Predictive Models for Normal Fetal Cardiac Structures

Reference Values for Fetal Cardiac Dimensions, Volumes, Ventricular Function and Left Ventricular Longitudinal Strain Using Doppler Ultrasound Gated Cardiac Magnetic Resonance Imaging in Healthy Third Trimester Fetuses

BACKGROUND

Recent advances in hardware and software permit the use of cardiac MRI of late gestation fetuses, however there is a paucity of MRI-based reference values.

PURPOSE

To provide initial data on fetal cardiac MRI-derived cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain in healthy developing fetuses >30 weeks gestational age.

STUDY TYPE

Prospective.

POPULATION

Twenty-five third trimester (34 ± 1 weeks, range of 32-37 weeks gestation) women with healthy developing fetuses.

FIELD STRENGTH/SEQUENCE

Studies were performed at 1.5 T and 3 T. Cardiac synchronization was achieved with a Doppler ultrasound device. The protocol included T2 single shot turbo spin echo stacks for fetal weight and ultrasound probe positioning, and multiplanar multi-slice cine balanced steady state free precession gradient echo sequences.

ASSESSMENT

Primary analyses were performed by a single observer. Weight indexed right ventricular (RV) and left ventricular (LV) volumes and function were calculated from short axis (SAX) stacks. Cardiac dimensions were calculated from the four-chamber and SAX stacks. Single plane LV longitudinal strain was calculated from the four-chamber stack. Interobserver variability was assessed in 10 participants. Cardiac MRI values were compared against available published normative fetal echocardiogram data using z-scores.

STATISTICAL TESTS

Mean and SDs were calculated for baseline maternal/fetal demographics, cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain. Bland-Altman and intraclass correlation coefficient analysis was performed to test interobserver variability.

RESULTS

The mean gestational age was 34 ± 1.4 weeks. The mean RV and LV end diastolic volumes were 3.1 ± 0.6 mL/kg and 2.4 ± 0.5 mL/kg respectively. The mean RV cardiac output was 198 ± 49 mL/min/kg while the mean LV cardiac output was 173 ± 43 mL/min/kg.

DATA CONCLUSION

This paper reports initial reference values obtained by cardiac MRI in healthy developing third trimester fetuses. MRI generally resulted in slightly larger indexed values (by z-score) compared to reports in literature using fetal echocardiography.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Successful prenatal treatment with continuous chronic maternal hyperoxygenation therapy in hypoplastic left heart in two pregnancies: Case report

Maternal hyperoxygenation (MH) has been studied as a diagnostic tool to evaluate pulmonary vasculature and as a treatment option to improve the growth of fetal left heart in fetuses with left-sided cardiac defects. Chronic maternal hyperoxygenation (CMH) therapy leads to an improvement in fetal pulmonary blood flow resulting in an enhanced venous return to the left heart with increased gestational age. With this manipulation it is anticipated to augment blood flow directed remodeling of the left heart structures and to improve left heart growth spanning from the mitral valve to the aortic isthmus. However, there are concerns about CMH therapy with regard to fetal complications with growth restriction and fetal brain development. Now, with two successful cases we try to discuss this fetal treatment option and related concerns.

Fetal Echocardiographic Z Score Pilot Project: Study Design and Impact of Gestational Age and Variable Type on Reproducibility of Measurements Within and Across Investigators

BACKGROUND

Fetal echocardiography is widely available, but normative data are not robust. In this pilot study, the authors evaluated (1) the feasibility of prespecified measurements in a normal fetal echocardiogram to inform study design and (2) measurement variability to assign thresholds of clinical significance and guide analyses in larger fetal echocardiographic Z score initiatives.

METHODS

Images from predefined gestational age groups (16-20, >20-24, >24-28, and >28-32 weeks) were retrospectively analyzed. Fetal echocardiography expert raters attended online group training and then independently analyzed 73 fetal studies (18 per age group) in a fully crossed design of 53 variables; each observer repeated measures for 12 fetuses. Kruskal-Wallis tests were used to compare measurements across centers and age groups. Coefficients of variation (CoVs) were calculated at the subject level for each measurement as the ratio of SD to mean. Intraclass correlation coefficients were used to show inter- and intrarater reliabilities. Cohen's d > 0.8 was used to define clinically important differences. Measurements were plotted against gestational age, biparietal diameter, and femur length.

RESULTS

Expert raters completed each set of measurements in a mean of 23 ± 9 min/fetus. Missingness ranged from 0% to 29%. CoVs were similar across age groups for all variables (P < .05) except ductus arteriosus mean velocity and left ventricular ejection time, which were both higher at older gestational age. CoVs were >15% for right ventricular systolic and diastolic widths despite fair to good repeatability (intraclass correlation coefficient > 0.5); ductal velocities and two-dimensional measures, left ventricular short-axis dimensions, and isovolumic times all had high CoVs and high interobserver variability despite good to excellent intraobserver agreement (intraclass correlation coefficient > 0.6). CoVs did not improve when ratios (e.g., tricuspid/mitral annulus) were used instead of linear measurements. Overall, 27 variables had acceptable inter- and intraobserver repeatability, while 14 had excessive variability between readers despite good intraobserver agreement.

CONCLUSIONS

There is considerable variability in fetal echocardiographic quantification in clinical practice that may affect the design of multicenter fetal echocardiographic Z score studies, and not all measurements may be feasible for standard normalization. As missingness was substantial, a prospective design will be needed. Data from this pilot study may aid in the calculation of sample sizes and inform thresholds for distinguishing clinically significant from statistically significant effects.

Lifesaving Treatments for the Tiniest Patients-A Narrative Description of Old and New Minimally Invasive Approaches in the Arena of Fetal Surgery

Fetal surgery has become a lifesaving reality for hundreds of fetuses each year. The development of a formidable spectrum of safe and effective minimally invasive techniques for fetal interventions since the early 1990s until today has led to an increasing acceptance of novel procedures by both patients and health care providers. From his vast personal experience of more than 20 years as one of the pioneers at the forefront of clinical minimally invasive fetal surgery, the author describes and comments on old and new minimally invasive approaches, highlighting their lifesaving or quality-of-life-improving potential. He provides easy-to-use practical information on how to perform partial amniotic carbon dioxide insufflation (PACI), how to assess lung function in fetuses with pulmonary hypoplasia, how to deal with giant CPAMS, how to insert shunts into fetuses with LUTO and hydrothorax when conventional devices are not available, and how to resuscitate a fetus during fetal cardiac intervention. Furthermore, the author proposes a curriculum for future fetal surgeons, solicits for the centralization of patients, for adequate maternal counseling, for adequate pain management and adequate hygienic conditions during interventions, and last but not least for starting the process of academic recognition of the matured field as an independent specialty. These steps will allow more affected expectant women and their unborn children to gain access to modern minimally invasive fetal surgery and therapy. The opportunity to treat more patients at dedicated centers will also result in more opportunities for the research of rare diseases and conditions, promising even better pre- and postnatal care in the future.

Assessment of the Size and Shape of the 4-Chamber View and the Right and Left Ventricles using Fetal Speckle Tracking in Normal Fetuses at 17-24 Gestational Weeks

INTRODUCTION

The aim of the study was to establish normal reference values obtained by fetal speckle tracking analysis of the fetal heart between 17-24 weeks of gestation among Thai fetuses and compare the nomograms with previous studies.

METHODS

The 4-chamber view of the fetal heart in 79 normal fetuses was analyzed by speckle tracking analysis to determine the best-fit regression model. The 95% reference intervals and Z-score equations of fetal cardiac parameters were computed.

RESULTS

The end-diastolic length, width, area, and circumference of the 4-chamber view (4CV) as well as the ventricular end-diastolic length, 24-segment widths, and area were all increased as a function of gestational age (GA) and 5 fetal biometric parameters. In contrast, the global sphericity index (SI), 24-segment SI, and right ventricle/left ventricle width and area ratios did not change with GA or fetal biometric measurements. There were few differences in Z-score reference ranges of fetal cardiac measurements between the current study and previous studies conducted in different patient populations.

CONCLUSION

Our study provided z-score and corresponding centile calculators, 5th and 95th centile reference tables, and corresponding graphs for evaluating the size and shape of the 4CV and the right and left ventricles using 6 independent variables between 17 and 24 weeks of gestation. These results provide normal reference ranges for future studies of fetuses with pathologies that may alter the size and shape of the 4-chamber view and ventricles.

Is Cardiomegaly an Indication of "Heart-Sparing Effect" in Small Fetuses?

INTRODUCTION

This study aimed to test the hypothesis that cardiac size is maintained in small fetuses presenting with cardiomegaly.

MATERIALS AND METHODS

We identified singleton fetuses with estimated fetal weight <10th centile and with cardiomegaly without another more likely cardiac or extra-cardiac cause. We used Z-scores for cardiac and thoracic circumferences normalized for gestational age (GA), biparietal diameter (BPD), head circumference (HC), and femur length (FL), obtained from 188 normally grown fetuses.

RESULTS

When comparing chest size, small fetuses had significantly lower thoracic circumferences median Z-scores (IQR) for GA = -4.82 (-6.15 to -3.51), BPD = -2.42 (-4.04 to -1.48), HC = -2.72 (-4.53 to -1.90), and FL = -1.60 (-2.87 to -0.71); p < 0.001 for all. When comparing heart size, small fetuses showed lower cardiac circumferences median Z-scores (IQR) for GA = -1.59 (-2.79 to -0.16); p < 0.001, similar cardiac circumferences Z-scores for BPD = 0.29 (-0.65 to 1.28); p = 0.284 and HC = 0.11 (-1.13 to 0.96); p = 0.953, and higher cardiac circumferences Z-scores for FL = 0.94 (-0.05 to 2.13); p < 0.001.

CONCLUSIONS

Our results show that in small fetuses with cardiomegaly, the heart maintains normal dimensions when normalized to cranial diameters and higher dimensions when normalized to long bones. This provides insight into cardiac adaptation to adverse intrauterine environment.

Fetal echocardiographic predictors of biventricular circulation in hypoplastic left heart complex

OBJECTIVES

To determine which echocardiographic features of hypoplastic left heart complex (HLHC) in the fetal period are predictive of biventricular (BV) circulation and to evaluate the long-term outcome of patients with HLHC, including rates of mortality, reintervention and development of further cardiac disease.

METHODS

Echocardiograms of fetuses with HLHC obtained at 18-26 weeks and 27-36 weeks' gestation between 2004 and 2017 were included in the analysis. The primary outcome was successful BV circulation (Group 1). Group 2 included patients with single-ventricle palliation, death or transplant. Univariate analysis was performed on data obtained at 18-26 and 27-36 weeks and multivariate logistic regression was performed on data obtained at 27-36 weeks only.

RESULTS

Of the 51 included cases, 44 achieved successful BV circulation (Group 1) and seven did not (Group 2). Right-to-left/bidirectional foramen ovale (FO) flow and a higher mitral valve (MV) annulus Z-score were associated with successful BV circulation on both univariate and multivariate analysis. Bidirectional or left-to-right FO flow, left ventricular length (LVL) Z-score of < -2.4 and a MV Z-score of < -4.5 correctly predicted 80% of Group 2 cases. Late follow-up was available for 41 patients. There were two late deaths in Group 2. Thirteen patients in Group 1 required reintervention, 12 developed mitral stenosis and five developed isolated subaortic stenosis.

CONCLUSIONS

BV circulation is common in fetuses with HLHC. Higher MV annulus and LVL Z-scores and right to left direction of FO flow are important predictors of BV circulation. Long-term sequelae in those with BV circulation may include mitral and subaortic stenosis. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Validation of Prenatal Aortic Arch Angle Measurements in the Diagnosis of Neonatal Coarctation of the Aorta

Prenatal prediction of coarctation of the aorta (CoA) is challenging. Methods identifying prenatal CoA have high sensitivity with significant false positives. We previously derived prenatal aortic arch angles for identifying CoA with high sensitivity and specificity and aim to validate these angles and compare them with a model utilizing ascending aorta (AAo) and isthmus (Aoi) measures. Retrospective case/cohort study of fetuses with prenatal suspicion for CoA. 35 fetuses were included. Measurements included: ascending-descending aortic angle (AAo.DAo), transverse-descending aortic angle (TAo.DAo); diameters and z-scores of Aoi from sagittal (Aoi-sag), three-vessel (Aoi-3VV) view and AAo. Discriminant functions for the 5 variables were compared using histograms and positive/negative predictive values (PPV/NPV). CoA was confirmed in 28/35 neonates. The PPV and NPV for angle measures were 100% and 77%. The AAo + Aoi-3VV model PPV and NPV were 92% and 80% and Aoi-sag + Aoi-3VV model were 82% and 71%. A linear discriminant model utilizing the 3 most predictive variables improved NPV to 90% and PPV to 100%. In conclusion, we validate that angle measures are superior to standard models of predicting CoA. An optimized 3 variable model maintains accuracy of identifying CoA while eliminating false positives.

Cardiac Measurements of Size and Shape in Fetuses With Absent or Reversed End-Diastolic Velocity of the Umbilical Artery and Perinatal Survival and Severe Growth Restriction Before 34 Weeks' Gestation

OBJECTIVES

The purpose of this study was to evaluate the end-diastolic size and shape of the 4-chamber view as well as the right ventricle (RV) and left ventricle (LV) in growth-restricted fetuses before 34 weeks' gestation with absent or reversed end-diastolic velocity of the umbilical artery and compare the results between those with perinatal deaths and those who survived the neonatal period.

METHODS

Forty-nine fetuses with growth restriction and absent or reversed end-diastolic velocity of the umbilical artery were studied. The size, shape, and sphericity index of the 4-chamber view, RV, and LV were assessed. The number and percentage of fetuses with z score values of less than -1.65 and greater than 1.65 were computed.

RESULTS

Of the 49 fetuses, there were 13 perinatal deaths (27%) and 36 (63%) neonatal survivors. Measurements that were unique for neonatal survivors were an increased RV apical transverse width and decreased measurements of the following: LV and RV widths, LV and RV areas, as well as RV sphericity indices.

CONCLUSIONS

Fetuses with a smaller RV and LV size and area and those with a globular-shaped RV were at significantly lower risk for perinatal death.

Contemporary Outcomes in Tetralogy of Fallot With Absent Pulmonary Valve After Fetal Diagnosis

Background

Tetralogy of Fallot with absent pulmonary valve is associated with high mortality, but it remains difficult to predict outcomes prenatally. We aimed to identify risk factors for mortality in a large multicenter cohort.

Methods and Results

Fetal echocardiograms and clinical data from 19 centers over a 10‐year period were collected. Primary outcome measures included fetal demise and overall mortality. Of 100 fetuses, pregnancy termination/postnatal nonintervention was elected in 22. Of 78 with intention to treat, 7 (9%) died in utero and 21 (27%) died postnatally. With median follow‐up of 32.9 months, no deaths occurred after 13 months. Of 80 fetuses with genetic testing, 46% had chromosomal abnormalities, with 22q11.2 deletion in 35%. On last fetal echocardiogram, at a median of 34.6 weeks, left ventricular dysfunction independently predicted fetal demise (odds ratio [OR], 7.4; 95% CI 1.3, 43.0; P=0.026). Right ventricular dysfunction independently predicted overall mortality in multivariate analysis (OR, 7.9; 95% CI 2.1–30.0; P=0.002). Earlier gestational age at delivery, mediastinal shift, left ventricular/right ventricular dilation, left ventricular dysfunction, tricuspid regurgitation, and Doppler abnormalities were associated with fetal and postnatal mortality, although few tended to progress throughout gestation on serial evaluation. Pulmonary artery diameters did not correlate with outcomes.

Conclusions

Perinatal mortality in tetralogy of Fallot with absent pulmonary valve remains high, with overall survival of 64% in fetuses with intention to treat. Right ventricular dysfunction independently predicts overall mortality. Left ventricular dysfunction predicts fetal mortality and may influence prenatal management and delivery planning. Mediastinal shift may reflect secondary effects of airway obstruction and abnormal lung development and is associated with increased mortality.

A "holistic" sonographic view on congenital heart disease: How automatic reconstruction using fetal intelligent navigation echocardiography eases unveiling of abnormal cardiac anatomy part II-Left heart anomalies

Volume ultrasound has been shown to provide valid complementary information on fetal anatomy. Four-dimensional assessment (4D) of the fetal cardiovascular system using spatial-temporal image correlation (STIC) allows for detailed examination of a highly complex organ from the early second trimester onward. There is compelling evidence that this technique harbors quite a number of diagnostic opportunities, but manual navigation through STIC volume datasets is highly operator dependent. In fact, STIC is not incorporated yet into daily practice. Application of the novel fetal intelligent navigation echocardiography (FINE) considerably simplifies fetal cardiac volumetric examinations. This automatic technique applied on cardiac volume datasets reportedly has both high sensitivity and specificity for the detection of congenital heart defects (CHDs). Part I reviewed current data regarding detection rates of CHDs and illustrated the additional value of an automatic approach in delineating cardiac anatomy exemplified by congenital lesions of the right heart. In part II of this pictorial essay, we focused on left heart anomalies and aimed to tabulate recent findings on the quantification of normal and abnormal cardiac anatomy.

Fetal Echocardiographic Dimension Indices: Important Predictors of Postnatal Coarctation

The aim of the study is to identify reliable quantitative fetal echocardiographic predictors for postnatal development of coarctation (CoA). In this retrospective study, we included 65 fetuses with a prenatally suspected, isolated CoA, born 2010-2018. Dimensions of the cardiac structures, aortic, and ductal arches expressed as ratios and Z-scores were analyzed in relation to outcome. Fetuses that developed CoA postnatally (34%) exhibited significantly smaller Z-scores of left cardiac structures from the mitral valve to the aortic isthmus. The most sensitive and specific predictors were a carotid-subclavian artery index (CSAI) of < 0.78 (92.3% sensitivity, 96.8% specificity) or a product of isthmus-to-duct ratio in the three-vessel trachea view (3VT) and the mitral-to-tricuspid valve ratio (I/D_3VTxMV/TV) of < 0.37 (100% sensitivity, 94.6% specificity). When comparing different Z-score datasets, we observed large and highly significant differences. Postnatal CoA can be predicted with high accuracy during fetal life using CSAI or I/D_3VTxMV/TV. The latter may be particularly useful if adequate sagittal aortic arch images cannot be obtained. As significant and clinically unacceptable differences in Z-scores were observed for the same measurements, this calls for a large multi-center collaboration to generate reliable fetal echocardiographic Z-scores.

Development of the Z-score for the measurement of myocardial thickness by two-dimensional echocardiography in normal fetuses

BACKGROUND

In the current literature, there is a tendency to describe normal values of echocardiographic measurements by means of the Z-score. In fetal cardiology, these Z-score equations are still being established. Measurement of myocardial thickness is an important assessment, especially in fetuses of diabetic mothers, because of the risk of developing myocardial hypertrophy secondary to elevated maternal blood glucose levels.

OBJECTIVE

To determine the percentiles and to develop the Z-score equations of right and left ventricular lateral walls and interventricular septum measurements using two-dimensional echocardiography in normal fetuses between 24 and 34 weeks of gestation.

METHODS

This is a prospective cross-sectional study that was performed in single fetuses with normal heart from nondiabetic pregnant women. Measurements of the lateral walls of the right and left ventricles and the interventricular septum were made.

RESULTS

Eight hundred and seventy three pregnant women were included. We determined the percentiles of the measurements for each gestational age. The Z-score equation was developed for each of the measurements: right ventricular lateral wall measurement [RVLW = x-(-1 + 0.109 * GA)/0.4], left ventricle lateral wall measurement [LVLW = x-(-1.366 + 0.12 * GA)/0.43], and interventricular septum, both at the four-chamber view [IVS_4ch = (x-(-1.113 + 0.107 * GA)/0.4] and at the left ventricular outflow tract plane [IVS_LVOT = (x-(-0.581 + 0.084 * GA)/0.35].

CONCLUSION

The present study allowed the demonstration of the percentiles and the Z-score equations for each of the measurements studied.

[Genital abnormalities: Contextualization of a neglected area in prenatal diagnosis]

OBJECTIVE

To reflect on how the area of genital abnormalities has fallen behind in prenatal diagnosis.

METHODS

Based on the thesis that prenatal diagnosis of genital abnormalities has scarcely developed, a comparison with other areas of prenatal diagnosis and with its postnatal counterpart is presented; different explanations for this situation are examined; and a reflection is presented on ways to expand this field of knowledge.

CONCLUSIONS

Compared to other disciplines, prenatal diagnosis of genital abnormalities finds itself lagging behind in terms of diagnostic tools, management protocols and scientific literature. Potential causes include a perception of low prevalence and limited importance, or exploration challenges. Integration of current knowledge, together with the acquisition of the appropriate tools and translation to clinical medicine, would be a way to make this discipline stronger.

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

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

Normal right and left ventricular volumes prospectively obtained from cardiovascular magnetic resonance in awake, healthy, 0- 12 year old children

INTRODUCTION

Pediatric z scores are necessary to describe size and structure of the heart in growing children, however, development of an accurate z score calculator requires robust normal datasets, which are difficult to obtain with cardiovascular magnetic resonance (CMR) in children. Motion-corrected (MOCO) cines from re-binned, reconstructed real-time cine offer a free-breathing, rapid acquisition resulting in cines with high spatial and temporal resolution. In combination with child-friendly positioning and entertainment, MOCO cine technique allows for rapid cine volumetry in patients of all ages without sedation. Thus, our aim was to prospectively enroll normal infants and children birth-12 years for creation and validation of a z score calculator describing normal right ventricular (RV) and left ventricular (LV) size.

METHODS

With IRB approval and consent/assent, 149 normal children successfully underwent a brief noncontrast CMR on a 1.5 T scanner including MOCO cines in the short axis, and RV and LV volumes were measured. 20% of scans were re-measured for interobserver variability analyses. A general linear modeling (GLM) framework was employed to identify and properly represent the relationship between CMR-based assessments and anthropometric data. Scatter plots of model fit and Akaike's information criteria (AIC) results were used to guide the choice among alternative models.

RESULTS

A total of 149 subjects aged 22 days-12 years (average 5.1 ± 3.6 years), with body surface area (BSA) range 0.21-1.63 m2 (average 0.8 ± 0.35 m2) were scanned. All ICC values were > 95%, reflecting excellent agreement between raters. The model that provided the best fit of volume measure to the data included BSA with higher order effects and gender as independent variables. Compared with earlier z score models, there is important additional growth inflection in early toddlerhood with similar z score prediction in later childhood.

CONCLUSIONS

Free-breathing, MOCO cines allow for accurate, reliable RV and LV volumetry in a wide range of infants and children while awake. Equations predicting fit between LV and RV normal values and BSA are reported herein for purposes of creating z scores.

TRIAL REGISTRATION

clinicaltrials.gov NCT02892136, Registered 7/21/2016.

Nomograms of Fetal Right Ventricular Fractional Area Change by 2D Echocardiography

OBJECTIVES

Fetal right ventricular (RV) function assessment is challenging due to the RV geometry and limitations of in utero assessment. Postnatally, 2D echocardiographic RV fractional area change (FAC) is used to assess RV global systolic function by calculating the percentage of change in RV area from systole to diastole. Reports on FAC are scarce in prenatal life, and nomograms throughout pregnancy are not available. Our aims were (1) to study prenatal RV FAC feasibility and reproducibility and (2) to construct nomograms for RV FAC and end-diastolic (ED) and end-systolic (ES) RV areas from 18 to 41 weeks of gestation.

METHODS

Prospective cohort study including 602 low-risk singleton pregnancies undergoing a fetal echocardiography from 18 to 41 weeks of gestation. RV ED and ES areas were measured following standard recommendations for ventricular dimensions and establishing strict landmarks to identify the different phases of the cardiac cycle. RV FAC was calculated as: ([ED area - ES area]/ED area) × 100. RV FAC intra- and inter-observer reproducibility was evaluated in 45 fetuses by calculating the intraclass correlation coefficient (ICC). Parametric regressions were tested to model each parameter against gestational age (GA) and estimated fetal weight (EFW).

RESULTS

RV areas and FAC were successfully obtained in ∼99% of fetuses with acceptable reproducibility throughout gestation (RV ED area inter-observer ICC [95% CI] 0.96 [0.93-0.98], RV ES area 0.97 [0.94-0.98], and FAC 0.69 [0.44-0.83]). Nomograms were constructed for RV ED and ES areas and FAC. RV areas showed a quadratic and logarithmic increase with GA and EFW, respectively. In contrast, RV FAC showed a slight quadratic decrease throughout gestation (mean RV FAC ranged from 36% at 18 weeks of gestation [10-90th centiles: 25-47%, respectively] to 29% at 41 weeks [10-90th centiles: 18-40%, respectively]). The best models for RV areas and FAC were a second-degree polynomial.

CONCLUSIONS

RV FAC is a feasible and reproducible parameter to assess RV global systolic function in fetal life. We provide reference ranges adjusted by GA and EFW that can be used as normal references for the assessment of RV function in prenatal conditions.

Fetal Cardiac Intervention in Critical Aortic Stenosis with Severe Mitral Regurgitation, Severe Left Atrial Enlargement, and Restrictive Foramen Ovale

OBJECTIVE

To assess the intrauterine course and outcome of fetal cardiac intervention (FCI) in fetuses with critical aortic stenosis (CAS), severe mitral regurgitation (MR), severe left atrial dilatation (LAD), and restrictive foramen ovale (RFO) or intact atrial septum.

METHODS

All fetuses with a prenatal diagnosis of CAS, severe MR, severe LAD, and RFO were retrospectively collected in one tertiary center for fetal medicine over a period of 10 years. Video recordings, pre- and postnatal charts were reviewed for cardiac and extracardiac anomalies, intrauterine course, and postnatal outcome.

RESULTS

Nineteen fetuses with CAS, severe MR, severe LAD, and RFO were diagnosed in the study period. In 5 cases, FCI was not considered as the parents either opted for expectative management or for termination. In the remaining 14 fetuses, 21 FCI were performed: 14 balloon valvuloplasties, 2 atrioseptostomies, and 5 fetal atrial stent insertions. Seven of 14 fetuses (50%) had fetal hydrops, 5 of 14 fetuses (36%) presented with intact atrial septum. Procedure-related death occurred in 5 fetuses after aortic valvuloplasty or concomitant atrioseptostomy but in none after fetal atrial stenting. Due to progressive hydrops, two terminations of pregnancy were performed. Among the 7 live births, 3 died in the neonatal period. The remaining 4 received single ventricle palliation, 2 following fetal aortic valvuloplasty and 2 after fetal atrial stent insertion.

CONCLUSIONS

CAS with severe MR, severe LAD, and RFO has a high overall mortality even in cases undergoing intrauterine intervention. Parameters that accurately predict the intrauterine and postnatal outcome have yet to be defined.

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

BACKGROUND

Assessment of the outflow tract views is an integral part of routine fetal cardiac scanning. For some congenital heart defects, notably coarctation of the aorta, pulmonary valve stenosis, and aortic valve stenosis, the size of vessels is important both for diagnosis and prognosis. Existing reference ranges of fetal outflow tracts are derived from a small number of cases.

METHODS AND RESULTS

The study population comprised 7945 fetuses at 13 to 36 weeks' gestation with no detectable abnormalities from pregnancies resulting in normal live births. Prospective measurements were taken of (1) the aortic and pulmonary valves in diastole at the largest diameter with the valve closed, (2) the distal transverse aortic arch on the 3 vessel and trachea view beyond the trachea at the distal point at its widest systolic diameter, and (3) the arterial duct on the 3 vessel and trachea view at its widest systolic diameter. Regression analysis, with polynomial terms to assess for linear and nonlinear contributors, was used to establish the relationship between each measurement and gestational age. The measurement for each cardiac diameter was expressed as a z score (difference between observed and expected value divided by the fitted SD corrected for gestational age) and percentile. Analysis included calculation of gestation-specific SDs. Regression equations are provided for the cardiac outflow tracts and for the distal transverse aortic arch:arterial duct ratio.

CONCLUSIONS

The study established reference ranges for fetal outflow tract measurements at 13 to 36 weeks' gestation that are useful in clinical practice.

Fetal Echocardiographic Parameters and Surgical Outcomes in Congenital Left-Sided Cardiac Lesions

This study aimed to evaluate fetal echocardiographic parameters associated with neonatal intervention and single-ventricle palliation (SVP) in fetuses with suspected left-sided cardiac lesions. Initial fetal echocardiograms (1/2002-1/2017) were interpreted by the contemporary fetal cardiologist as coarctation of the aorta (COA), left heart hypoplasia (LHH), hypoplastic left heart syndrome (HLHS), mitral valve hypoplasia (MVH) ± stenosis, and aortic valve hypoplasia ± stenosis (AS). The cohort comprised 68 fetuses with suspected left-sided cardiac lesions (COA n = 15, LHH n = 9, HLHS n = 39, MVH n = 1, and AS n = 4). Smaller left ventricular (LV) length Z score, aortic valve Z score, ascending aorta Z score, and aorta/pulmonary artery ratio; left-to-right shunting at the foramen ovale; and retrograde flow in the aortic arch were associated with the need for neonatal intervention (p = 0.005-0.04). Smaller mitral valve (MV) Z score, LV length Z score, aortic valve Z score, ascending aorta Z score, aorta/pulmonary artery ratio, and LV ejection fraction, as well as higher tricuspid valve-to-MV (TV/MV) ratio, right ventricular-to-LV (RV/LV) length ratio, left-to-right shunting at the foramen ovale, abnormal pulmonary vein Doppler, absence of prograde aortic flow, and retrograde flow in the aortic arch were associated with SVP (p < 0.001-0.008). The strongest independent variable associated with SVP was RV/LV length ratio (stepwise logistical regression, p = 0.03); an RV/LV length ratio > 1.28 was associated with SVP with a sensitivity of 76% and specificity of 96% (AUC 0.90, p < 0.001). A fetal RV/LV length ratio of > 1.28 may be a useful threshold for identifying fetuses requiring SVP.

Comprehensive Evaluation of Fetal Cardiac Ventricular Widths and Ratios Using a 24-Segment Speckle Tracking Technique

INTRODUCTION

This study was conducted to evaluate the 24-segment transverse widths of the right and left ventricles distributed from the base to the apex of the ventricular chambers and compute the right ventricular (RV)/left ventricular (LV) ratios for each segment.

METHODS

Two hundred control fetuses were examined between 20 and 40 weeks' gestation. Using offline speckle-tracking software, the 24 end-diastolic transverse widths were computed and the RV/LV ratios were regressed against 7 independent variables related to the size, weight, and age of the fetuses. Five fetuses with coarctation of the aorta and 5 fetuses with pulmonary stenosis were examined to exemplify the utility of these measurements.

FINDINGS

The 24-segment transverse widths were associated with changes in fetal size, weight, and age. Regression equations were developed to describe these changes with R² values between .5 and .82. The measurements were normally distributed (Shapiro-Wilk > 0.5). The RV/LV ratio for the 24 segments did not strongly correlate (R²  = .001 to -.2) with fetal size, weight, or gestational age. Fetuses with coarctation of the aorta and pulmonary stenosis demonstrated characteristic changes in the 24-segment transverse widths and the RV/LV ratios in the basal (segments 1-8), mid (segments 9-16) and apical (segments 17-24) sections of the ventricles.

CONCLUSIONS

The 24-segment transverse widths of the right and left ventricles and the RV/LV ratios provide a comprehensive method to examine the width of the ventricular chambers.

Temporal analysis of cardiovascular control and function following incomplete T3 and T10 spinal cord injury in rodents

Spinal cord injury (SCI) is a devastating condition that results in whole‐body dysfunction, notably cardiovascular (CV) disruption and disease. Injury‐induced destruction of autonomic pathways in conjunction with a progressive decline in physical fitness contribute to the poor CV status of SCI individuals. Despite the wide use of exercise training as a therapeutic option to reduce CV dysfunction, little is known about the acute hemodynamic responses to the exercise itself. We investigated CV responses to an exercise challenge (swimming) following both high and low thoracic contusion to determine if the CV system is able to respond appropriately to the challenge of swimming. Blood pressure (BP) telemetry and echocardiography were used to track the progression of dysfunction in rodents with T3 and T10 SCI (n = 8 each) for 10 weeks postcontusion. At 1 week postinjury, all animals displayed a drastic decline in heart rate (HR) during the exercise challenge, likely a consequence of neurogenic shock. Furthermore, over time, all groups developed a progressive inability to maintain BP within a narrow range during the exercise challenge despite displaying normal hemodynamic parameters at rest. Echocardiography of T10 animals revealed no persistent signs of cardiac dysfunction; T3 animals exhibited a transient decline in systolic function that returned to preinjury levels by 10 weeks postinjury. Novel evidence provided here illustrates that incomplete injuries produce hemodynamic instability that only becomes apparent during an exercise challenge. Further, this dysfunction lasts into the chronic phase of disease progression despite significant recovery of hindlimb locomotion and cardiac function.

Quantile Score: A New Reference System for Quantitative Fetal Echocardiography Based on a Large Multicenter Study

BACKGROUND

Normative ranges of fetal echocardiographic measurements are important for quantitative diagnosis of fetal cardiovascular disease. The current normative ranges were derived from small samples and were based on the hypothesis of a normal distribution of these measurements during fetal cardiovascular growth. The aims of this study were to test the hypothesis of a normal distribution of fetal echocardiographic measurements in a large multicenter cohort and to propose a reference system without the normal distribution hypothesis to improve accuracy of fetal echocardiographic measurements.

METHODS

Fifty-two variables from 6,343 normal fetal echocardiographic examinations were acquired from seven Chinese centers. The hypothesis of a normal distribution used in ordinary least squares regression was tested with the Jarque-Bera test. The quantile score (q score) derived from quantile regression without normal distribution hypothesis was compared with the Z score derived from ordinary least squares regression. A total of 288 fetuses with outflow tract and great artery abnormalities and 300 normal fetuses were used to compare the diagnostic accuracy of q and Z scores.

RESULTS

All fetal echocardiographic measurements showed non-normal distributions (P < .001). The normal range was underestimated by ordinary least squares regression compared with quantile regression by 30 ± 11%. The partial normalized areas under the receiver operating characteristic curve within the 20% false-positive rate were 0.62 and 0.50 for the q and Z scores, respectively.

CONCLUSIONS

The q score provides a more robust system for determining normative ranges of fetal echocardiographic measurements. The improved sensitivity of matched false-positive rates makes the q score a more accurate reference for prenatal diagnosis, assessment, and prognosis of fetal cardiovascular disease.