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..

Speckle Tracking Analysis in Fetuses with D-Transposition: Predicting the Need for Urgent Neonatal Balloon Atrial Septostomy.

INTRODUCTION: Speckle tracking analysis of the endocardium of the right (RV) and left (LV) ventricles was used to evaluate the size, shape, and contractility of these chambers in fetuses with D-Transposition of the great arteries (D-TGA) to identify fetuses that would require emergent balloon atrial septostomy (BAS) after birth. METHODS: This was a retrospective analysis of fetuses with D-TGA and intact ventricular septum that were divided into 2 groups. Group 1 underwent urgent BAS after birth because of a restrictive atrial septum and group 2 did not. Using speckle tracking analysis, the end-diastolic and end-systolic RV and LV areas, lengths, widths, sphericity indices, and contractility were computed. Logistic regression analysis was performed to identify fetuses who would require urgent neonatal BAS. RESULTS: Of the 39 fetuses with D-TGA, 55% (n = 22) required urgent neonatal BAS (group 1) and 45% (n = 17) (group 2) did not. When comparing D-TGA groups 1 and 2, differences were seen in RV and LV area, sphericity index for segment 1 of the LV, LV fractional area of change and free wall annular plane systolic excursion, fractional shortening for LV segment 12, and RV free wall strain. Regression analysis of these measurements identified 91% of neonates who underwent BAS, with a false-positive rate of 12%. CONCLUSION: Using speckle tracking analysis to evaluate the RV and LV, measurable differences were identified for the RV and LV size, shape, and contractility between fetuses who underwent neonatal urgent BAS vs. those who did not require this procedure.

Speckle tracking analysis to evaluate the size, shape, and function of the atrial chambers in fetuses with d-transposition of the great arteries to predict the need for neonatal urgent balloon atrial septostomy.

INTRODUCTION: Speckle tracking analysis was used to evaluate right (RA) and left (LA) atria size, shape and contractility to create a probability calculator to identify fetuses at risk for urgent neonatal balloon atrial septostomy (BAS). METHODS: The study group consisted of 39 fetuses with D-TGA, of which 55% (N = 22) required neonatal BAS and 45% (N = 17) did not. The RA and LA end-diastolic areas, lengths, widths, and sphericity indices as well as global, longitudinal, and transverse contractility were measured with speckle tracking analysis. The z-scores of the measurements were compared to 200 controls. Logistic regression analysis of the computed z-score measurements was performed to separate fetuses requiring urgent neonatal atrial BAS from those who did not. RESULTS: The following z-score values for all fetuses with D-TGA, irrespective of whether they required neonatal BAS, that were significantly less than controls: RA base sphericity index, basal-apical length fractional shortening, fractional area change, lateral wall annular plane systolic excursion (APSE), and longitudinal reservoir strain; LA mid-chamber width, fractional shortening, ejection fraction, basal-apical length fractional shortening, atrial ejection volume, septal wall APSE, and reservoir strain. The following z-score values were significantly larger than control values: RA/LA mid-chamber width, RA/LA base width, and RA mid-chamber length. Logistic regression analysis identified the following five measurements that correctly identified 19 of 22 fetuses requiring urgent neonatal atrial BAS with a sensitivity of 86.4%, a false-positive rate of 11.8% and a positive predictive value of 90.4%: (1) LA mid-chamber transverse fractional shortening, (2) RA mid-chamber end-diastolic width, (3) RA basal-apical length fractional shortening, (4) RA mid-chamber fractional shortening, and (5) RA fractional area change. CONCLUSION: Using the measurements described in this study identified significant differences between all fetuses with D-TGA and controls, as well as identified measurements that predicted the probability of D-TGA fetuses requiring neonatal septostomy.

Assessing maternal cardiac function by obstetricians: technique and reference ranges.

BACKGROUND: A strong body of evidence has now coalesced indicating that some obstetrical syndromes may result from maladaptive responses of the maternal cardiovascular system. Longitudinal studies have shown that these changes are complex and present before the clinical recognition of preeclampsia and fetal growth restriction, suggesting that hemodynamic maladaptation may play an etiologic role in obstetrical complications. Chronic hypertension is one of the most frequent complications of pregnancy, and recent evidence suggests that control of mild hypertension in early pregnancy improves outcome. The management of chronic hypertension can be improved by understanding specific cardiovascular hemodynamic abnormalities such as increased cardiac output or increased systemic vascular resistance, which can respond to either beta or calcium channel blockers, depending on the hemodynamic findings. Evaluation of maternal cardiac function has not been previously available to obstetrical healthcare providers using diagnostic ultrasound equipment used for fetal evaluation. OBJECTIVE: Obstetrical ultrasound machines may be configured for various probes (endovaginal, abdominal, 3D/4D, and cardiac). This study used a cardiac probe placed in the suprasternal notch to image and measure the descending aorta diameter and the velocity time integral using pulsed and continuous wave Doppler ultrasound in normal pregnant women between 11 and 39 weeks of gestation. These measurements were followed by computation of maternal left ventricular preload, afterload, contractility, and blood flow. STUDY DESIGN: This was a prospective cross-sectional study. A total of 400 pregnant women were recruited between 11 and 39 weeks of gestation. Imaging of the maternal aortic arch was performed by placing a cardiac probe in the suprasternal notch to identify the aortic arch using 2D and color Doppler ultrasound. The end-systolic diameter of the aorta was measured at the junction of the left subclavian artery with the descending aorta, which was followed by insonation of the descending aorta to obtain the Doppler waveform. Following insonation of the descending aorta, measurements of the aortic diameter, velocity time integral, ejection time, mean pressure gradient, heart rate, maternal weight and height, and systolic and diastolic blood pressures were entered into an Excel spreadsheet to compute the following: (1) preload measurements of stroke volume, stroke volume index, and stroke work index; (2) afterload measurements of systemic vascular resistance and the potential-to-kinetic energy ratio; (3) contractility measurements of inotropy and the Smith-Madigan inotropy index; and (4) blood flow measurements of cardiac output and the cardiac output index. Fractional polynomial regression analysis was performed for each of the above measurements using gestational age as the independent variable. RESULTS: The diastolic and mean arterial blood pressure decreased from 11 to 18 weeks of gestation and then increased until term. The afterload measurements demonstrated similar characteristics, as all values decreased from 11 weeks until the mid and late second trimester, after which all values increased until term. Changes in contractility demonstrated an increase from 11 weeks to 25 to 28 weeks, followed by a decline until term. Changes in blood flow demonstrated an increase from 11 to 27 weeks and then declined until term. The continuous wave Doppler values were greater than the pulsed Doppler values except for the contractility measurements. Examples of abnormal cardiac measurements were identified in pregnant patients with hypertension and fetal growth restriction. An Excel calculator was created to provide quick computation of z-score measurements and their corresponding centiles described in this study. CONCLUSION: The technique for evaluation of maternal cardiac function described in this study would allow screening of maternal left ventricular preload, afterload, contractility, and blood flow in the obstetrical clinical milieu once a cardiac probe is acquired for obstetrical ultrasound machines used for fetal evaluation. The above measurements would allow the clinician to select appropriate hypertensive medication on the basis of the results of the evaluation of the maternal left ventricle.

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.

Umbilical Venous Volume Flow in Late-Onset Fetal Growth Restriction.

OBJECTIVES: Umbilical vein flow (UVF) is reduced in fetal growth restriction (FGR). We compared absolute and size-adjusted UVF (estimated fetal weight [EFW] and abdominal circumference [AC]) and rates of abnormal UVF parameters (<10th percentile) among FGR fetuses meeting Delphi criteria (FGR-D) against small for gestational age (SGA) fetuses and appropriate for gestational age (AGA) controls. METHODS: Absolute UVF, UVF/EFW, and UVF/AC were compared between 73 FGR pregnancies (35 FGR-D, 38 SGA) and 108 AGA controls. Rates of abnormal UVF were compared to abnormal umbilical artery pulsatility index (UAPI). Independent samples t-tests, Mann-Whitney U, odds ratio (OR), chi-squared, and Fisher's exact tests were used as appropriate. RESULTS: Mean absolute UVF was significantly decreased in FGR-D compared to AGA (P = .0147), but not between SGA and AGA fetuses. The incidence of both abnormal absolute UVF and UVF/AC values (<10th centile) was higher among late-onset FGR fetuses versus AGA fetuses (UVF: OR 2.7, confidence interval [CI] 1.37-5.4; UVF/AC: OR 2.73, CI 1.37-5.4). UVF was more frequently abnormal than UAPI and in only two fetuses were both Doppler values abnormal. CONCLUSION: Absolute UVF is altered in late-onset FGR, and most pronounced among FGR-D. UVF may provide additional insight into fetal compromise in those affected by growth restriction.

Longitudinal Surveillance of Fetal Heart Failure Using Speckle Tracking Analysis.

Long-term monitoring of a fetus with heart failure is an undeniable challenge for prenatal cardiology. Echocardiography is constrained by many fetal and maternal factors, and it is difficult to maintain the reproducibility of the measured and analyzed parameters. In our study, we presented the possibilities of using modern speckle tracking technology in combination with standard echocardiography parameters that may be insufficient or less sensitive in the context of monitoring life-threatening fetal conditions. Our analysis shows the superiority of the parameters used to assess fetal cardiac architecture, such as the GSI Global sphericity Index, and fetal cardiac function, such as the FAC fractional area change and the EF ejection fraction, which temporal change may indicate a worsening condition of the fetus with heart failure. The significant increase in the parameters of fetal heart size in speckle tracking allows for an improved echocardiographic diagnosis and monitoring of the fetus with heart failure and the prognostic conclusions about the clinical condition after birth. Significant decreases in FAC for the left and right ventricles and EF for the left ventricle may indicate an unfavourable prognosis for the monitored fetus due to heart failure.

Prenatal Detection of Congenital Heart Disease: Importance of Fetal Echocardiography Following Normal Fetal Cardiac Screening.

Fetal echocardiography may be performed because of noncardiac indications (the pregnancy is identified as high risk for fetal cardiac disease), or because of fetal cardiac indications (abnormal fetal heart at the time of a screening ultrasound). Considering recent improvements in fetal cardiac screening over the past decade, the goal of this single institution study was to reconsider the importance of performing fetal echocardiography purely for screening (noncardiac) indications. We performed a retrospective analysis to review screening and fetal cardiac indications and fetal cardiac findings for fetal echocardiograms performed at UCLA between 2015 and 2019. Fetal heart disease was identified in 391 (15%) of 2592 pregnancies in this study. Among these 391 cases, 227 (58%) occurred in low-risk pregnancies (without screening indications). While 79% of the cases of fetal cardiac disease were referred with fetal cardiac indications, 21% of the cases were referred with exclusively screening indications. Fetal cardiac disease was discovered on fetal echocardiograms in 4% of pregnancies referred for exclusively screening indications, but the frequency of fetal cardiac disease following normal fetal cardiac screening has decreased from 6% in 2015 to 3% in 2019. In our population, we recommend continued referral for fetal echocardiography for pregnancies identified as high risk for CHD. However, as fetal cardiac screening continues to improve, referral for fetal echocardiography following normal fetal cardiac screening will have diminishing value and yield.

Speckle-Tracking Analysis in Fetuses With Tetralogy of Fallot: Evaluation of Right and Left Ventricular Contractility and Left Ventricular Function.

OBJECTIVES: This study examines fetuses with tetralogy of Fallot (TOF) and evaluates the right (RV) and left (LV) ventricular contractility and LV function using speckle-tracking analysis of the endocardium. METHODS: The study group consisted of 44 fetuses with TOF, of which 34% had pulmonary valve atresia (N = 15) and 59% (N = 26) had pulmonary valve stenosis. The RV and LV global fractional area change, longitudinal contractility (longitudinal strain, free wall strain, septal strain, free wall and septal annular fractional shortening, and free wall and septal wall annular plane systolic excursion), and transverse contractility (24-segment fractional shortening) as well as LV functional assessment (stroke volume, cardiac output, and ejection fraction) were measured using speckle-tracking analysis. The z-scores of the measurements were compared to 200 controls. RESULTS: Compared to controls, measurements of LV contractility in fetuses with TOF demonstrated significantly abnormal values for global contractility, longitudinal contractility, and transverse contractility of the mid and apical segments. LV function was abnormal for stroke volume (SV), cardiac output (CO), and ejection fraction (EF). In comparison, RV contractility demonstrated no significant difference between TOF and control z-score values for RV global contractility. Only two RV measurements were found to be abnormal: longitudinal contractility and transverse contractility of the apical segments. CONCLUSION: Using multiple measurement tools to evaluate global, longitudinal, and transverse contractility, this study identified significant differences between fetuses with TOF and healthy controls, with greater contractility abnormalities seen in the LV than in the RV.

The role of the fetal biophysical profile in the management of fetal growth restriction.

Growth-restricted fetuses are at risk of hypoxemia, acidemia, and stillbirth because of progressive placental dysfunction. Current fetal well-being, neonatal risks following delivery, and the anticipated rate of fetal deterioration are the major management considerations in fetal growth restriction. Surveillance has to quantify the fetal risks accurately to determine the delivery threshold and identify the testing frequency most likely to capture future deterioration and prevent stillbirth. From the second trimester onward, the biophysical profile score correlates over 90% with the current fetal pH, and a normal score predicts a pH >7.25 with a 100% positive predictive value; an abnormal score on the other hand predicts current fetal acidemia with similar certainty. Between 30% and 70% of growth-restricted fetuses with a nonreactive heart rate require biophysical profile scoring to verify fetal well-being, and an abnormal score in 8% to 27% identifies the need for delivery, which is not suspected by Doppler findings. Future fetal well-being is not predicted by the biophysical profile score, which emphasizes the importance of umbilical artery Doppler and amniotic fluid volume to determine surveillance frequency. Studies with integrated surveillance strategies that combine frequent heart rate monitoring with biophysical profile scoring and Doppler report better outcomes and stillbirth rates of between 0% and 4%, compared with those between 8% and 11% with empirically determined surveillance frequency. The variations in clinical behavior and management challenges across gestational age are better addressed when biophysical profile scoring is integrated into the surveillance of fetal growth restriction. This review aims to provide guidance on biophysical profile scoring in the in- and outpatient management of fetal growth restriction.

Feasibility of 4D-Spatio Temporal Image Correlation (STIC) in the Comprehensive Assessment of the Fetal Heart Using FetalHQ®.

Fetal Heart Quantification (FetalHQ®) is a novel speckle tracking software that permits the study of global and regional ventricular shape and function from a 2D four-chamber-view loop. The 4D-Spatio Temporal Image Correlation (STIC) modality enables the offline analysis of optimized and perfectly aligned cardiac planes. We aimed to evaluate the feasibility and reproducibility of 4D-STIC speckle tracking echocardiography (STE) using FetalHQ® and to compare it to 2D STE. We conducted a prospective study including 31 low-risk singleton pregnancies between 20 and 40 weeks of gestation. Four-chamber view volumes and 2D clips were acquired with an apex pointing at 45° and with a frame rate higher than 60 Hz. Morphometric and functional echocardiography was performed by FetalHQ®. Intra- and interobserver reproducibility were evaluated by the intraclass correlation coefficient (ICC). Our results showed excellent reproducibility (ICC > 0.900) for morphometric evaluation (biventricular area, longitudinal and transverse diameters). Reproducibility was also good (ICC > 0.800) for functional evaluation (biventricular strain, Fractional Area Change, left ventricle volumes, ejection fraction and cardiac output). On the contrary, the study of the sphericity index and shortening fraction of the different ventricular segments showed lower reproducibility (ICC < 0.800). To conclude, 4D-STIC is feasible, reproducible and comparable to 2D echocardiography for the assessment of cardiac morphometry and function.

Measuring the Area of the Interventricular Septum in the 4-Chamber View: A New Technique to Evaluate the Fetus at Risk for Septal Hypertrophy.

OBJECTIVES: One of the problems for the clinician who desires to measure the interventricular septum (IVS) in a high-risk fetus is to know where to make the measurement. The purpose of this study was to use speckle-tracking analysis to measure the IVS area, 24-segment widths, and length at end-diastole (ED) and end-systole (ES) in normal fetuses. METHODS: From the 4-chamber view, speckle-tracking analysis was performed at ED and ES on the IVS in 200 normal fetuses. The following were computed and regressed against gestational age (GA) and fetal biometric (FB) measurements: area, length, and the 24-segment transverse widths from the apex to the crux. The 24-segment width/length ratio was also measured. The speckle-tracking measurements of the ED area and length were compared using a point-to-point measurement tool available on all ultrasound machines. RESULTS: The ED and ES areas, lengths, and 24-segment widths increased with GA and FB. The ED and ES areas were virtually identical. The 24-segment width/length ratio decreased from the apex to the crux of the septum. There was no significant difference in the measurement of the ED area and the length between speckle-tracking and the point-to-point measurements. CONCLUSIONS: Measurement of the area and length of the IVS are simple to obtain and provide a new diagnostic tool to evaluate the fetus at risk for IVS hypertrophy which may be observed in fetuses of mothers with pregestational and gestational diabetes.

Cardiac Size, Shape, and Ventricular Contractility in Fetuses at Sea Level With an Estimated Weight Less-than 10th Centile.

OBJECTIVES: To investigate cardiac size, shape, and ventricular contractility in fetuses with estimated fetal weight (EFW) <10th centile at sea level (Houston). METHODS: A prospective ultrasound study examined 37 fetuses with EFW <10th centile at sea level. High-frequency cine clips were used to evaluate the 4-chamber view including end-diastolic measurements and global sphericity index. The size, shape, and contractility of both ventricles were analyzed with speckle tracking methods. Z scores were calculated using the mean ± standard deviation (SD) derived from normal controls. Measurements were abnormal if their Z score values were <-1.65 or >+1.65. The proportion of small fetuses with abnormal parameters was compared to normal reference ranges. Results were compared to a similar published study of small fetuses at higher altitude in Denver. RESULTS: About one-third of Houston fetuses with EFW <10th centile had enlarged globular shaped 4-chamber hearts with increased right ventricle (RV) area, RV basal-apical length, RV base width, and left ventricle (LV) basal-apical length measurements. Bilateral ventricular hypertrophy was often present. An increased proportion of Houston fetuses had increased ventricular contractility. However, decreased ventricular contractility was more prevalent for higher altitude fetuses. CONCLUSIONS: Third trimester fetuses at sea level, with an EFW <10th centile, were often associated with enlarged and globular-shaped hearts. They had increased global and longitudinal ventricular contractility as compared to controls. Higher altitude fetuses also had enlarged globular-shaped hearts but with a greater proportion of cases having decreased ventricular contractility as compared to the sea level cohort.

Clinical Opinion: The diagnosis and management of suspected fetal growth restriction: an evidence-based approach.

This study reviewed the literature about the diagnosis, antepartum surveillance, and time of delivery of fetuses suspected to be small for gestational age or growth restricted. Several guidelines have been issued by major professional organizations, including the International Society of Ultrasound in Obstetrics and Gynecology and the Society for Maternal-Fetal Medicine. The differences in recommendations, in particular about Doppler velocimetry of the ductus venosus and middle cerebral artery, have created confusion among clinicians, and this review has intended to clarify and highlight the available evidence that is pertinent to clinical management. A fetus who is small for gestational age is frequently defined as one with an estimated fetal weight of <10th percentile. This condition has been considered syndromic and has been frequently attributed to fetal growth restriction, a constitutionally small fetus, congenital infections, chromosomal abnormalities, or genetic conditions. Small for gestational age is not synonymous with fetal growth restriction, which is defined by deceleration of fetal growth determined by a change in fetal growth velocity. An abnormal umbilical artery Doppler pulsatility index reflects an increased impedance to flow in the umbilical circulation and is considered to be an indicator of placental disease. The combined finding of an estimated fetal weight of <10th percentile and abnormal umbilical artery Doppler velocimetry has been widely accepted as indicative of fetal growth restriction. Clinical studies have shown that the gestational age at diagnosis can be used to subclassify suspected fetal growth restriction into early and late, depending on whether the condition is diagnosed before or after 32 weeks of gestation. The early type is associated with umbilical artery Doppler abnormalities, whereas the late type is often associated with a low pulsatility index in the middle cerebral artery. A large randomized clinical trial indicated that in the context of early suspected fetal growth restriction, the combination of computerized cardiotocography and fetal ductus venosus Doppler improves outcomes, such that 95% of surviving infants have a normal neurodevelopmental outcome at 2 years of age. A low middle cerebral artery pulsatility index is associated with an adverse perinatal outcome in late fetal growth restriction; however, there is no evidence supporting its use to determine the time of delivery. Nonetheless, an abnormality in middle cerebral artery Doppler could be valuable to increase the surveillance of the fetus at risk. We propose that fetal size, growth rate, uteroplacental Doppler indices, cardiotocography, and maternal conditions (ie, hypertension) according to gestational age are important factors in optimizing the outcome of suspected fetal growth restriction.

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.

Computing Z-Score Equations for Clinical Use to Measure Fetal Umbilical Vein Size and Flow Using Six Independent Variables of Age and Size.

INTRODUCTION: Measurements of the umbilical vein diameter (UVD) and blood flow (mL/min) (UVF) have been demonstrated to be decreased in fetuses with growth restriction (FGR) using gestational age (GA) as the independent variable. However, no previous studies have used the biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and the estimated fetal weight (EFW) to create equations to be used for z-score computations when evaluating fetuses at risk foran abnormal UVD and UVF. METHODS: Two hundred and forty normal fetuses between 20 and 40 weeks of gestation were examined in which the UVD and time averaged maximal velocity (TAMX) were measured from which the UVF, UVF/HC, UVF/AC, and UVF/kg were computed. Fractional polynomial regression analysis was used to compute z-score equations using the above independent variables. Thirty-six fetuses with abnormal growth of the AC were examined to test the validity of the equations. RESULTS: The UVD, TAMX, UVF, UVF/HC, and UVF/AC all increased with gestatonal age and fetal growth except for the UVF/kg, which decreased with age and growth. From the regression equations, two z-score calculators were created using an Excel spreadsheet that can be used in clinical practice. Abnormal measurements of the UVD, UVF, UVF/HC, UVF/AC, and UVF/kg were observed in the 36 study fetuses, 21 with an AC < 10th centile and 15 with an AC > 90th centile. CONCLUSION: Using the equations generated from this study and the z-score calculators provides a clinical tool to measure the size and flow of the umbilical vein that may have clinical implications.