Jolien Oben

Non-invasive assessment of gestational hemodynamics: benefits and limitations of impedance cardiography versus other techniques

To obtain data for maternal stroke volume and cardiac output during pregnancy, it is preferable to use a non-invasive, accurate and reproducible method. In this aspect, impedance cardiography is an excellent technique which is also highly accessible and easy to perform. This paper is a comprehensive review on the published literature about impedance cardiography and highlights the strengths and limitations of its applications in obstetrics.

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

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

Maternal venous hemodynamics in gestational hypertension and preeclampsia

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

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 cardiovascular profiling in the first trimester of pregnancies complicated with gestation-induced hypertension or fetal growth retardation: a pilot study

Abstract Objective: In this study, we determine whether maternal cardiovascular (CV) profiling can detect first trimester differences between women with uncomplicated pregnancies (UP) and those who will develop gestational hypertensive disorders (GHD) or normotensive fetal growth retardation (FGR). Methods: Cardiac, arterial, and venous function were evaluated in 242 pregnant women around 12 weeks of gestation, using impedance cardiography (ICG) and combined electrocardiogram – Doppler ultrasonography. After postnatal determination of gestational outcome, first trimester measurements were compared between groups using Mann–Whitney U test for continuous data or Fisher’s Exact test for categorical variables (SPSS 20.0). Results: Compared to UP, first trimester aortic flow velocity index [71 ± 0.96 versus 61 ± 4.91 1/1000/s (p = 0.016)], acceleration index [133 ± 2.25 versus 106 ± 11.26 1/100/s2 (p = 0.023)] and Heather index [23.1 ± 0.35 versus 19.2 ± 1.70 Ω/s2 (p = 0.019)] were lower in GHD pregnancies, and first trimester stroke volume [77 ± 1.16 versus 67 ± 3.97 ml (p = 0.033)] and cardiac output [7.3 ± 0.10 versus 6.2 ± 0.31 l/min (p = 0.025)] were lower in FGR pregnancies. Conclusions: Maternal CV function in the first trimester of pregnancy differs between UP and those destined to develop GHD or FGR. This can be assessed with non-invasive maternal CV profiling, opening perspectives for the application of this technique in early gestational screening for GHD and FGR.

Maternal venous hemodynamics assessment for prediction of preeclampsia should be longitudinal

Abstract 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 individuals venous function for prediction of PE should be serial and longitudinal.

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 Fishers exact tests for categorical data. Significant linear dependence between variables was identified using Pearsons 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.

B4. Normal and abnormal blood pressures in early pregnancy: are we using the right cut off values?

Abstract Introduction: Subclinical hypertension has been reported in the first trimester of future hypertensive patients compared to normotensive patients. However, in clinical practice today, a cut off of 140/90 mmHg is still used to discriminate normotension from hypertension during pregnancy. We aim to investigate the most appropriate threshold for early gestational blood pressure values, which allow discriminating pregnant women between those at low or at high risk for gestational hypertensive diseases. Methods: Singleton pregnancies were included. A standard protocol was used to measure systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) in supine and standing position, by mode of an oscillometric sphygmomanometer around 12 weeks and 20 weeks of gestation. After delivery, gestational outcome was categorized in normotensive pregnancies (NP) or gestational hypertensive disease (GHD). ROC analysis was used to define the early gestational blood pressure cut off value with best possible performance in predicting GHD. Mann–Whitney U tests at nominal level a <0.05 were performed using SPSS for intergroup comparison. Results: A total of 780 women were measured at 12 weeks. Of these, 433 pregnant women were reevaluated around 20 weeks. At 12 and 20 weeks, blood pressures in GHD were higher than in NP (Table 1).Figure 1. (A) Boxplot NP versus GHD of DBP at 12 weeks, where redline indicates the threshold. (B) Boxplot UP versus GHD of DBP at 20 weeks with red line as threshold. Conclusions: Simple sphygmomanometric blood pressure measurements in standing position under standardized conditions at 12 weeks and 20 weeks has ≥96% negative predictive value for gestational hypertensive disease when DBP cut off is set at 81 and 78 mm Hg, respectively.

PP070. Maternal cardiovascular profiling in the first trimester ofpregnancies complicated with gestation induced hypertension or fetal growth restriction

INTRODUCTION Maternal cardiovascular (CV) profiling is useful in the assessment of gestational hypertensive disorders (GHD)(1). The onset of GHD occurs during the first weeks of gestation(2). OBJECTIVE To evaluate whether CV profiling can detect first trimester differences between women with uncomplicated pregnancies (UP) and those who will develop GHD or fetal growth restriction (FGR). METHODS CV function was evaluated according to standardised protocols in 242 pregnant women around 12 weeks of gestation, using impedance cardiography (ICG) and combined ECG - Doppler ultrasonography. Outcome was evaluated after delivery and categorized as UP (n=218), GHD with or without proteinuria (n=13), and pregnancies complicated with FGR (n=11). Measurements were compared between groups using Mann-Whitney U test for continuous data or Fishers Exact test for categorical variables. RESULTS As compared to UP, women destined to develop GHD showed increased systolic blood pressure, diastolic blood pressure and mean arterial pressure; and decreased ICG aortic velocity - and acceleration index. Pregnancies complicated with FGR showed decreased stroke volume and cardiac output when compared to UP. No differences were found concerning the maternal veins. CONCLUSION First trimester maternal CV function differs between women with uncomplicated pregnancies and those destined to develop GHD or FGR. Non-invasive CV profiling enables the identification of these differences.

PP078. The influence of maternal position on gestational hemodynamics

INTRODUCTION Cardiovascular profiling is useful for gestational hemodynamic studies. Conflicting results of cardiac output evolution from third trimester pregnancy to term are frequently reported. OBJECTIVES To stress the effect of maternal position in the assessment of maternal cardiac and arterial parameters during normal pregnancy. METHODS Impedance cardiography measurements were executed during 16 normal pregnancies using a standard protocol with known reproducibility. Gestational evolution of stroke volume, cardiac output, cardiac cycle time intervals, aortic flow parameters and total peripheral vascular resistance was measured in supine, standing and sitting positions. SAS procedure MIXED for linear mixed models was used for each parameter separately. RESULTS Evolution of stroke volume and cardiac output in supine position differed from standing (p<0.01) and sitting positions (p<0.05). Next to this, pre-ejection period, left ventricular ejection time index, systolic time ratio and total peripheral vascular resistance also showed a different evolution between supine and standing positions (p<0.05); no differences were observed between standing and sitting positions (p⩾0.19). CONCLUSION Next to the frequently reported cardiac output, gestational evolutions of other pre-load dependent parameters are influenced by maternal position. This study shows the importance of a standardized protocol for the measurement of cardiovascular parameters in pregnancy.