Functional echocardiography in the fetus with non-cardiac disease

Fetal Pulmonary Vein Pulsatility Index in the Third Trimester of Pregnancy as a Predictor of Small for Gestational Age

OBJECTIVE

This study aimed to establish whether the increased fetal pulmonary venous pulsatility index (PVPI) in late pregnancy can independently predict small for gestational age (SGA) and to verify its cut point value and efficacy.

METHOD

The PVPI was measured in women with singleton pregnancies between 25 and 39 gestational weeks. Maternal hypertension and diabetes, estimated fetal weight (EFW) and percentile of the corresponding weeks of pregnancy (USG_PER), gestational weeks at delivery, and birth weight and percentile of the corresponding weeks of pregnancy (BABY_PER) were reviewed. To assess whether PVPI was independently correlated with BABY_PER, Pearson's correlation analysis was performed. The cut point value of PVPI for the prediction of SGA was established using a receiver operating characteristic (ROC) curve.

RESULTS

A total of 129 mothers were included in this study. Both USG_PER and PVPI were significantly related to SGA, independently (P <.001 and P = .004, respectively). The cut point value of PVPI was found to be 1.13. The AUCs of PVPI and USG_PER were not significantly different (P = .624). The sensitivity of PVPI was 70.27%, and the specificity was 92.39%.

CONCLUSION

PVPI could predict SGA independently, and the efficacy was comparable to EFW during pregnancy.

Global longitudinal reference ranges for fetal myocardial deformation in the second half of pregnancy

PURPOSE

To construct longitudinal fetal reference ranges for global longitudinal myocardial deformation (strain and strain rate) of the left and right ventricles in the second half of pregnancy.

METHODS

A prospective, observational, longitudinal study of 120 women with uncomplicated singleton pregnancies. The participants underwent ultrasonographic scans every 4 weeks from enrolment (18-28 weeks) until delivery. Strain and strain rate were measured at each examination using velocity vector imaging. Changes in strain and strain rate as functions of gestational age (GA) were modeled using Bayesian mixed effects models.

RESULTS

A total of 406 assessments of global longitudinal strain and strain rate were performed for 120 women. Global longitudinal strain and strain rate decreased with increasing GA in the left ventricle. There was, however, no change in strain measurements of the right ventricle over the same gestational time frame. Posterior predictive distributions were used to derive reference centiles for each week of GA.

CONCLUSION

Assessment of myocardial deformation of the fetal heart is easily performed and may be useful for quantitative assessment of heart function, particularly in fetuses at risk of cardiac dysfunction.

Fetal Cardiac Function and Ventricular Volumes Determined by Three-Dimensional Ultrasound Using STIC and VOCAL Methods in Fetuses from Pre-gestational Diabetic Women

To assess the fetal cardiac function and ventricular volumes by three-dimensional (3D) ultrasound using spatio-temporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL) methods in fetuses from pre-gestational diabetic women. This was a prospective and cross-sectional study that evaluated 53 fetuses from pre-gestational diabetic women and 53 fetuses from healthy mothers between 20 and 34 weeks of gestation. Only fetuses with no structural or genetic abnormalities and singleton pregnant women were included in this study. The fetal cardiac volumes were assessed by STIC and VOCAL methods. The ejection fraction, stroke volume, and cardiac output were calculated from these measurements to evaluate fetal cardiac function. The Mann-Whitney U test was performed to compare the two groups. For calculation of intra- and interobserver reproducibility's, we used concordance correlation coefficients. The mean differences in the right atrial volumes between the diabetic and normal groups ranged from 0.05 mL to 0.1 mL (p = 0.917 and 0.355, respectively). The median of left atrium (LA) volume measurement in pre-gestational diabetic group was significantly lower than healthy mothers (LA: 0.62 vs. 0.68 mL; p < 0.001). The fetal right and left ventricular volumes were similar in both groups. No significant differences in ejection fraction, stroke volume and cardiac output were observed (p value range 0.086-0.815). The majority of fetal atrial/ventricular volumes showed good intra- and interobserver reliabilities. Conversely, the majority cardiac function parameters showed poor intra- and interobserver agreements. STIC and VOCAL methods gave reproducible quantitative results for fetal atrial and ventricular volumes. Significant differences in fetal left atrial volumes were observed between the two groups, which be related to LA atrial dysfunction and /or left ventricle (LV) compliance, reflecting earlier stages of cardiac dysfunction.

Reference ranges for the fetal mitral, tricuspid, and interventricular septum annular plane systolic excursions (mitral annular plane systolic excursion, tricuspid annular plane systolic excursion, and septum annular plane systolic excursion) between 20 and 36 + 6 weeks of gestation

Objectives This study aimed to establish reference ranges for fetal mitral, tricuspid, and interventricular septum annular plane systolic excursions (MAPSE, TAPSE, and SAPSE) in normal pregnant women between 20 and 36 + 6 weeks of gestation. Methods This prospective and cross-sectional study included 360 low-risk singleton pregnancies between 20 and 36 + 6 weeks of gestation. MAPSE, TAPSE, and SAPSE were measured by M-mode in real time in an apical or basal four-chamber view through placing the cursor at the atrioventricular junction, marked by the valve rings at the tricuspid, mitral, and basal septum, respectively. A regression analysis was done to determine the appropriate polynomial equation model for both measurements and standard deviation (SD) values in relation to gestational age (GA). The intra- and inter-observer reproducibility was evaluated using the concordance correlation coefficient (CCC) and limits of agreement (LoA). Results There was a significant positive correlation between MAPSE (r=0.705, p<0.0001), TAPSE (r=0.804, p<0.0001), and SAPSE (r=0.690, p<0.0001) and GA. The mean of each parameter ranged as follows: 2.87-5.56 mm, MAPSE; 3.98-8.07 mm, TAPSE; and 2.34-4.21 mm, SAPSE. Poor/moderate intra- and inter-observer reliability (CCC between 0.70 and 0.90) and poor/moderate agreement of all the tested parameters were evaluated (LoA between 10 and 50%). Conclusions Reference values were established for the fetal MAPSE, TAPSE, and SAPSE between 20 and 36 + 6 weeks of gestation in low-risk pregnant women. These parameters showed poor/moderate reproducibility.

Reference ranges of filling time and systolic-to-diastolic time index of the left ventricle, right ventricle, and interventricular septum using both spectral and tissue Doppler of fetal heart between 20 and 36 + 6 weeks of gestation

OBJECTIVE

The objective of this study is to determine the reference ranges for filling time (FT) and systolic-to-diastolic time index (SDI) of the left ventricle (LV) by using spectral Doppler, and FT' and SDI' of the LV, right ventricle, and interventricular septum (IVS) by using tissue Doppler of the fetal heart.

STUDY DESIGN

This prospective and cross-sectional study included 360 low-risk singleton pregnancies between 20 and 36 + 6 weeks of gestation. The SDI/SDI' is the sum of the ejection time, isovolumic contraction time, and isovolumic relaxation time (IRT) divided by the FT. We measured FT/FT' from the beginning of the opening click of the E wave of the mitral valve to the closing click of the A wave of the mitral valve. We used regression analysis to obtain the best-fit model polynomial equation for the parameters. Additionally, we assessed intra- and inter-observer reproducibility by using concordance correlation coefficient (CCC).

RESULTS

There was a weak correlation among FT LV (r = 0.31, p < 0.0001), SDI LV (r = -0.23, p < 0.0001), and gestational age (GA). Additionally, there was a very weak positive correlation among FT' RV (r = 0.09, p = 0.0001), FT' LV (r = 0.07, p < 0.0001), FT' IVS (r = 0,08, p < 0.0001), and GA. In contrast, there was a very weak negative correlation among SDI' LV (r=-0.09, p < 0.0001), SDI' IVS (r=-0.05, p < 0.0021), and GA. There was no significative correlation between SDI' RV (r=-0.06, p < 0.081) and GA. Poor/very poor intra- and inter-observer reliability was observed for all the parameters (CCC = 0.19-0.79), whereas moderate intra- and inter-observer agreement was observed for all parameters (CCC = 0.37-0.72).

CONCLUSIONS

The reference ranges for FT and SDI were determined by using spectral and tissue Doppler of the fetal heart and showed a poor reproducibility.

Longitudinal Reference Ranges for Tricuspid Annular Plane Systolic Excursion and Mitral Annular Plane Systolic Excursion in Normally Grown Fetuses

OBJECTIVES

The aim of this study was to construct reference ranges for fetal tricuspid annular plane systolic excursion (TAPSE) and mitral annular plane systolic excursion (MAPSE) using conventional M-mode ultrasound (US) in the second half of pregnancy.

METHODS

Participants underwent US scans every 4 weeks from 18 weeks' gestation until delivery. The TAPSE and MAPSE were measured by conventional M-mode US at each examination. The relationships between TAPSE and MAPSE and gestational age and estimated fetal weight were modeled by Bayesian mixed effects linear regression.

RESULTS

Positive linear relationships were observed between both MAPSE and TAPSE and gestational age and estimated fetal weight. Reference centiles for TAPSE and MAPSE were developed.

CONCLUSIONS

This simple technique is a useful tool for assessing cardiac function and could be used for quantitative assessments of fetal cardiac function, particularly in high-risk pregnancies such as those complicated by maternal diabetes.

Impact of type I and type II maternal diabetes mellitus on fetal cardiac function assessment parameters using spectral and tissue Doppler

The aim of this study was to evaluate the impact of pregestational diabetes mellitus (DM) on fetal cardiac function two-dimensional parameters using spectral and tissue Doppler. Pregnant women between 20 and 36 + 6 weeks gestation were divided into three groups: controls, type I DM, and type II DM. The right ventricle (RV) and left ventricle (LV) annular velocity peaks were measured using spectral (E, A) and tissue (E', A', S') Doppler. The myocardial performance index was calculated as (isovolumetric contraction time [ICT] + isovolumetric relaxation time [IRT])/ejection time using tissue (MPI') and the spectral Doppler (MPI). A general linear model, with fetal heart rate as a covariant, was used to evaluate the effect of DM on the fetal heart function assessment parameters. To assess the association of type I and II DM with adverse perinatal outcomes, Fisher's exact test was used. A receiver operating characteristic curve was used to determine the best cutoff for fetal cardiac function assessment parameters to identify the neonatal composite outcomes. The sample comprised 179 pregnant women. DM had significant effect on RV and LV A peak velocities (p = 0.026 and p = 0.011, respectively). LV ICT (p < 0.001) and LV MPI (p < 0.001) were significantly affected by maternal DM. Fetuses from pregnant women with type II DM showed significantly higher LV MPI (0.492 vs. 0.459, p = 0.006) and RV S' (7.2 vs. 6.44 cm/s, p = 0.024) than controls. Fetuses from type I DM pregnant women showed increase in cardiac parameters that evaluated the LV and RV diastolic function (LV IRT' p < 0.001 and RV MPI' p = 0.044). Type I and II DM were associated with adverse perinatal outcomes: neonatal intensive care unit stay (p < 0.0001), macrosomia (p < 0.0001), hyperbilirubinemia (p < 0.0001), and hypoglycemia (p < 0.0001). The LV MPI' showed significant but moderate sensitivity in identifying the composite neonatal outcomes (AUC: 0.709, 95% CI 0.629-0.780, p < 0.001). Tissue Doppler and MPI parameters can be useful to detect subclinical cardiac dysfunction in the fetal heart of pregestational DM pregnant women.

Comparison of strain and dyssynchrony measurements in fetal two-dimensional speckle tracking echocardiography using Philips and TomTec

Background The aim of this study was to compare Philips and TomTec two-dimensional speckle tracking echocardiography (2D-STE) software measurements of strain and dyssynchrony values in healthy fetuses. Methods This was an explorative observational study in which the echocardiographic data of 93 healthy fetuses between the 20th and 38th week of gestation were determined from a four-chamber view using 2D speckle tracking. The global and segmental longitudinal strain values of both ventricles, inter-ventricular and left intra-ventricular dyssynchrony were analyzed using QLab version 10.8 (Philips Medical Systems, Andover, MA, USA) and TomTec-Arena version 2.30 (TomTec, Unterschleißheim, Germany). Results TomTec showed persistently lower values for all of the assessed strain and dyssynchrony variables. For all variables, the bias between vendors tended to increase with gestational age, though not to a significant extent. Left ventricular dyssynchrony and longitudinal strain within the mid segment of the septum correlated best between vendors; however, the limits of agreement were wide in both cases. None of the variables assessed in the two-chamber view compared well between QLAB and TomTec. Conclusion Speckle tracking software cannot be used interchangeably between vendors. Further investigations are necessary to standardize fetal 2D-STE.

Intrauterine growth restriction is associated with sex-specific alterations in the nitric oxide/cyclic GMP relaxing pathway in the human umbilical vein

INTRODUCTION

Intrauterine growth restriction (IUGR) is a leading cause of perinatal mortality and morbidity, and is linked to an increased risk to develop chronic diseases in adulthood. We previously demonstrated that IUGR is associated, in female neonates, with a decreased nitric oxide (NO)-induced relaxation of the umbilical vein (UV). The present study aimed to investigate the contribution of the smooth muscle components of the NO/cyclic GMP (cGMP) pathway to this alteration.

METHODS

UVs were collected in growth-restricted or appropriate for gestational age (AGA) human term newborns. Soluble guanylyl cyclase (sGC) and cGMP-dependent protein kinase (PKG) were studied by Western blot, cGMP production by ELISA and cyclic nucleotide phosphodiesterases (PDEs) activity using a colorimetric assay. Contribution of PDEs was evaluated using the non-specific PDEs inhibitor 3-isobutyl-1-methylxanthine (IBMX) in isolated vessel tension studies.

RESULTS

NO-induced relaxation was reduced in IUGR females despite increased sGC protein and activity, and some increase in PKG protein compared to AGA. In males, no significant difference was observed between both groups. In the presence of IBMX, NO-stimulated cGMP production was significantly higher in IUGR than AGA females. Pre-incubation with IBMX significantly improved NO-induced relaxation in all groups and abolished the difference between IUGR and AGA females.

CONCLUSION

IUGR is associated with sex-specific alterations in the UV's smooth muscle. The impaired NO-induced relaxation observed in growth-restricted females is linked to an imbalance in the NO/cGMP pathway. The beneficial effects of IBMX suggest that PDEs are implicated in such alteration and they could represent promising targets for therapeutic intervention.

Fetal cardiac function by three-dimensional ultrasound using 4D-STIC and VOCAL - an update

Three- and four-dimensional (3D/4D) ultrasonography with spatio-temporal image correlation (4D-STIC) allows obtaining fetal cardiac volumes and their static and real-time analysis in multiplanar and rendering modes. Cardiac biometrics and Doppler-echocardiographic parameters for evaluation of fetal heart function, including cardiac output and stroke volume, can be analyzed using M-mode, two-dimensional (2D), and 3D/4D cardiac ultrasound. In recent years, functional echocardiography has been used to study fetuses without a structurally cardiac defect but who are at risk of heart failure due to the presence of extra-cardiac conditions, such as, fetal growth restriction, tumors/masses, twin-to-twin transfusion syndrome, fetal anemia (Rh alloimmunization), congenital infections, or maternal diabetes mellitus. The assessment of cardiac function provides important information on hemodynamic status and can help optimize the best time for delivery and reduce perinatal morbidity and mortality. Since 2003, with the advent of the 4D-STIC software, it is possible to evaluate the fetal heart in multiplanar, and rendering modes. This technology associated with virtual organ computer-aided analysis (VOCAL) enables determining the ventricular volume (end-diastole, end-systole), the stroke-volume, the ejection fraction, and the cardiac output of each ventricle. Since 2004, several studies demonstrated that the 4D-STIC and VOCAL had good reproducibility to measure cardiac volumes This study reviews published studies that evaluated the fetal cardiac function by 3D ultrasound using 4D-STIC and VOCAL software.

Sertraline use during pregnancy and effect on fetal cardiac function

Objectives: The objective of this study was to evaluate the fetal cardiac function in human pregnancies exposed to sertraline (a selective serotonin reuptake inhibitor) compared to unexposed pregnancies.Method: We included 44 women in gestational week 25 + 0 days to week 26 + 6 days. Fifteen women used sertraline (50-150 mg per day), and 29 women used no daily medication. We assessed fetal cardiac function by Myocardial Performance Index (MPI), E/A ratios and by tricuspid and mitral annular plane systolic excursion (TAPSE and MAPSE) measured by 2D M-mode and by 4D eSTIC M-mode.Results: There were no differences between the sertraline exposed and the unexposed. The mean difference of MPI was 0.03 (95% CI -0.08-0.03), of tricuspid and mitral E/A ratios 0.00 (95% CI -0.03-0.05) and 0.03 (95% CI -0.07-0.01), respectively. The mean difference of TAPSE, by 2D and eSTIC, was 0.07 mm (95% CI -0.56-0.41) and 0.10 mm (95% CI -0.55-0.34). Mean difference of MAPSE, by 2D and eSTIC was 0.16 mm (95% CI -0.22-0.53) and 0.24 mm (95% CI -0.16-0.65), respectively. Serum levels of sertraline in exposed participants ranged from 33-266, median 92 nmol/L.Conclusions: We found no significant differences in fetal cardiac function, assessed by TAPSE, MAPSE, MPI and E/A ratios, in pregnancies exposed to sertraline compared to the unexposed.

Postnatal Myocardial Function in Monochorionic Diamniotic Twins with Twin-to-Twin Transfusion Syndrome following Selective Laser Photocoagulation of the Communicating Placental Vessels

BACKGROUND

Monochorionic diamniotic (MCDA) twins are at risk for developing twin-to-twin transfusion syndrome (TTTS) throughout pregnancy. This may lead to myocardial dysfunction in the recipient and/or donor twin that persists beyond delivery. Selective laser photocoagulation of the communicating placental vessels (SLPCV) attempts to mitigate the cardiovascular outcomes. The objective of this study was to characterize early postnatal myocardial performance in MCDA twins with TTTS with and without SLPCV.

METHODS

A prospective study was performed of four MCDA twin groups: (1) uncomplicated MCDA twins, (2) MCDA twins with selective fetal growth restriction, (3) MCDA twins with TTTS following SLPCV (TTTS with SLPCV), and (4) MCDA twins with TTTS who did not undergo SLPCV (TTTS without SLPCV). Fifty-four twin pairs were enrolled: 23 uncomplicated MCDA twin pairs, 15 pairs with selective fetal growth restriction, seven TTTS pairs with SLPCV, and seven TTTS pairs without SLPCV. In each group, twin pairs were divided by birth weight into donor (smaller) and recipient (larger) and compared. Echocardiography was performed on day 1, day 2, and between days 5 and 7 of age, and myocardial performance was characterized by speckle-tracking echocardiography-derived left ventricular and right ventricular longitudinal strain (LS) and systolic strain rate (LSR). Longitudinal strain and longitudinal systolic strain rate are expressed as absolute values.

RESULTS

Compared with all recipient groups, recipient TTTS without SLPCV infants had lower left ventricular LS (16 ± 3% vs 22%-24%, P < .01) and right ventricular LS (15 ± 5% vs 21%-24%, P < .01) on day 1 that persisted throughout the first week of age. Left ventricular LSR (1.7 ± 0.3 vs 2.3 ± 0.3 sec^-1, P < .05) and right ventricular LSR (1.5 ± 0.4 vs 1.7 ± 0.5 sec^-1, P < .05) were both lower in the recipient compared with the donor twin in the TTTS without SLPCV group. LS and LSR measurements were similar among all four donor twin groups.

CONCLUSIONS

Biventricular performance is diminished in recipient MCDA twins with TTTS who are not treated with SLPCV, highlighting the need for close monitoring of their hemodynamic status during the early neonatal period.

Comparison of Longitudinal and Apical Foetal Speckle Tracking Echocardiography Using Tissue Motion Annular Displacement and Segmental Longitudinal Strain

The aim of our prospective pilot study with exploratory analysis was to compare longitudinal and apical foetal speckle tracking echocardiography (STE) using tissue motion annular displacement (TMAD) and segmental longitudinal strain (SLS). We compared two different STE quantification tools in a longitudinal and apical four-chamber view in 57 normal foetuses between 20 and 40 wk of gestation. Myocardial mechanical dyssynchrony and strain were assessed using offline quantification software (QLab Version 10.3, Philips Medical Systems, Andover, MA, USA). We compared the dyssynchrony measurements with TMAD and SLS in longitudinal and apical four-chamber views. Furthermore, we examined the segmental strain values of both ventricles with SLS and compared the differences between longitudinal and apical measurements. Dyssynchrony measurements with TMAD and SLS and strain measurements with SLS were feasible in all cases. In the apical view, the dyssynchrony measurements with TMAD were systematically greater than those achieved with SLS (p < 0.001). For the longitudinal view, no differences were observed between tools (p = 0.153). The application of SLS provided similar results for dyssynchrony in both views (intra-class correlation coefficient [ICC] = 0.281, p = 0.623), but the strain measurements in the left and right ventricles differed significantly between views (ICC = -0.082, p = 0.011, and ICC = -0.061, p = 0.024, respectively). For TMAD, we found large differences in the dyssynchrony values between longitudinal and apical assessment (ICC = -0.060, p = 0.03). Furthermore, TMAD exhibited reduced accuracy in the system's automatic tracking algorithm, limiting the data quality. The dyssynchrony assessment is affected less by the foetal position in SLS than in TMAD. The strain readings in SLS varied depending on the view in which they were assessed. The application of TMAD cannot be recommended for foetal STE.

Fetal Macrosomia, Polyhydramnios and Cardiac Anomalies may be Helpful to Predict Poor Outcome in Neonate – Case Report of a Possible Fetal Rasopathy with Sonographic and Neonatal Findings and Genetic Evaluation

This is a case report about very rare findings in 2nd half of pregnancy (after normal 1 trimester scan ) at 18th week of gestation fetal macrosomia was detected unrelated to maternal diabetes, and acceleration fetal growth later on with unusual cardiac abnormalities (fetal cardiomegaly, cardiomyopathy, partial abnormal venous connection ). Progressive features of congestive heart failure with polyhydramnios in a fetus with estimated 5500 g predicted a poor outcome and severe neonatal condition, which was presented and discussed with the parents to be. Casearean section was performed at 33rd weeks of gestation due to maternal dyscomfort, severe legs edema and her tachypnoe. Baby boy was delivered with birth weight of 5050g, Apgar 4 with mutiple tumors. Conservative care was introduced and neonated died on the 3rd day. Differential diagnosis was discussed with special attention to Costello syndrome however without proved by genetic make-up from neonatal blood.

Detection and assessment of brain injury in the growth-restricted fetus and neonate

Fetal growth restriction (FGR) is a common complication of pregnancy and, in severe cases, is associated with elevated rates of perinatal mortality, neonatal morbidity, and poor neurodevelopmental outcomes. The leading cause of FGR is placental insufficiency, with the placenta failing to adequately meet the increasing oxygen and nutritional needs of the growing fetus with advancing gestation. The resultant chronic fetal hypoxia induces a decrease in fetal growth, and a redistribution of blood flow preferentially to the brain. However, this adaptation does not ensure normal brain development. Early detection of brain injury in FGR, allowing for the prediction of short- and long-term neurodevelopmental consequences, remains a significant challenge. Furthermore, in FGR infants the detection and diagnosis of neuropathology is complicated by preterm birth, the etiological heterogeneity of FGR, timing of onset of growth restriction, its severity, and coexisting complications. In this review, we examine existing and emerging diagnostic tools from human and preclinical studies for the detection and assessment of brain injury in FGR fetuses and neonates. Increased detection rates, and early detection of brain injury associated with FGR, will offer opportunities for developing and assessing interventions to improve long-term outcomes.

Assessment of Cardiac Function in Fetuses of Gestational Diabetic Mothers During the Second Trimester

Fetuses of diabetic mothers may have structural or functional cardiac abnormalities which increase morbidity and mortality. Isolated functional abnormalities have been identified in the third trimester. The aim of the present study was to assess fetal cardiac function (systolic, diastolic, and global myocardial performance) in the second trimester in mothers with gestational diabetes, and also to relate cardiac function with glycemic control. Mothers with gestational diabetes mellitus referred for fetal cardiac evaluation in the second trimester (between 19 and 24 weeks) from March 2015 to February 2016 were enrolled as case subjects in this study. Non-diabetic mothers who had a fetal echocardiogram done between 19 and 24 weeks for other indications were enrolled as controls. Functional cardiac variables showed a statistically significant difference in isovolumetric relaxation and contraction times and the myocardial performance index and mitral E/A ratios in the gestational diabetic group (p = 0.003). Mitral annular plane systolic excursion was significantly less in the diabetic group (p = 0.01). The only functional cardiac variable found abnormal in mothers with poor glycemic control was the prolonged isovolumetric relaxation time. Functional cardiac abnormalities can be detected in the second trimester in fetuses of gestational diabetic mothers and timely intervention can improve postnatal outcomes.

N-terminal pro-B-type natriuretic peptide in amniotic fluid of fetuses with known or suspected cardiac load

Background

Myocardial dysfunction occurs in a variety of fetal disorders. Findings from adult cardiology, where n-terminal pro-B-type natriuretic peptide (nt-proBNP) is an established biomarker of left ventricular dysfunction have been extended to fetal life. Since fetal blood sampling is technically challenging we investigated amniotic fluid nt-proBNP for its suitability to diagnose fetal myocardial dysfunction.

Methods

Ultrasound, Doppler examination and echocardiography was applied to classify cases and controls. Amniotic fluid nt-proBNP to amniotic fluid total protein ratio was calculated and compared to the gestational age-dependent reference intervals. In a subset of cases, fetal and maternal plasma nt-proBNP levels were determined.

Results

Specimen from 391 fetuses could be analyzed (171 cases, 220 controls). There was a high correlation between amniotic fluid and fetal blood nt-proBNP levels (r = 0.441 for cases; r = 0.515 for controls), whereas no correlation could be detected between maternal and fetal (blood and amniotic fluid) nt-proBNP concentrations. Specificity and positive likelihood ratio of amniotic fluid nt-proBNP to amniotic fluid total protein ratio were high (0.97 and 4.3, respectively).

Conclusion

Amniotic fluid nt-proBNP measurement allows diagnostic confirmation of fetal myocardial dysfunction. It may serve as a useful adjunct in addition and correlation to existing tests of myocardial function, particularly in the context of invasive fetal therapy, where access to the amniotic cavity is part of the procedure.

The Aortic Isthmus: A Significant yet Underexplored Watershed of the Fetal Circulation

The aortic isthmus (AoI) is a unique fetal watershed with a waveform reflecting its complex haemodynamic physiology. The systolic component represents left and right ventricular systolic ejection, and the diastolic component represents comparative downstream vascular impedance between the brachiocephalic and subdiaphragmatic fetal circulations. Several indices have been devised to quantify different components of the waveform, including the pulsatility index, resistance index, isthmic flow index, and recently the isthmic systolic index. There have been promising preliminary studies applying these indices to both cardiac (congenital) and extracardiac pathologies, including intrauterine growth restriction and twin-twin transfusion syndrome. However, the waveform's multifactorial origin has proven to be challenging, and the difficulty in separating various components of the waveform could explain that AoI evaluation does not have a clear clinical utility. Further research is underway to realise the full potential of this vessel in fetal cardiac and haemodynamically compromised pathological conditions. In this review article we outline the physiological origin of this Doppler waveform, describe in detail the various published indices, summarise the published literature to date, and finally outline potential future research and hopefully clinical applications.