Fetal Heart Size: A Comparison Between the Point-to-Point Trace and Automated Ellipse Methods Between 20 and 40 Weeks' Gestation

Transversal cardiac diameter is increased in fetuses with dextro-transposition of the great arteries older than 28th weeks of gestation

OBJECTIVES

In majority of congenital heart defects the size of the fetal heart is normal (without cardiomegaly). Aim of this study was to establish normal ranges of fetal transversal cardiac diameter (4CV TW ED) and to compare fetal dextro-transposition of the great arteries (d-TGA) with normal ranges for 4CV TW ED.

METHODS

Retrospectively of 3,553 records we analyzed and included 1,154 healthy singleton fetuses as a control group. Consecutive percentiles for 4CV TW ED diameter according to the gestational age (GA) were calculated. 74 fetuses with d-TGA were analyzed in 3rd trimester.

RESULTS

The -2, -1, +1 and +2 Z-scores of 4CV TW ED between weeks 18 and 37 of gestation were calculated. In the group of fetuses with d-TGA 68 % of them had 4CV TW ED > +2 Z-score fitted for GA. Rashkind procedure during first 24 h after birth was performed in 63 % cases. Increased 4CV TW ED was more frequently seen in fetuses who needed Rashkind procedure after birth, but without statistical significance.

CONCLUSIONS

4CV TW ED measurement during the third trimester scans as a cardiac screening tool in obstetrical practice may potentially help to detect d-TGA and indicate further echocardiographic examination in case of d-TGA suspicion. 4CV TW ED was not helpful to predict the necessity for neonatal Rashkind procedure.

A New Method Using the Four-Chamber View to Identify Fetuses With Subsequently Confirmed Postnatal Aortic Coarctation

OBJECTIVE

To determine the sensitivity, specificity, and false-positive rate among fetuses suspected prenatally to have coarctation of the aorta (CoA) using size and shape measurements of the fetal heart from the four-chamber view (4CV).

METHODS

This was a retrospective study of 108 fetuses identified by pediatric cardiologists to be at risk for CoA. 4CV s from the last antenatal ultrasound performed by the cardiologists were analyzed. The end-diastolic area was computed using the point-to-point trace method around the epicardial border of the 4CV, and the largest end-diastolic length and width were measured from the epicardium to the epicardium to compute the global sphericity index (GSI) (length/width). Using speckle tracking analysis, the ventricular end-diastolic area, length, basal and mid-chamber widths were measured. The sphericity index of the base and mid-chamber of the ventricles was computed (length/width). In addition, the end-diastolic area ratios were computed as follows: right ventricular area/4CV area and the left ventricular area/4CV area. The z-scores for the above measurements were computed. Using logistic regression analysis, coefficients for predicting the probability of CoA from a test group of 27 fetuses with CoA and 27 without CoA was done. The logistic regression equation derived from the test group was applied to a validation group of 27 fetuses with CoA and 27 fetuses without CoA.

RESULTS

The regression equation from the test group identified the following end-diastolic measurements: 4CV GSI, RV area/heart area, LV base SI, and the RV Base SI. The test group consisted of 14 of 27 fetuses with an isolated CoA (52%) and 13 of 27 (48%) with additional heart abnormalities. For the validation group, 10 of 27 (37%) had an isolated CoA, and 17 (63%) had additional cardiac abnormalities. Using the logistic regression equation derived from the test group (54 fetuses: 27 with CoA and 27 without CoA), the validation group (54 fetuses: 27 with CoA and 27 without CoA) demonstrated the following: sensitivity for detecting CoA of 98.15%, specificity 98.15%, and a false-positive rate of 1.85%. When the logistic regression was applied to the test group of fetuses with isolated CoA, 100% (14/14) were identified with logistic regression analysis. For the validation group, 9 of 10 (90%) of fetuses with isolated CoA were identified using the logistic regression equation.

CONCLUSIONS

Using length, width, and area measurements of the 4CV and ventricles from which ratios are computed detects 98.15% of high-risk fetuses who will demonstrate CoA following birth, with a specificity of 98.15%, or a false-positive rate of 1.85%.

Reference Ranges and Z-Score Equations for 19 Fetal Cardiac Biometry Structures From 18 to 34 Weeks' Gestation

OBJECTIVE

To determine equations for calculating the Z-scores of fetal cardiac structures between 18+0 and 34+6 weeks of gestation, create percentile reference tables and curves for the structures, and assess the intra- and inter-observer reproducibility of the measurements.

METHODS

A cross-sectional study was conducted involving 340 normal fetuses from singleton pregnancies between 18 and 34 weeks of gestational age (GA). Nineteen cardiac structures were evaluated: diameters of the mitral, tricuspid, aortic, and pulmonary valve annuli; length, diameter, and area of the left and right ventricles; cardiac area and circumference; and diameters of the ascending aorta, aortic isthmus, main pulmonary artery, right pulmonary artery, left pulmonary artery, and ductus arteriosus. Regression analysis was performed to determine the equations for the mean and standard deviation of all structures using GA, biparietal diameter (BPD), and femur length (FL) as independent variables.

RESULTS

All equations had high coefficients of determination (R2). The best performance was achieved using the GA (R2 .819-.944), followed by FL (R2 .813-.937) and BPD (R2 .792-.934). The structure that demonstrated the highest R2 was the cardiac circumference and the smallest was the ductus arteriosus. Reference tables of percentiles 1, 5, 10, 50, 90, 95, and 99, and reference curves of Z-scores were created for all 19 cardiac structures, depending on the GA. All measurements demonstrated good and excellent reproducibility with an inter-observer intraclass correlation coefficient (ICC) of 0.774-0.972 and intra-observer ICC of 0.938-0.993.

CONCLUSIONS

Equations were produced to calculate Z-scores as well as percentile tables and curves for 19 fetal heart structures. All the measurements demonstrated good reproducibility.

MRI Reference Ranges for Fetal Cardiothoracic Ratio of Diameter, Area, and Circumference from 21 to 38 Weeks Gestational Age

BACKGROUND

Whether fetal cardiothoracic ratio (CTR) is constant or increasing with gestational age (GA) is controversial. The majority of the fetal CTR data has been obtained through ultrasound.

PURPOSE

To retrospectively analyze CTR of diameter, area, and circumference on prenatal MR images in a low-risk population of singleton pregnancies, and to clarify its diagnostic value.

STUDY TYPE

Retrospective.

SUBJECTS

1024 low-risk singleton pregnancies undergoing MRI.

FIELD STRENGTH

Balanced steady state free precession sequence and single shot-fast spin echo sequence at 1.5 Tesla.

ASSESSMENT

Pregnancy clinical data were recorded and diameter, area, and circumference of the fetal heart and thorax were measured by two researchers with 6 and 7 years of radiology experience, respectively, and their variation with GA was investigated. The relationship between CTRs with GA was also investigated. Finally, the value of CTR in the diagnosis of fetuses with abnormal development was explored by using receiver operating characteristic (ROC) curves.

STATISTICAL TESTS

Linear regression and ROC curves. A P value <0.05 was considered significant.

RESULTS

There were significant positive linear correlations (R2 > 0.7, P < 0.0001) between the diameter, area, and circumference of the heart and thorax with GA. The CTRs remain constant values and do not change with GA. The 5th, 50th, and 95th percentiles of the CTR in 21-38 weeks GA were 0.32, 0.39, and 0.48 respectively. The corresponding percentiles for the area ratio were 0.15, 0.21 and 0.27, respectively, and for the circumference ratio were 0.40, 0.46, and 0.52, respectively. Based on ROC curves of CTR with three methods, the area under curves (AUCs) were up to 0.95, the sensitivity and the specificity were more than 88%.

DATA CONCLUSION

Reference ranges of fetal CTR were established using MRI, which remain constant. These may be helpful in making a definitive diagnosis in fetuses with abnormal development.

LEVEL OF EVIDENCE: 4

TECHNICAL EFFICACY

Stage 2.

Measuring Atrial Size, Shape, and Contractility of the Fetal Heart Using FetalHQ: A New Technique Using Speckle Tracking Analysis

Measurements of fetal atrial size, shape, and contractility have been previously reported using the TomTec fetal heart speckle tracking analysis software, which currently is no longer available in the marketplace. At the present time, the only software available for speckle-tracking analysis of the fetal heart is fetalHQ, which analyzes the fetal heart ventricles using the same algorithms as the TomTec software used for speckle-tracking analysis. This communication will review how to use the fetalHQ software to measure the size, shape, and contractility of the atrial chambers.

Review of speckle tracking analysis to measure the size, shape, and contractility of the fetal heart in fetuses with congenital heart defects

Evaluation of the fetal heart involves two approaches. The first describes a screening protocol in which the heart is imaged in transverse planes that includes the four-chamber view (4CV), left and right outflow tracts, and the 3-vessel-tracheal view. The second approach is a fetal echocardiogram that requires additional cardiac images as well as evaluating ventricular function using diagnostic tools such as M-mode and pulsed Doppler ultrasound. Speckle tracking analysis of the ventricular and atrial endocardium of the fetal heart has focused primarily on computing longitudinal global strain. However, the technology enabling this measurement to occur has recently been adapted to enable the clinician to obtain numerous additional measurements of the size, shape, and contractility of the ventricles and atrial chambers. By using the increased number of measurements derived from speckle tracking analysis, we have reported the ability to screen for tetralogy of Fallot, D-transposition of the great arteries (D-TGA), and coarctation of the aorta by only imaging the 4CV. In addition, we have found that measurements derived from speckle tracking analysis of the ventricular and atrial chambers can be used to compute the risk for emergent neonatal balloon atrial septostomy in fetuses with D-TGA. The purpose of this review is to consolidate our experience in one source to provide perspective on the benefits of speckle tracking analysis to measure the size, shape, and contractility of the ventricles and atria imaged in the 4CV in fetuses with congenital heart defects.

Reference Ranges and Development Patterns of Fetal Myocardial Function Using Speckle Tracking Echocardiography in Healthy Fetuses at 17 to 24 Weeks of Gestation

OBJECTIVE

The purposes of the study were to develop reference ranges and maturation patterns of fetal cardiac function parameters measured by speckle tracking echocardiography (STE) using multiple biometric variables at 17 to 24 weeks' gestation among Thai fetuses and to compare with other previous reports.

STUDY DESIGN

The four-chamber view of the fetal heart in 79 healthy fetuses was suitably analyzed by STE to establish the best-fit regression model. The 95% reference intervals and Z-score equations of fetal cardiac function parameters were computed.

RESULTS

The fractional area change of both ventricles, left ventricular (LV) end-diastolic and end-systolic volumes, LV stroke volume, LV cardiac output (CO), and LV CO per kilogram were all increased according to gestational age (GA) and five fetal biometric measurements. However, the global longitudinal strain, basal-apical length fractional shortening (BAL-FS), BAL annular free wall and septal wall FS, BAL free wall and septal wall annular plane systolic excursions, 24-segment transverse width FS, as well as LV ejection fraction were all independent of GA or other somatic characteristics. There were varying development patterns between fetal right and left ventricles of these cardiac function indices across the gestation period.

CONCLUSION

Our study created Z-score and corresponding centile calculators, 5th and 95th centile reference tables, and corresponding graphs and determined the normal evolution across gestation using multiple somatic growth and age variables between 17 and 24 gestational weeks. These nomograms serve as an essential prerequisite for quantitatively evaluating fetal cardiac contractility and allow for precisely detecting early changes in the fetal heart function.

KEY POINTS

· Most fetal cardiac function measurements were correlated with all the independent variables.. · Fetal ventricular function parameters have their own characteristic maturation changes.. · Racial variability may not occupy an important place for fetal myocardial function during these GA..

Abnormalities of the Width of the Four-Chamber View and the Area, Length, and Width of the Ventricles to Identify Fetuses at High-Risk for D-Transposition of the Great Arteries and Tetralogy of Fallot

OBJECTIVES

The prenatal detection of D-Transposition of the great arteries (D-TGA) and tetralogy of Fallot (TOF) has been reported to be less than 50% to as high as 77% when adding the outflow tracts to the four-chamber screening protocol. Because many examiners still struggle with the outflow tract examination, this study evaluated whether changes in the size and shape of the heart in the 4CV as well as the ventricles occurred in fetuses with D-TGA and TOF could be used to screen for these malformations.

METHODS

Forty-four fetuses with the pre-and post-natal diagnosis of D-TGA and 44 with TOF were evaluated between 19 and 36 weeks of gestation in which the 4CV was imaged. Measurements of the end-diastolic width, length, area, and global sphericity index were measured for the four-chamber view and the right and left ventricles. Using z-score computed values, logistic regression was performed between the 88 study and 200 control fetuses using the hierarchical forward selection protocol.

RESULTS

Logistic regression identified 10 variables that correctly classified 83/88 of fetuses with TOF and TGA, for a sensitivity of 94%. Six of 200 normal controls were incorrectly classified for a false-positive rate of 3%. The area under the receiver operator classification curve was 98.1%. The true positive rate for D-TGA was 93.2%, with a false-negative rate to 6.8%. The true positive rate for TOF was 95.5%, with a false negative rate of 4.5%.

CONCLUSIONS

Measurements of the 4CV and of the RV and LV may help identify fetuses at risk for D-TGA or TOF.

Speckle Tracking Analysis to Evaluate the Size, Shape, and Function of the Atrial Chambers in Normal Fetuses at 20-40 Weeks of Gestation

OBJECTIVES

The purpose of this study was to use speckle tracking analysis to evaluate the size, shape, and function of the atrial chambers in normal fetuses and develop a z-score calculator that can be used in future studies in fetuses at risk for cardiovascular disease.

METHODS

The control group consisted of 200 normal fetuses examined between 20 and 40 weeks of gestation in which speckle tracking analysis of right (RA) and left (LA) atrial chambers was performed. The atrial end-diastolic and end-systolic endocardial borders for each chamber were identified from which measurements of atrial length, width, area, and volume were computed. Equations were derived using fractional polynomial regression analysis to compute z-score equations.

RESULTS

The LA end-diastolic volume, RA and LA end-diastolic area, length, base width, and mid-chamber widths increased with gestational age and fetal size. Left atrial emptying and ejection volumes increased with gestational age and fetal size. The fractional area change was significantly less for the RA than the LA. The LA base and mid-chamber fractional shortening were significantly greater than the RA. There was a significant difference between the RA and LA global contractile strain.

CONCLUSION

Mean and standard deviation equations for each of the measurements described in this study were computed to create a z-score calculator that can be utilized in the clinical environment when evaluating fetuses with suspected atrial pathology that could alter the size, shape, and function of the atrial chambers.

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.

Nomograms of fetal cardiothoracic ratio from 17 to 37 weeks' gestation as assessed by three different measurement techniques and their correlation with gestational age

OBJECTIVE

To create nomograms for fetal cardiothoracic (CT) ratio as assessed by three different 2-dimensional sonographic measurements, including CT diameter, circumference, and area ratios, in Thai fetuses with a gestational age (GA) of 17-37 weeks, and to evaluate both their correlation with GA or biparietal diameter (BPD) and variability among the three measurement methods.

METHODS

Two-dimensional sonographic measurements of fetal CT ratio in 4-chamber view were assessed by three different measurement techniques. The 95% reference intervals and Z-scores of all measurement methods based on GA or BPD were constructed. Intraclass correlation coefficients (ICC) for the reproducibility of each technique were compared.

RESULTS

A total of 511 uncomplicated singleton pregnancies were included. The fetal CT ratio values by all measurement techniques gradually and smoothly increased with increasing GA and BPD. The fetal CT circumference ratio showed the least correlation with both GA and BPD. The intraobserver and interobserver reliability coefficients of all techniques demonstrated almost excellent agreement (all ICCs at least 0.87).

CONCLUSION

Reference intervals and Z-score reference ranges were developed using three different techniques for fetal CT ratio with a GA of 17-37 weeks. These nomograms are a simple and reliable screening tool for identifying abnormal fetal heart size.

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.

Evaluation of the sphericity index of the fetal heart during middle and late pregnancy using fetalHQ

OBJECTIVE

To explore the feasibility of the fetal heart quantitative technique (fetalHQ) for evaluating the sphericity index (SI) of the fetal heart during middle and late pregnancy.

METHODS

Ninety-six normal fetuses in middle and late gestation who underwent systemic ultrasound examination in the Department of Ultrasound of the Maternal and Child Health Care Hospital of Hunan Province in November 2020 were enrolled, and dynamic images of the four-chamber view of the fetal heart were collected. The correlation between the global sphericity index (GSI), ventricular 24-segment SI, and gestational age (GA) was analyzed, and the differences between the left and right ventricular 24-segment SI were compared.

RESULTS

The success rate of fetalHQ analysis was 93.75%. There was no significant linear correlation between GSI and ventricular 24-segment SI and GA (all ps > .05). The differences in SI between segments 1 and 9 and 15 and 24 in the left and right ventricles were statistically significant (all ps < .05), while the differences in SI between segments 10 and 14 were not statistically significant (all ps > .05). In segments 1-9, the SI of the right ventricle was smaller than that of the left ventricle, indicating that the right ventricle was significantly more spherical than the left ventricle. In segments 15-24, the opposite was true.

CONCLUSION

FetalHQ is a simple and reliable method for evaluating the GSI and 24-segment SI of the left and right ventricles. It can provide some theoretical basis for the clinical quantitative evaluation of fetal heart geometry and lay a foundation for the quantitative evaluation of fetal heart function in cases of structural and functional abnormalities.

Fetal Heart Diameter as a Predictor of Hemoglobin Bart Disease at Midpregnancy

OBJECTIVES

To evaluate the efficacy of the fetal heart diameter (HD) in predicting fetal hemoglobin (Hb) Bart disease at midpregnancy.

METHODS

Video clips of fetal chest ultrasound examinations performed on fetuses at risk of Hb Bart disease at 18 to 22 weeks' gestation were randomly retrieved from our video clip database. The clips were replayed for fetal HD measurements, and the measured HDs were converted to z scores based on the z score model as a function of biparietal diameter. An HD z score greater than 2 or an actual HD value above the 95th percentile for gestational age was used as a cutoff in predicting Hb Bart disease. The best cutoff value of HD for identifying affected fetuses during midpregnancy was also evaluated by a receiver operating characteristic curve.

RESULTS

A total of 90 video clips, including 37 affected and 53 unaffected fetuses, were measured. An HD z score greater than 2 had sensitivity of 94.6% (95% confidence interval [CI], 81.8%-99.3%) and specificity of 84.9% (95% CI, 72.4%-93.3%). An actual HD value above the 95th percentile for gestational age had sensitivity of 100% (95% CI, 90.5%-100%) and specificity of 69.8% (95% CI, 55.7%-81.7%). The best cutoff values of the HD z score and actual HD value were 2.27 (with sensitivity of 94.6% and specificity of 88.7%) and 18.15 mm (with sensitivity of 91.9% and specificity of 77.4%), respectively.

CONCLUSIONS

The fetal HD is highly effective in predicting fetal Hb Bart disease among fetuses at risk at midpregnancy. Both the HD z score and the actual value can be used for noninvasive prenatal screening of fetal cardiomegaly in clinical practice.

Improved detection of coarctation of the aorta using speckle-tracking analysis of fetal heart on last examination prior to delivery

OBJECTIVE

The false-positive rate for prenatal diagnosis of coarctation of the aorta (FP-CoA) commonly exceeds 50%, with an accurate detection rate of < 50%. This study was conducted to determine if the sensitivity for prenatal detection of true CoA and the FP-CoA rate could be improved by evaluating the fetal epicardial size and shape in the four-chamber view (4CV) and the endocardial right (RV) and left (LV) ventricular size, shape and contractility.

METHODS

We analyzed retrospectively Digital Imaging and Communications in Medicine (DICOM) clips of the 4CV from the last examination prior to delivery in a series of 108 fetuses with CoA suspected prenatally by pediatric cardiologists using traditional diagnostic criteria. Postnatal evaluation distinguished those fetuses which subsequently required CoA surgery (true positives; true CoA) from those that were FP-CoA. Postnatal cardiac abnormalities were identified for each group. For the prenatal evaluation, we measured the 4CV end-diastolic epicardial area, circumference, length, width and global sphericity index. Speckle-tracking analysis was used to compute the endocardial RV and LV end-diastolic area, length, 24-segment sphericity index, 24-segment transverse width and the following functional parameters: fractional area change; global longitudinal, free-wall and septal-wall strain; basal-apical-length, basal free-wall and basal septal-wall fractional shortening; septal-wall annular plane systolic excursion; 24-segment transverse-width fractional shortening; and LV end-diastolic and end-systolic volumes, stroke volume, cardiac output and ejection fraction. In addition, the RV/LV end-diastolic area ratio was computed. Using a control group of 200 normal fetuses, the mean and SD for each of the above cardiac measurements was used to compute the Z-scores for each measurement in each of the 108 study fetuses. Logistic regression analysis was then performed on the Z-score values to identify variables that separated the true CoA group from the FP-CoA group.

RESULTS

Of the 108 study fetuses, 54 were confirmed postnatally to have true CoA and 54 were FP-CoA. Right/left area disproportion > 90^th  centile was present in 80% (n = 43) of the true-CoA fetuses and 76% (n = 41) of the FP-CoA fetuses. Fetuses with true CoA had a significantly greater number of associated cardiac abnormalities (93%, n = 50) compared with the FP-CoA fetuses (61%, n = 33) (P < 0.001). The most common associated malformations were bicuspid aortic valve (true CoA, 46% (n = 25) vs FP-CoA, 22% (n = 12); P < 0.01), aortic arch hypoplasia (true CoA, 31% (n = 17) vs FP-CoA, 11% (n = 6); P < 0.01), ventricular septal defect (true CoA, 33% (n = 18) vs FP-CoA, 11% (n = 6); P < 0.05) and mitral valve abnormality (true CoA, 30% (n = 16) vs FP-CoA, 4% (n = 2); P < 0.01). Logistic regression analysis identified 28 variables that correctly identified 96% (52/54) of the fetuses with true CoA, with a false-positive rate of 4% (2/54) and a false-negative rate of 4% (2/54). These variables included the epicardial size in the 4CV, size and shape of RV and LV, and abnormal contractility of RV and LV. The area under the receiver-operating-characteristics curve was 0.98 (SE, 0.023; 95% CI, 0.84-1). There was no significant difference in the percent of fetuses with RV/LV area disproportion between those with CoA and those that were FP-CoA.

CONCLUSIONS

Speckle-tracking analysis of multiple ventricular measurements may be helpful to refine the diagnosis in fetuses that are suspected to have CoA prenatally. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Evaluation of Fetal Left Ventricular Size and Function Using Speckle-Tracking and the Simpson Rule

OBJECTIVES

This study was conducted to evaluate left ventricular (LV) size and function in healthy fetuses and to test a cohort of fetuses at risk for abnormal function using speckle-tracking software.

METHODS

Two hundred control fetuses were examined between 20 and 40 weeks' gestation. With the use of offline speckle-tracking software, the end-diastolic and end-systolic volumes were measured and the following computed: stroke volume (SV), SV per kilogram, cardiac output (CO), CO per kilogram, and ejection fraction. These were regressed against 7 independent variables related to the size, weight, and age of the fetuses. Five fetuses with risk factors for LV dysfunction were examined to sample the validity of the data from the control group.

RESULTS

The R² values for measurements of the end-diastolic volume, SV, and CO correlated with the 7 independent variables of fetal size and age (0.7-0.78), whereas the SV/kg, CO/kg, and ejection fraction had lower R² values (0.02-0.1). The measurements were normally distributed (Shapiro-Wilke > 0.5). The 5 fetuses at risk for abnormal LV function had measurements of LV size and function that were consistent with the expected pathologic condition.

CONCLUSIONS

Speckle tracking can provide a comprehensive evaluation of the size and function of the fetal LV.

Twenty-four Segment Transverse Ventricular Fractional Shortening: A New Technique to Evaluate Fetal Cardiac Function

OBJECTIVES

Because of various fetal and maternal disease states, this study was conducted to evaluate the fractional shortening of 24 transverse segments distributed from the base to the apex of the ventricular chambers.

METHODS

Two hundred control fetuses were examined between 20 and 40 weeks' gestation. The transverse displacement of the ventricular endocardium during the cardiac cycle was computed by using offline software. From the output of the analysis, 24 end-diastolic and end-systolic segments were measured from the base (segment 1) to the apex (segment 24) of the right and left ventricles, and the fractional shortening was computed: [(end-diastolic length - end-systolic length)/end-diastolic length] × 100. Examples of fetal cardiovascular abnormalities were selected to demonstrate the utility of this technique.

RESULTS

The fractional shortening for each segment was independent of gestational age and fetal biometric measurements. There was no significant difference in fractional shortening for segments 1 to 5 between the right and left ventricles. However, the fractional shortening of the left ventricle was significantly greater (P < .0001) than that of the right ventricle for segments 6 to 24, suggesting that the mid and apical segments of the left ventricle have increased displacement toward the center of the chamber compared to the right ventricle. Fetuses with various cardiac structural abnormalities had abnormal fractional shortening values.

CONCLUSIONS

The fractional shortening of 24 segments of the right and left ventricles provides a comprehensive method to examine the contractility of the ventricular chambers.

24-segment sphericity index: a new technique to evaluate fetal cardiac diastolic shape

OBJECTIVE

Because of parallel circulation in the fetus and the differential effect that various disease states may have on the shape of the right and left ventricles, this study was conducted to evaluate the sphericity index (SI) of 24 transverse segments distributed from the base to the apex of each of the ventricular chambers.

METHODS

Two hundred control fetuses were examined between 20 and 40 weeks of gestation. The displacement of the ventricular endocardium during the cardiac cycle was computed using offline speckle-tracking software. From the ASCII output of the analysis, we analyzed 24 end-diastolic transverse segments, distributed from the base to the apex of each ventricle, as well as the end-diastolic mid-basal-apical length. The SI was computed for each of the 24 segments by dividing the mid-basal-apical length by the transverse length for each segment. Regression analysis was performed against biometric measurements and gestational age according to last menstrual period and ultrasound. Eight fetuses, in which the four-chamber view appeared subjectively to demonstrate chamber disproportion, were evaluated as examples to demonstrate the utility of this technology.

RESULTS

The SI for each segment was independent of gestational age and fetal biometric measurements. The SI of the right ventricle was significantly (P < 0.001) lower than that of the left ventricle for segments 1-18, suggesting that the right ventricle was more globular in shape than was the left ventricle at the base, mid and a portion of the apical segments of the chamber. Fetuses with various cardiac structural abnormalities and abnormal fetal growth had abnormal SI values that reflected either a more globular or a more flattened ventricular chamber.

CONCLUSION

Determination of SI for each of 24 segments of the fetal right and left ventricles provides a comprehensive method to examine the shape of the ventricular chambers. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Abnormal Fetal Findings Associated With a Global Sphericity Index of the 4-Chamber View Below the 5th Centile

OBJECTIVES

The purpose of this study was to evaluate the global sphericity index (GSI) of the 4-chamber view and correlate the results with abnormal ultrasound findings.

METHODS

The epicardial end-diastolic basal-apical length (BAL) and transverse length (TL) of the 4-chamber view were measured to compute the GSI (BAL/TL) in 200 control fetuses between 20 and 40 weeks' gestation. Three hundred study fetuses were prospectively examined between 17 and 39 weeks' gestation. The GSI, Z score, and centile were computed for each of the fetuses.

RESULTS

The GSI (1.233; SD, 0.0953) in the control fetuses was independent of gestational age. Eighteen percent of the study fetuses (55 of 300) had a GSI below the 5th centile (<1.08), of whom 96% (53 of 55) had additional abnormal ultrasound findings. Fetuses with an estimated fetal weight below the 10th centile had a significantly (P < .05) higher rate of an umbilical artery Doppler pulsatility index above the 95th centile (27% versus 17.7%), a middle cerebral artery Doppler pulsatility index below the 5th centile (27% versus 0%), an abnormal cerebroplacental ratio (27% versus 4.5%), and an amniotic fluid index of less than 5 cm (36% versus 9%). The TL was significantly increased compared with the BAL in fetuses with cardiac dysfunction, irrespective of the estimated fetal weight.

CONCLUSIONS

An abnormal GSI below the 5th centile is associated with abnormal fetal ultrasound findings.

Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach

Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.