Doppler Measurement of Renal Interlobar Vein Impedance Index in Uncomplicated and Preeclamptic Pregnancies

Early-onset preeclampsia is characterised by an increased vascular tone in internal jugular veins

Purpose

This study aimed to investigate Doppler characteristics of maternal internal jugular veins in uncomplicated pregnancies vs. those affected by hypertensive disorders.

Materials and methods

Venous pulse transit time and venous impedance index were measured at three different locations (right proximal, right distal, left proximal) of internal jugular veins according to a standardised combined Doppler-Electrocardiogram protocol in five different groups of pregnant women: uncomplicated pregnancy, early-onset preeclampsia, late-onset preeclampsia, gestational hypertension, and normotensive pregnancies with a small for gestational age foetus. Values of both parameters of the latter four groups were plotted against the reference range of uncomplicated pregnancies at corresponding gestation. Linear mixed models with random intercept were used to investigate gestational changes in venous pulse transit time and venous impedance index at the three internal jugular vein locations within and between the different groups.

Results

A total of 127 women were included: 41 had uncomplicated pregnancies, 13 had early-onset preeclampsia, 25 had late-onset preeclampsia, 22 had gestational hypertension, and 26 had normotensive pregnancies with a small for gestational age foetus. Venous pulse transit time values were lower than uncomplicated pregnancy (p ≤ 0.001) at all three locations in the third trimester of early-onset preeclampsia.

Conclusion

Contrary to late-onset preeclampsia and gestational hypertension, early-onset preeclampsia is characterised by a lower venous pulse transit time at internal jugular veins compared to uncomplicated pregnancy, suggesting increased venous vascular tone.

Characteristics of the Maternal Jugular Venous Pulse Waveform by Combined Doppler-Electrocardiogram Assessment

Standardized combined Doppler-electrocardiogram assessment was performed longitudinally at three different locations of internal jugular veins between 12 wk of gestation and 6 wk postnatally in 24 uncomplicated pregnancies. All images were classified as typical or non-typical based on the presence of the physiologic deflections A, X, H and C. Linear mixed models with random intercepts of typical images were used to investigate gestational changes in venous pulse transit time and venous impedance index. Unequivocal identification of venous pulse transit time and venous impedance index was possible in 2617 of 3798 (69%) and 2234 of 3798 (59%) images, respectively. The best identification rate (80%, 1018/1266) was at the right distal internal jugular vein. Venous pulse transit time increased with gestational age at all locations; venous impedance index decreased at the right sided internal jugular vein. Maternal jugular venous pulse waveform by combined Doppler-electrocardiogram allows unequivocal identification of A-deflection and calculation of venous pulse transit time and venous impedance index in around two-thirds of assessments, with the highest success rate at the right distal internal jugular vein. Gestational evolutions of venous pulse transit time and venous impedance index are similar to those reported at the level of renal interlobar and hepatic veins.

Cardiovascular determinants of impaired placental function in women with cardiac dysfunction

Female heart disease has for a long time been an underrecognized problem in the field of cardiology. With an ever-growing number of these patients getting pregnant, cardiac dysfunction during pregnancy is an increasingly large medical problem. Previous work has shown that maternal heart disease may have an adverse effect on pregnancy outcome in both mother and child. The placenta forms the connection and it is postulated that cardiac dysfunction negatively affects the placenta, and consequently, neonatal outcome. Given the paucity of data in this field, more research on the influence of cardiac (mal)function on placental (mal)function is needed. The present review describes placental function in women with various types of cardiac dysfunction, thereby aiming to provide more insight into possible underlying mechanisms of placental malfunction. Organ dysfunction in patients with heart failure is for an important part based on reduced perfusion and venous congestion. This has been shown in other organs such as kidneys, liver and brain. In pregnant women with cardiac dysfunction, placental dysfunction may follow similar patterns. Moreover, other factors, such as pre-existing hypertension and chronic hypoxia may lead to further impairment of placental function, through abnormal vascular remodeling of the uterine spiral arteries. The pathophysiology of placental dysfunction in pregnant women with cardiac dysfunction may thus be multifactorial. It is therefore important to monitor closely cardiac and placental function in such high-risk pregnancies. Gaining a better understanding of the underlying pathophysiological mechanisms may have important clinical implications in terms of pregnancy counseling, monitoring and outcome.

Diagnostic value of doppler ultrasound indices of maternal renal interlobar vasculature in the prediction of preeclampsia

We aimed to determine the diagnostic accuracy of maternal renal vasculature Doppler ultrasound indices in the prediction of preeclampsia. A total of 40 pregnant women with a gestational age of more than 20 weeks were included and followed. The pregnant women underwent a Doppler ultrasound examination to measure the resistance index (RI) of the interlobar arteries of right and left kidneys and the renal interlobar vein impedance index (RIVI). Of the included women, 15 patients developed preeclampsia based on clinical and laboratory criteria. The renal vascular Doppler ultrasound indices were compared between the two groups. Then, using the Receiver Operating Characteristic (ROC) analysis, the diagnostic accuracy of interlobar artery RI and RIVI were investigated in the prediction of preeclampsia occurrence. RIVI values of right and left kidneys were significantly higher in the preeclampsia group compared to the normal pregnancy group. The left kidney interlobar artery RI at a cut-point of 0.59 had a sensitivity of 100% and a specificity of 40% (area under curve=0.7, P-0.03) in the prediction of preeclampsia. The RIVI of the left kidney (adjusted odds ratio=17.14, 95% CI = 3.46 to 47.28) was statistically significant in predicting preeclampsia (P-0.006). We found that, besides other routine methods, using Doppler ultrasound and measuring RIVI can be reliable in the prediction of preeclampsia.

Maternal microvascular dysfunction during preeclamptic pregnancy

Preeclampsia is a hypertensive disorder of pregnancy effecting ∼5-8% of pregnancies in the United States, and ∼8 million pregnancies worldwide. Preeclampsia is clinically diagnosed after the 20th week of gestation and is characterized by new onset hypertension accompanied by proteinuria and/or thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or cerebral or visual symptoms. This broad definition emphasizes the heterogeneity of the clinical presentation of preeclampsia, but also underscores the role of the microvascular beds, specifically the renal, cerebral, and hepatic circulations, in the pathophysiology of the disease. While the diagnostic criteria for preeclampsia relies on the development of de novo hypertension and accompanying clinical symptoms after 20-week gestation, it is likely that subclinical dysfunction of the maternal microvascular beds occurs in parallel and may even precede the development of overt cardiovascular symptoms in these women. However, little is known about the physiology of the non-reproductive maternal microvascular beds during preeclampsia, and the mechanism(s) mediating microvascular dysfunction during preeclamptic pregnancy are largely unexplored in humans despite their integral role in the pathophysiology of the disease. Therefore, the purpose of this review is to provide a summary of the existing literature on maternal microvascular dysfunction during preeclamptic pregnancy by reviewing the functional evidence in humans, highlighting potential mechanisms, and providing recommendations for future work in this area.

Doppler parameters of renal hemodynamics in women with preeclampsia: A systematic review and meta-analysis

The present meta-analysis aims to compare renal arterial and venous Doppler parameters in women with preeclampsia and healthy pregnant controls. Medline, Scopus, Cochrane Central Register of Controlled Trials, Clinicaltrials.gov, and Google Scholar databases were systematically searched from inception to December 04, 2019. All observational studies reporting renal resistive index, pulsatility index, renal interlobar vein impedance, or pulse transit time among preeclamptic and healthy pregnant women were held eligible. Subgroup analysis was conducted on the basis of disease onset and side of measurement. Both pair-wise and network meta-analysis were performed using Review Manager 5.3 and R-3.4.3 software. Fourteen studies were included, with a total of 1118 women. No difference of renal resistive (MD: 0.00, 95% CI: [-0.03, 0.04]) and pulsatility index (MD: -0.01, 95% CI: [-0.14, 0.12]) was evident between the two groups. Renal interlobar vein impedance was estimated to be significantly higher in preeclampsia (MD: 0.07, 95% CI: [0.06, 0.09]), while venous pulse transit time was significantly lower (MD: -0.10, 95% CI: [-0.14, -0.05]) in women with the disease. Subgroup analysis indicated that early-onset preeclampsia was associated with significantly elevated renal interlobar vein impedance and lower venous pulse transit time than late-onset disease. The outcomes of the present meta-analysis suggest that preeclampsia is characterized by venous hemodynamic dysfunction as it is associated with significantly elevated renal interlobar vein impedance and shorter venous pulse transit time. Future large-scale prospective studies should introduce cutoff values and determine the optimal timing of measurement in order to achieve optimal predictive accuracy.

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.

Maternal Venous Hemodynamic Dysfunction in Proteinuric Gestational Hypertension: Evidence and Implications

This review summarizes current knowledge from experimental and clinical studies on renal function and venous hemodynamics in normal pregnancy, in gestational hypertension (GH) and in two types of preeclampsia: placental or early-onset preeclampsia (EPE) and maternal or late-onset (LPE) preeclampsia, presenting at <34 weeks and ≥34 weeks respectively. In addition, data from maternal venous Doppler studies are summarized, showing evidence for (1) the maternal circulation functioning closer to the upper limits of capacitance than in non-pregnant conditions, with intrinsic risks for volume overload, (2) abnormal venous Doppler measurements obtainable in preeclampsia, more pronounced in EPE than LPE, however not observed in GH, and (3) abnormal venous hemodynamic function installing gradually from first to third trimester within unique pathways of general circulatory deterioration in GH, EPE and LPE. These associations have important clinical implications in terms of screening, diagnosis, prevention and management of gestational hypertensive diseases. They invite for further hypothesis-driven research on the role of retrograde venous congestion in the etiology of preeclampsia-related organ dysfunctions and their absence in GH, and also challenge the generally accepted view of abnormal placentation as the primary cause of preeclampsia. The striking similarity between abnormal maternal venous Doppler flow patterns and those observed at the ductus venosus and other abdominal veins of the intra-uterine growth restricted fetus, also invites to explore the role of venous congestion in the intra-uterine programming of some adult diseases.

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.

Venous blood flow in maternal kidneys in third trimester of pregnancy

Objectives: Maternal intra-abdominal pressure and hemodynamics change during pregnancy. The left renal vein may be compressed between the uterus and the spine and aorta, causing congestion and impaired venous return from the left kidney during late pregnancy. The aim of this study was to compare venous and arterial blood flow between the right and left kidney in the third trimester in women without known pregnancy complications.Methods: We conducted a prospective cohort study in 50 women with uncomplicated third-trimester pregnancies at Trondheim University Hospital, Norway, from January to April 2018. The arterial and venous blood flow were examined with pulsed wave Doppler in the hilum of the kidneys and the cross section of the area (CSA) of the vessels was measured from 3D acquisitions. Two diameters of the main vein and artery were measured after rotating the image of the vessels in the C-plane to be as circular as possible. CSA was calculated as π×(mean diameter/2)². Blood flow volume (ml/minute) in the vessels were calculated as 0.5 × TAmax (cm/s)×CSA (cm²)×60. The main outcome was venous and arterial blood flow volumes, and secondary outcomes were maximum velocity (Vmax), minimum velocity (Vmin), pulsatile index (PI), time-averaged maximum flow (TAmax) and renal interolobar vein impedance index (RIVI). We also examined possible associations between blood flow and maternal age, BMI and blood pressure.Results: We observed differences in venous flow parameters between the two kidneys. The mean total flow volume in the renal veins was 274 ml/min in the left vein versus 358 ml/min in the right vein (p=.10). Vmax, TAmax, PI, and RIVI were all significantly lower in the left renal vein. No differences in arterial blood flow between the two kidneys were found. BMI was negatively correlated to flow in the left renal vein (r= -0.28; p<.05), but not associated to flow in the right renal vein.Conclusion: We found that venous flow pattern differs between left and right renal veins in uncomplicated late pregnancies, but the total flow was not significantly different. New studies should be done in women with preeclampsia.

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.

Renal Interlobar Vein Impedance Index as a First-Trimester Marker Does Not Predict Hypertensive Disorders of Pregnancy

OBJECTIVES

The purpose of this study was to examine whether the maternal renal interlobar vein impedance index as assessed by first-trimester sonography is able to predict the later development of hypertensive disorders of pregnancy.

METHODS

Venous Doppler parameters of both maternal kidneys were studied in 214 pregnant women at gestational ages of 11 weeks to 13 weeks 6 days. Patients were classified according to outcomes related to hypertensive disorders. Detection rates and areas under receiver operating characteristic curves were determined for the maternal renal interlobar vein impedance index as a first-trimester predictor of preeclampsia and gestational hypertension.

RESULTS

Among the 214 patients, 22 (10.3%) developed preeclampsia; 10 (4.7%) developed gestational hypertension; and 182 were unaffected by hypertensive disorders (controls; 85.0%). In the overall study population, there was no difference in the impedance index between the right (0.44; 95% confidence interval, 0.35-0.50) and left (0.43; 95% confidence interval, 0.35-0.53) sides (P = .86). The average impedance index did not differ among women destined to develop preeclampsia (0.46; 95% confidence interval, 0.38-0.57), gestational hypertension (0.39; 95% confidence interval, 0.33-0.46), or pregnancies uncomplicated by hypertensive disease (0.42; 95% confidence interval, 0.37-0.50; P = .15). Low detection rates and the area under the curve analysis demonstrated that the impedance index was not predictive of hypertensive disorders of pregnancy.

CONCLUSIONS

The maternal renal interlobar vein impedance index should not be considered a first-trimester marker of hypertensive disorders of pregnancy.

Maternal venous Doppler characteristics are abnormal in pre-eclampsia but not in gestational hypertension

OBJECTIVE

To compare functional characteristics of maternal thoraco-abdominal arteries and veins in proteinuric and non-proteinuric hypertension in pregnancy.

METHODS

This retrospective study included women with singleton pregnancies during the third trimester, which were either uncomplicated or complicated with different clinical types of hypertension: non-proteinuric gestational hypertension (GH), early-onset pre-eclampsia (PE) diagnosed < 34 weeks or late-onset PE diagnosed ≥ 34 weeks. Demographic maternal and neonatal data were recorded, together with maternal serum and urine analytes. All women underwent standardized automated blood-pressure measurement, together with non-invasive impedance cardiography (ICG), for measurement of cardiac output (CO), aortic flow velocity index (VI) and aortic flow acceleration index (ACI). A standardized combined Doppler-electrocardiography assessment of maternal venous hemodynamics was performed to measure renal interlobar vein impedance index (RIVI), hepatic vein impedance index (HVI) and venous pulse transit time (VPTT) in liver and kidneys. Finally, resistance index (RI), pulsatility index (PI) and arterial pulse transit time (APTT) were measured in the uterine arcuate arteries. Mann-Whitney U-tests and Fisher's exact tests were used for intergroup comparisons, and linear dependence between variables was assessed using Pearson's correlation coefficient (r).

RESULTS

A total of 150 pregnancies were evaluated: 22 with uncomplicated pregnancy, 41 GH, 31 early PE and 56 late PE. Aortic VI and ACI were lower in GH, early PE and late PE than in uncomplicated pregnancy. Both early PE and late PE differed from GH by having shorter APTT in the uterine arcuate arteries and higher RIVI. Hemodynamic abnormalities were most pronounced in early PE, during which uterine arcuate artery RI was higher and VPTT in kidneys was shorter than in late PE. There was a significant correlation between degree of proteinuria and RIVI for the left (r = 0.381) and right (r = 0.347) kidney in late PE, but this was not true for early PE.

CONCLUSIONS

There is a gradient of worsening arterial and venous hemodynamic abnormalities from GH to late PE and then to early PE. Venous hemodynamic abnormalities are present only in PE, with a linear correlation between proteinuria and RIVI in late PE. The role of the maternal venous compartment in the pathophysiology and etiology of PE-related symptoms may be much more important than considered at present.

Is there a correlation between maternal venous hemodynamic dysfunction and proteinuria of preeclampsia?

OBJECTIVES

To evaluate in early and late preeclampsia a correlation of maternal venous Doppler flow characteristics with biochemical parameters in maternal serum and urine, or with gestational outcome.

STUDY DESIGN

In this observational cross-sectional study, renal interlobar vein impedance index (RIVI) was measured according to a standardised protocol for combined electrocardiogram-Doppler ultrasonography in 86 women with uncomplicated pregnancy, 78 women with late onset preeclampsia (≥34w) and 67 with early onset preeclampsia (<34w). For each group, maternal age, pre-gestational BMI and parity were recorded together with birth weight and -percentile. For both early onset and late onset preeclampsia, maternal serum was analysed for thrombocyte count and concentrations of creatinine, ASAT, ALAT and uric acid and 24h urine collections were analysed for creatinine clearance and proteinuria (mg/24h). A non-parametric Mann-Whitney U-tests was performed for continuous data and a Fisher's exact tests for categorical data. Significant linear dependence between variables was identified using Pearson's correlation coefficient at nominal level a=0.05.

RESULTS

Proteinuria was higher in early onset than in late onset preeclampsia (1756mg [838-6116mg] versus 877mg [416-1696mg], p<0.001), and this was also true for RIVI in both left (0.45 [0.40-0.55] versus 0.41 [0.35-0.45], p=0.001) and right kidney (0.45 [0.39-0.55] versus 0.38 [0.30-0.43], p<0.001). In our data set, there was a significant correlation between proteinuria and RIVI of left (correlation coefficient=0.172, p=0.036) and right kidney (correlation coefficient=0.218, p=0.009) in late onset but not early onset preeclampsia.

CONCLUSION

Maternal RIVI may correlate with proteinuria of late onset preeclampsia.

Intra-abdominal pressure measurements in term pregnancy and postpartum: an observational study

Objective

To determine intra-abdominal pressure (IAP) and to evaluate the reproducibility of IAP-measurements using the Foley Manometer Low Volume (FMLV) in term uncomplicated pregnancies before and after caesarean section (CS), relative to two different reference points and to non-pregnant values.

Design

Observational cohort study.

Setting

Secondary level referral center for feto-maternal medicine.

Population

Term uncomplicated pregnant women as the case-group and non-pregnant patients undergoing a laparoscopic assisted vaginal hysterectomy (LAVH) as control group.

Methods

IAP was measured in 23 term pregnant patients, before and after CS and in 27 women immediately after and 1 day after LAVH. The midaxillary line was used as zero-reference (IAP_MAL) in all patients and in 13 CS and 13 LAVH patients, the symphysis pubis (IAP_SP) was evaluated as additional zero-reference. Intraobserver correlation (ICC) was calculated for each zero-reference. Paired student's t-tests were performed to compare IAP values and Pearson's correlation was used to assess correlations between IAP and gestational variables.

Main outcome measures

ICC before and after surgery, IAP before and after CS, IAP after CS and LAVH.

Results

The ICC for IAP_MAL before CS was lower than after (0.71 versus 0.87). Both mean IAP_MAL and IAP_SP were significantly higher before CS than after: 14.0±2.6 mmHg versus 9.8±3.0 mmHg (p<0.0001) and 8.2±2.5 mmHg versus 3.5±1.9 mmHg (p = 0.010), respectively. After CS, IAP was not different from values measured in the LAVH-group.

Conclusion

IAP-measurements using FMLV is reproducible in pregnant women. Before CS, IAP is increased in the range of intra-abdominal hypertension for non-pregnant individuals. IAP significantly decreases to normal values after delivery.

Hepatic portal vein flow and three dimensional indices of hepatic perfusion in pre-eclampsia compared with normal pregnancy

It has been suggested that the origins of pre-eclampsia arise from the maternal venous system dysfunction. This study aimed to test this hypothesis by assessing hepatic perfusion in pre-eclampsia using three-dimensional (3D) ultrasound. The hepatic portal vein flow in 12 women with normal pregnancy and 11 women with pre-eclampsia was measured using standard Doppler ultrasound. The 3D indices of hepatic perfusion: flow index (FI), vascular index (VI) and vascularisation flow index (VFI), which are believed to reflect vascularity and flow intensity were also measured. Because of small numbers, a non-parametric test was used to test differences between groups. Hepatic portal vein flow was no different between women with normal pregnancy compared with women with pre-eclampsia (228.1 (215.5-270.6) vs. 283.0 (145.9-344.6); p = 0.90). The 3D indices of hepatic perfusion were as follows (FI: 36.3(30.7-42.5) vs. 39.7 (27.7-44.2), p = 1.00; VI: 11.7 (3.6-21.2) vs. 3.0 (0.5-7.6), p = 0.04; VFI: 4.7 (1.2-8.3) vs. 1.2 (0.1-3.2), p = 0.06, respectively). This study was not able to support or refute the suggestion that the genesis of pre-eclampsia arises from the maternal venous circulation. There may be biological differences in the 3D indices of hepatic perfusion in women with pre-eclampsia compared with normal pregnant women.

Improving the reliability of venous Doppler flow measurements: relevance of combined ECG, training and repeated measures

The nature of venous Doppler waves is highly variable. An additional electrocardiogram (ECG) improves the interpretation of venous Doppler wave characteristics and allows measurement of venous pulse transit time. The purpose of this study was to assess the reproducibility of ECG-guided repeated measurements of venous Doppler flow characteristics before and after sonographer training and the inter- and intra-observer variability. In four groups of 25 healthy women, venous Doppler flow measurements were performed at the level of the kidneys and liver according to a standardized protocol. Intra-observer Pearson correlation coefficients of the renal interlobar vein Doppler indices were ≥ 0.80 with the addition of the ECG, which are higher than the results of a former study. The inter-observer correlation between an experienced ultrasonographer and an inexperienced ultrasonographer improved from ≥ 0.71 to ≥ 0.91 after training. The correlation range of all parameters between two independent observers improved when values were based on repeated measures. The addition of an ECG to the Doppler image, training and repeated measurements are helpful in improving venous Doppler wave interpretation.

Maternal venous hemodynamics in gestational hypertension and preeclampsia

Background

To evaluate characteristics of venous hemodynamics, together with cardiac and arterial function, in uncomplicated pregnancies (UP), non-proteinuric gestational hypertension (GH) and preeclampsia (PE).

Methods

In this observational cross-sectional study, venous hemodynamics was assessed using a standardised protocol for combined electrocardiogram (ECG)-Doppler ultrasonography, together with a non-invasive standardised cardiovascular assessment using impedance cardiography (ICG) in 13 women with UP, 21 with GH, 34 with late onset PE ≥ 34 w (LPE) and 22 with early onset PE < 34 w (EPE). ECG-Doppler parameters were impedance index at the level of hepatic veins (HVI) and renal interlobar veins (RIVI) together with venous pulse transit times (VPTT), as well as resistive and pulsatility index, and arterial pulse transit time (APTT) at the level of uterine arcuate arteries. ICG parameters were aortic flow velocity index (VI), acceleration index (ACI) and thoracic fluid content. Mann Whitney U-test, Kruskall-Wallis test and linear regression analysis with heteroskedastic variance was used for statistical analysis.

Results

RIVI in both kidneys was >15% higher (P ≤ .010) in LPE and EPE, as compared to GH and UP. Next to this, >30% lower values for VI and ACI (P ≤ .029), and > 15% lower values for APTT (P ≤ .012) were found in GH, LPE and EPE, as compared to GH.

Conclusion

In comparison to UP, similar abnormalities of central arterial function and APTT were found in GH, EPE and LPE. Proteinuria of LPE and EPE was associated with increased RIVI, this was not observed in GH.

Maternal venous hemodynamics assessment for prediction of preeclampsia should be longitudinal

OBJECTIVE

To address the question whether maternal venous abnormalities exist at the onset of, or develop during the course of pregnancy.

METHODS

We present five case reports of patients with early onset preeclampsia (EPE), late onset preeclampsia (LPE), gestational hypertension (GH), essential hypertension (EH) and an uncomplicated pregnancy (UP). Maternal renal and hepatic vein Doppler waves and maternal venous pulse transit times (VPTT) were assessed in early pregnancy and again shortly before delivery.

RESULTS

In all cases, maternal VPTT were normal in early pregnancy and changed to abnormal values in EPE and LPE, which was not true for UP and GH or EH.

CONCLUSION

These observations support the view that venous hemodynamic dysfunction of preeclampsia (PE) develops during the course of pregnancy. Therefore, assessment of an individual's venous function for prediction of PE should be serial and longitudinal.

Role of dysfunctional maternal venous hemodynamics in the pathophysiology of pre-eclampsia: a review

The venous compartment has an important function in regulation and control of cardiac output. Abnormalities of cardiac output have been found in early gestational stages of both early- and late-onset pre-eclampsia. The venous compartment also maintains the balance between circulating and non-circulating blood volumes and regulates the amount of reserve blood stored in the splanchnic venous bed. It is well known that adaptive regulation of maternal blood volume is disturbed in pre-eclampsia. Abnormal venous hemodynamics and venous congestion are responsible for secondary dysfunction of several organs, such as the kidneys in cardiorenal syndrome and the liver in cardiac cirrhosis. Renal and liver dysfunctions are among the most relevant clinical features of pre-eclampsia. Doppler sonography studies have shown that the maternal venous compartment is subject to gestational adaptation, and that blood flow characteristics at the level of renal interlobar and hepatic veins are different in pre-eclampsia compared with uncomplicated pregnancy. In comparison to late-onset pre-eclampsia, in early-onset pre-eclampsia venous Doppler flow abnormalities are more prominent and present up to weeks before clinical symptoms. This paper reviews the growing evidence that dysfunction of maternal venous hemodynamics is part of the pathophysiology of pre-eclampsia and may perhaps be more important than is currently considered. Doppler sonography is a safe and easily performed method with which to study maternal venous hemodynamics. Therefore, exploring the role of maternal venous hemodynamics using Doppler sonography is an exciting new research topic for those who are interested in cardiovascular background mechanisms, as well as prediction and clinical work-up of pre-eclampsia.

Maternal renal interlobar vein impedance index is higher in early- than in late-onset pre-eclampsia

OBJECTIVES

To test the hypothesis that Doppler characteristics of maternal renal interlobar veins (RIV) are different between pregnancies affected by early-onset pre-eclampsia (EP) and those affected by late-onset pre-eclampsia (LP).

METHODS

A gestational age of 34 weeks was considered to differentiate EP from LP. All women had a renal duplex scan according to a standard protocol, with known intraobserver correlation coefficient (0.88). Maximum (Vmax) and minimum (Vmin) RIV velocities were measured on two occasions (between 28 and 32 and between 34 and 37 weeks) in 18 women with uncomplicated pregnancy (UP). In women with EP (n = 32) or LP (n = 41), these variables were measured once, within 3 days following hospital admission. Delta velocity (DeltaV) was calculated as Vmax - Vmin and the RIV impedance index (RIVI) was calculated as DeltaV/Vmax. Data on neonatal outcome and maternal renal function were obtained for UP and those with EP and LP, and group-specific means +/- SD were calculated and compared.

RESULTS

Compared with UP, the RIVI of both left and right kidneys was higher in those with EP (0.49 +/- 0.13 vs. 0.36 +/- 0.04, P = 0.0001, and 0.46 +/- 0.15 vs. 0.33 +/- 0.04, P = 0.0008) and in those with LP (0.41 +/- 0.07 vs. 0.37 +/- 0.06, P = 0.04, and 0.38 +/- 0.12 vs. 0.30 +/- 0.05, P = 0.009). RIVI was higher in pregnancies with EP than in those with LP (P < or = 0.01), and this difference was associated with lower median birth-weight percentiles (22.5 (interquartile range (IQR), 15-35) vs. 40.0 (IQR, 12-55), P = 0.01), higher maternal serum uric acid concentrations (419 +/- 84 vs. 374 +/- 85 micromol/L, P = 0.03) and higher proteinuria (4131 +/- 3885 vs. 1190 +/- 1133 mg/24 h, P < 0.0001).

CONCLUSION

Maternal vascular maladaption in pre-eclampsia is associated with abnormal Doppler findings in the venous compartment. RIVI is higher in EP than in LP pregnancies and this is associated with lower birth-weight percentiles and higher proteinuria.

Maternal hepatic vein Doppler velocimetry during uncomplicated pregnancy and pre-eclampsia

Changes of Doppler velocity measurements of distinct hepatic vein (HV) Doppler wave components were evaluated during uncomplicated pregnancy (UP) as a reference to measurements in pre-eclampsia (PE). Women with UP (n = 13) were submitted to standardised duplex scanning of HV at 11 stages of pregnancy between 10 and 38 weeks. For each stage, mean +/- SD was calculated for HV A-, X-, V- and Y-peaks. Women with PE (n = 30) were evaluated once, and mean +/- SD was calculated for pregnancies <32 weeks, 32-34(+6) weeks and > or =35 weeks. PE and UP values at corresponding gestational age were compared statistically using t-test. HV A-velocity measurements changed markedly from negative values in early uncomplicated pregnancy, converting around 22-24 weeks to positive values until term. Changes throughout gestation were less prominent for HV X-, V- and Y-velocities. HV A-velocity measurements were significantly lower in PE than in UP, the difference being more pronounced at 30 weeks (-3.59 +/- 3.41 vs. 6.12 +/- 3.43, p = 0.0001) than at 37 weeks (2.35 +/- 4.54 vs. 5.32 +/- 1.92, p = 0.04). From our results, we conclude that HV Doppler velocimetry shows a gradual shift from central venous reversed flow during atrial contraction in uncomplicated early pregnancy to constantly forward moving flow until term. HV A-velocities are significantly lower in PE than in UP, the differences being more pronounced in late second trimester than near term.