Normal fetal foramen flap and transatrial Doppler velocity pattern

How reliably does prenatal echocardiography predict urgent balloon atrial septostomy in fetuses with d-TGA?

OBJECTIVE

To analyze the prenatal and postnatal outcomes of fetuses with d-TGA and to determine whether prenatal echocardiography may predict postnatal urgent BAS.

STUDY DESIGN

A retrospective study of fetuses with d-TGA, for which fetal echocardiography was performed at our tertiary hospital from January 2018 to May 2023. We assessed the appearance of the septum primum and the FO flap in the four-chamber view as to whether the FO had a restrictive appearance during measurement of the diameter of the FO at its maximal angle to the attachment point. Color Doppler was used to detect VSDs and measure its diameter both in the four-chamber view and when visualizing the outlets of the great arteries in the sagittal section of the heart.

RESULTS

During the study period, 64 fetuses were diagnosed with d-TGA, which was also confirmed postnatally. Of these, 16 fetuses were excluded due to additional cardiac anomalies or the inability to reach the mother. In total, 48 cases were included in this series. In our study, the FO diameter was significantly decreased in the urgent BAS group, compared with the fetuses without urgent BAS (5.1 mm vs 6.3 mm). A cut off of 6 mm for the FO diameter (sensitivity, 73.3 %; specificity, 72.2 %; area under the curve [AUC], 0.764) and 3.2 mm for the VSD diameter (sensitivity, 75 %; specificity, 75 %; AUC, 0.728) suggested urgent BAS.

CONCLUSION

Prenatal echocardiography performed after 37 weeks of gestation in fetuses with d-TGA provides valuable information to estimate the need for postnatal urgent BAS that would prevent immediate life-threatening complications.

Complete Transposition of the Great Arteries in the Pediatric Field: A Multimodality Imaging Approach

The complete transposition of the great arteries (C-TGA) is a congenital cardiac anomaly characterized by the reversal of the main arteries. Early detection and precise management are crucial for optimal outcomes. This review emphasizes the integral role of multimodal imaging, including fetal echocardiography, transthoracic echocardiography (TTE), cardiovascular magnetic resonance (CMR), and cardiac computed tomography (CCT) in the diagnosis, treatment planning, and long-term follow-up of C-TGA. Fetal echocardiography plays a pivotal role in prenatal detection, enabling early intervention strategies. Despite technological advances, the detection rate varies, highlighting the need for improved screening protocols. TTE remains the cornerstone for initial diagnosis, surgical preparation, and postoperative evaluation, providing essential information on cardiac anatomy, ventricular function, and the presence of associated defects. CMR and CCT offer additional value in C-TGA assessment. CMR, free from ionizing radiation, provides detailed anatomical and functional insights from fetal life into adulthood, becoming increasingly important in evaluating complex cardiac structures and post-surgical outcomes. CCT, with its high-resolution imaging, is indispensable in delineating coronary anatomy and vascular structures, particularly when CMR is contraindicated or inconclusive. This review advocates for a comprehensive imaging approach, integrating TTE, CMR, and CCT to enhance diagnostic accuracy, guide therapeutic interventions, and monitor postoperative conditions in C-TGA patients. Such a multimodal strategy is vital for advancing patient care and improving long-term prognoses in this complex congenital heart disease.

D-Transposition of the great arteries with restrictive foramen ovale in the fetus: the dilemma of predicting the need for postnatal urgent balloon atrial septostomy

OBJECTIVE

Restrictive foramen ovale (FO) in dextro-transposition of the great arteries (d-TGA) with intact ventricular septum may lead to severe life-threatening hypoxia within the first hours of life, making urgent balloon atrial septostomy (BAS) inevitable. Reliable prenatal prediction of restrictive FO is crucial in these cases. However, current prenatal echocardiographic markers show low predictive value, and prenatal prediction often fails with fatal consequences for a subset of newborns. In this study, we described our experience and aimed to identify reliable predictive markers for BAS.

METHODS

We included 45 fetuses with isolated d-TGA that were diagnosed and delivered between 2010 and 2022 in two large German tertiary referral centers. Inclusion criteria were the availability of former prenatal ultrasound reports, of stored echocardiographic videos and still images, which had to be obtained within the last 14 days prior to delivery and that were of sufficient quality for retrospective re-analysis. Cardiac parameters were retrospectively assessed and their predictive value was evaluated.

RESULTS

Among the 45 included fetuses with d-TGA, 22 neonates had restrictive FO postnatally and required urgent BAS within the first 24 h of life. In contrast, 23 neonates had normal FO anatomy, but 4 of them unexpectedly showed inadequate interatrial mixing despite their normal FO anatomy, rapidly developed hypoxia and also required urgent BAS ('bad mixer'). Overall, 26 (58%) neonates required urgent BAS, whereas 19 (42%) achieved good O2 saturation and did not undergo urgent BAS. In the former prenatal ultrasound reports, restrictive FO with subsequent urgent BAS was correctly predicted in 11 of 22 cases (50% sensitivity), whereas a normal FO anatomy was correctly predicted in 19 of 23 cases (83% specificity). After current re-analysis of the stored videos and images, we identified three highly significant markers for restrictive FO: a FO diameter < 7 mm (p < 0.01), a fixed (p = 0.035) and a hypermobile (p = 0.014) FO flap. The maximum systolic flow velocities in the pulmonary veins were also significantly increased in restrictive FO (p = 0.021), but no cut-off value to reliably predict restrictive FO could be identified. If the above markers are applied, all 22 cases with restrictive FO and all 23 cases with normal FO anatomy could correctly be predicted (100% positive predictive value). Correct prediction of urgent BAS also succeeded in all 22 cases with restrictive FO (100% PPV), but naturally failed in 4 of the 23 cases with correctly predicted normal FO ('bad mixer') (82.6% negative predictive value).

CONCLUSION

Precise assessment of FO size and FO flap motility allows a reliable prenatal prediction of both restrictive and normal FO anatomy postnatally. Prediction of likelihood of urgent BAS also succeeds reliably in all fetuses with restrictive FO, but identification of the small subset of fetuses that also requires urgent BAS despite their normal FO anatomy fails, because the ability of sufficient postnatal interatrial mixing cannot be predicted prenatally. Therefore, all fetuses with prenatally diagnosed d-TGA should always be delivered in a tertiary center with cardiac catheter stand-by, allowing BAS within the first 24 h after birth, regardless of their predicted FO anatomy.

Prenatal risk factors for urgent atrial septostomy at birth in fetuses with transposition of the great arteries: a systematic review and meta-analysis

MATERIAL AND METHODS

Medline, Embase, and Cochrane databases were searched. The primary aim was to explore the differences in prenatal echocardiographic parameters among fetuses diagnosed with TGA that required urgent BAS within 24 h of birth due to life-threatening cyanosis compared to those who did not require such procedure. Random-effect meta-analyses were used to compute the data.

RESULTS

Six studies (292 fetuses) were included. Restrictive appearance of the FO was present in 64.5% (95% CI = 39.8-85.7) of fetuses with TGA requiring BAS at birth compared to 7.9% (95% CI = 2.1-16.8) not requiring such procedure (OR = 71.1; 95% CI = 8.3-608.5, p < .0001). Hypermobile appearance of the atrial septum was present in 39.1% (95% CI = 26.4-56.5) of fetuses requiring BAS at birth compared to 9.8% (95% CI = 1.4-24.3) of those which did (OR 3.6; 95% CI = 1.4-9.0, p = .05). There was no difference in the prevalence of redundant (p = .374) or fixed (p = .051) atrial septum, bidirectional flow in the DA (p = .26) or an abnormal size of the DA (p = .06) in fetuses requiring urgent BAS at birth compared to those which did not. Mean (±SD) size of the right atrium was smaller in the fetuses with TGA undergoing urgent BAS at birth (23.4 ± 6.7) compared to those which did not (29.2 ± 6.2, p = .01). The mean (±SD) ratio between the FO and the aortic valve diameters (1.01 ± 0.41 versus 1.41 ± 0.43, p = .009) and the mean (±SD) ratio between the FO diameter and the septal length (0.36 ± 0.13 versus 0.51 ± 0.14, p = .001) were significantly smaller in fetuses requiring compared to those not undergoing urgent BAS at birth. The diagnostic accuracy of each independent ultrasound marker of the need for urgent BAS showed an overall good specificity but a low sensitivity.

CONCLUSION

Fetal echocardiography prior to birth can stratify the risk of BAS in fetuses with TGA. Further studies are needed to validate these findings and build individualized multiparametric predictive models in order to more accurately identify those fetuses with TGA at a higher risk of urgent BAS after birth.

Fetal aortic coarctation: A combination of third-trimester echocardiographic parameters to improve the prediction of postnatal outcome

OBJECTIVES

This study aims to determine a combination of third-trimester echocardiographic parameters for improving the prenatal prediction of coarctation of the aorta (CoA) after birth.

METHODS

We included all cases of suspected CoA during fetal echocardiography performed in the second and/or third trimester of pregnancy at Gaslini Children's Hospital between January 2010 and December 2020. The last prenatal ultrasound evaluation was reviewed considering most of the echocardiographic criteria were already published for prenatal CoA diagnosis. Associated minor cardiac anomalies, such as a ventricular septal defect, persistent left superior vena cava (PLSCV), and redundant foramen ovale (FO) membrane, as well as postnatal outcomes, were reported. Initial perinatal management was defined based on the risk stratification of CoA during prenatal echocardiography. Neonates were divided into two groups depending on the presence or absence of CoA after birth.

RESULTS

A total of 91 fetuses with CoA suspicion were selected, of which 27 (30%) were confirmed with CoA after birth and underwent surgical repair. All cardiac parameters except redundant FO membrane and PLSCV showed a significant correlation with CoA. Statistical analysis confirmed that cardiovascular disproportion with right predominance carries an increased risk for occurrence of CoA, especially if already evident during the ultrasound evaluation in the second trimester. Aortic valve (AV) z-score and distal transverse aortic arch (TAA) z-score resulted as the best predictors of CoA after birth. The best cutoff point for CoA discrimination with ROC analysis was an AV z-score of -1.25 and a distal TAA z-score of -0.37. A total of 46% of those without CoA were diagnosed with a cardiac defect, which was not diagnosed in utero, pulmonary hypertension, or a genetic syndrome.

CONCLUSION

The current criteria for diagnosing CoA in utero allow accurate diagnosis of most severe cases but the rate of false positives remains relatively high for milder cases. A combination of anatomic and functional echocardiographic parameters might be used in stratifying the risk of CoA. We proposed the AV and the TAA diameter z-scores as the best predictors of CoA after birth. In addition, neonates without CoA deserve proper monitoring at birth because prenatal evidence of a significant cardiovascular discrepancy between the right and left cardiac structures has an inherent risk for additional morbidity postnatally.

Reliability of Fetal Echocardiography in Predicting Postnatal Critical Hypoxia in Patients with Transposition of Great Arteries and Intact Ventricular Septum

Critical hypoxemia soon after birth is the most critical preoperative determinant of neurological outcomes and survival in newborns with Dextro Transposition of the Great Arteries and Intact Ventricular Septum (D-TGAIVS). Our study aimed to define fetal echocardiographic aspects that can better predict neonates with D-TGAIVS at risk for restricted interatrial communication after birth. 31 fetuses with a prenatal diagnosis of D-TGAIVS were included in our study. We divided patients with D-TGAIVS according to the timing of balloon atrial septostomy: Urgent, Not-Urgent and no BAS. We identified five fetal echocardiographic aspects of the interatrial septum (redundant, aneurysmal, flat, fixed, hypermobile). No significant differences in these fetal echocardiographic features were found between the three different groups of D-TGAIVS according to the timing of balloon atrial septostmy. However, only two patients showed flat appearance of interatrial communication: both needed Urgent balloon atrial septostomy. The prevalence of hypermobile septum primum was significantly lower in the control group compared to patients with D-TGAIVS. Fetal echocardiographic aspects cannot predict patients with D-TGAIVS who will not need Urgent balloon atrial septostomy. Therefore, we recommended a delivery in a tertiary center, equipped for Urgent balloon atrial septostomy, for all patients with D-TGAIVS regardless of fetal echocardiographic features.

Urgent neonatal balloon atrial septostomy in simple transposition of the great arteries: predictive value of fetal cardiac parameters

OBJECTIVES

To investigate the impact of abnormal perinatal loading conditions on cardiac geometry and function in term fetuses and neonates with transposition of the great arteries with intact interventricular septum (simple TGA), and to explore the predictive value of fetal cardiac parameters for an urgent balloon atrial septostomy (BAS) after birth.

METHODS

This was a prospective longitudinal follow-up study of women delivering at term, including both uncomplicated pregnancies with normal outcome and pregnancies affected by fetal simple TGA. Conventional, spectral-tissue Doppler and speckle-tracking echocardiographic parameters were obtained within 1 week before delivery and within the first few hours after delivery. Neonates with simple TGA that required urgent BAS were assessed after the procedure and before corrective arterial switch surgery. Cardiac parameters were normalized by cardiac cycle length, ventricular end-diastolic length or end-diastolic dimension, as appropriate. Fetal and neonatal cardiac parameters were compared between simple-TGA cases and controls, and perinatal changes in the simple-TGA group were assessed. Receiver-operating-characteristics (ROC)-curve analysis was used to assess the predictive value of fetal cardiac parameters for urgent BAS after birth in the simple-TGA group.

RESULTS

A total of 67 pregnant women delivering at term were included in the study (54 normal pregnancies and 13 with a diagnosis of fetal simple TGA). Compared with normal term fetuses, term fetuses with simple TGA exhibited more globular hypertrophied ventricles, increased biventricular systolic function and diastolic dysfunction (right ventricular (RV) sphericity index (SI), 0.58 vs 0.54; left ventricular (LV)-SI, 0.55 vs 0.49; combined cardiac output (CCO), 483 vs 406 mL/min/kg; LV torsion, 4.3 vs 3.0 deg/cm; RV isovolumetric relaxation time (IVRT'), 127 vs 102 ms; P < 0.01 for all). Compared with normal neonates, neonates with simple TGA demonstrated biventricular hypertrophy, a more spherical right ventricle and altered systolic and diastolic functional parameters (RV-SI, 0.61 vs 0.43; RV myocardial performance index, 0.47 vs 0.34; CCO, 697 vs 486 mL/min/kg; LV-IVRT', 100 vs 79 ms; RV-IVRT', 106 vs 71 ms; P < 0.001 for all). Paired comparison of neonatal and fetal cardiac indices in the simple-TGA group showed persistence of the fetal phenotype, increased biventricular systolic myocardial contractility and CCO, and diastolic dysfunction (RV systolic myocardial velocity (S'), 0.31 vs 0.24 cm/s; LV-S', 0.23 vs 0.18 cm/s; CCO, 697 vs 483 mL/min/kg; LV torsion, 1.1 vs 4.3 deg/cm; P < 0.001 for all). Several fetal cardiac parameters in term fetuses with simple TGA demonstrated high predictive value for an urgent BAS procedure after birth. Our proposed novel fetal cardiac index, LV rotation-to-shortening ratio, as a potential marker of subendocardial dysfunction, for a cut-off value of ≥ 0.23, had an area under the ROC curve (AUC) of 0.94, sensitivity of 100% and specificity of 83%. For RV/LV end-diastolic area ratio ≥ 1.33, pulmonary-valve-to-aortic-valve-dimension ratio ≤ 0.89, RV/LV cardiac output ratio ≥ 1.38 and foramen-ovale-dimension-to-total-interatrial-septal-length ratio ≤ 0.27, AUC was 0.93-0.98, sensitivity was 86% and specificity was 83-100% for all.

CONCLUSIONS

Simple-TGA fetuses exhibited cardiac remodeling at term with more profound alterations in these cardiac parameters after birth, suggestive of adaptation to abnormal loading conditions and possible adaptive responses to hypoxemia. Perinatal adaptation in simple TGA might reflect persistence of the abnormal parallel arrangement of cardiovascular circulation and the presence of widely patent fetal shunts imposing volume load on the neonatal heart. The fetal cardiac parameters that showed high predictive value for urgent BAS after birth might reflect the impact of late-gestation pathophysiology and progressive hypoxemia on fetal cardiac geometry and function in simple TGA. If these findings are validated in larger prospective studies, detailed cardiac assessment of fetuses with simple TGA near term could facilitate improvements in perinatal management and refinement of the timing of postnatal intervention strategies to prevent adverse pregnancy outcomes. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Statistical Treatment of Clinical Investigations in Pediatric Cardiology

This paper describes various statistical methods used by the author during multiple studies conducted by the author. Initially, the data were scrutinized to ensure normal distribution, and expressed as mean ± standard deviation (SD) or standard error of mean (SEM) for normally distributed variables. Medians and ranges were given for the data with skewed distribution. Two tailed, paired t tests or independent sample t tests (analysis of variance) were used for normally distributed data, while non-parametric chi-square or similar other tests were utilized for data with skewed distribution. Statistical significance was set at a p value of < 0.05. Bonferroni correction was applied when the study involves multiple comparisons. A number of other statistical methods used during these studies were also discussed. Finally, special methods used in evaluating aortic remodeling subsequent to balloon angioplasty of native aortic coarctation were reviewed.

The Author's Contributions to Echocardiography Literature (Part I-1978-1990) †

The author has undertaken multiple echocardiographic studies during his academic career; most of these were published in peer-reviewed journals. These studies include an evaluation of the role of echocardiography in the estimation of left-to-right shunt in isolated ventricular septal defects, an examination of the utility of contrast echocardiography in the diagnosis of anomalous connection of the right superior vena cava to the left atrium, a description of pitfalls in M-mode echocardiographic assessment of the aortic root in left ventricular hypoplasia syndromes, reviews of echocardiographic evaluation of left ventricular function, study of the role of contrast echocardiography in the evaluation of hypoxemia following open heart surgery, a quantification of left ventricular muscle mass by m-mode echocardiography in children, an examination of race and sex related differences in echocardiographic measurements in children, study of cardiac size and function in patients with sickle cell disease, an examination of afterload reduction in the management of primary myocardial disease, study of the utility of echo-Doppler studies in the evaluation of the results of balloon pulmonary valvuloplasty, study of the usefulness of Doppler in the prediction of pressure gradients in valvar pulmonary stenosis, a review of Doppler echocardiography in noninvasive diagnoses of heart disease, echo-Doppler studies of the evaluation of the results of balloon angioplasty of aortic coarctation, study of the value of Doppler in the prediction of pressure gradients across coarctation of the aorta, and a characterization of foramen ovale and transatrial Doppler velocity patterns in the normal fetus.

New method to predict need for Rashkind procedure in fetuses with dextro-transposition of the great arteries

OBJECTIVE

Prenatal congenital heart disease classification systems distinguish between critical dextro-transposition of the great arteries (d-TGA) with restriction of the foramen ovale (FO) (which requires a Rashkind procedure within the first 24 h following delivery) and d-TGA for which surgery is planned (after prostaglandin perfusion or Rashkind procedure later than 24 h after delivery). However, current prenatal diagnostic criteria for postnatal FO restriction in d-TGA are inadequate, resulting in a high false-negative rate. We aimed to identify echocardiographic features to predict the urgent need for Rashkind procedure.

METHODS

We identified retrospectively 98 patients with singleton pregnancy diagnosed prenatally with fetal d-TGA at two European centers from 2006 to 2013. Two groups were compared: (1) those in whom the Rashkind procedure was performed within the first 24 h postnatally; and (2) those who did not undergo a Rashkind procedure before cardiac surgery. Exclusion criteria were: (1) no fetal echocardiography within 3 weeks prior to delivery (n = 18); (2) delivery before 37 weeks of gestation (n = 6); (3) improper or lack of measurement of pulmonary vein maximum flow velocity (n = 10); (4) lack of neonatal follow-up data (n = 9); (5) Rashkind procedure performed more than 24 h after delivery (n = 4).

RESULTS

Fifty-one patients met the inclusion criteria: 29 who underwent the Rashkind procedure and 22 who did not. There were no differences between these two study groups in terms of maternal age, gestational age at time of fetal echocardiography, fetal biometric measurements, estimated fetal weight, rate of Cesarean delivery, newborn weight or Apgar score at 1 min. There were also no differences during prenatal life between the two groups in terms of fetal cardiac size (heart area/chest area ratio), rate of disproportion between left and right ventricle, FO diameter and maximum velocity of flow through the FO. However, the pulmonary vein maximum velocity was significantly higher in the group requiring a Rashkind procedure (47.62 ± 7.48 vs 32.21 ± 5.47 cm/s; P < 0.001). The cut-off value of 41 cm/s provided maximum specificity (100%) and positive predictive value (100%) at only a slight cost of sensitivity (82%) and NPV (86%). The prenatal appearance of the FO also differed between the groups, the FO valve being flat in 52% of those requiring a Rashkind procedure.

CONCLUSIONS

In fetuses with d-TGA, prenatal sonographic findings of increased pulmonary venous blood flow and flattened FO valve were associated with the need for a Rashkind procedure within the first 24 h postnatally; these echocardiographic features could be used to predict prenatally a need for the procedure following delivery. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal diagnosis of congenital heart disease: A review of current knowledge

This article reviews important features to improve the diagnosis of congenital heart disease (CHD) by applying ultrasound in prenatal cardiac screening. As low and high-risk pregnancies for CHD are subject to routine obstetric ultrasound, the diagnosis of structural heart defects represents a challenge that involves a team of specialists and subspecialists on fetal ultrasonography. In this review, the images highlight normal anatomy of the heart as well as pathologic cases consistent with cardiac malposition and isomerism, septal defects, pulmonary stenosis/atresia, aortic malformations, hypoplastic left ventricle, conotruncal anomalies, tricuspid dysplasia, and Ebstein’s anomaly, and univentricular heart, among other congenital cardiovascular defects. Anatomical details of most CHD in fetuses were provided by two-dimensional (2D) ultrasound with higher quality imaging, enhancing diagnostic accuracy in a variety of CHD. Moreover, the accuracy of the cardiac defects in obstetrics ultrasound improves the outcome of most CHD, providing planned delivery, aided genetic counseling, and perinatal management.

Relationship between interatrial communication, ductus arteriosus, and pulmonary flow patterns in fetuses with transposition of the great arteries: prediction of neonatal desaturation

BACKGROUND

The relationship between interatrial communication, ductus arteriosus, and pulmonary flow in transposition of the great arteries and intact ventricular septum may help predict postnatal desaturation.

METHODS

Echocardiographic data of 45 fetuses with transposition of the great arteries and intact ventricular septum and 50 age-matched controls were retrospectively reviewed. Interatrial communication, left and right ventricular output, flow in the ductus arteriosus, as well as effective pulmonary flow were measured. Patients were divided into two groups on the basis of postnatal saturations: group 1 had saturations ⩽50% and group 2 >50%.

RESULTS

Of 45 fetuses, 13 (26.7%) were classified into group 1. Compared with fetuses in group 2, they had a smaller interatrial communication (2.9 versus 4.0 mm, p=0.004) and more retrograde diastolic flow in the ductus arteriosus (92 versus 23%, p=0.002). Both groups showed a significant decrease in ductal flow compared with controls. Patients in group 2 had a higher effective pulmonary flow compared with controls. There was a mild correlation between left ventricular output and size of the interatrial communication (Spearman's rank correlation 0.44).

CONCLUSION

A retrograde diastolic flow is present in most of the fetuses with postnatal desaturation. Fetuses with transposition of the great arteries have a lower flow through the ductus arteriosus compared with controls. Fetuses without restrictive foramen ovale have higher effective pulmonary flow. Peripheral pulmonary vasodilatation due to higher oxygen saturation in pulmonary arteries in the case of transposition of the great arteries could be one possible cause.

Usefulness of the Prenatal Echocardiogram in Fetuses With Isolated Transposition of the Great Arteries to Predict the Need for Balloon Atrial Septostomy

The outcome of the arterial switch operation for transposition of the great arteries (TGA) is excellent, but there is still associated preoperative mortality. Hypoxemia due to inadequate mixing of the pulmonary and systemic circulations may be implicated. Prediction of early hypoxemia by prenatal echocardiographic criteria has proved difficult. We aimed to identify prenatal echocardiographic features that may predict the need for emergency balloon atrial septostomy (BAS) in isolated TGA. Third trimester fetal echocardiograms of the last 40 cases of isolated TGA were reviewed without knowledge of the postnatal outcome. Measurements of the arterial valves, arterial duct, total septal length (TSL), and foramen ovale (FO) length were made, in addition to a subjective assessment of the atrial septum. The first postnatal echocardiogram and charts were reviewed. Comparison with 40 gestation-matched control fetuses was performed. The FO length in normal fetuses was not significantly different from those with TGA who did not require an emergency BAS but was significantly smaller in fetuses with TGA who required an emergency BAS (p = 0.01). An emergency BAS was required in 12 of 40 cases. All 3 cases with limited movement of the atrial septum required emergency BAS. A hypermobile atrial septum was observed in 10 cases and was not associated with emergency BAS (p = 0.8). The FO:TSL was significantly smaller in those who required an emergency BAS with good predictive value (area under the receiver operating characteristics curve: 0.80). The sensitivity for FO:TSL <0.5 was 99%. There was no significant difference in arterial duct, pulmonary valve, or branch pulmonary artery diameters between those cases requiring emergency BAS and those who did not. In conclusion, the likelihood of an emergency BAS is increased by FO:TSL <0.5 and a fixed appearance of the flap valve. Hypermobile and/or aneurysmal atrial septum did not indicate inadequate postnatal mixing in our group.

Diagnostic ultrasound features and outcome of restrictive foramen ovale in fetuses with structurally normal hearts

Intrauterine foramen ovale (FO) restriction in association with congenital heart disease (CHD) carries a poor prognosis. However, in the absence of CHD, the clinical importance of restrictive FO in the fetus is not well understood. We evaluated the antenatal prevalence, clinical presentation, diagnostic ultrasound features, and outcome of restrictive FO in fetuses without CHD. We reviewed the echocardiographic and clinical records of 23 fetuses diagnosed with a restrictive FO and structurally normal heart between 2001 and 2012. The atrial septum, dimensions of cardiac structures, left and right cardiac output and Doppler interrogation of cardiac flows were examined. The clinical outcomes of all fetuses with restrictive FO were analysed. Restrictive FO was identified in 23 of 1,682 (1.4%) fetuses with no CHD. Enlarged right heart structures (100%), hypermobile or redundant primum atrial septum (91%), increased right-to-left ventricular cardiac output ratio (91%), and posteriorly angulated ductus arteriosus (68%) were the most common echocardiographic findings associated with this rare phenomenon. Additional noncardiac systemic abnormalities were identified in 13 (56%) babies. Seven (30%) neonates developed persistent pulmonary hypertension, and 7 infants died. Antenatal restrictive FO is an underrecognised entity despite being a common cause of right heart dilatation in the fetus. In the absence of CHD, restrictive FO is well tolerated antenatally, but its frequent association with noncardiac abnormalities and pulmonary hypertension in the neonate are noteworthy.

Assessment of flow distribution in the mouse fetal circulation at late gestation by high-frequency Doppler ultrasound

This study used high-frequency ultrasound to evaluate the flow distribution in the mouse fetal circulation at late gestation. We studied 12 fetuses (embryonic day 17.5) from 12 pregnant CD1 mice with 40 MHz ultrasound to assess the flow in 11 vessels based on Doppler measurements of blood velocity and M-mode measurements of diameter. Specifically, the intrahepatic umbilical vein (UVIH), ductus venosus (DV), foramen ovale (FO), ascending aorta (AA), main pulmonary artery (MPA), ductus arteriosus (DA), descending thoracic aorta (DTA), common carotid artery (CCA), inferior vena cava (IVC), and right and left superior vena cavae (RSVC, LSVC) were examined, and anatomically confirmed by micro-CT. The mouse fetal circulatory system was found to be similar to that of the humans in terms of the major circuit and three shunts, but characterized by bilateral superior vena cavae and a single umbilical artery. The combined cardiac output (CCO) was 1.22 ± 0.05 ml/min, with the left ventricle (flow in AA) contributing 47.8 ± 2.3% and the right ventricle (flow in MPA) 52.2 ± 2.3%. Relative to the CCO, the flow percentages were 13.6 ± 1.0% for the UVIH, 10.4 ± 1.1% for the DV, 35.6 ± 2.4% for the DA, 41.9 ± 2.6% for the DTA, 3.8 ± 0.3% for the CCA, 29.5 ± 2.2% for the IVC, 12.7 ± 1.0% for the RSVC, and 9.9 ± 0.9% for the LSVC. The calculated flow percentage was 16.6 ± 3.4% for the pulmonary circulation and 31.2 ± 5.3% for the FO. In conclusion, the flow in mouse fetal circulation can be comprehensively evaluated with ultrasound. The baseline data of the flow distribution in normal mouse fetus serve as the reference range for future studies.

Diagnostic value of an ROC curve of the size of the antepartum foramen ovale in the prediction of puerperal atrial septal defect

The aim of this study was to determine the diagnostic value of an ROC curve of the antepartum foramen ovale (AFO) size and the ratio of FO size to aorta (AO) size (FO/AO) for the prediction of puerperal atrial septal defect in different gestational weeks (DGWs). A total of 958 cases were divided into five groups according to number of gestational weeks. Comparisons of FO size, AO size and FO/AO were determined by variance analysis. The correlations between FO size, AO size and gestational age were determined using regression analysis and comparisons between atrial septal defect (ASD) diagnosed in DGWs and normal cardiac FO size and FO/AO were analyzed by t-test. ROC curve analysis was used for FO size and FO/AO to predict the demarcation point of puerperal ASD (pASD). The differences between FO size and AO size in the five groups at DGWs were statistically significant (P=0.000). The sizes of FO and AO increased with gestational age. The differences among pASD, normal cardiac FO size and FO/AO were statistically significant (P=0.000). FO size in the five DGW groups (18–22, 23–26, 27–30, 31–34 and 35–40 weeks) was able to predict the demarcation points of pASD, which were 5.02, 5.15, 6.55, 8.55 and 7.90 mm, respectively. The prediction of pASD with AFO size and FO/AO was accurate and may provide reliable reference values in the clinic.

CURRENT ASPECTS OF FETAL CARDIOVASCULAR FUNCTION

Investigation of fetal cardiac function remains a challenging task. Although the response of the heart to changes in load is well-known in animal models and the adult human, the developmental changes in fetal cardiac response remain poorly characterised. However, quantitative evaluation of cardiovascular function is important to predict the clinical course and to manage the fetus optimally. To date, the routine evaluation of fetal cardio vascular function has relied largely on Doppler echocardiography which enables an estimate of haemodynamics; newer modalities such as measurement of myocardial velocities are employed less routinely. Fetal magnetic resonance imaging still lacks the resolution necessary to contribute significantly to morphological or functional assessment of the fetal cardiovascular system.

Rendering in fetal cardiac scanning: the intracardiac septa and the coronal atrioventricular valve planes

OBJECTIVE

In this study we aimed to apply spatio-temporal image correlation (STIC) rendering to visualize the virtual planes of the interventricular and interatrial septa (IVS, IAS) as well as the atrioventricular (AV) annuli plane just distal to the semilunar valves (coronal atrioventricular (CAV) plane) in normal and pathological fetal hearts, to ascertain whether these planes add to fetal cardiac examination.

METHODS

Unselected gravidae presenting for anatomy scan or patients referred for fetal echocardiography in the second and third trimesters of pregnancy with suspected or diagnosed cardiac malformation were scanned using the five planes technique with the STIC modality to obtain cardiac volume sets for each patient. Rendering capabilities were employed to obtain the 'virtual planes' to evaluate the IVS, IAS, AV annuli, and size and alignment of the great vessels.

RESULTS

A total of 136 normal scans were performed to establish a learning curve for STIC acquisition and post-processing rendering and analysis. An additional 35 cases with cardiac anomalies were accrued. In 131/136 (96.3%) normal scans the IAS and IVS were visualized successfully, while in 127/136 (93.4%) normal fetuses the CAV plane was successfully visualized. In 13 anomalous cases the IVS plane improved ventricular septal defect (VSD) evaluation, and in four the IAS plane contributed to foramen ovale evaluation. The modality improved visualization of the septa and the assessment of the defects, as well as the foramen ovale flap and pattern of movement of the foramen ovale. In five cases the CAV plane improved evaluation of the alignment of the major vessels in relation to the AV annuli, and in three the evaluation of the semilunar valves, with or without malalignment of the great vessels.

CONCLUSIONS

Rendering STIC technology allows the visualization of virtual planes (IAS, IVS, AV annuli-CAV plane), which can clarify our understanding of anatomical defects and may improve communication with the management team and family.

Physiology of the fetal circulation

Our understanding of fetal circulatory physiology is based on experimental animal data, and this continues to be an important source of new insight into developmental mechanisms. A growing number of human studies have investigated the human physiology, with results that are similar but not identical to those from animal studies. It is time to appreciate these differences and base more of our clinical approach on human physiology. Accordingly, the present review focuses on distributional patterns and adaptational mechanisms that were mainly discovered by human studies. These include cardiac output, pulmonary and placental circulation, fetal brain and liver, venous return to the heart, and the fetal shunts (ductus venosus, foramen ovale and ductus arteriosus). Placental compromise induces a set of adaptational and compensational mechanisms reflecting the plasticity of the developing circulation, with both short- and long-term implications. Some of these aspects have become part of the clinical physiology of today with consequences for surveillance and treatment.

Diagnosis and management of restricted or closed foramen ovale in fetuses with congenital heart disease

The incidence of foramen ovale restriction or closure is greater in fetuses with congenital heart defects (CHDs) and obligate atrial shunting and/or left atrial hypertension. Foramen ovale restriction or closure in fetuses with CHD can cause distress in utero or at birth. We suggest performing serial ultrasound assessment for at-risk fetuses with CHD to best assure fetal well-being plan the timing and mode of delivery, and develop management protocols for in utero and postnatal care. The future for these patients may be more optimistic as fetal intervention procedures are developed and mastered.

Sensitivity and Specificity of Prenatal Features of Physiological Shunts to Predict Neonatal Clinical Status in Transposition of the Great Arteries

BACKGROUND

Although prenatal diagnosis of transposition of the great arteries (TGA) reduces neonatal mortality, the preoperative course can be complicated in infants with a restrictive foramen ovale (FO) or a ductus arteriosus (DA) constriction. We sought to determine the specificity and sensitivity of prenatal features of physiological shunts in predicting postnatal clinical status in prenatally diagnosed TGA in babies delivered in a tertiary care center providing all facilities for neonatal urgent care.

METHODS AND RESULTS

The outcomes of 130 fetuses with TGA were reviewed over a period of 5.5 years. Restriction of the FO and/or constriction of the DA could be analyzed in 119/130 fetuses at 36+/-2.7 weeks of gestation. Twenty-four out of 119 had at least 1 abnormal shunt (23 FO, 5 DA, and 4 both). Thirteen of 130 neonates had profound hypoxemia (PaO2<25 mm Hg) and metabolic acidosis (pH <7.15) in the first 30 minutes and required immediate balloon atrioseptostomy. Two who had abnormal FO and DA died despite aggressive resuscitation. The specificity and sensitivity of the fetal echo in predicting neonatal emergency were 84% and 54%, respectively. The specificity and sensitivity of a combination of restrictive FO and DA constriction were 100% and 31%, respectively.

CONCLUSIONS

Restriction of the FO and/or of the DA has a high specificity to predict the need for emergency neonatal care in fetuses with TGA, but the sensitivity is too low to detect all high-risk fetuses. Exceptional procedures should be considered for fetuses that have a combination of restrictive FO and DA constriction.

Foramen ovale changes in growth-restricted fetuses

OBJECTIVE

In animal experiments hypoxemia induces an increased shunting through the fetal foramen ovale (FO). Based on the hypothesis that the FO is expanded to permit more flow, the aim of this study was to determine the size of the FO in growth-restricted human fetuses.

METHODS

Thirty-one women with singleton pregnancies complicated with growth-restriction (< 5th percentile) were examined at 24-39 weeks of gestation. The diameter between the FO valve and the atrial septum was determined during maximum excursion in a horizontal transverse section of the fetal heart, and the transverse diameter of the right atrium (RA) was noted. The pulsatility index (PI) was determined in the umbilical artery (UA) and absent or reversed end-diastolic flow velocity was noted. The measurements were compared with a reference population using Z-scores.

RESULTS

In comparison with normally grown fetuses, the growth-restricted fetuses had a normal RA size (P = 0.08) but a smaller FO (P = 0.002), particularly when expressed as a relative size by the ratio FO/RA (P < 0.0001). This effect on the FO and FO/RA was seen mainly at < 32 weeks of gestation (P = 0.003 and P < 0.0001, respectively), and was not significant later in pregnancy. There was a tendency towards a negative relationship between relative size of the FO (FO/RA) and progressive placental compromise (overall P < 0.0001).

CONCLUSIONS

Growth-restricted fetuses maintain a normally grown heart (expressed by the RA diameter) but a reduced FO diameter. The effect is seen before 32 weeks and tends to be more marked in fetuses with pronounced hemodynamic compromise of the placenta. This supports the theory that FO shunting is impaired in severely premature fetuses with placental compromise.

Intrauterine pulmonary venous flow and restrictive foramen ovale in fetal hypoplastic left heart syndrome

OBJECTIVES

We sought to determine whether direct foramen ovale (FO) assessment or pulmonary venous (PV) flow patterns in fetal hypoplastic left heart syndrome (HLHS) correlate with clinical markers of postnatal left atrial (LA) hypertension severity associated with restrictive FO.

BACKGROUND

Restrictive FO places a newborn with HLHS at high risk of mortality and morbidity.

METHODS

We reviewed the prenatal and postnatal echocardiograms and outcomes of 45 fetuses with variants of HLHS diagnosed since May 1999 to determine whether direct FO assessment or PV flow patterns correlate with clinical LA hypertension after birth.

RESULTS

Direct FO assessment in utero showed a poor correlation with postnatal FO size, Pao(2), base excess, and the need for atrial septoplasty (p > 0.05). In 40 fetuses with available PV spectra, three PV flow patterns were observed: 1). continuous forward flow with a small a-wave reversal (velocity time integral [VTI] for reverse/forward flow [VTIR/VTIF ratio <0.18]); 2). continuous forward flow with increased a-wave reversal (VTIR/VTIF ratio >or=0.18); and 3). brief to-and-fro flow. Among 19 live-borns, the postnatal FO diameter was smaller in patients with type B than in those with type A flow (1.6 +/- 1.6 mm and 4.5 +/- 2.1 mm, respectively; p = 0.0015), and all patients with type C flow had an intact atrial septum. All three patients with type C flow were critically ill at birth, requiring emergent atrial septoplasty, and two died after heart transplantation, whereas patients with type A or B flow were clinically stable, with only one postoperative death.

CONCLUSIONS

Prenatal PV flow patterns in HLHS identify the fetus at risk of severe LA hypertension at birth.

The fetal circulation

Accumulating data on the human fetal circulation shows the similarity to the experimental animal physiology, but with important differences. The human fetus seems to circulate less blood through the placenta, shunt less through the ductus venosus and foramen ovale, but direct more blood through the lungs than the fetal sheep. However, there are substantial individual variations and the pattern changes with gestational age. The normalised umbilical blood flow decreases with gestational age, and, at 28 to 32 weeks, a new level of development seems to be reached. At this stage, the shunting through the ductus venosus and the foramen ovale reaches a minimum, and the flow through the lungs a maximum. The ductus venosus and foramen ovale are functionally closely related and represent an important distributional unit for the venous return. The left portal branch represents a venous watershed, and, similarly, the isthmus aorta an arterial watershed. Thus, the fetal central circulation is a very flexible and adaptive circulatory system. The responses to increased afterload, hypoxaemia and acidaemia in the human fetus are equivalent to those found in animal studies: increased ductus venosus and foramen ovale shunting, increased impedance in the lungs, reduced impedance in the brain, increasingly reversed flow in the aortic isthmus and a more prominent coronary blood flow.

Ultrasound assessment of the fetal foramen ovale

OBJECTIVES

Based on the assumption that the horizontal area between the fetal foramen ovale valve and the atrial septum (the outlet) represents the limiting structure for the foramen ovale flow, our objective was to determine the normal size of this section during the second half of pregnancy.

METHODS

One hundred and thirty-eight women with low-risk singleton pregnancies were examined in a cross-sectional study between 18 and 42 weeks of gestation. Using ultrasound imaging and M-mode, the area and diameter between the foramen ovale valve and the atrial septum were determined in a four-chamber view of the fetal heart above the foramen ovale limbus. The inferior vena cava cross section and right atrial width were also determined.

RESULTS

The mean foramen ovale width increased from 3 mm at 18 weeks to 6 mm at term. Correspondingly, the horizontal area grew from 15 to 50 mm2. The mean ratio between this area and the area of the inferior vena cava fell from 1 at 18 weeks to 0.5 at term. The ratio between the transverse width of the foramen ovale and the right atrium remained at average 0.45-0.50 until 32 weeks, when a slight reduction was observed towards term.

CONCLUSIONS

Normal values for the horizontal cross section and transverse diameter of the foramen ovale outlet were established for the second half of pregnancy. In particular, the horizontal transverse diameter and its ratio to the right atrial width are easy to determine, and use of these measurements is thus suggested for the assessment of the fetal foramen ovale.

Prenatal features of ductus arteriosus constriction and restrictive foramen ovale in d-transposition of the great arteries

BACKGROUND

Although most neonates with d-transposition of the great arteries (TGA) have an uncomplicated preoperative course, some with a restrictive foramen ovale (FO), ductus arteriosus (DA) constriction, or pulmonary hypertension may be severely hypoxemic and even die shortly after birth. Our goal was to determine whether prenatal echocardiography can identify these high-risk fetuses with TGA.

METHODS AND RESULTS

We reviewed the prenatal and postnatal echocardiograms and outcomes of 16 fetuses with TGA/intact ventricular septum or small ventricular septal defect. Of the 16 fetuses, 6 prenatally had an abnormal FO (fixed position, flat, and/or redundant septum primum). Five of the 6 had restrictive FO at birth. Five fetuses had DA narrowing at the pulmonary artery end in utero, and 6 had a small DA (diameter z score of <-2.0). Of 4 fetuses with the most diminutive DA, 2 also had an abnormal appearance of the FO, and both died immediately after birth. One other fetus had persistent pulmonary hypertension. Eight fetuses had abnormal Doppler flow pattern in the DA (continuous high-velocity flow, n=1; retrograde diastolic flow, n=7).

CONCLUSIONS

Abnormal features of the FO, DA, or both are present in fetuses with TGA at high risk for postnatal hypoxemia. These features may result from the abnormal intrauterine hemodynamics in TGA. A combination of restrictive FO and DA constriction in TGA may be associated with early neonatal death.

The echocardiographic assessment of the human fetal foramen ovale

The foramen ovale size and interatrial flow patterns were studied by combined real-time and Doppler echocardiography in 100 normal human fetuses between 20 and 38 weeks gestation. The foramen ovale, atrioventricular, and semilunar valve diameters increased linearly with gestational age. The foramen flap motion and interatrial flow patterns showed biphasic flow patterns with interatrial flow reversal with atrial systole. Color flow mapping of the diameter of the interatrial flow profile showed good correlation with the foramen ovale size as measured by two-dimensional echocardiography. These data represent the first large study of the normal human foramen ovale correlated with gestational age, thus expanding the reference base for ultrasound assessment of fetal heart.