Association of Prenatally Diagnosed Isolated Single Left Superior Vena Cava and Postnatal Development of Coarctation of the Aorta.

To report the prevalence of coarctation of the aorta (CoA) in fetuses with single left superior vena cava (SL-SVC) and to evaluate changes in echocardiographic measurements. Additionally, to report the prevalence of associated malformations. Retrospective observational study of fetuses diagnosed with SL-SVC between 2012 and 2021 at a tertiary fetal cardiology unit. In fetuses without intracardiac abnormalities, Z-scores of the ventricles, great arteries, and Doppler flow patterns are reported. We identified 47 fetuses with SL-SVC of which 8/47 (17%) had abnormal intracardiac anatomy. One fetus was lost to follow-up. Of those with normal intracardiac anatomy and postnatal follow-up (38), karyotype abnormalities were confirmed in 2/38 (5%) and ECA in 8/38 (21%). 33/38 were live-born. None developed CoA postnatally. Paired analysis of Z-scores between early and late scans of 24 fetuses showed that diameters of the right heart structures and Doppler flows of tricuspid valve increased significantly during pregnancy, while the left heart structures and flow patterns did not change. The median risk of CoA did not change between the early and the late scan. We did not observe CoA in this cohort. A degree of ventricular asymmetry was present, but this was due to right heart dominance rather than hypoplasia of left heart structures. This likely reflects redistribution of blood and does not appear to confer increased risk of CoA. Predictive models of the postnatal development of CoA which set the dimensions of right and left heart structures in relation might not be applicable in this situation.

Impact on the trachea in children with prenatally diagnosed vascular ring formed by a right aortic arch.

OBJECTIVE: There has been a rise in the prenatal detection of right sided aortic arch (RAA). When associated with a left-sided arterial duct (LD), this forms a vascular ring encircling the trachea. Infants may have symptoms or signs suggestive of tracheoesophageal compression but many are asymptomatic. The objective of this study was to investigate the relationship between symptoms and severity of tracheobronchial compression assessed by bronchoscopy. METHODS: Retrospective review of all cases of prenatally diagnosed RAA-LD in the absence of associated congenital heart disease at Evelina London Children's Hospital and Kings College Hospital over a 4-year period between April 2015-2019. Clinical records, fetal echocardiograms, and free-breathing flexible bronchoscopy (FB) data were reviewed. RESULTS: One hundred and twelve cases of isolated RAA-LD were identified of whom 82 cases (73%) underwent FB. FB was performed median age of 11 months (range 1-36 months), no complications occurred. Aberrant left subclavian artery (ALSA) was present in 86% (96/112) and mirror image branching (MIB) in 13% (15/112). 34/112 (30%) reported symptoms during follow-up. 36/77 (47%) with ALSA who underwent FB showed moderate-severe compression mostly at distal tracheal and carinal level of whom 38% had parent-reported symptoms. Moderate-severe compression was seen in 3/5 (60%) with MIB mostly at mid tracheal level; 3 were symptomatic but only 2 had tracheal compression. In total 36% (18/50) of investigated asymptomatic patients showed moderate-severe compression. Respiratory symptoms were poorly predictive of moderate-severe tracheal compression (positive predictive value 66%, negative predictive value 64%). CONCLUSION: The absence of symptoms did not exclude significant tracheal compression. The anatomical effect of the vascular ring is under appreciated when symptoms alone are used as a marker of tracheal compression.

Post-operative Outcomes for Vascular Rings: A Systematic Review and Meta-analysis.

OBJECTIVES: Vascular rings may cause tracheal and/or oesophageal compression. For many patients, symptoms/signs have been present for a long period before diagnosis. However, in the era of prenatal diagnosis, some units advocate universal early surgery. The risks and efficacy of surgery must be known to adequately counsel for the operation. This meta-analysis sought to define the morbidity and mortality associated with surgical correction, and persistent post-operative symptoms. METHODS: PubMed, Cochrane Library and CINAHL databases were searched for studies that described the outcome of patients undergoing surgery for a double or right aortic arch (DAA or RAA). Non-comparative and random effects model-based meta-analyses were conducted to calculate the pooled rates of mortality, surgical complications, reintervention, and persistent follow-up symptoms. RESULTS: Nineteen eligible studies were included comprising 18 studies describing outcomes for DAA surgery and 15 for RAA surgery. For DAA surgery, overall mortality rate was 0% [95% confidence interval (CI) 0.0-1.0], post-surgical complication rate 18% [95% CI: 12.0-23.0], prevalence of reintervention 3% [95% CI: 1.0-5.0] and prevalence of symptoms at last follow-up was 33% [95% CI: 17.0-52.0]. For RAA surgery, overall pooled mortality was 0% [95% CI: 0.0-0.0], prevalence of post-surgical complications was 15% [95% CI: 8.0-23.0], reintervention rate was 2% [95% CI: 0.0-4.0], prevalence of symptoms at last follow-up was 40% [95% CI: 26.0-55.0]. CONCLUSIONS: While surgery to correct a vascular ring is safe, the rate of persistent symptoms is high and further strategies must be sought to reduce this burden.

Systematic review of long QT syndrome identified during fetal life.

Fetal long QT syndrome (LQTS) may present with sinus bradycardia, functional 2:1 atrioventricular block (AVB), and ventricular arrhythmias (ventricular tachycardia [VT]/torsades de pointes [TdP]) and lead to fetal or postnatal death. We performed a systematic review and individual participant data meta-analysis of 83 studies reporting outcomes of 265 fetuses for which suspected LQTS was confirmed postnatally and determined risk of adverse perinatal and postnatal outcomes using logistic and stepwise logistic regression. A longer fetal QTc was more predictive of death than any other antenatal factor (receiver operating characteristic [ROC] area under the curve [AUC] 0.85; 95% confidence interval [CI] 0.66-1.00). Risk of death was significantly increased with fetal QTc >600 ms. Neither fetal heart rate nor heart rate z-score predicted death (ROC AUC 0.51; 95% CI 0.31-0.71; and ROC AUC 0.59; 95% CI 0.37-0.80, respectively). The combination of antenatal VT/TdP or functional 2:1 AVB and lack of family history of LQTS was also highly predictive of death (ROC AUC 0.82; 95% CI 0.76-0.88). Our data provide clinical screening tools to enable prediction and intervention for fetuses with LQTS at risk of death.

Contemporary surgical outcome and symptomatic relief following vascular ring surgery in children: effect of prenatal diagnosis.

OBJECTIVES: Our goal was to describe postoperative complications and outcomes in a large contemporary cohort of children with an isolated double aortic arch (DAA) or a right aortic arch (RAA) with left arterial ligament and to assess the impact of foetal diagnosis on outcomes. METHODS: We performed a retrospective analysis of all patients who underwent surgery for DAA or RAA with left arterial ligament between 2005 and 2019. RESULTS: A total of 132 children were operated on for a DAA (n = 77) or a RAA (n = 55). Prenatal diagnosis was made in 100/132 (75.8%). Median age at surgery for DAA was 5.0 (1.7-13.3) months and for RAA was 13.9 (6.4-20.1) months. There was no difference in the age at surgery between the prenatal and postnatal cases (8.6 [4.0-15.6] vs 5.4 months [1.8-17.7]; P = 0.37). No surgical deaths occurred. Vocal cord palsy was the most common complication, occurring in 12/132 (9%): of these, 11 resolved spontaneously and 1 required a temporary tracheostomy. Logistic regression demonstrated that older age at operation was the only predictor for a postoperative complication (P = 0.02). Overall, 21/67 (31%) of prenatally detected, symptomatic cases reported residual symptoms/signs 1 year after surgery compared to 18/28 (64%) of postnatally detected cases. Postnatal diagnosis was associated with persistent postoperative symptoms/signs [P = 0.006, odds ratio = 3.9 (95% confidence interval 1.5-9.4)]. CONCLUSIONS: Surgery to relieve a vascular ring resolves trache-oesophageal compressive symptoms in most cases, but parents/patients should be aware that symptoms/signs may persist in the first postoperative year despite effective release of the vascular ring. Earlier surgery and prenatal diagnosis may improve outcomes.

Fetal echocardiographic markers to differentiate between a right and double aortic arch.

OBJECTIVES: To describe the fetal echocardiographic features of a double aortic arch (DAA) and secondly, to assess the performance of these features to differentiate between a right aortic arch with left duct (RAA-LD) in a blinded cohort of vascular rings. METHODS: Review of records to identify surgically confirmed cases of DAA diagnosed prenatally from 2014 to 2018 (cohort-A). Prenatal echocardiograms were reviewed and the segments of the aortic arches anterior and posterior to the trachea, aortic isthmuses and the presence/absence of the Z-sign were described. The utility of these markers were assessed in a separate cohort (B) of fetuses with surgically confirmed cases of DAA or RAA-LD. RESULTS: Cohort-A comprised 34 cases with DAA; there was a dominant RAA in 32/34 (94%) and balanced left aortic arch (LAA) and RAA in two cases. The proximal LAA was seen in 29/34 (85%), distal LAA in 15/34 (44%) and the LAA aortic isthmus in 4/34 (12%). The "Z" configuration was present in 29/34 (85%) cases. The most predictive marker for DAA in cohort-B was the Z-sign (sensitivity: 100%, specificity: 81%). CONCLUSION: The "Z" sign is a useful differentiator between RAA-LD and DAA. The absence of visualization of the left aortic isthmus does not preclude the presence of a DAA.

Outcome and Impact of Associated Left-Sided Cardiac Lesions in Coarctation of the Aorta Diagnosed During Fetal Life.

Significant effort has been put into the optimization of the antenatal diagnosis of coarctation of the aorta (CoA). However, although left-sided cardiac lesions are known to cluster, the necessity to intervene postnatally for other left-sided cardiac lesions has not been reported in a cohort of fetuses with suspected CoA. We report a study of all 89 fetuses with antenatally suspected and postnatally confirmed diagnosis of CoA who underwent CoA repair as the primary procedure at a single tertiary congenital heart disease center over 10 years (January 1, 2010, to December 31, 2019). Almost 1 in 5 patients (18%) had to undergo surgery and/or transcatheter intervention on additional left-sided cardiac lesions (14%) and/or reintervention on the aortic arch (12%) during follow-up to median age of 2.85 years. Freedom from intervention at 5 years was 78% (95% confidence interval [CI] 67 to 88%) if reintervention on CoA was excluded, and 72% (95% CI 60 to 82%) if this was included. Five-year survival was 95% (95% CI 90 to 100%). Furthermore, 20% of affected infants had genetic (10%) and/or extracardiac (16%) abnormalities. Our study highlights the need for comprehensive antenatal counseling, including the prognosis of primary repair of CoA and the potential development of additional left-sided cardiac lesions, which may be difficult to diagnose prenatally even in expert hands or impossible to diagnose because of the physiology of the fetal circulation.

Dilated ascending aorta in the fetus.

INTRODUCTION: Prenatal recognition of dilated aortic root is extremely rare and there are significant challenges in counselling these patients. The primary aim of this case series is to describe the prevalence, associations and outcome of dilated ascending aorta diagnosed during fetal life. METHODS: This is a retrospective cohort study from two tertiary fetal cardiology centres. Dilated ascending aorta was defined as gestation-specific standard deviation > 1.96 at some point during gestation. RESULTS: Sixteen infants were live born and underwent postnatal echocardiography. Prenatally suspected bicuspid aortic valve (BAV) (n = 6) was confirmed in 5 cases (83%) postnatally. Thirteen children have been followed up for a period of minimum one year. No connective tissue disease was found. CONCLUSIONS: Prenatal dilated ascending aorta is a rare finding (0.06%). It is associated with BAV in 37% of cases and extracardiac abnormalities in 15.7%. Nuchal translucency measurement was >3.5 in 13% of cases. Connective tissue disease was not diagnosed postnatally. This is the largest prenatal cohort with dilated ascending aorta and postnatal outcomes to date. We showed a postnatal persistence of ascending aortic dilatation in 43% of babies. In the absence of extra-cardiac abnormalities, medium term outcome appears good but postnatal surveillance of aortic dilation is required.

Analysis of 3-Dimensional Arch Anatomy, Vascular Flow, and Postnatal Outcome in Cases of Suspected Coarctation of the Aorta Using Fetal Cardiac Magnetic Resonance Imaging.

BACKGROUND: Identifying fetuses at risk of severe neonatal coarctation of the aorta (CoA) can be lifesaving but is notoriously challenging in clinical practice with a high rate of false positives. Novel fetal 3-dimensional and phase-contrast magnetic resonance imaging (MRI) offers an unprecedented means of assessing the human fetal cardiovascular system before birth. We performed detailed MRI assessment of fetal vascular morphology and flows in a cohort of fetuses with suspected CoA, correlated with the need for postnatal intervention. METHODS: Women carrying a fetus with suspected CoA on echocardiography were referred for MRI assessment between 26 and 36 weeks of gestation, including high-resolution motion-corrected 3-dimensional volumes of the fetal heart and phase-contrast flow sequences gated with metric optimized gating. The relationship between aortic geometry and vascular flows was then analyzed and compared with postnatal outcome. RESULTS: Seventy-two patients (51 with suspected fetal CoA and 21 healthy controls) underwent fetal MRI with motion-corrected 3-dimensional vascular reconstructions. Vascular flow measurements from phase-contrast sequences were available in 53 patients. In the CoA group, 25 of 51 (49%) required surgical repair of coarctation after birth; the remaining 26 of 51 (51%) were discharged without neonatal intervention. Reduced blood flow in the fetal ascending aorta and at the aortic isthmus was associated with increasing angulation (P=0.005) and proximal displacement (P=0.006) of the isthmus and was seen in both true positive and false positive cases. A multivariate logistic regression model including aortic flow and isthmal displacement explained 78% of the variation in outcome and correctly predicted the need for intervention in 93% of cases. CONCLUSIONS: Reduced blood flow though the left heart is associated with important configurational changes at the aortic isthmus in fetal life, predisposing to CoA when the arterial duct closes after birth. Novel fetal MRI techniques may have a role in both understanding and accurately predicting severe neonatal CoA.

Reference Ranges for Pulsed-Wave Doppler of the Fetal Cardiac Inflow and Outflow Tracts from 13 to 36 Weeks' Gestation.

BACKGROUND: Doppler assessment of ventricular filling and outflow tract velocities is an integral part of fetal echocardiography, to assess diastolic function, systolic function, and outflow tract obstruction. There is a paucity of prospective data from a large sample of normal fetuses in the published literature. The authors report reference ranges for pulsed-wave Doppler flow of the mitral valve, tricuspid valve, aortic valve, and pulmonary valve, as well as heart rate, in a large number of fetuses prospectively examined at a single tertiary fetal cardiology center. METHODS: The study population comprised 7,885 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective pulsed-wave Doppler blood flow measurements were taken of the mitral, tricuspid, aortic, and pulmonary valves. The fetal heart rate was recorded at the time of each assessment. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. RESULTS: The measurement for each cardiac Doppler measurement was expressed as a Z score (difference between observed and expected values divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac inflow and outflow tracts. CONCLUSIONS: This study establishes reference ranges for fetal cardiac Doppler measurements and heart rate between 13 to 36 weeks' gestation that may be useful in clinical practice.

Prenatal incidence of isolated right aortic arch and double aortic arch.

OBJECTIVE: To define the incidence of variants of aortic arch sidedness in fetuses undergoing routine first trimester ultrasound examination. METHODS: The data for this study were derived from prospective routine ultrasound examination at 11+0 to 13+6 weeks' gestation in singleton pregnancies examined in a local population between January 2014 and March 2018. We examined the incidence of isolated right aortic arch (RAA) and double aortic arch (DAA) in the local, screened population and compared the groups with and without these abnormalities. RESULTS: The study population of 33,202 pregnancies included 18 (5.4 per 10,000) cases with isolated RAA and 5 (1.5 per 10,000) with DAA. In the group with isolated RAA or DAA, compared to those without, the median maternal age was higher and the incidence of conceptions from in vitro fertilization (IVF) was eight-fold higher. The prevalence of 22q11microdeletion was 5% in patients with RAA from this local population. CONCLUSIONS: The incidence of isolated RAA and DAA in a local population undergoing routine first-trimester ultrasound examination is 2-3-fold higher than that reported in postnatal studies and the risk for these abnormalities is substantially increased in fetuses conceived by IVF.

Postnatal impact of a prenatally diagnosed double aortic arch.

BACKGROUND: A double aortic arch (DAA) is increasingly identified before birth; however, there are no published data describing the postnatal outcome of a large prenatal cohort. OBJECTIVE: To describe the associations, symptoms and impact of prenatally diagnosed DAA. METHODS: Retrospective review of consecutive cases seen at two fetal cardiology units from 2014 to 2019. Clinical records including symptoms and assessment of tracheobronchial compression using flexible bronchoscopy were reviewed. Moderate-severe tracheal compression was defined as >75% occlusion of the lumen. RESULTS: There were 50 cases identified prenatally and 48 with postnatal follow-up. Array comparative genomic hybridisation (aCGH) was abnormal in 2/50 (4%), aCGH was normal in 33/50 (66%) and of those reviewed after birth, 13 were phenotypically normal. After birth, there was a complete DAA with patency of both arches in 8/48 (17%) and in 40/48 (83%) there was a segment of the left arch which was a non-patent, ligamentous connection.Stridor was present in 6/48 (13%) on the day of birth. Tracheo-oesophageal compressive symptoms/signs were present in 31/48 (65%) patients at median age of 59 days (IQR 9-182 days). Tracheal/carinal compression was present in 40/45 (88%) cases. Seven of 17 (41%) asymptomatic cases demonstrated moderate-severe tracheal compression. All morphologies of DAA caused symptoms and morphology type was not predictive of significant tracheal compression (p=0.3). CONCLUSIONS: Genetic testing should be offered following detection of double aortic arch. Early signs of tracheal compression are common and therefore delivery where onsite neonatal support is available is recommended. Significant tracheal compression may be present even in the absence of symptoms.

Fetal Speckle-Tracking: Impact of Angle of Insonation and Frame Rate on Global Longitudinal Strain.

BACKGROUND: There is a growing body of research on fetal speckle-tracking echocardiography because it is considered to be an angle-independent modality. The primary aim of this study was to investigate whether angle of insonation and acquisition frame rate (FR) influence left ventricular endocardial global longitudinal peak strain (GLS) in the fetus. METHODS: Four-chamber views of 122 healthy fetuses were studied at three different angles of insonation (apex up/down, apex oblique, and apex perpendicular) at high and low acoustic FRs. GLS was calculated, and a linear mixed-model analysis was used for analysis. Six hundred fifty-six fetal echocardiographic clips were analyzed (288 in the second trimester, at a median gestation of 21 weeks [interquartile range (IQR), 1 week], and 368 in the third trimester, at a median gestation of 36 weeks [IQR, 2 weeks]). RESULTS: Angle of insonation and FRs were significant determinants of GLS. Ventricular septum perpendicular to the ultrasound beam was associated with higher (more negative) GLS compared with apex up/down (at high FR: -21.8% vs -19.7%, P < .001; at low FR: -24.1% vs -21.4%, P < .001). Higher frames per second (FPS; median 149 FPS [IQR, 33 FPS] = 61 frames per cycle [FPC] [IQR, 17 FPC]) compared with lower FPS (median 51 FPS [IQR, 15 FPS] = 22 FPC [IQR, 7 FPC]) at the same insonation angle resulted in lower GLS (apex up/down: -19.7% vs -21.4%, P < .001; apex oblique: -21.2% vs -22.7%, P < .001; apex perpendicular: -21.8% vs -24.1%, P < .001). CONCLUSIONS: The present findings show that insonation angle and FR influence GLS significantly. These factors need to be considered when comparing studies with different acquisition protocols, when establishing normative values, and when interpreting pathology. Speckle-tracking echocardiography cannot be considered an angle-independent modality during fetal life.

Initial Experience of Superb Microvascular Imaging for Key Cardiac Views in Foetal Assessment before 15 Weeks Gestation.

BACKGROUND: In the first trimester, ultrasound confirmation of normal or abnormal cardiac anatomy is difficult. B-mode and colour flow Doppler (CFD) are used to assess the foetal heart. Superb microvascular imaging (SMI) can visualise blood flow within the heart and vessels in early gestation. OBJECTIVE: We report an initial experience of SMI for visualisation of normal and abnormal cardiac anatomy in the first trimester. METHODS: Transabdominal foetal echocardiography was performed between 11 + 6 and 14 + 3 weeks (Aplio 500 US system, Toshiba Medical Systems, Tokyo, Japan) from January 2017 to December 2017. All scans were performed at a tertiary foetal cardiology unit. To assess the potential utility of the technique for early gestation screening, normal scans were reviewed by foetal medicine trainees with respect to the B-mode, CFD and SMI. Three key views were selected to compare modalities: the 4-chamber view, outflow tracts and the 3-vessel and trachea view (VTV). Visualisation rates of key echocardiographic features of significant cardiac abnormalities by SMI were reviewed. RESULTS: Fifty-five normal echocardiograms and 34 cardiac abnormalities were included. In the normal heart, when B-mode, CFD and SMI were assessed separately, SMI had the highest rate of visualisation of 4-chamber, outflow tracts and 3-VTV (93, 85 and 83%, respectively). Intra-observer reliability was moderate for SMI of the 3 standard views (kappa 1, 0.64 and 0.64); inter-observer for 4-chamber and outflow tract views was moderate (kappa 0.64 and 0.77). In 29/34 abnormal cases, SMI showed key features, enhancing greyscale visualisation. CONCLUSION: SMI has potential to become a useful, complementary modality for early foetal echocardiography. Further prospective studies are warranted to establish the place of the technique in assessment of the first trimester foetal heart.

Postnatal Outcome Following Prenatal Diagnosis of Discordant Atrioventricular and Ventriculoarterial Connections.

Discordant atrioventricular and ventriculoarterial connection(s) (DAVVAC) are a rare group of congenital heart lesions. DAVVAC can be isolated or associated with a variety of other cardiac abnormalities. Previous studies examining the outcome of prenatally diagnosed DAVVAC have described only fetal and early postnatal outcome in small cohorts. We aimed to describe the medium-term outcome of these fetuses. Cases were identified by searching the fetal cardiac databases of two centers. Follow-up data were collected from the electronic patient records. We identified 98 fetuses with DAVVAC. 39 pregnancies were terminated and 51 resulted in a liveborn infant. Postnatal data were available for 43 patients. The median length of follow-up was 9.5 years (range 36 days to 22.7 years). The overall 5-year survival of the cohort was 80% (95% confidence interval 74-86%), no deaths were seen after this period. Associated cardiac lesions had a significant effect on both survival and surgery-free survival. Isolated DAVVAC and DAVVAC with pulmonary stenosis ± ventricular septal defect had a low mortality (89% and 100% 5-year survival, respectively). Poorer survival was seen in the group with Ebstein's anomaly of the tricuspid valve, and other complex cardiac abnormalities. Antenatal tricuspid regurgitation had a significant negative impact on postnatal survival. In conclusion, the short- and medium-term outlook for fetuses with isolated DAVVAC, and those with DAVVAC and pulmonary stenosis are good. Antenatal risk factors for postnatal mortality include Ebstein's anomaly of the tricuspid valve, especially if associated with tricuspid regurgitation, and the presence of complex associated lesions.

Three-dimensional visualisation of the fetal heart using prenatal MRI with motion-corrected slice-volume registration: a prospective, single-centre cohort study.

BACKGROUND: Two-dimensional (2D) ultrasound echocardiography is the primary technique used to diagnose congenital heart disease before birth. There is, however, a longstanding need for a reliable form of secondary imaging, particularly in cases when more detailed three-dimensional (3D) vascular imaging is required, or when ultrasound windows are of poor diagnostic quality. Fetal MRI, which is well established for other organ systems, is highly susceptible to fetal movement, particularly for 3D imaging. The objective of this study was to investigate the combination of prenatal MRI with novel, motion-corrected 3D image registration software, as an adjunct to fetal echocardiography in the diagnosis of congenital heart disease. METHODS: Pregnant women carrying a fetus with known or suspected congenital heart disease were recruited via a tertiary fetal cardiology unit. After initial validation experiments to assess the general reliability of the approach, MRI data were acquired in 85 consecutive fetuses, as overlapping stacks of 2D images. These images were then processed with a bespoke open-source reconstruction algorithm to produce a super-resolution 3D volume of the fetal thorax. These datasets were assessed with measurement comparison with paired 2D ultrasound, structured anatomical assessment of the 2D and 3D data, and contemporaneous, archived clinical fetal MRI reports, which were compared with postnatal findings after delivery. FINDINGS: Between Oct 8, 2015, and June 30, 2017, 101 patients were referred for MRI, of whom 85 were eligible and had fetal MRI. The mean gestational age at the time of MRI was 32 weeks (range 24-36). High-resolution (0·50-0·75 mm isotropic) 3D datasets of the fetal thorax were generated in all 85 cases. Vascular measurements showed good overall agreement with 2D echocardiography in 51 cases with paired data (intra-class correlation coefficient 0·78, 95% CI 0·68-0·84), with fetal vascular structures more effectively visualised with 3D MRI than with uncorrected 2D MRI (657 [97%] of 680 anatomical areas identified vs 358 [53%] of 680 areas; p<0·0001). When a structure of interest was visualised in both 2D and 3D data (n=358), observers gave a higher diagnostic quality score for 3D data in 321 (90%) of cases, with 37 (10%) scores tied with 2D data, and no lower scores than for 2D data (Wilcoxon signed rank test p<0·0001). Additional anatomical features were described in ten cases, of which all were confirmed postnatally. INTERPRETATION: Standard fetal MRI with open-source image processing software is a reliable method of generating high-resolution 3D imaging of the fetal vasculature. The 3D volumes produced show good spatial agreement with ultrasound, and significantly improved visualisation and diagnostic quality compared with source 2D MRI data. This freely available combination requires minimal infrastructure, and provides safe, powerful, and highly complementary imaging of the fetal cardiovascular system. FUNDING: Wellcome Trust/EPSRC Centre for Medical Engineering, National Institute for Health Research.

Prenatal diagnosis and clinical implications of an apparently isolated right aortic arch.

OBJECTIVE: To define the associations of a prenatally diagnosed, apparently isolated right aortic arch (RAA) with chromosomal or genetic abnormalities and tracheal compression. METHODS: This was a retrospective study of apparently isolated RAA assessed by fetal cardiologists and fetal medicine specialists at Kings College Hospital, London between 2000 and 2017. RESULTS: The search identified 138 cases of apparently isolated RAA. Invasive testing was performed in 75, and chromosomal or genetic anomalies were identified in 16 (22%), and the most common was 22q11 microdeletion. An aberrant left subclavian artery was seen in 51% of cases. Symptoms of a vascular ring were present in 24 of 97 (25%) children who were reviewed after birth. Bronchoscopy was performed in 33 children, and significant tracheal compression was diagnosed in 28, including 18 of 19 symptomatic and 10 of 14 asymptomatic children. CONCLUSIONS: An apparently isolated RAA is associated with a high incidence of chromosomal or genetic abnormalities and a high incidence of tracheal compression in symptomatic and asymptomatic patients. Prenatal counselling for genetic associations and postnatal airway assessment in the context of the vascular anatomy is recommended.

Reference Ranges for the Size of the Fetal Cardiac Outflow Tracts From 13 to 36 Weeks Gestation: A Single-Center Study of Over 7000 Cases.

BACKGROUND: Assessment of the outflow tract views is an integral part of routine fetal cardiac scanning. For some congenital heart defects, notably coarctation of the aorta, pulmonary valve stenosis, and aortic valve stenosis, the size of vessels is important both for diagnosis and prognosis. Existing reference ranges of fetal outflow tracts are derived from a small number of cases. METHODS AND RESULTS: The study population comprised 7945 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective measurements were taken of (1) the aortic and pulmonary valves in diastole at the largest diameter with the valve closed, (2) the distal transverse aortic arch on the 3 vessel and trachea view beyond the trachea at the distal point at its widest systolic diameter, and (3) the arterial duct on the 3 vessel and trachea view at its widest systolic diameter. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. The measurement for each cardiac diameter was expressed as a z score (difference between observed and expected value divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac outflow tracts and for the distal transverse aortic arch:arterial duct ratio. CONCLUSIONS: The study established reference ranges for fetal outflow tract measurements at 13 to 36 weeks' gestation that are useful in clinical practice.

Effect of Prenatal Laterality Disturbance and Its Accompanying Anomalies on Survival.

In this retrospective, observational study of fetuses diagnosed with a laterality disturbance we describe the findings and outcome of fetuses diagnosed between 1980 and 2017 at a tertiary fetal-pediatric cardiology unit. In addition we sought to identify features which impact on outcome. Left atrial isomerism (LAI) was diagnosed in 177 babies and right atrial isomerism (RAI) in 100. Major structural heart disease was present in all cases of RAI and 91% with LAI. Complete heart block (CHB) was present in 40% of LAI. For surviving live-born infants a biventricular circulation was feasible in 3% with RAI and 43% with LAI. The median survival for live-borns with LAI was 13 months (range 0 to 272 months) and for RAI 19 months (range 0.3 to 292 months). The median postnatal survival with CHB was 0.2 months (range 0 to 228 months) compared to 44 months with sinus rhythm (interquartile range 0 to 272 months; p <0.0001). The 5-year survival was 1980 to 1989, RAI 0%, LAI 0%; 1990 to 1999, RAI 62%, LAI 54%; 2000 to 2009, RAI 59%, LAI 53%; 2010 to 2017, RAI 67%, LAI 75% by era. The rate of intrauterine death remained. Risk factors for death/transplantation for RAI were total anomalous pulmonary venous drainage, left heart obstruction (hazard ratios 2.7, p = 0.048; 5.8, p = 0.03) and for LAI: CHB, anomalous pulmonary venous drainage and right heart obstruction (hazard ratios 11.5, 6.2, 3.8, respectively (p = 0.008, p = 0.003, p <0.001)). In conclusion, laterality disturbances represent a complex form of congenital heart disease and although survival is improved, it remains poor especially in the presence of anomalous pulmonary venous drainage, stenotic and/or atretic valves, and CHB.