positively correlated (systole, p = 0.0175; diastole, p = 0.0149).

CONCLUSION

The normal values of FMD in Taiwanese women with normal singleton pregnancies were established, and data suggests that both systolic and diastolic FMD increase with gestational age. Because of the high failure rate, measurement of FMD may not be suitable as a routine clinical examination.

Pre-eclampsia: the Potential of GSNO Reductase Inhibitors

PURPOSE OF REVIEW

Pre-eclampsia remains a leading worldwide cause of maternal death and of perinatal morbidity. There remains no definitive treatment except delivery of the fetus.

RECENT FINDINGS

Recent insights into the cardiovascular changes that are evident prior to, during, and persist after pre-eclampsia have improved understanding of the underlying pathophysiology-disruption of normal endothelial function and decreased nitric oxide bioavailability. S-nitrosoglutathione (GSNO) is an endogenous S-nitrosothiol that acts as a NO pool and, by replenishing or preventing the breakdown of GSNO, endothelial dysfunction can be ameliorated. GSNO reductase inhibitors are a novel class of drug that can increase NO bioavailability. GSNO reductase inhibitors have demonstrated improvement of endothelial dysfunction in animal models, and in vivo human studies have shown them to be well tolerated. GSNOR inhibitors offer a potentially promising option for the management of pre-eclampsia.

Impaired Flow-Mediated Dilation Before, During, and After Preeclampsia: A Systematic Review and Meta-Analysis

Endothelial dysfunction is believed to play a critical role in preeclampsia; however, it is unclear whether this dysfunction precedes the pregnancy or is caused by pathophysiological events in early pregnancy. It is also unclear for how long vascular dysfunction may persist postpartum and whether it represents a mechanism linking preeclampsia with future cardiovascular disease. Our objective was to determine whether women with preeclampsia had worse vascular function compared with women who did not have preeclampsia by performing a systematic review and meta-analysis of studies that examined endothelial dysfunction using flow-mediated dilation. We included studies published before May 29, 2015, that examined flow-mediated dilation before, during, or after preeclampsia. Differences in flow-mediated dilation between study groups were evaluated by standardized mean differences. Out of 610 abstracts identified through PubMED, EMBASE, and Web of Science, 37 studies were eligible for the meta-analysis. When compared with women who did not have preeclampsia, women who had preeclampsia had lower flow-mediated dilation before the development of preeclampsia (≈20-29 weeks gestation), at the time of preeclampsia, and for 3 years postpartum, with the estimated magnitude of the effect ranging between 0.5 and 3 standard deviations. Similar effects were observed when the analysis was limited to studies that excluded women with chronic hypertension, smokers, or both. Vascular dysfunction predates preeclampsia and may contribute to its pathogenesis. Future studies should address whether vascular changes that persist after preeclamptic pregnancies may represent a mechanistic link with increased risk for future cardiovascular disease.

Elevated inflammatory markers in preeclamptic pregnancies, but no relation to systemic arterial stiffness

OBJECTIVES

To investigate if circulating markers of systemic and vascular inflammation are associated with systemic arterial properties at term and 6months post-partum in women with preeclampsia (PE) and normal pregnancy (NP).

STUDY DESIGN

Longitudinal, sampling at term and 6months post-partum in 34 women (32±6years) with PE and 61 women (32±5years) with NP.

MAIN OUTCOME MEASURES

Circulating markers related to systemic and vascular inflammation were measured by enzyme immune-assay. Systemic arterial properties were estimated by Doppler (transthoracic echocardiography) and calibrated right subclavian artery pulse traces.

RESULTS

CXCL16, soluble tumor necrosis factor receptor type 1 (sTNF-R1), monocyte chemoattractant peptide 1, pentraxin 3 and soluble vascular adhesion molecule 1 (sVCAM-1) were elevated at term in PE, and sTNF-R1 remained elevated 6months post partum compared to NP. However, apart from a negative correlation between mean arterial pressure and sTNF-R1 and sVCAM-1 at term, no associations between systemic and vascular inflammatory markers and systemic arterial properties as reflected by characteristic impedance and arterial elastance, representing proximal aortic stiffness and effective arterial elastance, were found at any time point.

CONCLUSIONS

Preeclamptic pregnancies are characterized by increased circulating levels of systemic and vascular inflammatory markers. However, these are not associated with systemic arterial properties at term or 6months post partum.

Flow-mediated dilation: can new approaches provide greater mechanistic insight into vascular dysfunction in preeclampsia and other diseases?

Endothelial dysfunction is a key feature of preeclampsia and may contribute to increased cardiovascular disease risk years after pregnancy. Flow-mediated dilation (FMD) is a non-invasive endothelial function test that predicts cardiovascular event risk. New protocols allow researchers to measure three components of the FMD response: FMD, low flow-mediated constriction, and shear stimulus. This review encourages researchers to think beyond "low FMD" by examining how these three components may provide additional insights into the mechanisms and location of vascular dysfunction. The review then examines what FMD studies reveal about vascular dysfunction in preeclampsia while highlighting opportunities to gain greater mechanistic insight from new protocols. Studies using traditional protocols show that FMD is low in mid-pregnancy prior to preeclampsia, at diagnosis, and for 3 years post-partum. However, FMD returns to normal by 10 years post-partum. Studies using new protocols are needed to gain more mechanistic insight.

[The age-related macular degeneration as a vascular disease/part of systemic vasculopathy: contributions to its pathogenesis]

The wall of blood vessels including those in choroids may be harmed by several repeated and/or prolonged mechanical, physical, chemical, microbiological, immunologic, and genetic impacts (risk factors), which may trigger a protracted response, the so-called host defense response. As a consequence, pathological changes resulting in vascular injury (e. g. atherosclerosis, age-related macular degeneration) may be evolved. Risk factors can also act directly on the endothelium through an increased production of reactive oxygen species promoting an endothelial activation, which leads to endothelial dysfunction, the onset of vascular disease. Thus, endothelial dysfunction is a link between the harmful stimulus and vascular injury; any kind of harmful stimuli may trigger the defensive chain that results in inflammation that may lead to vascular injury. It has been shown that even early age-related macular degeneration is associated with the presence of diffuse arterial disease and patients with early age-related macular degeneration demonstrate signs of systemic and retinal vascular alterations. Chronic inflammation, a feature of AMD, is tightly linked to diseases associated with ED: AMD is accompanied by a general inflammatory response, in the form of complement system activation, similar to that observed in degenerative vascular diseases such as atherosclerosis. All these facts indicate that age-related macular degeneration may be a vascular disease (or part of a systemic vasculopathy). This recognition could have therapeutic implications because restoration of endothelial dysfunction may prevent the development or improve vascular disease resulting in prevention or improvement of age-related macular degeneration as well.

Hypertension in pregnancy

Hypertensive disorders of pregnancy represent the second commonest cause of direct maternal death and complicate an estimated 5-10 % of pregnancies. Classification systems aim to separate hypertension similar to that seen outside pregnancy (chronic and gestational hypertension) from the potentially fatal pregnancy-specific conditions. Preeclampsia, HELLP syndrome, and eclampsia represent increasing severities of this disease spectrum. The American College of Obstetricians and Gynecologists' 2013 guidelines no longer require proteinuria as a diagnostic criterion, because of its variable appearance in the disease spectrum. The cause involves inadequate cytotrophoblastic invasion of the myometrium, resulting in placental hypoperfusion and diffuse maternal endothelial dysfunction. Changes in angiogenic and antiangiogentic peptide profiles precede the onset of clinical preeclampsia. Women with preeclampsia should be closely monitored and receive magnesium sulfate intravenously if severe features, HELLP syndrome, or eclampsia occur. Definitive therapy is delivery of the fetus. Hypertension in pregnancy increases future maternal risk of hypertension and cardiovascular disorders.

Endothelial function progressively deteriorates during normal pregnancy

OBJECTIVE

To elucidate changes in endothelial function throughout the gestational period in normal pregnancy and its relationship with plasma soluble fms-like tyrosine kinase-1 (sFlt-1) levels.

METHODS

Endothelial function was evaluated by reactive hyperemia index (RHI) using Endo-PAT2000 and plasma sFlt-1 levels were measured simultaneously by ELISA.

RESULTS

RHI gradually deteriorated with increasing gestational age. Plasma sFlt-1 levels exhibited a gradual increase at late pregnancy and were inversely correlated with RHI.

CONCLUSION

Maternal endothelial function gradually deteriorates with increasing gestational age and there is an inverse correlation between endothelial function and plasma sFlt-1 levels in normal pregnancy.

Beyond the placental bed: placental and systemic determinants of the uterine artery Doppler waveform

The uterine artery Doppler waveform has been extensively investigated, though its widespread clinical use as a predictor of adverse pregnancy outcome remains under debate. The determinants of the waveform have classically been ascribed to transformation of the spiral arteries and the development of a low resistance uteroplacental circulation, failure of which predisposes to pre-eclampsia, fetal growth restriction and other adverse outcomes. It has become increasingly evident that although spiral artery transformation determines in some part the characteristics of the Doppler waveform, factors pertaining to maternal vascular and endothelial function are also important.

Hypertension in pregnancy

Hypertension in pregnancy is diagnosed on systolic blood pressure greater than or equal to 140 mm Hg and/or diastolic greater than or equal to 90 mm Hg. The classification systems separate chronic and gestational hypertension from preeclampsia. Significant uncertainty regarding optimal management is reflected in the differing major international society recommendations. Blood pressure treatment is designed to minimize maternal end-organ damage. Methyldopa, labetalol, hydralazine, and nifedipine are oral options; angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists are contraindicated. Women with preeclampsia should be closely monitored and receive intravenous magnesium sulfate.