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.

Management of prenatally detected vascular rings: a United Kingdom national survey.

OBJECTIVE: To investigate UK variability in prenatal and postnatal management strategy of right aortic arch and double aortic arch (RAA/DAA). METHODS: Online surveys were sent to senior physicians (consultants) of the National Fetal Cardiology Working Group regarding prenatal diagnosis, counselling, and perinatal management of antenatally diagnosed RAA/DAA and to the British Congenital Cardiovascular Association regarding postnatal management strategies. RESULTS: There were 28 prenatal and 90 postnatal surveys completed. Prenatally, there was consensus for potential associated chromosomal/genetic anomalies, but there was variation in the risk quoted. Confidence in defining aortic arch morphology was reported by 43% (12/28) of fetal cardiologists. There was variation in what was felt to be possible symptoms/signs of a compressive vascular ring, postnatal investigation, postnatal management, follow-up duration of asymptomatic patients, and indications for surgical intervention. CONCLUSION: This study has highlighted important areas for future research: improving accuracy of prenatal diagnosis, clarification of potential symptoms, optimal investigation strategies, and indications for surgery.

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.

Early Postnatal Echocardiography in Neonates with a Prenatal Suspicion of Coarctation of the Aorta.

Coarctation of the aorta (COA) is suspected prenatally when there is ventricular asymmetry, arterial disproportion, and hypoplasia of the aortic arch/isthmus. The presence of fetal shunts creates difficulty in prenatal confirmation of the diagnosis so serial echocardiography after birth is necessary to confirm or refute the diagnosis. The first neonatal echocardiogram in prenatally suspected cases of COA was assessed for prediction of neonatal COA repair (NCOAR). This included morphological assessment, measurement of the aortic arch and calculation of the distal arch index (DAI = distance between left common carotid and left subclavian artery/diameter of the distal arch). NCOAR was undertaken in 23/60 (38%) cases. Transverse arch, aortic isthmus z-score, and DAI had an area under the receiver operator curve of 0.88 (95% CI 0.77-0.98), 0.86 (95% CI 0.75-0.96), and 0.84 (95% CI 0.74-0.95), respectively for the prediction of NCOAR. Using transverse arch z-score threshold < - 3 gave sensitivity 100%, NPV: 100%, specificity 76%; aortic isthmus z-score < - 3: NPV 92%, specificity 62% and DAI > 1.4: NPV 88%, specificity 78%. The size of the distal aortic arch in infants with a common origin of the innominate artery and left common carotid artery who did not require COA repair was similar to the NCOAR cases (p = 0.22). The early postnatal assessment of the size and morphology of the aortic arch can assist in risk stratification for development of neonatal COA. The branching pattern of the head/neck vessels impacts on the size of the distal aortic arch adding to the complexity of predicting COA based on vessel size.

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.

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.

Hypertension in Coarctation of the Aorta: Challenges in Diagnosis in Children.

Evidence indicates that patients with coarctation of the aorta (COA) suffer from increased cardiovascular morbidity and mortality in later life despite successful repair of COA in childhood. Systolic arterial hypertension is common, presenting in up to one-third of patients, and is regarded as the main driver of premature cardiovascular events in this group of patients. In this review, we discuss the prevalence and pathophysiology of hypertension in children following successful COA repair with no residual arch obstruction. The challenges in accurate blood pressure assessment at this early phase are considered and non-invasive measures of central blood pressure are discussed. Although the pathways for investigations in adults are well defined, we highlight the need to address the issues of cardiovascular surveillance in children and describe techniques which can provide complementary information for cardiovascular assessment in this group of patients such that timely treatment can occur.

Correlation of Symptoms with Bronchoscopic Findings in Children with a Prenatal Diagnosis of a Right Aortic Arch and Left Arterial Duct.

A right aortic arch (RAA) with a left arterial duct (LAD) together encircle the trachea and have the potential to cause tracheobronchial compression and published guidelines recommend bronchoscopy in symptomatic patients. The aim of the study was to describe the incidence of tracheal compression in a cohort of prenatally diagnosed RAA and LAD. Retrospective review of clinical course and imaging of prenatal cases of RAA and LAD assessed with flexible bronchoscopy over an 11-year period. 34 cases of prenatally diagnosed RAA with LAD underwent bronchoscopy at median age of 9 months (range 0.4-123) of whom 11 had respiratory symptoms and 23 were asymptomatic. In the neonatal period, three cases demonstrated respiratory symptoms. An aberrant left subclavian artery (ALSA) was identified in 29 cases. Pulsatile tracheal compression was identified in 32/34 (94%) cases and two cases showed normal tracheal appearances. Significant tracheal compression (> 70% occlusion) was present in 25/34 (74%) cases of which 16 were asymptomatic. Significant carinal compression (> 70% occlusion) was identified in 14/34 (42%) cases, an ALSA was observed in 13/14. Surgical relief of a vascular ring has been performed in 27 (79%) cases at a median age of 15 months (range 0.6-128 months). At surgery, a fibrous remnant of an atretic left aortic arch was identified in 11/27 (41%) cases. Significant tracheal compression may be present in infants even without symptoms. If early relief of airway compression is to be achieved to promote normal development of tracheal cartilage, early bronchoscopy should be considered.

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.

Learning the Hidden Signature of Fetal Arch Anatomy: a Three-Dimensional Shape Analysis in Suspected Coarctation of the Aorta.

Neonatal coarctation of the aorta (CoA) is a common congenital heart defect. Its antenatal diagnosis remains challenging, and its pathophysiology is poorly understood. We present a novel statistical shape modeling (SSM) pipeline to study the role and predictive value of arch shape in CoA in utero. Cardiac magnetic resonance imaging (CMR) data of 112 fetuses with suspected CoA was acquired and motion-corrected to three-dimensional volumes. Centerlines from fetal arches were extracted and used to build a statistical shape model capturing relevant anatomical variations. A linear discriminant analysis was used to find the optimal axis between CoA and false positive cases. The CoA shape risk score classified cases with an area under the curve of 0.907. We demonstrate the feasibility of applying a SSM pipeline to three-dimensional fetal CMR data while providing novel insights into the anatomical determinants of CoA and the relevance of in utero arch anatomy for antenatal diagnosis of CoA.

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.

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.

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.

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.

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.

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.

Speckle-Tracking Echocardiography for the Assessment of Atrial Function during Fetal Life.

INTRODUCTION: Speckle-tracking echocardiography has become a major tool in the evaluation of heart function. Atrial strain has emerged as an important component in the assessment of cardiac function, but there is a paucity of prenatal data. The aim of this study was to describe our initial experience of measurement of atrial strain in fetuses, with respect to both feasibility and the strain patterns observed. METHODS: Four-chamber Digital Imaging and Communications in Medicine loops were acquired prospectively for deformation imaging. Fifty-three normal fetuses with no morphologic or functional abnormalities were selected for analysis. The three strain components of atrial cycle for both left atrium (LA) and right atrium (RA) were acquired-reservoir (LAres or RAres), conduit, and contraction (LAct or RAct)-and are expressed as a percentage. Ratios of these components were calculated. Simple linear regression was used to analyze how the dependent variables changed according to gestational age and frame rate. RESULTS: The median gestational age was 30 weeks (range, 23-35), and the frame rate was 74 frames per second (fps; range, 35-121). Left atrial strain was feasible in 48/53 (91%), and right atrial strain in 46/53 (87%) of cases. The onset of LA contraction could be identified on the strain curves in 32 of 48 (67%) cases, and of the RA in 17 of 46 (37%) cases. The values of RAres and RAct were higher compared with those of LAres and LAct (33.9% vs 30.3%, P = .014; and 21.5% vs 16.8%, P = .005), and the contraction:reservoir ratio was also higher for RA (0.63 vs 0.55 for LA, P = .003). Higher values for LAres, LAct, RAres, and RAct were associated with higher frame rate (P = .007, .020, .049, and .012, respectively). The onset of LA contraction was better identified with a higher frame rate (mean 77 vs 59 fps when not seen, P = .007). A higher LA contraction:reservoir ratio was associated with a lower gestational age (P = .042). CONCLUSION: Measurement of atrial strain is feasible in the fetal heart. The values are influenced by gestational age and frame rate, so it is necessary to account for these variables. Comparison of left versus right atrial strain values contrasts with those observed postnatally. Atrial function merits further study during fetal life, to aid understanding of maturational changes and disease states.

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.