Prepregnancy Low-Plasma Volume and Predisposition to Preeclampsia and Fetal Growth Restriction

Maternal Hemodynamics from Preconception to Delivery: Research and Potential Diagnostic and Therapeutic Implications: Position Statement by Italian Association of Preeclampsia and Italian Society of Perinatal Medicine

OBJECTIVE

 The Italian Association of Preeclampsia (AIPE) and the Italian Society of Perinatal Medicine (SIMP) developed clinical questions on maternal hemodynamics state of the art.

STUDY DESIGN

 AIPE and SIMP experts were divided in small groups and were invited to propose an overview of the existing literature on specific topics related to the clinical questions proposed, developing, wherever possible, clinical and/or research recommendations based on available evidence, expert opinion, and clinical importance. Draft recommendations with a clinical rationale were submitted to 8th AIPE and SIMP Consensus Expert Panel for consideration and approval, with at least 75% agreement required for individual recommendations to be included in the final version.

RESULTS

 More and more evidence in literature underlines the relationship between maternal and fetal hemodynamics, as well as the relationship between maternal cardiovascular profile and fetal-maternal adverse outcomes such as fetal growth restriction and hypertensive disorders of pregnancy. Experts agreed on proposing a classification of pregnancy hypertension, complications, and cardiovascular states based on three different hemodynamic profiles depending on total peripheral vascular resistance values: hypodynamic (>1,300 dynes·s·cm-5), normo-dynamic, and hyperdynamic (<800 dynes·s·cm-5) circulation. This differentiation implies different therapeutical strategies, based drugs' characteristics, and maternal cardiovascular profile. Finally, the cardiovascular characteristics of the women may be useful for a rational approach to an appropriate follow-up, due to the increased cardiovascular risk later in life.

CONCLUSION

 Although the evidence might not be conclusive, given the lack of large randomized trials, maternal hemodynamics might have great importance in helping clinicians in understanding the pathophysiology and chose a rational treatment of patients with or at risk for pregnancy complications.

KEY POINTS

· Altered maternal hemodynamics is associated to fetal growth restriction.. · Altered maternal hemodynamics is associated to complicated hypertensive disorders of pregnancy.. · Maternal hemodynamics might help choosing a rational treatment during hypertensive disorders..

Remote multimodality monitoring of maternal physiology from the first trimester to postpartum period: study results

OBJECTIVES

Current antenatal care largely relies on widely spaced appointments, hence only a fraction of the pregnancy period is subject to monitoring. Continuous monitoring of physiological parameters could represent a paradigm shift in obstetric care. Here, we analyse the data from daily home monitoring in pregnancy and consider the implications of this approach for tracking pregnancy health.

METHODS

Prospective feasibility study of continuous home monitoring of blood pressure, weight, heart rate, sleep and activity patterns from the first trimester to 6 weeks postpartum.

RESULTS

Fourteen out of 24 women completed the study (58%). Compared to early pregnancy [week 13, median heart rate (HR) 72/min, interquartile range (IQR) 12.8], heart rate increased by week 35 (HR 78/min, IQR 16.6; P  = 0.041) and fell postpartum (HR 66/min, IQR 11.5, P  = 0.021). Both systolic and diastolic blood pressure were lower at mid-gestation (week 20: SBP 103 mmHg, IQR 6.6; DPB 63 mmHg, IQR 5.3 P  = 0.005 and P  = 0.045, respectively) compared to early pregnancy (week 13, SBP 107 mmHg, IQR 12.4; DPB 67 mmHg, IQR 7.1). Weight increased during pregnancy between each time period analyzed, starting from week 15. Smartwatch recordings indicated that activity increased in the prepartum period, while deep sleep declined as pregnancy progressed.

CONCLUSION

Home monitoring tracks individual physiological responses to pregnancy in high resolution that routine clinic visits cannot. Changes in the study protocol suggested by the study participants may improve compliance for future studies, which was particularly low in the postpartum period. Future work will investigate whether distinct adaptative patterns predate obstetric complications, or can predict long-term maternal cardiovascular health.

The feasibility of multimodality remote monitoring of maternal physiology during pregnancy

To ascertain whether remote multimodality cardiovascular monitoring of health in pregnancy is feasible, 24 participants were asked to daily monitor body weight, heart rate, blood pressure, activity levels, and sleep patterns. Study participants took on average 4.3 (standard deviation = 2.20) home recordings of each modality per week across the 3 trimesters and 2.0 postpartum (standard deviation = 2.41), out of a recommended maximum of 7. Thus, remote monitoring indicative of cardiovascular health throughout and after pregnancy might be feasible for routine clinical care or within the context of a research study.

Maternal Low Volume Circulation Relates to Normotensive and Preeclamptic Fetal Growth Restriction

This narrative review summarizes current evidence on the association between maternal low volume circulation and poor fetal growth. Though much work has been devoted to the study of cardiac output and peripheral vascular resistance, a low intravascular volume may explain why high vascular resistance causes hypertension in women with preeclampsia (PE) that is associated with fetal growth restriction (FGR) and, at the same time, presents with normotension in FGR itself. Normotensive women with small for gestational age babies show normal gestational blood volume expansion superimposed upon a constitutionally low intravascular volume. Early onset preeclampsia (EPE; occurring before 32 weeks) is commonly associated with FGR, and poor plasma volume expandability may already be present before conception, thus preceding gestational volume expansion. Experimentally induced low plasma volume in rodents predisposes to poor fetal growth and interventions that enhance plasma volume expansion in FGR have shown beneficial effects on intrauterine fetal condition, prolongation of gestation and birth weight. This review makes the case for elevating the maternal intravascular volume with physical exercise with or without Nitric Oxide Donors in FGR and EPE, and evaluating its role as a potential target for prevention and/or management of these conditions.

Maternal Vascular Lesions in the Placenta Predict Vascular Impairments a Decade After Delivery

Women with adverse pregnancy outcomes later experience excess hypertension and cardiovascular disease, but how the events are linked is unknown. Examination of the placenta may provide clues to vascular impairments after delivery. Maternal vascular malperfusion lesions (MVMs) were abstracted from clinical reports, validated and characterized using clinical guidelines and severity score. A total of 492 women (170 with MVMs and 322 without MVMs) participated in a study visit 8 to 10 years after delivery to assess blood pressure, cardiometabolic factors, and sublingual microvascular features using sidestream dark field imaging. Covariates included age, race, adverse pregnancy outcomes (preeclampsia, small for gestational age, and preterm birth), and health behaviors. Women with versus without MVM had a distinct sublingual microvascular profile comprised of (1) lower microvascular density (-410 μm/mm², P=0.015), (2) higher red blood cell filling as a marker of perfusion (2%, P=0.004), and (3) smaller perfused boundary region (-0.07 µm, P=0.025) as a measure of glycocalyx integrity, adjusted for covariates including adverse pregnancy outcomes. Women with MVM also had higher adjusted diastolic blood pressure (+2.6 mm Hg, P=0.021), total and LDL (low-density lipoprotein)-cholesterol (+11.2 mg/dL, P=0.016; +8.7 mg/dL, P=0.031). MVM associations with subsequent cardiovascular measures did not vary by type of adverse pregnancy outcome, except among women with preterm births where blood pressure was higher only among those with MVM. Results were similar when evaluated as MVM severity. A decade after delivery, women with placental vascular lesions had an adverse cardiovascular profile comprised of microvascular rarefaction, higher blood pressure and more atherogenic lipids. Placental histopathology may reveal a woman's early trajectory toward subsequent vascular disease.

Fetal Growth Restriction: Does an Integrated Maternal Hemodynamic-Placental Model Fit Better?

In recent years, a growing interest has arisen regarding the possible relationship between adverse pregnancy outcomes (APOs) and inadequate maternal hemodynamic adaptations to the pregnancy. A possible association between "placental syndromes," such as preeclampsia (PE) and fetal growth restriction (FGR), and subsequent maternal cardiovascular diseases (CVD) later in life has been reported. The two subtypes of FGR show different pathogenetic and clinical features. Defective placentation, due to a poor trophoblastic invasion of the maternal spiral arteries, is believed to play a central role in the pathogenesis of early-onset PE and FGR. Since placental functioning is dependent on the maternal cardiovascular system, a pre-existent or subsequent cardiovascular impairment may play a key role in the pathogenesis of early-onset FGR. Late FGR does not seem to be determined by a primary abnormal placentation in the first trimester. The pathological pathway of late-onset FGR may be due to a primary maternal cardiovascular maladaptation: CV system shows a flat profile and remains similar to those of non-pregnant women. Since the second trimester, when the placenta is already developed and increases its functional request, a hypovolemic state could lead to placental hypoperfusion and to an altered maturation of the placental villous tree and therefore to an altered fetal growth. Thus, this review focalizes on the possible relationship between maternal cardiac function and placentation in the development of both early and late-onset FGR. A better understanding of maternal hemodynamics in pregnancies complicated by FGR could bring various benefits in clinical practice, improving screening and therapeutic tools.

Low Plasma Volume and Increased Pressure Load Relate to Concentric Left Ventricular Remodeling After Preeclampsia: A Longitudinal Study

Background During uncomplicated pregnancy, left ventricular remodeling occurs in an eccentric way. In contrast, during preeclamptic gestation, the left ventricle hypertrophies concentrically, concurrent with loss in circulatory volume and increased blood pressure. Concentric cardiac structure persists in a substantial proportion of women and may be associated with pressure and volume load after preeclampsia. We hypothesize that low volume load, as indicated by plasma volume (PV) after preeclampsia and increased pressure load, is associated with remote concentric remodeling. Methods and Results In this longitudinal cohort study, we included 100 formerly preeclamptic women. Two visits were performed: at 0.8 years postpartum and at 4.8 years postpartum. During visit 1, we measured blood pressure and PV (I125 dilution technique, low PV ≤48 mL/kg lean body mass). During the second visit, we assessed cardiac geometry by cardiac ultrasound. Concentric remodeling was defined as relative wall thickness >0.42 and left ventricular mass index ≤95 g/m2. We adjusted multivariable analysis for primiparity, systolic blood pressure, PV mL/kg lean body mass, and antihypertensive medication at visit 1. Low PV is associated with remote concentric remodeling (odds ratio [OR], 4.37; 95% CI, 1.06-17.40; and adjusted OR, 4.67; 95% CI, 1.02-21.42). Arterial pressure load (systolic, diastolic, and mean arterial pressure) is also associated with development of concentric remodeling (OR, 1.15 [95% CI, 0.99-1.35]; OR, 1.24 [95% CI, 0.98-1.58]; and OR, 1.20 [95% CI, 0.98-1.47], respectively). Conclusions In former preeclamptic women, development toward left ventricular concentric remodeling is associated with low volume load and increased pressure load.

Plasma volume variation across the menstrual cycle among healthy women of reproductive age: A prospective cohort study

Increases in reproductive hormones like estrogen, play an important role in the remarkable increases in plasma volume observed in pregnancy. Accurate estimates of plasma volume expansion during pregnancy depend on correctly timing and measuring plasma volume in nonpregnant women. However, to date, there is no consensus on the pattern of plasma volume across the menstrual cycle. We prospectively measured plasma volume in 45 women across a single menstrual cycle. A urine-based fertility monitor was used to time three clinic visits to distinct points in the menstrual cycle: the early follicular phase (~day 2), periovulation (~day 12), and the mid-point of the luteal phase (~day 21)-based on a 28-day cycle length. Healthy women aged 18-41 years with regular menstrual cycles and a healthy body weight were enrolled in the study. At each visit, blood samples were collected before and after injection of 0.25 mg/kg body weight of indocyanine green dye (ICG). Pre- and post-ICG injection plasma samples were used to measure plasma volume. Preinjection samples were used to measure ovarian hormones and plasma osmolality. Mean plasma volume was highest during the early follicular phase (2,276 ± 478 ml); it declined to 2,232 ± 509 ml by the late follicular phase and to 2,228 ± 502 ml by the midluteal phase. This study found that overall variations in plasma volume are small across the menstrual cycle. Therefore, in clinical practice and research, the menstrual cycle phase may not be an important consideration when evaluating plasma volume among women of reproductive age.

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

BACKGROUND

Plasma volume expansion is an important physiologic change across gestation. High or low expansion has been related to adverse pregnancy outcomes, yet there is a limited understanding of normal/healthy plasma volume expansion. We aimed to evaluate the pattern of plasma volume expansion across healthy pregnancies from longitudinal studies.

METHODS

We conducted a systematic review and meta-analysis to identify original studies that measured plasma volume in singleton pregnancies of healthy women. Specifically, we included studies that measured plasma volume at least two times across gestation and one time before or after pregnancy in the same women. PubMed, Web of Science, Cochrane, CINAHL, and clinicaltrials.gov databases were searched from the beginning of each database to February 2019. We combined data across studies using a random effects model.

RESULTS

Ten observational studies with a total of 347 pregnancies were eligible. Plasma volume increased by 6% (95% CI 3-9) in the first trimester compared to the nonpregnant state. In the second trimester, plasma volume was increased by 18% (95% CI 12-24) in gestational weeks 14-20 and 29% (95% CI 21-36) in weeks 21-27 above the nonpregnant state. In the third trimester, plasma volume was increased by 42% (95% CI 38-46) in weeks 28-34 and 48% (95% CI 44-51) in weeks 35-38. The highest rate of increase occurred in the first half of the second trimester. Included studies were rated from moderate to high quality; 7 out of 10 studies were conducted over 30 years ago.

CONCLUSIONS

In healthy pregnancies, plasma volume begins to expand in the first trimester, has the steepest rate of increase in the second trimester, and peaks late in the third trimester. The patterns observed from these studies may not reflect the current population, partly due to the changes in BMI over the last several decades. Additional longitudinal studies are needed to better characterize the range of normal plasma volume expansion across maternal characteristics.

An efficient method for measuring plasma volume using indocyanine green dye

Plasma volume (PV) can be an important marker of health status and may affect the interpretation of plasma biomarkers, but is rarely measured due to the complexity and time required. Indocyanine green (ICG) is a water-soluble tricarbocyanine dye with a circulatory half-life of 2–3 min, allowing for quick clearance and repeated use. It is used extensively in medical diagnostic tests including ophthalmologic imaging, liver function, and cardiac output, particularly in critical care. ICG has been validated for measuring PV in humans, however previous work has provided minimal published details or has focused on a single aspect of the method. We aimed to develop a detailed, optimal protocol for the use of ICG to measure PV in women of reproductive age. We combined best practices from other studies and optimized the protocol for efficiency.

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This method reduces the time from blood collection to PV determination to ˜2 h and the amount of plasma required to estimate PV to 2.5 mL (1.5 mL before ICG injection and 1.0 mL post-injection).

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Participant inconvenience is reduced by inserting an intravenous (IV) catheter in only one arm, not both arms.

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Five post-injection plasma samples (2–5 min after ICG bolus) are enough to accurately develop the decay curve for plasma ICG concentration and estimate PV by extrapolation.

Low Volume Circulation in Normotensive Women Pregnant with Neonates Small for Gestational Age

BACKGROUND

Pregnancies complicated with small for gestational age (SGA) neonates are reported with maternal circulatory maladaptations.

OBJECTIVES

We aimed to understand the pathophysiology of the maternal circulation in normotensive SGA pregnancies and to point out the trimestral differences from those with appropriate-to-large (non-SGA [NGA]) neonates.

METHODS

An observational study was conducted in 3 trimestral cohorts of normotensive pregnancies, categorized after birth according to neonatal birth weight percentile (BW%) as SGA (BW% ≤10, n = 158) or NGA (BW% > 10, n = 1,038). Standardized electrocardiogram-Doppler ultrasound, impedance cardiography, and bio-impedance were used to assess the maternal heart, arteries, veins, and fluid.

RESULTS

Diastolic blood pressure and mean arterial pressure were not significantly different, unless in the third trimester. In SGA compared to NGA pregnancies, total peripheral resistance (TPR) was higher and total arterial compliance, cardiac output (CO), and total body water (TBW) were lower throughout pregnancy. Venous return-enhancing functions were activated. In NGA but not SGA pregnancies, a positive correlation was found between BW% and CO + TBW and a negative correlation between BW% and TPR.

CONCLUSIONS

SGA pregnancies are characterized by lower maternal body fluid volume and CO, while normal blood pressures are maintained via increased TPR already from the first trimester onwards. Pregnancy-induced hemodynamic changes are superimposed on these characteristics.

Assessment of venous hemodynamics and volume homeostasis during pregnancy: recommendations of the International Working Group on Maternal Hemodynamics

Venous hemodynamics and volume homeostasis are important aspects of cardiovascular physiology. However, today their relevance is still very much underappreciated. Their most important role is maintenance and control of venous return and, as such, cardiac output. A high-flow/low-resistance circulation, remaining constant under physiological circumstances, is mandatory for an uncomplicated course of pregnancy. In this article, characteristics of normal and abnormal venous and volume regulating functions are discussed with respect to normal and pathologic outcomes of pregnancy, and current (non-invasive) methods to assess these functions are summarized. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Association Between Prepregnancy Cardiovascular Function and Subsequent Preeclampsia or Fetal Growth Restriction

Preeclampsia and fetal growth restriction during pregnancy are associated with increased risk of maternal cardiovascular disease later in life. It is unclear whether this association is causal or driven by similar antecedent risk factors. Clarification requires recruitment before conception which is methodologically difficult with high attrition rates and loss of outcome numbers to nonconception/miscarriage. Few prospective studies have, therefore, been adequately powered to address these questions. We recruited 530 healthy women (mean age: 35.0 years) intending to conceive and assessed cardiac output, cardiac index, stroke volume, total peripheral resistance, mean arterial pressure, and heart rate before pregnancy. Participants were followed to completion of subsequent pregnancy with repeat longitudinal assessments. Of 356 spontaneously conceived pregnancies, 15 (4.2%) were affected by preeclampsia and fetal growth restriction. Women who subsequently developed preeclampsia/fetal growth restriction had lower preconception cardiac output (4.9 versus 5.8 L/min; P=0.002) and cardiac index (2.9 versus 3.3 L/min per meter²; P=0.031) while mean arterial pressure (87.1 versus 82.3 mm Hg; P=0.05) and total peripheral resistance (1396.4 versus 1156.1 dynes sec cm^-5; P<0.001) were higher. Longitudinal trajectories for cardiac output and total peripheral resistance were similar between affected and healthy pregnancies, but the former group showed a more exaggerated fall in mean arterial pressure in the first trimester, followed by a steeper rise and a steeper fall to postpartum values. Significant relationships were observed between cardiac output, total peripheral resistance, and mean arterial pressure and gestational epoch. We conclude that in healthy women, an altered prepregnancy hemodynamic phenotype is associated with the subsequent development of preeclampsia/fetal growth restriction.

Maternal hemodynamics: a method to classify hypertensive disorders of pregnancy

BACKGROUND

The classification of hypertensive disorders of pregnancy is based on the time at the onset of hypertension, proteinuria, and other associated complications. Maternal hemodynamic interrogation in hypertensive disorders of pregnancy considers not only the peripheral blood pressure but also the entire cardiovascular system, and it might help to classify the different clinical phenotypes of this syndrome.

OBJECTIVE

This study aimed to examine cardiovascular parameters in a cohort of patients affected by hypertensive disorders of pregnancy according to the clinical phenotypes that prioritize fetoplacental characteristics and not the time at onset of hypertensive disorders of pregnancy.

STUDY DESIGN

At the fetal-maternal medicine unit of Ziekenhuis Oost-Limburg (Genk, Belgium), maternal cardiovascular parameters were obtained through impedance cardiography using a noninvasive continuous cardiac output monitor with the patients placed in a standing position. The patients were classified as pregnant women with hypertensive disorders of pregnancy who delivered appropriate- and small-for-gestational-age fetuses. Normotensive pregnant women with an appropriate-for-gestational-age fetus at delivery were enrolled as the control group. The possible impact of obesity (body mass index ≥30 kg/m²) on maternal hemodynamics was reassessed in the same groups.

RESULTS

Maternal age, parity, body mass index, and blood pressure were not significantly different between the hypertensive disorders of pregnancy/appropriate-for-gestational-age and hypertensive disorders of pregnancy/small-for-gestational-age groups. The mean uterine artery pulsatility index was significantly higher in the hypertensive disorders of pregnancy/small-for-gestational-age group. The cardiac output and cardiac index were significantly lower in the hypertensive disorders of pregnancy/small-for-gestational-age group (cardiac output 6.5 L/min, cardiac index 3.6) than in the hypertensive disorders of pregnancy/appropriate-for-gestational-age group (cardiac output 7.6 L/min, cardiac index 3.9) but not between the hypertensive disorders of pregnancy/appropriate-for-gestational-age and control groups (cardiac output 7.6 L/min, cardiac index 4.0). Total vascular resistance was significantly higher in the hypertensive disorders of pregnancy/small-for-gestational-age group than in the hypertensive disorders of pregnancy/appropriate-for-gestational-age group and the control group. All women with hypertensive disorders of pregnancy showed signs of central arterial dysfunction. The cardiovascular parameters were not influenced by gestational age at the onset of hypertensive disorders of pregnancy, and no difference was observed between the women with appropriate-for-gestational-age fetuses affected by preeclampsia or by gestational hypertension with appropriate-for-gestational-age fetuses. Women in the obese/hypertensive disorders of pregnancy/appropriate-for-gestational-age and obese/hypertensive disorders of pregnancy/small-for-gestational-age groups showed a significant increase in cardiac output, as well as significant changes in other parameters, compared with the nonobese/hypertensive disorders of pregnancy/appropriate-for-gestational-age and nonobese/hypertensive disorders of pregnancy/small-for-gestational-age groups.

CONCLUSION

Significantly low cardiac output and high total vascular resistance characterized the women with hypertensive disorders of pregnancy associated with small for gestational age due to placental insufficiency, independent of the gestational age at the onset of hypertension. The cardiovascular parameters were not significantly different in the women with appropriate-for-gestational-age or small-for-gestational-age fetuses affected by preeclampsia or gestational hypertension. These findings support the view that maternal hemodynamics may be a candidate diagnostic tool to identify hypertensive disorders in pregnancies associated with small-for-gestational-age fetuses. This additional tool matches other reported evidence provided by uterine Doppler velocimetry, low vascular growth factors in the first trimester, and placental pathology. Obesity is associated with a significantly higher cardiac output and outweighs other determinants of hemodynamics in pregnancy; therefore, in future studies on hypertensive disorders, obesity should be studied as an additional disease and not simply as a demographic characteristic.

Physiological adaptation of maternal plasma volume during pregnancy: a systematic review and meta-analysis

OBJECTIVE

To describe the physiological pattern of gestational plasma volume adjustments in normal singleton pregnancy and compare this with the pattern in pregnancies complicated by pregnancy-induced hypertension, pre-eclampsia or fetal growth restriction.

METHODS

We performed a meta-analysis of the current literature on plasma volume adjustments during physiological and complicated pregnancies. Literature was retrieved from PubMed (NCBI) and EMBASE (Ovid) databases. Included studies reported both reference plasma volume measurements (non-pregnant, prepregnancy or postpartum) and measurements obtained during predetermined gestational ages. Mean differences bet ween the reference and pregnancy plasma volume measurements were calculated for predefined intervals of gestational age using a random-effects model described by DerSimonian and Laird.

RESULTS

Thirty studies were included in the meta-analysis with publication dates ranging from 1934 to 2007. Plasma volume increased in the first weeks of pregnancy, with the steepest increase occurring during the second trimester. Plasma volume continued to increase in the third trimester with a pooled maximum increase of 1.13 L (95% CI, 1.07-1.19 L), an increase of 45.6% (95% CI, 43.0-48.1%) in physiological pregnancies compared with the reference value. The plasma volume expansion in gestational hypertensive and growth-restricted pregnancies was 0.80 L (95% CI, 0.59-1.02 L), an increase of 32.3% (95% CI, 23.6-41.1%) in the third trimester, a smaller increase than in physiological pregnancies (P < 0.0001).

CONCLUSIONS

During physiological pregnancy, plasma volume increases by, on average, more than 1 L as compared with non-pregnant conditions. In pregnancies complicated by pregnancy-induced hypertension, pre-eclampsia or fetal growth restriction, plasma volume increase in the third trimester is 13.3% lower than in normal pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Adaptación fisiológica del volumen del plasma materno durante el embarazo: una revisi\xF3n sistemática y metaanálisis RESUMEN OBJETIVO: Describir el patrón fisiológico de los cambios en el volumen del plasma gestacional en embarazos normales con feto único y compararlo con el patrón en los embarazos complicados por hipertensión gestacional, preeclampsia o restricción del crecimiento fetal. MÉTODOS: Se realizó un metaanálisis de la literatura actual sobre los cambios en el volumen de plasma durante embarazos complicados y fisiológicos. La literatura se obtuvo de las bases de datos PubMed (NCBI) y EMBASE (Ovid). Los estudios incluidos mencionaban tanto mediciones de referencia del volumen plasmático (no embarazada, antes del embarazo o después del parto) como mediciones tomadas a edades gestacionales predeterminadas. Se calcularon las medias de las diferencias entre las mediciones de referencia y las del embarazo para el volumen plasmático a intervalos predefinidos de la edad gestacional, utilizando un modelo de efectos aleatorios descrito por DerSimonian y Laird.

RESULTADOS

En el metaanálisis se incluyeron treinta estudios con fechas de publicación entre 1934 y 2007. El volumen plasmático aumentó en las primeras semanas de embarazo y el mayor incremento se produjo durante el segundo trimestre. El volumen de plasma continuó aumentando en el tercer trimestre con un aumento combinado máximo de 1,13L (IC 95%, 1,7-1,19 L), lo que supone un aumento del 45,6% (IC 95%, 43,0-48,1%) en embarazos fisiológicas en comparación con el valor de referencia. El aumento del volumen plasmático en los embarazos con hipertensión y con crecimiento intrauterino restringido fue de 0,80L (IC 95%, 0,59-1,02 L), lo que supone un aumento del 32,3% (IC 95%, 23,6-41,1%) en el tercer trimestre, y un incremento menor que en los embarazos fisiológicos (P <0,0001).

CONCLUSIONES

Durante el embarazo fisiológico el volumen de plasma aumenta, en promedio, más de 1L, en comparación con el de las no embarazadas. En los embarazos complicados por hipertensión gestacional, preeclampsia o restricción del crecimiento fetal, el aumento del volumen plasmático en el tercer trimestre es un 13,3% menor que en el embarazo normal. :meta : ,、。 : meta。PubMed(NCBI)EMBASE(Ovid)。(、)。DerSimonianLaird,。 : Meta30,19342007。,。,1.13 L(95% CI,1.07~1.19 L),,45.6%(95% CI,43.0%~48.1%)。0.80 L(95%CI,0.59~1.02 L),32.3%(95% CI,23.6%~41.1%),(P<0.0001)。 : ,,1 L。、,13.3%。.

Recurrent pre-eclampsia in women with metabolic syndrome and low plasma volume: a retrospective cohort study

OBJECTIVE

To determine the prevalence of recurrent pre-eclampsia in women with a history of pre-eclampsia with both metabolic syndrome and low plasma volume postpartum, as compared with women without either entity.

DESIGN

Retrospective cohort study.

SETTING

Three tertiary referral hospitals in the Netherlands.

POPULATION

Women with a history of pre-eclampsia.

METHODS

In 196 women with a history of pre-eclampsia we determined the presence or absence of metabolic syndrome using the World Health Organization criteria and measured plasma volume with the (125) I-human serum albumin indicator dilution technique. We compared the prevalence of recurrent pre-eclampsia in four groups, classified according to presence or absence of metabolic syndrome and low or normal plasma volume, calculating odds ratios (OR), adjusted for confounders.

MAIN OUTCOME MEASURE

Recurrence of pre-eclampsia in the subsequent pregnancy.

RESULTS

The prevalence of recurrent pre-eclampsia was 12% (12/99) in women without metabolic syndrome with normal plasma volume, versus 47% (8/17) in women with both metabolic syndrome and low plasma volume: OR 6.44 (95% CI 2.09-19.90), adjusted OR 7.90 (95% CI 2.30-27.16). Recurrent pre-eclampsia was present in 44% (10/23) and 25% (14/57) of women with isolated metabolic syndrome and low plasma volume, respectively.

CONCLUSIONS

In the concomitant presence of metabolic syndrome and low plasma volume, the prevalence of recurrent pre-eclampsia was nearly 50%, which is four times as high as the prevalence in women without either entity.

TWEETABLE ABSTRACT

Metabolic syndrome and low plasma volume raise the risk of recurrent pre-eclampsia to nearly 50%.

Persistent Maternal Cardiac Dysfunction After Preeclampsia Identifies Patients at Risk for Recurrent Preeclampsia

The purpose of our study was to assess cardiac function in nonpregnant women with previous early preeclampsia before a second pregnancy to highlight the cardiovascular pattern, which may take a risk for recurrent preeclampsia. Seventy-five normotensive patients with previous preeclampsia and 147 controls with a previous uneventful pregnancy were enrolled in a case-control study and submitted to echocardiographic examination in the nonpregnant state 12 to 18 months after the first delivery. All patients included in the study had pregnancy within 24 months from the echocardiographic examination and were followed until term. Twenty-two (29%) of the 75 patients developed recurrent preeclampsia. In the nonpregnant state, patients with recurrent preeclampsia compared with controls and nonrecurrent preeclampsia had lower stroke volume (63 ± 14 mL versus 73 ± 12 mL and 70 ± 11 mL, P<0.05), cardiac output (4.6 ± 1.2 L versus 5.3 ± 0.9 L and 5.2 ± 1.0 L, P<0.05), higher E/E' ratio (11.02 ± 3.43 versus 7.34 ± 2.11 versus 9.03 ± 3.43, P<0.05), and higher total vascular resistance (1638 ± 261 dyne · s(-1) · cm(-5) versus 1341 ± 270 dyne · s(-1) · cm(-5) and 1383 ± 261 dyne · s(-1) · cm(-5), P<0.05). Left ventricular mass index was higher in both recurrent and nonrecurrent preeclampsia compared with controls (30.0 ± 6.3 g/m(2.7) and 30.4 ± 6.8 g/m(2.7) versus 24.8 ± 5.0 g/m(2.7), P<0.05). Signs of diastolic dysfunction and different left ventricular characteristics are present in the nonpregnant state before a second pregnancy with recurrent preeclampsia. Previous preeclamptic patients with nonrecurrent preeclampsia show left ventricular structural and functional features intermediate with respect to controls and recurrent preeclampsia.

Low Plasma Volume in Normotensive Formerly Preeclamptic Women Predisposes to Hypertension

Formerly preeclamptic women are at risk for cardiovascular disease. Low plasma volume may reflect latent hypertension and potentially links preeclampsia with chronic cardiovascular disease. We hypothesized that low plasma volume in normotensive formerly preeclamptic women predisposes to hypertension. We longitudinally studied n=104 formerly preeclamptic women in whom plasma volume was measured 3 to 30 months after the preeclamptic pregnancy. Cardiovascular variables were assessed at 2 points in time (3-30 months postpartum and 2-5 years thereafter). Study population was divided into low plasma volume (≤1373 mL/m(2)) and normal plasma volume (>1373 mL/m(2)). Primary end point was hypertension at the second visit: defined as ≥140 mm Hg systolic or ≥90 mm Hg diastolic. Secondary outcome of this study was change in traditional cardiovascular risk profile between visits. Variables correlating univariately with change in blood pressure between visits were introduced in regression analysis. Eighteen of 104 (17%) formerly preeclamptic women who were normotensive at first visit had hypertension at second evaluation 2 to 5 years later. Hypertension developed more often in women with low plasma volume (10/35 [29%]) than in women with normal plasma volume (8/69 [12%]; odds ratio, 3.2; 95% confidence interval, 1.4-8.6). After adjustments, relationship between plasma volume status and subsequent hypertension persisted (adjusted odds ratio, 3.0; 95% confidence interval, 1.1-8.5). Mean arterial pressure at second visit correlated inverse linearly with plasma volume (r=-0.49; P<0.01). Initially normotensive formerly preeclamptic women have 17% chance to develop hypertension within 5 years. Women with low plasma volume have higher chance to develop hypertension than women with normal plasma volume. Clinically, follow-up of blood pressure seems warranted in women with history of preeclampsia, even when initially normotensive.

Cardiovascular and thrombogenic risk of decidual vasculopathy in preeclampsia

OBJECTIVE

Women with a history of preeclampsia (PE) have an increased prevalence of cardiometabolic, cardiovascular, and prothrombotic risk factors. Remotely, these women are at increased risk of developing cardiovascular and thrombotic disease. Decidual vasculopathy (DV) describes vascular lesions in the maternal spiral arteries of the uterus, which are found in approximately 40-60% of women with PE. DV is thought to be related to atherosclerosis because of their morphological similarity. The aim of this study was to investigate the association of cardiovascular and thrombogenic risk factors with DV in women with a history of PE.

STUDY DESIGN

We retrospectively analyzed the cardiovascular and thrombogenic risk of women with a history of PE, comparing cases with DV (n = 95) with cases without the lesions (n = 81) 7 months after the index pregnancy. Data from a cohort of patients with a history of PE were matched with records from our pathology database.

RESULTS

The DV group showed higher diastolic blood pressure (73 vs 70 mm Hg, P = .031), lower left ventricular stroke volume (71 vs 76 mL, P = .032), higher total peripheral vascular resistance (1546 vs 1385, P = .009), and a higher percentage of low plasma volume (34% vs 19%, P = .030). DV did not relate to other cardiovascular parameters, urinary protein, body mass index, lipid or glucose metabolism parameters, or thrombophilia.

CONCLUSION

In this study, in women with a history of PE, cases with DV had increased cardiovascular risk, exhibiting circulatory alterations, suggesting reduced venous reserves and elevated arterial tone, without metabolic or thrombophilic disturbances.

Clinical features of isolated gestational proteinuria progressing to pre-eclampsia: retrospective observational study

OBJECTIVES

Some women with isolated gestational proteinuria (IGP) later develop hypertension and are diagnosed with pre-eclampsia (PE). This study was performed to determine whether clinical features of such proteinuria preceding PE (P-PE) differ from those of other PE (O-PE).

DESIGN

Retrospective observational study after approval of the institutional review board of ethics.

SETTING

A single university hospital. Proteinuria was defined as a protein-to-creatinine ratio (mg/mg; P/Cr) of ≥0.27 in the spot urine specimen. IGP was defined as proteinuria in the absence of hypertension. P-PE was defined as PE in which proteinuria preceded hypertension by more than 2 days.

PARTICIPANTS

All of 10 and 18 consecutive women with P-PE and O-PE, respectively, who gave birth between January 2008 and August 2013.

RESULTS

Proteinuria appeared earlier (at 30.2±3.0 vs 35.3±4.3 weeks, p=0.001), the P/Cr level was greater at birth (7.28±2.14 vs 3.19±2.49, p<0.001), net maternal weight gain during the last antenatal 1 week was greater (3.1±1.8 vs 1.3±1.7 kg, p=0.023) and length of pregnancy was shorter (32.5±1.9 vs 36.1±3.6 weeks, p=0.001) in women with P-PE than in O-PE. The duration of IGP was 10.0±5.9 days (range 3-20), and the time interval until delivery after diagnosis of PE was 6.1±8.2 days (range 0-23) in 10 women with P-PE. The P/Cr levels at birth were significantly inversely correlated with the antenatal lowest antithrombin activity and fibrinogen levels among the 28 women with PE.

CONCLUSIONS

Women with P-PE were likely to exhibit greater proteinuria in the urine, greater water retention in the interstitial space and more enhanced coagulation-fibrinolysis, thus suggesting that they may constitute a more severe form of PE than women with O-PE do.

The relationship of a family history for hypertension, myocardial infarction, or stroke with cardiovascular physiology in young women

Cardiovascular disease (CVD) and preeclampsia share several pathophysiologic risk factors. We examined family history (FH) and physiologic status in 60 healthy, nulliparous women to determine the relationship between FH and known risk factors for CVD. Data are presented as mean ± standard error (SE). Decreased uterine blood flow was observed in women with FH of hypertension (+FH: 21.5 ± 1.7, no FH: 33.3 ± 9.0 mL/min; P = .04). Women reporting an FH of stroke showed increased alpha- and beta-adrenergic response, as measured by Valsalva maneuver (α: FH: 24.7 ± 1.9, -FH: 18.9 ± 1.1 mm Hg, P = .02; β: FH: 22.0 ± 2.1, -FH: 16.9 ± 1.4 mm Hg; P = .04), and increased cardiac output (4.83 ± 0.22 vs 4.31 ± 0.12 L/min; P = .01). We identified no significant physiologic associations linked to an FH of myocardial infarction. Our observations show significant differences in physiologic characteristics in women with specific CVD family histories. These data, coupled with known heritable contributions to CVD and preeclampsia, suggest a distinct physiologic phenotype that may link preeclampsia risk with FH of CVD, independent of pregnancy.

Measurement of plasma volume using fluorescent silica-based nanoparticles

Plasma volume (PV) is an important determinant of cardiovascular function and organ perfusion, and it is the target of infusion and diuretic therapies in daily clinical practice. Despite its fundamental importance PV is not commonly measured because available methods of tracer dilution are reliant on dye substances that suffer from numerous drawbacks including binding plasma proteins, spectral changes, and clearance kinetics that complicate analysis and interpretation. To address these issues, we have tested the utility of fluorescent nanoparticles comprised of a dye-rich silica core and polyethylene glycol-coated shell. Photophysical and visual analysis showed discrete size-gradated nanoparticle populations could be synthesized within a distribution tolerance of ±4 nm, which were optically unaffected in the presence of plasma/albumin. In normal mice, the cutoff for renal filtration of nanoparticles from blood into urine was ≤11 nm. A linear relationship between body weight and PV was readily determined in mice administered far red fluorescent nanoparticles sized either 20 or 30 nm. PV measurements using nanoparticles were correlated to values obtained with Evans blue dye. Induced expansion or contraction of PV was demonstrated with albumin or furosemide administration, respectively, in mice. Longitudinal experiments >30 min required matched untreated control mice to correct for nanoparticle loss (≈30%) putatively to the reticuloendothelial/phagocyte system. Collectively, the findings support a nanotechnology-based solution to methodological problems in measure of PV, notably in clinical settings where information on hemodynamic changes may improve treatment of injury and disease.