Why non-invasive maternal hemodynamics assessment is clinically relevant in early pregnancy: a literature review

Advanced maternal age alters cardiac functional and structural adaptations to pregnancy in rats

A significant number of pregnancies occur at advanced maternal age (>35 yr), which is a risk factor for pregnancy complications. Healthy pregnancies require massive hemodynamic adaptations, including an increased blood volume and cardiac output. There is growing evidence that these cardiovascular adaptations are impaired with age, however, little is known about maternal cardiac function with advanced age. We hypothesized that cardiac adaptations to pregnancy are impaired with advanced maternal age. Younger (4 mo; ∼early reproductive maturity in humans) and aged (9 mo; ∼35 yr in humans) pregnant Sprague-Dawley rats were assessed and compared with age-matched nonpregnant controls. Two-dimensional echocardiographic images were obtained (ultrasound biomicroscopy; under anesthesia) on gestational day 19 (term = 22 days) and compared with age-matched nonpregnant rats (n = 7-9/group). Left ventricular structure and function were assessed using short-axis images and transmitral Doppler signals. During systole, left ventricular anterior wall thickness increased with age in the nonpregnant rats, but there was no age-related difference between the pregnant groups. There were no significant pregnancy-associated differences in left ventricular wall thickness. Calculated left ventricular mass increased with age in nonpregnant rats and increased with pregnancy only in young rats. Compared with young pregnant rats, the aortic ejection time of aged pregnant rats was greater and Tei index was lower. Overall, the greater aortic ejection time and lower Tei index with age in pregnant rats suggest mildly altered cardiac adaptations to pregnancy with advanced maternal age, which may contribute to adverse outcomes in advanced maternal age pregnancies.NEW & NOTEWORTHY We demonstrated that even before the age of reproductive senescence, rats show signs of age-related alterations in cardiac structure that suggests increased cardiac work. Our data also demonstrate, using an in vivo echocardiographic approach, that advanced maternal age in a rat model is associated with altered cardiac function and structure relative to younger pregnant controls.

Origins of abnormal placentation: why maternal veins must not be forgotten

The importance of uterine microvascular adaptations during placentation in pregnancy has been well established for decades. Inadequate dilatation of spiral arteries is associated with gestational complications, such as preeclampsia and/or intrauterine growth restriction. More recently, it has become clear that trophoblast cells invade and adapt decidual veins and lymphatic vessels 1 month before spiral arteries become patent and before intervillous space perfusion starts. Normal intervillous space hemodynamics is characterized by high volume flow at low velocity and pressure in the interseptal compartments surrounding the chorionic villi, hereby facilitating efficient maternal-fetal exchange. In case of shallow decidual vein dilatation, intervillous arterial supply exceeds venous drainage. This will cause congestion in the interseptal compartments with subsequently reduced perfusion and increased pressure. An efficient mechanism to counteract venous congestion and safeguard the viability of the conceptus is by reducing arterial inflow via shallow dilatation of the spiral arteries. This review made the case for intervillous space congestion as an unexplored trigger for inadequate spiral artery dilatation during the placentation process, eventually leading to abnormal systemic circulatory dysfunctions. An abnormal maternal venous function can result from an abnormal maternal immune response to paternal antigens with an imbalanced release of vasoactive mediators or can exist before conception. To get the full picture of abnormal placentation, maternal veins must not be forgotten.

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.

Use of Ballistocardiography to Monitor Cardiovascular Hemodynamics in Preeclampsia

Objective: Pregnancy requires a complex physiological adaptation of the maternal cardiovascular system, which is disrupted in women with pregnancies complicated by preeclampsia, putting them at higher risk of future cardiovascular events. The measurement of body movements in response to cardiac ejection via ballistocardiogram (BCG) can be used to assess cardiovascular hemodynamics noninvasively in women with preeclampsia.

Methods: Using a previously validated, modified weighing scale for assessment of cardiovascular hemodynamics through measurement of BCG and electrocardiogram (ECG) signals, we collected serial measurements throughout pregnancy and postpartum and analyzed data in 30 women with preeclampsia and 23 normotensive controls. Using BCG and ECG signals, we extracted measures of cardiac output, J-wave amplitude × heart rate (J-amp × HR). Mixed-effect models with repeated measures were used to compare J-amp × HRs between groups at different time points in pregnancy and postpartum.

Results: In normotensive controls, the J-amp × HR was significantly lower early postpartum (E-PP) compared with the second trimester (T2; p = 0.016) and third trimester (T3; p = 0.001). Women with preeclampsia had a significantly lower J-amp × HR compared with normotensive controls during the first trimester (T1; p = 0.026). In the preeclampsia group, there was a trend toward an increase in J-amp × HR from T1 to T2 and then a drop in J-amp × HR at T3 and further drop at E-PP.

Conclusions: We observe cardiac hemodynamic changes consistent with those reported using well-validated tools. In pregnancies complicated by preeclampsia, the maximal force of contraction is lower, suggesting lower cardiac output and a trend in hemodynamics consistent with the hyperdynamic disease model of preeclampsia.

Maternal Hypertension, Advanced Doppler Haemodynamics and Therapeutic Precision: Principles and Illustrative Cases

PURPOSE OF REVIEW

Maternal hypertension is a common and serious condition associated with increased maternal and foetal morbidity and mortality, with early detection and management improving outcomes.

RECENT FINDINGS

Blood pressure (BP) changes of pre-eclampsia are defined after 20 gestational weeks, while haemodynamic changes can be detected at 5-11 weeks using a specialised non-invasive Doppler stroke volume (SV) monitor. Thus, advanced haemodynamic monitoring allows for physiologically precise identification of circulatory abnormalities, and implementation of appropriate therapy within the first trimester. We measured the oscillometric BP and advanced haemodynamics (USCOM 1A) of 3 unselected women with singleton pregnancies, consecutively listed for therapeutic induction for maternal hypertension at 32-41 weeks gestational age. While the BP's of the patients varied, it was the haemodynamics, particularly SV, cardiac output, systemic vascular resistance, Smith Madigan Inotropy Index, and oxygen deliver, that identified differing patterns of circulatory dysfunction, therapeutic objectives, and predicted post-partum complications of the mother and child. First trimester screening of maternal haemodynamics may allow for earlier detection of circulatory derangements, selection of patient precise interventions, and improved maternal-foetal outcomes.

Obesity in pregnancy causes a volume overload in third trimester

BACKGROUND

Obesity is a major risk factor for cardiovascular diseases. In this study, we aimed to investigate the maternal circulatory differences during pregnancy between obese and normal weight women.

MATERIALS AND METHODS

The functioning of the maternal circulation (arteries, veins, heart and body fluid) was assessed by ECG-Doppler ultrasound, impedance cardiography (ICG) and bio-impedance during pregnancy in obese women (BMI ≥30 kg/m² ) and normal weight, nonobese women (BMI 20-25 kg/m² ). In this observational study, 232 assessments were performed in the obese group, whereas 919 assessments were performed in the nonobese group.

RESULTS

Relative to nonobese women, the overall cardiovascular function in obese women during first and second trimester is consistent with a high volume/low-resistance circulation. In third trimester, cardiac output of obese women decreases from 9.2 (8.2-10.7) L/min to 8.5 (7.6-9.6) L/min (P = .037) whereas this is not true in the nonobese women (from 7.8 (7-8.5) L/min to 7.8 (6.8-8.9) L/min, P = .536). Simultaneously, the persistently lower peripheral vascular resistance in obese vs nonobese women disappears (880 (761-1060) dyn.sec/cm⁵ vs 928 (780-1067).

CONCLUSIONS

The circulatory gestational adaptations between nonobese and obese women were generally similar. The findings in the third trimester suggest that a pregnancy in obese women start as a state of high volume/low resistance, gradually shifting to a volume overload with decrease of cardiac output and disappearance of low vascular resistance. This evolution makes obese women vulnerable for gestational hypertensive diseases.

Development of a biophysical screening model for gestational hypertensive diseases

Background

To investigate the possibility of using maternal biophysical parameters only in screening for the different types of gestational hypertensive diseases.

Methods

A total of 969 pregnant women were randomly screened in first and second trimester, of which 8 developed Early-onset Preeclampsia, 29 Late-onset Preeclampsia, 35 Gestational Hypertension and 897 women had a normal outcome. An observational maternal hemodynamics assessment was done via standardized electrocardiogram-Doppler ultrasonography, Impedance Cardiography and bio-impedance, acquiring functional information on heart, arteries, veins and body fluid. Preliminary prediction models were developed to test the screening potential for early preeclampsia, late preeclampsia and gestational hypertension using a Partial Least Square Discriminant Analysis.

Results

A combined model using maternal characteristics with cardiovascular parameters in first and second trimester offers high screening performance with Area Under the Curve of 99,9% for Early-onset Preeclampsia, 95,3% for Late-onset Preeclampsia and 94% for Gestational Hypertension.

Conclusions

Using biophysical parameters as fundament for a new prediction model, without the need of biochemical parameters, seems feasible. However, validation in a large prospective study will reveal its true potential.

Gestational hypertensive disorders show unique patterns of circulatory deterioration with ongoing pregnancy

A combined assessment of heart, arteries, veins, and body fluid content throughout pregnancy has not yet been reported. We hypothesized that a gradual aggravation of circulatory dysfunction exists from the latent to the clinical phase of gestational hypertensive disease (GHD), and that pathways are unique for preeclampsia with early onset < 34 wk (EPE) and late onset ≥ 34 wk (LPE), and gestational hypertension (GH). Women with singleton pregnancy and no known diseases were invited for a prospective, observational study and had standardized sphygmomanometric blood pressure measurement, bioimpedance body water spectrum analysis, impedance cardiography for cardiac and arterial assessment, and combined Doppler-ECG of hepatic and renal interlobar veins and uterine arteries. Outcome was categorized as uncomplicated (UP, n = 1,700), EPE ( n = 87), LPE ( n = 218), or GH ( n = 188). A linear mixed model for repeated measurements, corrected for age, parity, and body mass index, was employed in SAS 9.4 to analyze trimestral changes within and between groups. From the first to the third trimester, body water increased in all groups, and an increasing number of abnormal parameters relative to UP occurred in all GHD. First-trimester blood pressure and peripheral resistance were higher in GHD than UP, together with increased uterine flow resistance and extracellular water in EPE, and with lower heart rate and aorta flow velocity in LPE. An overall gestational rise of body water volumes coexists with a gradual worsening of cardiovascular dysfunction in GHD, of which pathophysiological pathways are unique for EPE, LPE, and GH, respectively.

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.

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.