Fetal echocardiography: accuracy and limitations in a population at high and low risk for heart defects

Prenatal diagnosis and postnatal verification in fetuses with total anomalous pulmonary venous connection

Objective

To systematically verify the accuracy of a four-step prenatal ultrasonography in diagnosing fetal total anomalous pulmonary venous connection (TAPVC).

Methods

A total of 62 TAPVC fetuses received prenatal ultrasonography and were confirmed by postnatal echocardiography, surgery, or postabortion autopsy. The suspected TAPVC fetuses were further screened by a four-step prenatal ultrasonography for TAPVC classification, pulmonary venous obstruction, and the associated malformations, and followed postpartum. The sonographic features, clinical data, and prognosis of the TAPVC fetuses were retrospectively analyzed.

Results

Of the 62 TAPVC fetuses, supracardiac TAPVC was found in 20 cases, intracardiac TAPVC in 12, infracardiac TAPVC in 21, and mixed TAPVC in 9. A total of 30 cases with right atrium isomerism were correctly diagnosed. Of the 11 cases with other intracardiac and extracardiac malformations, 1 case was missed to be diagnosed. Of the 21 isolated TAPVC cases, 6 were missed prenatally and 1 case was prenatally diagnosed as intracardiac and postnatally proved to be mixed (intracardiac type + supracardiac type) by echocardiography. Of the 13 TAPVC live births, 4 infants died in the neonatal period without operation. Of the nine infants undergoing the operation, five recuperated and survived; one survived but had complications with superior vena cava obstruction and collateral circulation formation, and three died postoperatively.

Conclusion

The four-step prenatal ultrasound procedure can comprehensively and systematically evaluate fetal TAPVC, detailing the classification, potential obstruction, and associated malformations. It provides substantial support for subsequent prenatal counseling and neonatal assessment. The retrospective analysis also reveals that isolated TAPVC is more prone to be missed in diagnosis.

Fetal intelligent navigation echocardiography (FINE) has superior performance compared to manual navigation of the fetal heart by non-expert sonologists

OBJECTIVES

Manual and intelligent navigation (i.e. fetal intelligent navigation echocardiography or FINE) by the operator are two methods to obtain standard fetal cardiac views from spatiotemporal image correlation (STIC) volumes. The objective was to compare the performance between manual and intelligent navigation (FINE) of the fetal heart by non-expert sonologists.

METHODS

In this prospective observational study, ten sonologists underwent formal training on both navigational methods. Subsequently, they were tested on their ability to obtain nine cardiac views from five STIC volumes of normal fetal hearts (19-28 gestational weeks) using such methods. The following parameters were determined for both methods: (1) success rate of obtaining nine cardiac views; (2) mean time to obtain nine cardiac views per sonologist; and (3) maximum number of cardiac views successfully obtained for each STIC volume.

RESULTS

All fetal cardiac images obtained from 100 STIC volumes (50 for each navigational method) were reviewed by an expert in fetal echocardiography. Compared to manual navigation, FINE was associated with a significantly: (1) higher success rate of obtaining eight (excluding the abdomen view) appropriate cardiac views (92-100% vs. 56-88%; all p<0.05); (2) shorter mean time (minute:seconds) to obtain nine cardiac views (2:11 ± 0:37 vs. 15:49 ± 7:44; p<0.0001); and (3) higher success rate of obtaining all nine cardiac views for a given STIC volume (86 vs. 14%; p<0.001).

CONCLUSIONS

When performed by non-expert sonologists, intelligent navigation (FINE) had a superior performance compared to manual navigation of the normal fetal heart. Specifically, FINE obtained appropriate fetal cardiac views in 92-100% of cases.

Impact of prenatally diagnosed congenital heart defects on outcomes and management

Fetal echocardiogram aids in prenatal identification of neonates at high risk for congenital heart defects (CHD). Prenatal detection rates for CHD have increased with improved ultrasound technology, the use of the early fetal echocardiography, and standardization of the performance of the fetal echocardiogram. Accurate prenatal detection of CHD, particularly complex CHD, is an important contributor to improved survival rates for patients with CHD. Early detection allows for families to choose whether or not to continue with pregnancy, referral to pediatric cardiology specialists for patient education, and delivery planning. Better psychosocial supports are needed for families with CHD.

First-trimester ultrasound detection of fetal heart anomalies: systematic review and meta-analysis

OBJECTIVES

To determine the diagnostic accuracy of ultrasound at 11-14 weeks' gestation in the detection of fetal cardiac abnormalities and to evaluate factors that impact the detection rate.

METHODS

This was a systematic review of studies evaluating the diagnostic accuracy of ultrasound in the detection of fetal cardiac anomalies at 11-14 weeks' gestation, performed by two independent reviewers. An electronic search of four databases (MEDLINE, EMBASE, Web of Science Core Collection and The Cochrane Library) was conducted for studies published between January 1998 and July 2020. Prospective and retrospective studies evaluating pregnancies at any prior level of risk and in any healthcare setting were eligible for inclusion. The reference standard used was the detection of a cardiac abnormality on postnatal or postmortem examination. Data were extracted from the included studies to populate 2 × 2 tables. Meta-analysis was performed using a random-effects model in order to determine the performance of first-trimester ultrasound in the detection of major cardiac abnormalities overall and of individual types of cardiac abnormality. Data were analyzed separately for high-risk and non-high-risk populations. Preplanned secondary analyses were conducted in order to assess factors that may impact screening performance, including the imaging protocol used for cardiac assessment (including the use of color-flow Doppler), ultrasound modality, year of publication and the index of sonographer suspicion at the time of the scan. Risk of bias and quality assessment were undertaken for all included studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.

RESULTS

The electronic search yielded 4108 citations. Following review of titles and abstracts, 223 publications underwent full-text review, of which 63 studies, reporting on 328 262 fetuses, were selected for inclusion in the meta-analysis. In the non-high-risk population (45 studies, 306 872 fetuses), 1445 major cardiac anomalies were identified (prevalence, 0.41% (95% CI, 0.39-0.43%)). Of these, 767 were detected on first-trimester ultrasound examination of the heart and 678 were not detected. First-trimester ultrasound had a pooled sensitivity of 55.80% (95% CI, 45.87-65.50%), specificity of 99.98% (95% CI, 99.97-99.99%) and positive predictive value of 94.85% (95% CI, 91.63-97.32%) in the non-high-risk population. The cases diagnosed in the first trimester represented 63.67% (95% CI, 54.35-72.49%) of all antenatally diagnosed major cardiac abnormalities in the non-high-risk population. In the high-risk population (18 studies, 21 390 fetuses), 480 major cardiac anomalies were identified (prevalence, 1.36% (95% CI, 1.20-1.52%)). Of these, 338 were detected on first-trimester ultrasound examination and 142 were not detected. First-trimester ultrasound had a pooled sensitivity of 67.74% (95% CI, 55.25-79.06%), specificity of 99.75% (95% CI, 99.47-99.92%) and positive predictive value of 94.22% (95% CI, 90.22-97.22%) in the high-risk population. The cases diagnosed in the first trimester represented 79.86% (95% CI, 69.89-88.25%) of all antenatally diagnosed major cardiac abnormalities in the high-risk population. The imaging protocol used for examination was found to have an important impact on screening performance in both populations (P < 0.0001), with a significantly higher detection rate observed in studies using at least one outflow-tract view or color-flow Doppler imaging (both P < 0.0001). Different types of cardiac anomaly were not equally amenable to detection on first-trimester ultrasound.

CONCLUSIONS

First-trimester ultrasound examination of the fetal heart allows identification of over half of fetuses affected by major cardiac pathology. Future first-trimester screening programs should follow structured anatomical assessment protocols and consider the introduction of outflow-tract views and color-flow Doppler imaging, as this would improve detection rates of fetal cardiac pathology. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal Diagnosis of Double Aortic Arch: Associated Findings and Postnatal Clinical Outcomes

OBJECTIVES

The aim of this study is to share our experience in the prenatal diagnosis and characteristics of double aortic arc and neonatal consequences.

METHODS

We retrospectively analyzed 2153 fetal echocardiography reports between 2014 and 2019 years. Records of 14 fetuses with double aortic arc were examined. Prenatal and postnatal medical records, sonographic images, genetic reports, associated cardiac and extracardiac anomalies, and neonatal clinical results of affected fetuses were reviewed retrospectively.

RESULTS

DAA was isolated in 9 of 14 (64.2%) cases, while the other five cases had cardiac or extracardiac accompanying ultrasound findings. Three of cases (21.4%) were associated with other heart pathologies, including ventricular septal defect, double outlet right ventricle, and persistent left superior vena cava. In 10 cases (71.43%), the right aortic arch diameter was dominant. The left aortic arc was dominant in two cases and both arcs were symmetrical in the remaining two cases. 22q11 microdeletion was the only chromosomal abnormality and was detected in two of nine patients who accepted genetic analysis. Intrauterine fetal death occurred in two of the cases. After birth, in 58.3% (7/12) of the live born cases various degrees of symptoms. Surgical repair was performed with the division of the aorta to all symptomatic cases at different times according to severity of the complaints.

CONCLUSIONS

Since it can cause severe respiratory distress in the postnatal period and may accompany chromosomal anomalies, it is important to provide antenatal diagnosis of double aortic arc and adequate counseling to the family.

Cost-effectiveness of prenatal screening methods for congenital heart defects in pregnancies conceived by in-vitro fertilization

OBJECTIVES

To determine if a policy of universal fetal echocardiography (echo) in pregnancies conceived by in-vitro fertilization (IVF) is cost-effective as a screening strategy for congenital heart defects (CHDs) and to examine the cost-effectiveness of various other CHD screening strategies in IVF pregnancies.

METHODS

A decision-analysis model was designed from a societal perspective with respect to the obstetric patient, to compare the cost-effectiveness of three screening strategies: (1) anatomic ultrasound (US): selective fetal echo following abnormal cardiac findings on detailed anatomic survey; (2) intracytoplasmic sperm injection (ICSI) only: fetal echo for all pregnancies following IVF with ICSI; (3) all IVF: fetal echo for all IVF pregnancies. The model initiated at conception and had a time horizon of 1 year post-delivery. The sensitivities and specificities for each strategy, the probabilities of major and minor CHDs and all other clinical estimates were derived from the literature. Costs, including imaging, consults, surgeries and caregiver productivity losses, were derived from the literature and Medicare databases, and are expressed in USA dollars ($). Effectiveness was quantified as quality-adjusted life years (QALYs), based on how the strategies would affect the quality of life of the obstetric patient. Secondary effectiveness was quantified as number of cases of CHD and, specifically, cases of major CHD, detected.

RESULTS

The average base-case cost of each strategy was as follows: anatomic US, $8119; ICSI only, $8408; and all IVF, $8560. The effectiveness of each strategy was as follows: anatomic US, 1.74487 QALYs; ICSI only, 1.74497 QALYs; and all IVF, 1.74499 QALYs. The ICSI-only strategy had an incremental cost-effectiveness ratio (ICER) of $2 840 494 per additional QALY gained when compared to the anatomic-US strategy, and the all-IVF strategy had an ICER of $5 692 457 per additional QALY when compared with the ICSI-only strategy. Both ICERs exceeded considerably the standard willingness-to-pay threshold of $50 000-$100 000 per QALY. In a secondary analysis, the ICSI-only strategy had an ICER of $527 562 per additional case of major CHD detected when compared to the anatomic-US strategy. All IVF had an ICER of $790 510 per case of major CHD detected when compared with ICSI only. It was determined that it would cost society five times more to detect one additional major CHD through intensive screening of all IVF pregnancies than it would cost to pay for the neonate's first year of care.

CONCLUSION

The most cost-effective method of screening for CHDs in pregnancies following IVF, either with or without ICSI, is to perform a fetal echo only when abnormal cardiac findings are noted on the detailed anatomy scan. Performing routine fetal echo for all IVF pregnancies is not cost-effective. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Feasibility of ventricular volumetry by cardiovascular MRI to assess cardiac function in the fetal sheep

KEY POINTS

The application of fetal cardiovascular magnetic resonance imaging (CMR) to assess fetal cardiovascular physiology and cardiac function through the quantification of ventricular volumes has previously been investigated, but the approach has not yet been fully validated. Ventricular output measurements calculated from heart rate and stroke volumes (SV) of the right and left ventricles measured by ventricular volumetry (VV) exhibited a high level of agreement with phase-contrast (PC) blood flow measurements in the main pulmonary artery and ascending aorta, respectively. Ejection fraction of the right ventricle, which is lower than that of the left ventricle in postnatal subjects, was similar to the left ventricular ejection fraction in the fetus; probably due to the different loading conditions present in the fetal circulation. This study provides evidence to support the reliability of VV in the sheep fetus, providing evidence for its use in animal models of human diseases affecting the fetal circulation.

ABSTRACT

The application of ventricular volumetry (VV) by cardiovascular magnetic resonance imaging (CMR) in the fetus remains challenging due to the small size of the fetal heart and high heart rate. The reliability of this technique in utero has not yet been established. The aim of this study was to assess the feasibility and reliability of VV in a fetal sheep model of human pregnancy. Right and left ventricular outputs by stroke volume (SV) measured using VV were compared with 2D phase-contrast (PC) CMR measurements of blood flow in the main pulmonary artery (MPA) and ascending aorta (AAo). At 124-140 days (d) gestation, singleton bearing Merino ewes underwent CMR under general anaesthesia using fetal femoral artery catheters, implanted at 109-117d, to trigger cine steady state free precession acquisitions of ventricular short-axis stacks. The short-axis cine stacks were segmented at end-systole and end-diastole, yielding right and left ventricular SV, ejection fraction, and cardiac outputs (SV × heart rate). PC cine acquisitions of MPA and AAo were analysed to measure blood flow, which served as comparators for the right and left cardiac outputs by VV. There was good correlation and agreement between VV and PC measures of ventricular outputs with no significant bias (r²  = 0.926; P < 0.0001; Bias = -4.7 ± 10.5 ml min^-1  kg^-1 ; 95% limits of agreement: -15.9 to 25.2 ml min^-1  kg^-1 ). This study validates fetal VV by CMR in a large animal model of human pregnancy and provides preliminary reference values of fetal sheep right and left ventricles in late gestation.

Barriers to Sonographer Screening for Fetal Heart Defects: A U.S. National Survey

OBJECTIVE

We surveyed obstetric sonographers, who are at the forefront of the screening process to determine how barriers to prenatal cardiac screening impacted screening abilities.

METHODS

We performed a cross-sectional national survey of obstetric sonographers in the United States using a sampling frame from American Registry of Diagnostic Medical Sonography mailing lists. The web survey measured the ability to obtain and interpret fetal heart images. Several cognitive, sociodemographic, and system-level factors were measured, including intention to perform cardiac imaging. Regression and mediation analyses determined factors associated with intention to perform and ability to obtain and interpret cardiac images. Subgroup analyses of sonographers in tertiary versus nontertiary centers were also performed.

RESULTS

Survey response rate either due to noncontact or nonresponse was 40%. Of 480 eligible sonographers, ~30% practiced in tertiary settings. Sonographers had lower intention to perform outflow views compared to 4 chambers. Higher self-efficacy and professional expectations predicted higher odds of intention to perform outflow views (OR 2.8, 95% CI 1.9-4.2 and 1.9, 95% CI 1.1-3.0, respectively). Overall accuracy of image interpretation was 65% (±14%). For the overall cohort and nontertiary subgroup, higher intention to perform outflows was associated with increased accuracy in overall image interpretation. For the tertiary subgroup, self-efficacy and feedback were strongly associated with accuracy.

CONCLUSIONS

We identified several modifiable (some heretofore unrecognized) targets to improve prenatal cardiac screening. Priorities identified by sonographers that are associated with screening success should guide future interventions.

The Extended Fetal Cardiac Examination: Is It Feasible in a High-Risk Practice?

The aims of this study were to demonstrate the feasibility of obtaining additional cardiac views as proposed on an extended fetal cardiac examination and to see if there was any variation in individual components of that examination stratified by sonographer training, patient body habitus, or equipment. We retrospectively reviewed 200 consecutive detailed second-trimester high-risk fetal obstetric sonograms that included additional extended cardiac views. We analyzed the percentage of the time individual views were obtained, with variation based on (1) a sonographer with greater than 3 years of training compared with a group with 6 to 12 months of training, (2) 2 different ultrasound units, and (3) different body mass indices. Overall, the highest rate of visualization was achieved with the 4-chamber view (98.2%), whereas the 3-vessel tracheal view had the lowest percentage of visualization (40.2%), among the less experienced sonographers. Differences in successful completion of the extended cardiac views were not statistically different between the sonographer with a level of training greater than 3 years as compared with those with 6 to 12 months' training except for the 3-vessel tracheal view (P < 0.001). There is no statistically significant difference in our ultrasound equipment, when considering only inexperienced sonographers. Increasing body mass index had an inverse relationship with obtaining the components of the detailed cardiac examination. Using state-of-the-art ultrasound equipment and with focused additional training of obstetric sonographers, the majority of extended cardiac views can be obtained. There are exceptions.

Pre natal evaluation of heterotaxy syndrome by fetal echocardiography and correlating with autopsy

Introduction

Heterotaxy syndrome/ isomerism is characterized by an abnormal symmetry of the viscera that are normally dissimilar due to abnormal lateralization of thoracic and abdominal viscera and is frequently associated with complex cardiac anomalies. Isomerism may be of right or left.

Materials and methods

This article describes the morphological characteristics of heterotaxy and suggests an approach in evaluating the spectrum of abnormalities associated with this syndrome. This study is based on 12 cases diagnosed on antenatal ultrasound as heterotaxy syndrome. Results of the examinations were re-evaluated and compared by fetal autopsy.

Result

Based on the following echocardiographic criteria, a diagnosis of left isomerism was made if there was viscerocardiac heterotaxy associated with an interruption of inferior vena cava or with bilateral finger-like atrial appendages or if it was associated with heart block. If there was evidence of viscerocardiac heterotaxy with complex cardiac anomalies then it was diagnosed as right atrial isomerism or visceral heterotaxy syndrome. We diagnosed 6/12 as left isomerism and rest of the cases as right isomerism/visceral heterotaxy syndrome. In Autopsy we evaluated visceral situs and morphology of the lungs and the main bronchi, the state of the liver, spleen, bowel, and the precise anatomy of the heart and confirmed 4/12 as left isomerism 4/12 as right isomerism and two cases as visceral heterotaxy syndrome (VHS). Rest of the two cases were included in the study despite missing autopsy data, as the combination of abnormal situs with interrupted inferior vena cava, and cardiac malformation allowed a diagnosis of left isomerism with high probability.

Conclusion

In this study, we aimed to find common features of heterotaxy syndrome on prenatal ultrasound as well as on fetal autopsy. This syndrome should be accurately diagnosed in the prenatal period in order to allow appropriate counseling of parents.

Prenatal detection of critical cardiac outflow tract anomalies remains suboptimal despite revised obstetrical imaging guidelines

BACKGROUND

Fetal echocardiography can accurately diagnose critical congenital heart disease prenatally, but relies on referrals from abnormalities identified on routine obstetrical ultrasounds. Critical congenital heart disease that is frequently missed due to inadequate outflow tract imaging includes anomalies such as truncus arteriosus, double outlet right ventricle, transposition of the great arteries, tetralogy of Fallot, pulmonary stenosis, and aortic stenosis.

OBJECTIVE

This study evaluated the prenatal detection rate of critical outflow tract anomalies in a single urban pediatric hospital before and after "AIUM Practice Guideline for the Performance of Obstetric Ultrasound Examinations," which incorporated outflow tract imaging.

DESIGN

Infants with outflow tract anomalies who required cardiac catheterization and/or surgical procedure(s) in the first 3 months of life were retrospectively identified. This study evaluated two time periods; pre-guidelines from June 2010 to May 2013 and post-guidelines from January 2015 to June 2016. June 2013-December 2014 was excluded as a theoretical period necessary for obstetrical practices to implement the revised guidelines.

RESULTS

Overall, prenatal diagnosis occurred in 55% of infants with critical outflow tract anomalies; of the three most common defects, prenatal diagnosis occurred in 53% of D-transposition of the great arteries, 63% of tetralogy of Fallot, and 80% of double outlet right ventricle patients. Pre-guidelines, prenatal diagnosis occurred in 52% (52 of 102) infants with critical outflow tract anomalies requiring early cardiac intervention. Post-guidelines, prenatal diagnosis occurred in 61% (33 of 54) infants, not significantly different than the prenatal detection rate pre-guidelines (P = .31).

CONCLUSIONS

Despite revised obstetrical guidelines highlighting the importance of outflow tract imaging, referrals and prenatal diagnosis of these types of critical congenital heart disease remain low. Education of obstetrical sonographers and practitioners who perform fetal anatomic screening is vital to increase referrals and prenatal detection of critical outflow tract anomalies.

[Ultrasound screening for birth defects: A medico-economic review]

OBJECTIVES

The systematic use of ultrasound during pregnancy aims at birth defect detection. Our objective was to assess the economic efficiency of prenatal ultrasound screening for fetal malformations.

METHODS

We carried out a literature review on Medline via PubMed between 1985 and 2015, from the economic perspective of the prenatal ultrasound screening for fetal malformations.

RESULTS

The literature on this subject was sparse and we selected only twelve articles presenting relevant economic data, of which only eight were proper medico-economic studies. We found arguments for the economic effectiveness of ultrasound screening for fetal malformation detection, which is largely linked to the terminations of pregnancies and to the cost of the handicaps "avoided". However, none of the reviewed articles could reach medico-economic conclusions. Additionally, we highlighted various elements making economic analyses more complex in this field: the choice of the method, the uncertainty around two essential parameters (the efficiency of ultrasound and the costs of procedures) and the difficulties to compare or to generalize results. We also noticed important methodological heterogeneity among the studies and the absence of French study.

CONCLUSIONS

Previously published data are insufficient to assess the economic efficiency of prenatal ultrasound screening for fetal malformations.

Sonographer-Identified Barriers and Facilitators to Prenatal Screening for Congenital Heart Disease

Background: Fetal ultrasound screening for congenital heart disease has high detection rates in efficacy studies but not in practice. We investigated sonographers’ perspectives on barriers to screening and their association with intermediate measures of cardiac imaging. Methods: Barriers to fetal heart screening were identified in focus groups with obstetric sonographers. A web-based survey measured reported barriers and sonographers’ ability to interpret fetal heart screening images. Generalized linear random effect models assessed associations between barriers and image interpretation. Results: Four themes were identified: intrinsic barriers (self-efficacy), external barriers (time), informational needs, and provider and patient expectations. Among 224 sonographers surveyed, an average of 77.6% of fetal heart images were interpreted correctly. Perceptions about self-efficacy ( P = .03) and ease of performing imaging ( P = .01) were associated with accuracy of image interpretation. Conclusions: Several sonographer-identified barriers associated with image interpretation may be novel targets for improving prenatal detection of congenital heart disease.

Fetal aorta larger than the main pulmonary artery on the three-vessel view: Correlation with postnatal echocardiographic findings

PURPOSE

This study investigated postnatal cardiac anomalies determined by postnatal echocardiography in fetuses with the ascending aorta (AA) diameter larger than that of the main pulmonary artery (MPA) on the three-vessel view (3VV).

METHODS

The study included 17 pregnancies. The diameters of the AA and MPA were assessed on the 3VV in second-trimester sonographic screening, and all the patients underwent postnatal echocardiography to assess the cardiac outcome.

RESULTS

In the study population, the mean AA diameter was 3.7 mm (range, 2.2-5.6 mm), and the mean MPA diameter was 3.2 mm (range, 1.8-5.2 mm). The mean AA/MPA ratio was 1.2 (range, 1.1-1.9). According to the postnatal echocardiograms, one of the patients had tetralogy of Fallot. This patient had the highest prenatal AA/MPA ratio (1.9). Among the remaining 16 cases, five had secundum atrial septal defects, with two having concomitant dilatation of the AA. There was one case of isolated dilatation of the AA.

CONCLUSIONS

Although an AA with a diameter larger than that of the MPA on the 3VV does not usually indicate severe congenital heart disease involving the ventricular outflow tract and/or great arteries, careful prenatal and postnatal echocardiographic examinations are mandatory to determine the presence of congenital heart disease. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:423-428, 2016.

Prospective evaluation of the fetal heart using Fetal Intelligent Navigation Echocardiography (FINE)

OBJECTIVE

To evaluate prospectively the performance of Fetal Intelligent Navigation Echocardiography (FINE) applied to spatiotemporal image correlation (STIC) volume datasets of the normal fetal heart.

METHODS

In all women between 19 and 30 weeks' gestation with a normal fetal heart, an attempt was made to acquire STIC volume datasets of the apical four-chamber view if the following criteria were met: (1) fetal spine located between 5- and 7-o'clock positions; (2) minimal or absent shadowing (including a clearly visible transverse aortic arch); (3) absence of fetal breathing, hiccups, or movement; and (4) adequate image quality. Each STIC volume successfully acquired was evaluated by STICLoop™ to determine its appropriateness before applying the FINE method. Visualization rates of fetal echocardiography views using diagnostic planes and/or Virtual Intelligent Sonographer Assistance (VIS-Assistance®) were calculated.

RESULTS

One or more STIC volumes (365 in total) were obtained successfully in 72.5% (150/207) of women undergoing ultrasound examination. Of the 365 volumes evaluated by STICLoop, 351 (96.2%) were considered to be appropriate. From the 351 STIC volumes, only one STIC volume per patient (n = 150) was analyzed using the FINE method, and consequently nine fetal echocardiography views were generated in 76-100% of cases using diagnostic planes only, in 98-100% of cases using VIS-Assistance only, and in 98-100% of cases when using a combination of diagnostic planes and/or VIS-Assistance.

CONCLUSIONS

In women between 19 and 30 weeks' gestation with a normal fetal heart undergoing prospective sonographic examination, STIC volumes can be obtained successfully in 72.5% of cases. The FINE method can be applied to generate nine standard fetal echocardiography views in 98-100% of these cases using a combination of diagnostic planes and/or VIS-Assistance. This suggests that FINE could be implemented in fetal cardiac screening programs. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

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

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

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

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

Diagnosis of congenital heart disease in an era of universal prenatal ultrasound screening in southwest Ohio

OBJECTIVES

Diagnostic ultrasound is widespread in obstetric practice, yet many babies with major congenital heart disease remain undiagnosed. Factors affecting prenatal diagnosis of major congenital heart disease are not well understood. This study aims to document prenatal detection rates for major congenital heart disease in the Greater Cincinnati area, and identify factors associated with lack of prenatal diagnosis.

METHODS

All living infants diagnosed with major congenital heart disease by 4 months of age at our centre were prospectively identified. Prenatal care data were obtained by parent interview. Neonatal records were reviewed for postnatal data. Obstetricians were contacted for diagnostic ultrasound data.

RESULTS

A total of 100 infants met the inclusion criteria. In all, 95 infants were analysed, of whom 94 were offered diagnostic ultrasound. In all, 41 had a prenatal diagnosis of major congenital heart disease. The rate of prenatal detection varied by cardiac lesion, with aortic arch abnormalities, semilunar valve abnormalities, and venous anomalies going undetected in this sample. Among subjects without prenatal detection, the highest proportion consisted of those having Level 1 diagnostic ultrasound only (66%). Prenatal detection was not significantly influenced by maternal race, education level, income, or insurance type.

CONCLUSIONS

Despite nearly universal diagnostic ultrasound, detection rates of major congenital heart disease remain low in southwest Ohio. An educational outreach programme including outflow tract sweeps for community-level obstetrical personnel may improve detection rates.

Second trimester cardiac diagnosis: screening standards and outcomes

Second trimester screening for congenital heart defects occurs during the routine 18-20 weeks' anomaly scan in many countries. Most congenital heart defects can be prenatally detected by experts in foetal echocardiography working in tertiary centres with high-risk pregnancies. Many studies, however, have shown that detection rates obtained by experts are not reproducible in the low-risk peripheral practices where most of the foetal screening takes place. As the majority of foetuses with congenital heart defects are born to mothers with no identifiable risk factors, it is important that widespread screening of the low-risk population occurs. To facilitate this, standard protocols have been introduced in several countries, but they are not universal and have differing sensitivities depending on the screening views advocated and the area studied. Initially, only performing the four-chamber view (basic scan) was advocated. By adding the outflow tract views (extended scan), three-vessel, and laterality views, the sensitivity of the examination can be significantly increased. Unfortunately, the sensitivity of these extended protocols still does not meet that obtainable in experienced hands, reflecting the additional skill required to obtain these extended views. Thus, close links are required between the tertiary centres and the screening centres to teach and maintain the skills required to obtain and interpret the required views, and to support the sonographer's commitment. Furthermore, an audit system is required to trace false-positive and -negative cases so that targeted interventions can be planned. This is important, as a missed case of prenatal congenital heart defect is potentially a missed opportunity to reduce postnatal morbidity and mortality.

Prenatal findings in total anomalous pulmonary venous return: a diagnostic road map starts with obstetric screening views

OBJECTIVES

Optimal perinatal management of total anomalous pulmonary venous return (TAPVR) involves timely identification followed by surgical correction. Antenatal diagnosis, however, has long been a challenge. We aimed to identify consistent prenatal sonographic features in this condition in a large cohort in whom the diagnosis was made antenatally and confirmed postnatally.

METHODS

We conducted a systematic retrospective review of the 2-dimensional and Doppler sonographic features that had helped make the diagnosis of TAPVR at our institution from 2001 to 2012.

RESULTS

Twenty-six patients had prenatal diagnosis of TAPVR (mean gestational age, 24.1 weeks). Four of the fetuses with a prenatal diagnosis represented isolated cases of TAPVR; 22 had heterotaxy syndrome, additional cardiac abnormalities, or both. Prenatally diagnosed abnormal pulmonary venous connections were supracardiac (type I) in 18 cases, cardiac (type II) in 1, and infradiaphragmatic (type III) in 7. Lack of a visible connection of the pulmonary veins to the atrium (100%) and the presence of a visible venous confluence on axial 4-chamber views (96%) were the most consistent findings. Cardiac asymmetry and the presence of additional vertical venous channels on 3-vessel or axial abdominal views were also noted but less consistently. Abnormal pulmonary venous spectral Doppler findings were present in 25 of the 26 fetuses.

CONCLUSIONS

The diagnosis of TAPVR can be suspected on standard axial views included in second-trimester obstetric screening examinations of the fetal heart and confirmed on fetal echocardiography with the use of pulsed wave Doppler imaging. Clues recognizable on obstetric sonographic screening have the potential to contribute to increasing the diagnostic yield for prenatal detection of TAPVR.

Cost-effectiveness of prenatal screening strategies for congenital heart disease

OBJECTIVE

The economic implications of strategies to improve prenatal screening for congenital heart disease (CHD) in low-risk mothers have not been explored. The aim was to perform a cost-effectiveness analysis of different screening methods.

METHODS

We constructed a decision analytic model of CHD prenatal screening strategies (four-chamber screen (4C), 4C + outflow, nuchal translucency (NT) or fetal echocardiography) populated with probabilities from the literature. The model included whether initial screens were interpreted by a maternal-fetal medicine (MFM) specialist and different referral strategies if they were read by a non-MFM specialist. The primary outcome was the incremental cost per defect detected. Costs were obtained from Medicare National Fee estimates. A probabilistic sensitivity analysis was undertaken on model variables commensurate with their degree of uncertainty.

RESULTS

In base-case analysis, 4C + outflow referred to an MFM specialist was the least costly strategy per defect detected. The 4C screen and the NT screen were dominated by other strategies (i.e. were more costly and less effective). Fetal echocardiography was the most effective, but most costly. On simulation of 10 000 low-risk pregnancies, 4C + outflow screen referred to an MFM specialist remained the least costly per defect detected. For an additional $580 per defect detected, referral to cardiology after a 4C + outflow was the most cost-effective for the majority of iterations, increasing CHD detection by 13 percentage points.

CONCLUSIONS

The addition of examination of the outflow tracts to second-trimester ultrasound increases detection of CHD in the most cost-effective manner. Strategies to improve outflow-tract imaging and to refer with the most efficiency may be the best way to improve detection at a population level.

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

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

Fetal Intelligent Navigation Echocardiography (FINE): a novel method for rapid, simple, and automatic examination of the fetal heart

OBJECTIVE

To describe a novel method (Fetal Intelligent Navigation Echocardiography (FINE)) for visualization of standard fetal echocardiography views from volume datasets obtained with spatiotemporal image correlation (STIC) and application of 'intelligent navigation' technology.

METHODS

We developed a method to: 1) demonstrate nine cardiac diagnostic planes; and 2) spontaneously navigate the anatomy surrounding each of the nine cardiac diagnostic planes (Virtual Intelligent Sonographer Assistance (VIS-Assistance®)). The method consists of marking seven anatomical structures of the fetal heart. The following echocardiography views are then automatically generated: 1) four chamber; 2) five chamber; 3) left ventricular outflow tract; 4) short-axis view of great vessels/right ventricular outflow tract; 5) three vessels and trachea; 6) abdomen/stomach; 7) ductal arch; 8) aortic arch; and 9) superior and inferior vena cava. The FINE method was tested in a separate set of 50 STIC volumes of normal hearts (18.6-37.2 weeks of gestation), and visualization rates for fetal echocardiography views using diagnostic planes and/or VIS-Assistance® were calculated. To examine the feasibility of identifying abnormal cardiac anatomy, we tested the method in four cases with proven congenital heart defects (coarctation of aorta, tetralogy of Fallot, transposition of great vessels and pulmonary atresia with intact ventricular septum).

RESULTS

In normal cases, the FINE method was able to generate nine fetal echocardiography views using: 1) diagnostic planes in 78-100% of cases; 2) VIS-Assistance® in 98-100% of cases; and 3) a combination of diagnostic planes and/or VIS-Assistance® in 98-100% of cases. In all four abnormal cases, the FINE method demonstrated evidence of abnormal fetal cardiac anatomy.

CONCLUSIONS

The FINE method can be used to visualize nine standard fetal echocardiography views in normal hearts by applying 'intelligent navigation' technology to STIC volume datasets. This method can simplify examination of the fetal heart and reduce operator dependency. The observation of abnormal echocardiography views in the diagnostic planes and/or VIS-Assistance® should raise the index of suspicion for congenital heart disease.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Fetal diagnosis and imaging in cardiology

BACKGROUND

Fetal echocardiography plays a critical role in the diagnosis and management of structural, functional and rhythm-related fetal cardiovascular disease.

OBJECTIVES/METHODS

This article reviews the history of fetal echocardiography and the prenatal diagnosis of fetal cardiovascular disease as well as the evolution of the field of fetal cardiology. The clinical application of fetal echocardiography, including indications for referral, timing of referral and considerations in the diagnosis and serial assessment of fetal cardiovascular disease, is presented.

CONCLUSIONS

Newer directions in the field of fetal cardiology, including first trimester diagnoses and fetal intervention, will continue to expand its role in the evaluation and treatment of affected pregnancies in the future; however, equally as important are efforts to continue to improve prenatal detection rates.

Barriers to prenatal detection of congenital heart disease: a population-based study

OBJECTIVE

To evaluate the extent and determinants of missed prenatal detection of congenital heart disease (CHD) in a population-based setting.

METHODS

This was a retrospective cohort study of cases with CHD, excluding minor defects, identified between 1997 and 2007 by a statewide surveillance program. We examined a comprehensive list of potential risk factors for which data were available in the surveillance database from abstracted medical charts. We analyzed the association of fetal, maternal and encounter factors with 1) whether a prenatal ultrasound was performed and 2) prenatal detection of CHD.

RESULTS

CHD was detected prenatally in only 39% of 1474 cases, with no improvement in detection rate over the 10-year period. Among the 97% (n = 1431) of mothers who underwent one or more ultrasound examinations, 35% were interpreted as abnormal; fetal echocardiography was performed in 27% of the entire cohort. Maternal and encounter factors increasing the adjusted odds of prenatal detection included: family history of CHD (OR, 4.3 (95% CI, 1.9-9.9)), presence of extracardiac defects (OR, 2.7 (95% CI, 1.9-3.9)) and ultrasound location i.e. high risk clinic vs clinic (OR, 2.1 (95% CI, 1.3-3.1)). Defects that would be expected to have an abnormal outflow-tract view were missed more often (64%) than were those that would be expected to have an abnormal four-chamber view (42%).

CONCLUSION

The majority of CHD cases over the 10-year study period were missed prenatally and detection rates did not increase materially during that time. The failure to detect CHD prenatally was related to encounter characteristics, specifically involving screening ultrasound examinations, which may be targeted for improvement.

Magnetic resonance imaging in the normal fetal heart and in congenital heart disease

OBJECTIVE

To evaluate prospectively the feasibility of magnetic resonance imaging (MRI) for assessment of the fetal heart for congenital heart disease (CHD).

METHODS

This was a cross-sectional study, including 66 fetuses with a normal heart and 40 with CHD. The fetal heart was examined on MRI using axial steady-state free precession (SSFP) sequences. Regression analysis was used to investigate the effect on the ability to visualize cardiac anatomy of gestational age at examination, maternal body mass index, presence of fetal cardiac abnormality, fetal movements, fetal lie and twinning. The sensitivity and specificity of detecting cardiac defects were calculated.

RESULTS

The four-chamber view was visualized in 98.1% of fetuses. The sensitivity of detecting a cardiac defect on the four-chamber view was 88% and the specificity 96%. The ability to visualize the left and right outflow tracts was only influenced by the presence of fetal movements: for the left outflow tract 94.4 vs. 50.0% visualization and for the right outflow tract 92.6 vs. 53.8% visualization without and with fetal movements, respectively. The sensitivity of detecting a cardiac defect of the left outflow tract was 63% and the specificity 100%, while sensitivity and specificity were 59 and 97%, respectively, for the right outflow tract.

CONCLUSIONS

Despite the use of SSFP sequences, MRI in the fetal heart remains of limited value. It can only be used as a second-line approach for abnormalities of the four-chamber view suspected at prenatal ultrasound.

Contemporary clinical applications of spatio-temporal image correlation in prenatal diagnosis

PURPOSE OF REVIEW

Four-dimensional fetal echocardiography has the potential to reduce the operator dependency of two-dimensional ultrasonography and increase the detection rate of congenital heart defects (CHDs). This review is intended to summarize recent evidence of the important role that four-dimensional ultrasonography with spatio-temporal image correlation (STIC) may play in the prenatal diagnosis of CHDs.

RECENT FINDINGS

Four-dimensional ultrasonography with STIC may provide the opportunity for telemedicine in the prenatal diagnosis of CHDs because four-dimensional volume datasets can be remotely acquired and accurately interpreted by different centers. Four-dimensional ultrasonography with STIC is an accurate and reproducible technique for the prenatal diagnosis of CHDs. Different four-dimensional rendering techniques can provide important insight into the spatial relationships of normal and abnormal fetal vascular structures.

SUMMARY

Four-dimensional fetal echocardiography with STIC may facilitate the examination of the fetal heart and could potentially increase the detection rate of CHDs.

Simple targeted arterial rendering (STAR) technique: a novel and simple method to visualize the fetal cardiac outflow tracts

OBJECTIVE

To describe a novel and simple technique—simple targeted arterial rendering (STAR)—to visualize the fetal cardiac outflow tracts from dataset volumes obtained with spatiotemporal image correlation (STIC) and applying a new display technology (OmniView).

METHODS

We developed a technique to image the outflow tracts by drawing three dissecting lines through the four-chamber view of the heart contained in a STIC volume dataset. Each line generated the following plane: (a) Line 1: ventricular septum en face with both great vessels (pulmonary artery anterior to the aorta); (b) Line 2: pulmonary artery with continuation into the longitudinal view of the ductal arch; and (c) Line 3: long-axis view of the aorta arising from the left ventricle. The pattern formed by all three lines intersecting approximately through the crux of the heart resembles a star. The technique was then tested in 50 normal fetal hearts at 15.3–40.4 weeks' gestation. To determine whether the technique could identify planes that departed from the normal images, we tested the technique in four cases with proven congenital heart defects (ventricular septal defect (VSD), transposition of great vessels, tetralogy of Fallot and pulmonary atresia with intact ventricular septum).

RESULTS

The STAR technique was able to generate the intended planes in all 50 normal cases. In the abnormal cases, the STAR technique allowed identification of the VSD, demonstrated great vessel anomalies and displayed views that deviated from what was expected from the examination of normal hearts.

CONCLUSIONS

This novel and simple technique can be used to visualize the outflow tracts and ventricular septum en face in normal fetal hearts. Inability to obtain expected views or the appearance of abnormal views in the generated planes should raise the index of suspicion for congenital heart disease involving the great vessels and/or the ventricular septum. The STAR technique may simplify examination of the fetal heart and could reduce operator dependency.

Four-chamber view and 'swing technique' (FAST) echo: a novel and simple algorithm to visualize standard fetal echocardiographic planes

OBJECTIVE

To describe a novel and simple algorithm (four-chamber view and 'swing technique' (FAST) echo) for visualization of standard diagnostic planes of fetal echocardiography from dataset volumes obtained with spatiotemporal image correlation (STIC) and applying a new display technology (OmniView).

METHODS

We developed an algorithm to image standard fetal echocardiographic planes by drawing four dissecting lines through the longitudinal view of the ductal arch contained in a STIC volume dataset. Three of the lines are locked to provide simultaneous visualization of targeted planes, and the fourth line (unlocked) 'swings' through the ductal arch image (swing technique), providing an infinite number of cardiac planes in sequence. Each line generates the following plane(s): (a) Line 1: three-vessels and trachea view; (b) Line 2: five-chamber view and long-axis view of the aorta (obtained by rotation of the five-chamber view on the y-axis); (c) Line 3: four-chamber view; and (d) 'swing line': three-vessels and trachea view, five-chamber view and/or long-axis view of the aorta, four-chamber view and stomach. The algorithm was then tested in 50 normal hearts in fetuses at 15.3-40 weeks' gestation and visualization rates for cardiac diagnostic planes were calculated. To determine whether the algorithm could identify planes that departed from the normal images, we tested the algorithm in five cases with proven congenital heart defects.

RESULTS

In normal cases, the FAST echo algorithm (three locked lines and rotation of the five-chamber view on the y-axis) was able to generate the intended planes (longitudinal view of the ductal arch, pulmonary artery, three-vessels and trachea view, five-chamber view, long-axis view of the aorta, four-chamber view) individually in 100% of cases (except for the three-vessels and trachea view, which was seen in 98% (49/50)) and simultaneously in 98% (49/50). The swing technique was able to generate the three-vessels and trachea view, five-chamber view and/or long-axis view of the aorta, four-chamber view and stomach in 100% of normal cases. In the abnormal cases, the FAST echo algorithm demonstrated the cardiac defects and displayed views that deviated from what was expected from the examination of normal hearts. The swing technique was useful for demonstrating the specific diagnosis due to visualization of an infinite number of cardiac planes in sequence.

CONCLUSIONS

This novel and simple algorithm can be used to visualize standard fetal echocardiographic planes in normal fetal hearts. The FAST echo algorithm may simplify examination of the fetal heart and could reduce operator dependency. Using this algorithm, inability to obtain expected views or the appearance of abnormal views in the generated planes should raise the index of suspicion for congenital heart disease.

Collaborative study on 4-dimensional echocardiography for the diagnosis of fetal heart defects: the COFEHD study

OBJECTIVE

Congenital anomalies are the leading cause of infant mortality in the United States, and congenital heart defects (CHDs) are the most common type of birth defects. Recently, 4-dimensional ultrasonography (4DUS) with spatiotemporal image correlation (STIC) has been introduced for fetal echocardiography. Accumulating evidence indicates that 4DUS with STIC may facilitate the examination of the fetal heart. Our objectives were to determine the accuracy of 4DUS for the diagnosis of CHDs and the agreement among centers.

METHODS

This study included 7 centers with expertise in 4D fetal echocardiography. Fetuses with and without confirmed heart defects were scanned between 18 and 26 weeks, and their volume data sets were uploaded onto a centralized file transfer protocol server. Intercenter agreement was determined using a κ statistic for multiple raters.

RESULTS

Ninety volume data sets were randomly selected for blinded analysis. Overall, the median (range) sensitivity, specificity, positive and negative predictive values, and false-positive and -negative rates for the identification of fetuses with CHDs were 93% (77%-100%), 96% (84%-100%), 96% (83%-100%), 93% (79%-100%), 4.8% (2.7%-25%), and 6.8% (5%-22%), respectively. The most frequent CHDs were conotruncal anomalies (36%). There was excellent intercenter agreement (κ = 0.97).

CONCLUSIONS

(1) Four-dimensional volume data sets can be remotely acquired and accurately interpreted by different centers. (2) Among centers with technical expertise, 4DUS is an accurate and reliable method for fetal echocardiography.

Four-dimensional volume-rendered imaging of the fetal ventricular outflow tracts and great arteries using inversion mode for detection of congenital heart disease

AIM

Using four-dimensional (4D) sonography with an inversion mode, we evaluated fetal ventricular outflow tracts and great vessels for the detection of congenital heart disease.

METHODS

Volume datasets of the fetal heart were acquired with spatiotemporal image correlation (STIC), which uses automated transverse and longitudinal sweeps of the anterior chest wall. A total of 12 normal fetuses and seven fetuses with congenital heart disease (one case of double-outlet right ventricle, one case of tetralogy of Fallot, one case of transposition of the great arteries, one case of hypoplastic pulmonary artery with a large ventricular septal defect, and three cases of hypoplastic left heart syndrome) at 16-37 weeks of gestation were studied using transabdominal 4D sonography with an inversion mode. 4D inversion mode images of great arteries were evaluated.

RESULTS

4D ultrasound with an inversion mode demonstrated real-time 3D angiographic features of fetal cardiac outflow tracts in both normal and abnormal fetal hearts. This modality facilitated visualization of the relationships, size, and course of the outflow tracts, thus helping the examiner to more effectively understand the spatial relationships between the vessels. In normal fetal hearts, it was clearly shown that the pulmonary artery crosses in front of the aorta. In the three cases of hypoplastic left heart syndrome, an extremely small ascending aorta was evident. In the one case of tetralogy of Fallot, a relatively small pulmonary artery was noted. In the one case of hypoplastic pulmonary artery with a large ventricular septal defect, a markedly small main pulmonary artery was depicted. In the case of transposition of the great arteries, the vessels left the ventricles parallel to each other. In the case of double-outlet right ventricle, great arteries leaving the right ventricle in parallel were shown.

CONCLUSION

4D ultrasound in the inversion mode provides a means of evaluating fetal cardiac outflow tracts in 3D in real time. This technique may assist in the evaluation of spatial relationships between the great vessels and both ventricles, and the difference in the size of great vessels. Moreover, the inversion mode images should be more readily discernible than those obtained by conventional ultrasonography. 4D ultrasound in the inversion mode may be an important modality in future fetal cardiac research and in the evaluation of fetal congenital heart disease.

Defining laterality of the descending thoracic aorta in a 4-chamber view of the heart

OBJECTIVE

Right descending aortas have been correlated with an increased risk of congenital heart disease. Nevertheless, the aortic position remains a largely overlooked diagnostic tool in second-trimester sonography because no formal system for assessing the position exists. By developing a method of assigning the position of the aorta relative to the thoracic midline, diagnostic use of the descending aorta's position might be implemented more easily.

METHODS

The method of assessing the position relative to the midline was tested by comparing the analysis of 2 independent observers, who showed a 94.4% concordance rate.

RESULTS

Comparison of the percentages of aortic positions between the gestational ages (GAs) of 18 and 21 weeks showed no significant correlation between the aortic position and GA.

CONCLUSIONS

We suggest simply paying attention to the aortic position in an already standard view. The extra effort is minimal, and it has the potential to improve the diagnostic accuracy of the 4-chamber view.

Basic versus detailed sonography: what do we miss?

OBJECTIVE

The purpose of this study was to evaluate the impact of restrictive versus routine use of "detailed" second-trimester sonography.

METHODS

Records of singleton pregnancies undergoing evaluation from 2004 to 2008 were reviewed. A detailed examination (Current Procedural Terminology [CPT] code 76811) was routinely performed on all patients. Major structural abnormalities were categorized on the basis of whether the structure would be included in a "basic" examination (CPT code 76805). Risk factors for anomalies were identified. The Fisher exact test and Student t test were used for statistical comparison.

RESULTS

Major anomalies were identified in 218 patients, 75 of whom elected to undergo abortion. In 88 patients (40.4%), the abnormal structure would not be included in a basic examination. Risk factors were not more prevalent in those with anomalies requiring a detailed examination for diagnosis or in those patients who chose to undergo abortion.

CONCLUSIONS

Restricting detailed evaluation to those with risk factors would have prevented detection of a substantial proportion of anomalies.

Four-dimensional fetal echocardiography with spatiotemporal image correlation (STIC): A systematic study of standard cardiac views assessed by different observers

OBJECTIVE

To test the agreement between observers and reproducibility of a technique to display standard cardiac views of the left and right ventricular outflow tracts from four-dimensional volume datasets acquired with Spatiotemporal Image Correlation (STIC).

METHODS

A technique was developed to obtain dynamic multiplanar images of the left ventricular outflow tract (LVOT) and right ventricular outflow tract (RVOT) from volume datasets acquired with STIC. Volume datasets were acquired from fetuses with normal cardiac anatomy. Twenty volume datasets of satisfactory quality were pre-selected by one investigator. The data was randomly assigned for a blinded review by two independent observers with previous experience in fetal echocardiography. Only one volume dataset was used for each fetus. After a training session, the observers obtained standardized cardiac views of the LVOT and RVOT, which were scored on a scale of 1 to 5, based on diagnostic value and image quality (1=unacceptable, 2=marginal, 3=acceptable, 4=good, and 5=excellent). Median scores and interquartile range, as well as inter- and intraobserver agreement were calculated for each view.

RESULTS

The mean menstrual age at the time of volume acquisition was 25.5+/-4.5 weeks. Median scores (interquartile range) for LVOT images, obtained by the first and second observers, were 3.5 (2.25-5.00) and 4 (3.00-5.00), respectively. The median scores (interquartile range) for RVOT images obtained by the first and second observers were 3 (3.00-5.00) and 3 (2.00-4.00), respectively. The interobserver intraclass correlation coefficient for the LVOT was 0.693 (95% CI 0.380-0.822), and 0.696 (95% CI 0.382-0.866) for the RVOT. For the intraobserver agreement analysis, observer 1 gave higher scores to the LVOT the second time the volumes were analyzed [LVOT: 3.50 (2.25-5.00) vs. 5.00 (4.00-5.00, p=0.008)].

CONCLUSION

STIC can be reproducibly used to evaluate fetal cardiac outflow tracts by independent examiners. Slightly better image quality rating scores during the intraobserver variability trial suggests the presence of a learning curve for the manipulation and analysis of volume data obtained by STIC.

Prenatal screening for major congenital heart disease: superiority of outflow tracts over the 4-chamber view

OBJECTIVE

The purpose of this study was to determine the relative importance of the 4-chamber view (4CV) compared with the outflow tract views (OFTVs) in prenatal screening for major congenital heart disease (CHD).

METHODS

We prospectively evaluated 200 consecutive infants undergoing cardiac surgery at our institution for major CHD. By reviewing the infants' medical records and conducting bedside interviews with their parents or guardians, we evaluated detection rates both prenatally and postnatally (before and after discharge to home), and we noted any prenatally identifiable risk factors for CHD. For each infant, we determined whether the 4CV or OFTVs would be expected to have been normal or abnormal on routine midgestation screening fetal sonography.

RESULTS

A prenatal diagnosis of CHD was made in 65 infants (33%): 30 of 124 low-risk pregnancies (24%) and 35 of 76 high-risk pregnancies (46%). An abnormal screening midgestation 4CV would have been expected in up to 63% of the infants, whereas abnormal midgestation OFTVs would have been expected in up to 91% of the infants. Thus, the potential sensitivity for detecting major CHD was higher with the OFTVs than with the 4CV (91% versus 63%; P < .001). Moreover, the OFTVs were more sensitive than the 4CV for detecting ductal-dependent forms of CHD. Diagnosis after discharge to home occurred in 39 of 135 postnatal diagnoses (29%), including many cases of isolated outflow tract abnormalities requiring early invasive intervention.

CONCLUSIONS

Cases of major neonatal CHD with OFTV abnormalities predominate over cases with 4CV abnormalities, particularly among those forms of CHD requiring early invasive intervention.

A primer for fetal cardiac imaging: a stepwise approach for 2-dimensional imaging

Detection of congenital heart disease (CHD) remains problematic, even with advances in imaging. Imaging modalities, such as magnetic resonance imaging, have been helpful in better understanding certain abnormalities, such as the fetal central nervous system. However, because of cardiac motion, screening and detection of CHD are best performed by sonography. Although newer technical advances in sonography, including 3-dimensional (3-D) dynamic multiplanar imaging and Doppler techniques, are extremely helpful in better delineating CHD, the mainstay of detection of CHD remains 2-D real-time imaging. Understanding 2-D imaging of the heart, using multiple views, is necessary to perform any type of multiplanar imaging as both require basic understanding of the same basic views. Although it is beyond the scope of this article to review all facets of fetal cardiac imaging, we will present a stepwise approach using 2-D imaging in the detection of CHD.

A systematic approach to the use of the multiplanar display in evaluation of abnormal vascular connections to the fetal heart using 4-dimensional ultrasonography

OBJECTIVE

The multiplanar display is a modality that allows the simultaneous visualization of 3 orthogonal planes from volume data sets obtained with 3- and 4-dimensional ultrasonography. Simultaneous display of standard views used in fetal echocardiography and their orthogonal planes may provide novel ultrasonographic views for examination of the fetal heart and its vascular connections. This study was designed to determine the clinical utility of the multiplanar display in the examination of abnormal vascular connections to the fetal heart.

METHODS

We reviewed 4-dimensional volume data sets, acquired with the spatiotemporal image correlation technique, from patients with abnormal vascular connections to the fetal heart. Multiplanar views of the fetal heart were used to simultaneously display standard planes used in fetal echocardiography and their corresponding orthogonal planes.

RESULTS

This study included 4 volume data sets from fetuses with confirmed abnormal vascular connections to the heart, including: (1) an interrupted inferior vena cava with azygos or hemiazygos vein continuation; (2) a persistent left superior vena cava draining into a dilated coronary sinus; and (3) a dilated superior vena cava associated with a thoracic lymphangioma. Simultaneous visualization of orthogonal planes displaying abnormal vascular connections to the fetal heart facilitated identification of the abnormal vessels and their spatial relationships with other vascular structures.

CONCLUSIONS

Multiplanar imaging can be used to assess abnormal vascular connections to the fetal heart and may provide novel ultrasonographic planes for fetal echocardiography using 3- and 4-dimensional ultrasonography.

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

OBJECTIVES

Congenital heart disease is associated with high mortality and morbidity rates, being the most life-threatening defect in the first month of postnatal life and accounting for approximately half of all childhood mortality from birth defects. Despite this, the prenatal detection rate for congenital outflow tract anomalies by ultrasound imaging is relatively low. The aim of this study was to establish a nomogram for the pulmonary artery/aorta (PA/AO) ratio measured in the three-vessel view plane. This ratio was investigated as a simple screening tool for congenital cardiac outflow tract abnormalities.

METHODS

The study was a prospective evaluation of 966 singleton fetuses at 16-24 weeks of gestation and 46 fetuses with congenital cardiac outflow tract abnormalities. The diameters of the pulmonary artery and aorta were measured in the three-vessel view. The PA/AO ratio was calculated and a nomogram was constructed. The mean and 95% CI for the ratio were defined and the PA/AO ratios of cases with outflow tract abnormalities were plotted against the values for normal fetuses.

RESULTS

The gestational age of the normal group ranged from 16 to 24 weeks, with a median of 19 weeks. The pulmonary artery diameter measured between 2.1 and 4.93 mm (mean, 3.3 mm) and the aorta measured between 2.1 and 5.2 mm (mean, 2.93 mm). The mean (SD) PA/AO ratio was 1.16 (0.18) (95% CI, 0.87-1.58; range 0.61-1.86; median, 1.14). For fetuses with outflow tract abnormalities, the median gestation was 19 weeks and 37/43 (86%) had a PA/AO ratio outside the 95% CI.

CONCLUSIONS

The PA/AO ratio derived from measurements in the three-vessel view plane can be used as an initial screening tool for outflow tract anomalies and may have a sensitivity of up to 86%, with a 5% false-positive rate.