Pulmonary artery/aorta ratio in simple screening for fetal outflow tract abnormalities during the second trimester

Fetal cardiac screening: 1st trimester and beyond

Congenital heart defects (CHD) are the most common birth defect and a leading cause of infant morbidity and mortality. CHD often occurs in low-risk pregnant patients, which underscores the importance of routine fetal cardiac screening at the time of the 2nd trimester ultrasound. Prenatal diagnosis of CHD is important for counseling and decision-making, focused diagnostic testing, and optimal perinatal and delivery management. As a result, prenatal diagnosis has led to improved neonatal and infant outcomes. Updated fetal cardiac screening guidelines, coupled with technological advancements and educational efforts, have resulted in increased prenatal detection of CHD in both low- and high-risk populations. However, room for improvement remains. In recent years, fetal cardiac screening for specific high-risk populations has started in the 1st trimester, which is a trend that is likely to expand over time. This review discusses fetal cardiac screening throughout pregnancy.

Longitudinal Behavior of Left-Ventricular Strain in Fetal Growth Restriction

Fetal growth restriction (FGR) is associated with an increased risk of adverse outcomes resulting from adaptive cardiovascular changes in conditions of placental insufficiency, leading to cardiac deformation and dysfunction, which can be evaluated with 2D speckle tracking echocardiography (2D-STE). The aim of the present study was to evaluate whether reduced fetal growth is associated with cardiac left-ventricle (LV) dysfunction, using 2D-STE software widely used in postnatal echocardiography. A prospective longitudinal cohort study was performed, and global (GLO) and segmental LV longitudinal strain was measured offline and compared between FGR and appropriate-for-gestational-age (AGA) fetuses throughout gestation. All cases of FGR fetuses were paired 1:2 to AGA fetuses, and linear mixed model analysis was performed to compare behavior differences between groups throughout pregnancy. Our study shows LV fetal longitudinal strain in FGR and AGA fetuses differed upon diagnosis and behaved differently throughout gestation. FGR fetuses had lower LV strain values, both global and segmental, in comparison to AGA, suggesting subclinical cardiac dysfunction. Our study provides more data regarding fetal cardiac function in cases of placental dysfunction, as well as highlights the potential use of 2D-STE in the follow-up of cardiac function in these fetuses.

Tetralogy of Fallot and Outlet Ventricular Septal Defect with Anterior Malalignment Detected at Early Fetal Echocardiography

OBJECTIVES

To examine the evolution of tetralogy of Fallot (TOF) and outlet ventricular septal defect (VSD) with anterior malalignment (am) from the initial diagnosis at early fetal echocardiography through the gestation and to evaluate the impact of the first-trimester scan on the outcome.

METHODS

We identified cases of TOF or outlet VSD with am diagnosed before 16 weeks' gestation. For all cases, prenatal data and pregnancy outcomes were evaluated. In continuing pregnancies, the evolution in severity of the disease was assessed.

RESULTS

Fifty-one fetuses with TOF or outlet VSD with am were diagnosed at early fetal echocardiography. Parents opted for termination of pregnancy in all 23 cases associated with additional anomalies. In 2 of 28 continuing pregnancies, there was an intrauterine death. In the remaining 26, there was progression in severity in 7 (by 20-22 weeks in 3 cases and during the third trimester in the remaining 4).

CONCLUSIONS

TOF and outlet VSD with am diagnosed before 16 weeks' gestation can progress in severity throughout pregnancy in over one-quarter of cases. In addition, a high proportion of cases diagnosed in the first trimester may have associated extracardiac anomalies, with a significant impact on clinical management and on the rate of early termination of pregnancy.

Reference ranges and Z-scores for fetal cardiac measurements from two-dimensional echocardiography in Asian population

Currently available fetal echocardiographic reference values are derived mainly from North American and European population studies, and there is a lack of reference z-score for fetal echocardiographic measurement in Asian populations. The aim of this study was to establish normal ranges of echocardiographic measurements and z-scores in healthy Asian fetuses. A total of 575 healthy pregnant Taiwanese with an estimated gestational age from 14 to 38 weeks were enrolled voluntarily for this observational study. Standard two-dimensional echocardiography was performed to obtain measurements of the cardiac chambers and great arteries of the developing fetuses. In contrast to past studies, our sample was more evenly distributed for estimated gestational age (p<0.001). We present percentile graphs for 13 fetal echocardiographic measurements from the knowledge of estimated gestational age, biparietal distance, head circumference, abdominal circumference, and femur length. Most cardiac structures and developmental markers had linear models as the best-fitting, except for transverse aortic isthmus by estimated gestational age and transverse ductus arteriosus by femur length. Our findings indicate that estimated gestational age was generally the best model for fetal heart development, while head circumferences could be used as an optimal developmental marker to predict left atrium, right atrium, right ventricle, pulmonary annulus, and ductus arteriosus. Lastly, we developed nomograms for each of the 13 fetal heart measurements by each developmental markers. This is the first study providing echocardiographic reference ranges and nomograms for Asian fetuses. Computing z-scores from nomograms helps in standardizing comparisons and adds additional prognostic information to the diagnosis of congenital heart disease.

Differential diagnosis of fetal large ventricular septal defect and tetralogy of Fallot based on big data analysis

BACKGROUND AND OBJECTIVES

To analyze echocardiographic parameters of fetal large ventricular septal defect (VSD) and tetralogy of Fallot (TOF) in the context of multicenter data and big data analysis because these two diseases are often misdiagnosed in fetuses, and to find the key parameters for the differential diagnosis of these two diseases.

METHODS

A total of 305 cases of large VSD and 192 cases of TOF diagnosed by fetal echocardiography from August 2010 to July 2016 from the database of Beijing Key Laboratory of Fetal Heart Defects were analyzed. Quantile regression of the 48 echocardiographic parameters of the 6272 normal fetuses from seven Chinese medical institutions was performed to determine the Q-score. The forward selection method and the naive Bayesian classification method were used to analyze the core differential diagnostic variables of fetal TOF and VSD.

RESULTS

The Q-score of the internal diameter of the aorta (AO Q-score), the ratio of the diameter of the pulmonary artery to the internal diameter of the aorta (PA/AO), and the Q-score of the ratio of the diameter of the pulmonary artery to the internal diameter of the aorta (PA/AO Q-score) were key parameters for the differential diagnosis of fetal large VSD and TOF. PA/AO was the primary parameter, with an area under the receiver operating characteristic curve of 0.951.

CONCLUSIONS

These findings provide a new method for the prenatal diagnosis of large VSD and TOF and a theoretical basis for the intelligent diagnosis of large VSD and TOF.

Smart-planes fetal heart (S-planes FH) software to quantitative evaluate the fetal great arteries

OBJECTIVES

To explore the feasibility of applying smart-planes fetal heart (S-Planes FH) to 3D volumes to generate and display the outflow tract views (OFTVs) and evaluate its agreement and reliability in determining fetal vessel dimensions.

METHODS

A total of 147 normal fetuses in the second or third trimester were enrolled. Once conventional 2D sonographic examination was finished, one or more 3D static volumes were then acquired in the 4-chamber view (4CV). The OFTVs automatically generated and displayed via a simple offline operation using S-Planes FH software. Per fetus, a single qualified S-Planes FH image was selected by an expert. The inner diameters of the aorta (AO) and pulmonary artery (PA) were measured in 2D and S-Planes FH images, respectively. The agreement and reliability of the two methods were verified by the Bland-Altman method and the intraclass correlation coefficient (ICC), respectively.

RESULTS

A total of 515 3D static volumes were successfully acquired in 147 fetuses. The OFTVs were generated and displayed using S-Planes FH in 138 (93.9%) cases. S-Planes FH had good agreement in measuring the diameters of great arteries (95% CI of limits, -0.9419 to 1.1464 for AO diameter, -0.8871 to 1.7007 for PA diameter). The intraobserver and interobserver ICCs in this study were greater than 0.81, indicating almost perfect reliability of the two methods with regard to observers.

CONCLUSIONS

S-Planes FH software is a feasible method for generating OFTVs as well as determining vessel dimensions in the second and third trimesters and had good agreement with 2D examination. Therefore, it possesses clinical value in screening for CHD and can be operated by different sonographers.

Main pulmonary artery cross-section ratio is low in fetuses with tetralogy of Fallot and ductus arteriosus-dependent pulmonary circulation

OBJECTIVES

This study aimed to determine fetal echocardiographic features of tetralogy of Fallot in association with postnatal outcomes.

METHODS

The Z-scores of the main and bilateral pulmonary arteries and the aorta were measured, and the following variables were calculated in 13 fetuses with tetralogy of Fallot: pulmonary artery-to-aorta ratio and main pulmonary artery cross-section ratio - the main pulmonary artery diameter squared divided by the sum of the diameter squared of the left and right pulmonary arteries. Fetuses were classified as having ductus arteriosus-dependent or ductus arteriosus-independent pulmonary circulation.

RESULTS

We included two infants with pulmonary atresia and six infants with ductus-dependent pulmonary circulation, who underwent systemic-to-pulmonary shunt surgeries at ⩽1 month of age. The Z-scores of the main pulmonary artery and the pulmonary artery-to-aorta ratio in fetuses with ductus-dependent pulmonary circulation were lesser than those in fetuses with ductus independence, but not significantly. The main pulmonary artery cross-section ratio in fetuses with ductus dependence was significantly lesser (0.65±0.44 versus 1.56±0.48, p<0.005). Besides, the flow of the ductus arteriosus was directed from the aorta to the pulmonary artery in the ductus arteriosus-dependent group during the fetal period.

CONCLUSIONS

The main pulmonary artery cross-section ratio was the most significant variable for predicting postnatal outcomes in fetuses with tetralogy of Fallot.

Antenatal diagnosis of idiopathic dilatation of pulmonary artery with 3D power doppler imaging

We present a case of antenatal diagnosis of idiopathic dilatation of the pulmonary artery by three-dimensional power Doppler imaging (HDliveFlow with silhouette mode). Two-dimensional sonography clearly demonstrated a 10.4-mm-diameter fetal pulmonary artery (PA), whereas the aorta (Ao) diameter was 5.04 mm. HDliveFlow clearly demonstrated the spatial relationships and different sizes of PA and Ao. The PA size returned to normal (8.0 mm) on the 11th day after birth (Ao: 9.0 mm). HDliveFlow may be an adjunctive tool to two-dimensional sonography to diagnose abnormalities of fetal great vessels. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:121-123, 2017.

Length to width ratio of the ductus venosus in simple screening for fetal congenital heart diseases in the second trimester

Antenatal diagnosis of congenital heart disease (CHD) is still low even though screening was first introduced over 25 years ago. The purpose of our study was to determine the efficacy of a second-trimester prenatal ultrasonographic method of screening for CHD.From September 2012 to September 2013, the length and width of the fetal ductus venosus were measured sonographically in 1006 singleton fetuses, and the ratio of length to width was calculated. The accuracy of each fetal measurement and Doppler ultrasonography were determined. The standard fetal echocardiographic evaluations including 2-dimensional gray-scale imaging, color, and Doppler color flow mapping were performed. The transducer was aligned to the long axis of the fetal trunk to view the ductus venosus in its full length, including the inlet (isthmus) and outlet portions of the vessel. The diameters of the vessel inner wall and mid-point of the ductus venosus were measured using calipers. All scans and fetal measurements were conducted by a registered sonographer with more than 20 years of perinatal ultrasound screening experience.Of the 1006 singleton fetuses between 19 and 28 weeks' gestation, 36 had CHD. The ductus venosus length/width ratio (DVR) for the first CHD screening was extremely sensitive at 88.90%, with a specificity of 99.10% for the cardiac abnormalities included in this study. Chromosomal anomalies accompanied CHD in 0.4% (4/1006) of all cases and 11.11% (4/36) of the CHD cases.The DVR differed significantly between fetuses with CHD and normal fetuses during the second trimester. Careful assessment of the ratio should be a part of the sonographic examination of every fetus. In the case of a small DVR, advanced echocardiography and karyotype analysis should be performed. The ratio is a helpful tool for screening CHD abnormalities prenatally in the Chinese population.

Simplifying ultrasound assessment of the fetal heart: Incorporating the complete Three Vessel View into routine screening

Introduction: As our experience and ultrasound resolution have improved significantly in last 30 years it is possible to detect most of the major cardiac abnormalities prenatally with high degree of accuracy.

Method: Current screening techniques have poor detection rate for congenital heart diseases (CHD) and nearly half of the major cardiac abnormalities mainly of Great Arteries goes unrecognised. A high detection rate for major CHDs can be achieved in a screening setting by improving techniques of routine screening in the low risk population.

Conclusion: This article summarises the alternative strategies to examine the outflow tracts and Great Arteries, its correct interpretation and examples of abnormal views.

Pattern-based approach to fetal congenital cardiovascular anomalies using the transverse aortic arch view on prenatal cardiac MRI

Fetal echocardiography is the imaging modality of choice for prenatal diagnosis of congenital cardiovascular anomalies. However, echocardiography has limitations. Fetal cardiac magnetic resonance imaging (MRI) has the potential to complement US in detecting congenital cardiovascular anomalies. This article draws on our experience; it describes the transverse aortic arch view on fetal cardiac MRI and important clues on an abnormal transverse view at the level of the aortic arch to the diagnosis of fetal congenital cardiovascular anomalies.

Cardiovascular Z-scores in fetuses with tetralogy of Fallot

OBJECTIVE

To establish formulae for the calculation of fetal cardiovascular Z-scores based on femur length (FL), and to compare cardiovascular parameters between fetuses with tetralogy of Fallot (TOF) and normal fetuses in order to assess their value for the prenatal diagnosis of TOF.

METHODS

A total of 329 normal fetuses and 43 fetuses with TOF were included in this study. Eleven cardiovascular dimensions were measured offline after cardiac spatiotemporal image correlation volume acquisition. Normal cardiovascular Z-score formulae were constructed for these measurements based on FL by performing a standard regression analysis followed by weighted regression of absolute residual values. The following ratios were calculated: right ventricular internal diameter (RVID) to left ventricular internal diameter (LVID) and pulmonary artery diameter (PA) to aorta diameter (Ao). Subsequently, all parameters were compared between the normal and TOF groups.

RESULTS

Formulae for calculating Z-scores for the 11 cardiovascular dimensions were constructed. FL was significantly correlated with all cardiovascular dimensions assessed (r = 0.816-0.944, P < 0.001 for all). RVID, Ao, PA, aortic arch isthmus, and ductus arteriosus mean Z-scores and PA/Ao ratio were statistically significantly different between normal fetuses and those with TOF. In the TOF group, all Ao Z-scores (43/43) were > + 2 and all PA/Ao ratios (43/43) were below the normal 95% range. However, only 48.8% (21/43) of the PA Z-scores were < -2.

CONCLUSIONS

The cardiovascular Z-score formulae developed can provide a quantitative basis for the prenatal diagnosis of TOF. Aortic dilatation and abnormal PA/Ao ratio may be markers for the antenatal diagnosis of TOF.

Prenatal ultrasound screening of congenital heart disease in the general population: general concepts, guidelines, differential diagnoses

Congenital heart diseases (CHDs) carry a high prevalence rate in the general population (0.8%-1%). Most fetal CHDs occur in patients without any risk factors. The prenatal recognition of CHD has major impacts on the pregnancy and its outcome. The aforementioned data justify prenatal ultrasound (US) screening of CHD in the general low-risk population. As demonstrated in the literature, the application of an extended basic US cardiac examination improves the detection of CHD, in particular the conotruncal anomalies. The stepwise method suggested for fetal heart US screening during the mid-second trimester sonogram is based on 4 routine axial views of heart and great vessels: (1) a transverse view of the superior abdomen, (2) a 4-chamber view, (3) a 3-vessel view, and (4) a transverse view of the aortic arch. This protocol can be obtained rapidly because these scans are easy to perform. Despite the fact that the sequential segmental approach universally used in the postnatal diagnosis of CHD is not specifically addressed here, the detected anomalies can be categorized according to these views, and a short differential diagnosis proposed. Abnormal cardiac and/or vascular landmarks shown on these key scans should lead to a referral in the fetal cardiac center for a more precise evaluation, as well as for counseling.

Performance of different scan protocols of fetal echocardiography in the diagnosis of fetal congenital heart disease: a systematic review and meta-analysis

OBJECTIVE

The rapid progress in fetal echocardiography has lead to early detection of congenital heart diseases. Increasing evidences have shown that prenatal diagnosis could be life saving in certain cases. However, there is no agreement on which protocol is most adaptive diagnostic one. Thus, we use meta-analysis to conduct a pooled performance test on 5 diagnostic protocols.

METHODS

We searched PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials and WHO clinical trails registry center to identify relevant studies up to August, 2012. We performed meta-analysis in a fixed/random-effect model using Meta-disc 1.4. We used STATA 11.0 to estimate the publication bias and SPSS 17.0 to evaluate variance.

RESULTS

We use results from 81 studies in 63 articles to analyze the pooled accuracy. The overall performance of pooled sensitivities of spatiotemporal image correlation (STIC), extend cardiac echography examination (ECEE) and 4 chambers view + outflow tract view + 3 vessels and trachea view (4 CV+OTV+3 VTV) were around 0.90, which was significant higher than that of 4 chambers view + outflow tract view or 3 vessels and trachea view (4 CV+OTV/3 VTV) and 4 chambers view (4 CV). Unfortunately the pooled specificity of STIC was 0.92, which was significant lower than that of other 4 protocols which reached at 1.00. The area under the summary receiver operating characteristic curves value of STIC, ECEE, 4 CV+OTV+3 VTV, 4 CV+OTV/3 VTV and 4 CV were 0.9700, 0.9971, 0.9983, 0.9929 and 0.9928 respectively.

CONCLUSION

These results suggest a great diagnostic potential for fetal echocardiography detection as a reliable method of fetal congenital heart disease. But at least 3 sections view (4 CV, OTV and 3 VTV) should be included in scan protocol, while the STIC can be used to provide more information for local details of defects, and can not be used to make a definite diagnosis alone with its low specificity.

Detailed ultrasound screening in the second trimester: pictorial essay of normal fetal anatomy

Today, ultrasound is the main diagnostic tool in the prenatal detection of congenital abnormalities. Therefore, ultrasound examination should be offered to all pregnant women. A detailed sonographic examination of the fetus is usually performed between 18 and 22 weeks of pregnancy. The accurate recognition of normal fetal anatomy is very important for the detection of both minor and major defects. The purpose of this pictorial essay is to show fetal anatomic structures, which have to be examined between the 18(th) and 22(nd) weeks of pregnancy, and present their standard measurements systematically and thoroughly in accordance with sonographically obtained ideal sections.

Comparison of cardiac Z-score with cardiac asymmetry for prenatal screening of congenital heart disease

OBJECTIVE

To determine the best screening tests for discriminating early indicators of cardiac hypoplasia in congenital heart disease (CHD) from normal variations in fetal cardiac growth.

METHODS

We retrospectively examined fetal echocardiograms from 90 infants with confirmed CHD: Group 1 (n = 35) with right-sided obstructive lesions and Group 2 (n = 55) with left-sided obstructive lesions. Our control group comprised 2735 normal fetuses, from which we determined fetal cardiac Z-scores of right ventricle (RV), left ventricle (LV), aorta (Ao) and pulmonary artery (PA) diameters and ratios of right to left ventricle (RV:LV) and pulmonary artery to aorta (PA:Ao) size. We compared our control group to Groups 1 and 2 using ANOVA and area under receiver-operating characteristics curve (AUC) analysis.

RESULTS

For Group 1, RV:LV ratio, RV-Z-score and PA:Ao ratio were the best screening tests, with highest AUCs (0.879, 0.868 and 0.832, respectively). For Group 2, the Ao-Z-score, PA:Ao and RV:LV ratios were the best screening tests, with AUCs of 0.770, 0.723 and 0.716, respectively.

CONCLUSION

None of the screening tests was found to be a perfect early discriminator for the cardiac lesions tested. Although ratios of PA:Ao and RV:LV are useful, they should be combined with fetal cardiac Z-scores to maximize screening sensitivity.

Simultaneous real-time imaging of four-chamber and left ventricular outflow tract views using xPlane imaging capability of a matrix array probe

OBJECTIVES

To determine the feasibility and reliability of using xPlane imaging to examine simultaneously the four-chamber and left ventricular outflow tract (LVOT) views in real time, to assess rotation angles from the four-chamber view to the LVOT view, and to investigate factors affecting the angles.

METHODS

In 145 fetuses at 11-37 weeks' gestation, we visualized the four-chamber view in one of three cardiac positions: a subcostal view with the apex at the 3 or 9 o'clock position; an apical view with the apex at the 12 or 6 o'clock position; or a view with the fetal heart apex midway between these two positions. We then used the rotation function of xPlane imaging, using the four-chamber view as the reference plane, to visualize the LVOT view simultaneously in real time on the secondary image plane, on the right side of the split screen, by rotating a reference line from 0° with a rotation step of 5°. The rotation angle necessary for the first appearance of LVOT was recorded as the first rotation angle. The reference line was then rotated until the LVOT was just out of view, and this last rotation angle was recorded as the second rotation angle. The difference between these two angles was recorded as the angle span of the LVOT display. Reliability was assessed by intraclass correlation coefficient (ICC).

RESULTS

Of the 145 fetuses examined, 29 had cardiac defects. Using xPlane imaging, the LVOT was visualized successfully after 14 weeks in 95.1% of cases. The first and second rotation angles varied significantly with cardiac position (P < 0.001); when the fetal heart was examined using a subcostal approach with the apex at the 3 or 9 o'clock position, the first rotation angle was smaller than that at the apical view for normal hearts (20° vs. 50°, P < 0.001). There was also a significant difference for the second rotation angle and for the angle span, between fetuses with and without normal LVOT (P = 0.038 and 0.006, respectively). Regarding intra- and interobserver reliability for measurement of first and second rotation angles, the ICCs were high (range, 0.847-0.980).

CONCLUSION

Using xPlane imaging, it is feasible to examine simultaneously the four-chamber and LVOT views in real time, and measurement of the rotation angles between these two views is reproducible. The rotation angles depend on the position of the fetal heart, and the normality of the LVOT. Proposed algorithms for examination of the fetal heart with three-/four-dimensional ultrasonography may need to be adapted to optimize visualization of the standard planes.

The 'question mark' sign as a new ultrasound marker of tetralogy of Fallot in the fetus

OBJECTIVE

To describe a new ultrasonographic marker, the 'question-mark' sign, to assist in the diagnosis of tetralogy of Fallot (TOF) in the fetus, and to evaluate its prevalence in TOF as compared with other cardiac defects.

METHODS

A prospective evaluation over a 5-year period of a consecutive series of 3998 pregnant women undergoing fetal echocardiography from 12 to 40 weeks' gestation due to high risk for congenital heart disease (CHD). Standard echocardiographic planes with color Doppler assessment and evaluation of the whole aortic arch, from the left ventricular outflow tract to the descending aorta in the axial upper mediastinum views, were performed. The question-mark sign corresponded with an enlarged and dilated ascending aorta and aortic arch in the three-vessel view of the upper fetal mediastinum. The frequency of this sign was evaluated in cases with TOF and in other cases of cardiac defects, as well as in fetuses with normal cardiac scans in this series.

RESULTS

CHD was diagnosed in a total of 447 (11.2%) fetuses at a median gestational age of 24 (range, 12-40) weeks. Forty-two of the 447 (9.4%) had TOF, of which 29 cases (69.0%) had classical TOF (pulmonary stenosis), nine (21.4%) pulmonary atresia and four (9.5%) absent pulmonary valve syndrome. A question-mark sign was observed in 16/29 (55.2%) cases of classical TOF and in 8/9 (88.9%) cases of TOF with pulmonary atresia. The sign was never observed in any of the cases of TOF with a right-sided aortic arch. Likewise, the sign was observed in 1/405 (0.2%) cases with other cardiac anomalies (a fetus with a complex cardiac defect) and in none of the fetuses with normal hearts.

CONCLUSIONS

The finding of an enlarged aorta with a question-mark shape should raise a strong suspicion of tetralogy of Fallot, in particular the variant with pulmonary atresia. This sign may be useful in screening considering that prenatal diagnosis of TOF by routine ultrasonography remains a challenge.

Analysis of the harmonized growth pattern of fetal organs by multidimensional scaling and hierarchical clustering

The development of an organ may be affected by various growth and differentiation factors released from other organs. These factors are believed to have important effects on the development of multiple organs. To detect and analyze harmonized development among multiple organs, similarities in growth patterns among fetal organs were examined using multivariate analysis. Ninety human fetuses obtained from the Kyoto Collection of Human Embryos were dissected. Harmonized development of organs was evaluated by multidimensional scaling and cluster analysis using measurements (length, width, height, and weight) of the fetal organs. Similar growth patterns were observed between the brain, including cerebrum, diencephalon, and midbrain (cerebrum-to-midbrain [Cer-Mid]), and pituitary (crown-rump length [CRL] 95-155 mm). Further, similar growth patterns were observed between the liver and Cer-Mid and cerebellum (Cb; CRL 156-202 mm), and between Cer-Mid and Cb (CRL 203-253 mm). Similarities in growth patterns were also observed between right and left lungs (CRL 99-235 mm) and between the aorta and heart (CRL 139-187 mm), but not between the lung and pulmonary trunk. These findings revealed synchronized development among fetal organs and suggested a functional and structural relationship among different organs in the prenatal period. These relationships include the existence of common factors in organ development, such as cross-talk mediated by humoral factors, and the presence of an anatomical and functional relationship in the fetal circulatory system.

Aorta larger than pulmonary artery in the fetal 3-vessel view

OBJECTIVE

Fetal great artery asymmetry may accompany congenital heart disease. The fetal echocardiographic 3-vessel view (3VV) allows assessment of the superior vena cava, ascending aorta (AA), and main pulmonary artery (MPA). Our aim was to determine the association of congenital heart disease in fetuses with an AA/MPA ratio of greater than 1.

METHODS

We electronically searched our fetal echocardiographic database for studies performed between March 2002 and January 2008 that showed 3VVs with AA/MPA ratios of greater than 1 and correlated the findings with the presence of congenital heart disease.

RESULTS

In 2797 fetal echocardiograms, we identified 31 fetuses with normal 4-chamber views showing AA/MPA ratios of greater than 1 in the 3VV. Of 31 fetuses, 25 (81%) had tetralogy of Fallot (ToF) or a ToF variant, and 6 (19%) had an aortic valve abnormality or isolated dilatation of the AA.

CONCLUSIONS

Screening obstetric fetal sonography showing a 3VV AA/MPA ratio of greater than 1 suggests congenital heart disease and indicates the need for comprehensive fetal echocardiography.

Screening for fetal abnormalities with ultrasound

PURPOSE OF REVIEW

This review serves to explore literature published during the past year that has focussed on sonographic screening for fetal abnormalities.

RECENT FINDINGS

The evolving nature of screening for fetal aneuploidy has continued to feature strongly in recent literature. There is growing interest in early detailed ultrasound of fetal anatomy at the time of nuchal translucency thickness assessment. Demonstration of tricuspid regurgitation and ductus venosus assessment have been shown to be beneficial additional second-line tests for aneuploidy screening in high-risk patients. Frontomaxillary facial angle assessment has been explored as a new marker for aneuploidy. The limitations of first-trimester nasal bone measurement were reiterated while its measurement has been shown to be beneficial in the second trimester, especially when calculated with multiples of the median. As regards second-trimester screening, studies have explored the effectiveness of congenital heart-defect screening and the efficiency of the genetic sonogram for trisomy 21. The role of nuchal translucency discordance in monochorionic twins has also been readdressed.

SUMMARY

Screening for fetal abnormalities continues to evolve with the introduction of novel techniques and the further refinement of previously proposed screening tools. How these modalities are implemented into routine clinical practice remains to be seen.

In vitro hemodynamic investigation of the embryonic aortic arch at late gestation

This study focuses on the dynamic flow through the fetal aortic arch driven by the concurrent action of right and left ventricles. We created a parametric pulsatile computational fluid dynamics (CFD) model of the fetal aortic junction with physiologic vessel geometries. To gain a better biophysical understanding, an in vitro experimental fetal flow loop for flow visualization was constructed for identical CFD conditions. CFD and in vitro experimental results were comparable. Swirling flow during the acceleration phase of the cardiac cycle and unidirectional flow following mid-deceleration phase were observed in pulmonary arteries (PA), head-neck vessels, and descending aorta. Right-to-left (oxygenated) blood flowed through the ductus arteriosus (DA) posterior relative to the antegrade left ventricular outflow tract (LVOT) stream and resembled jet flow. LVOT and right ventricular outflow tract flow mixing had not completed until approximately 3.5 descending aorta diameters downstream of the DA insertion into the aortic arch. Normal arch model flow patterns were then compared to flow patterns of four common congenital heart malformations that include aortic arch anomalies. Weak oscillatory reversing flow through the DA junction was observed only for the Tetralogy of Fallot configuration. PA and hypoplastic left heart syndrome configurations demonstrated complex, abnormal flow patterns in the PAs and head-neck vessels. Aortic coarctation resulted in large-scale recirculating flow in the aortic arch proximal to the DA. Intravascular flow patterns spatially correlated with abnormal vascular structures consistent with the paradigm that abnormal intravascular flow patterns associated with congenital heart disease influence vascular growth and function.