Common Findings in Late-Gestation Fetal Echocardiography.

OBJECTIVES: Fetal echocardiography provides detailed information about cardiac structure and function in utero. Limited information is available regarding normal findings late in pregnancy. We therefore sought to identify and describe common cardiac findings in late gestation. METHODS: Fetuses with structurally normal hearts were identified in mid gestation within a subset of pregnant women in a prospective study. The atrioventricular valves, right and left atria, aortic isthmus and ductus arteriosus dimensions and flow abnormalities, aneurysm of the septum primum, and presence and grade of tricuspid regurgitation were assessed throughout pregnancy. Linear and logistic regression analyses were used to characterize changes in quantitative and qualitative fetal echocardiographic parameters by gestational age (GA). RESULTS: Forty fetuses between 24 and 38 weeks' GA were studied. Each had a fetal echocardiographic study completed before and after 34 weeks' gestation, which were compared. Tricuspid-to-mitral valve and right-to-left atrium ratios increased with GA (P < .001). More frequently noted after 34 weeks were tapering of the ductus arteriosus (2.5% versus 32%), prominent aortic isthmus diastolic flow (5% versus 67%), prominent ductus arteriosus diastolic flow (2.5% versus 25%), trivial or mild tricuspid regurgitation (35% versus 80%), and aneurysms of the septum primum (37.5% versus 80%). These findings all increased linearly with GA (P < .001). CONCLUSIONS: Atrioventricular valve and right/left atrium disproportion, mild ductus arteriosus tapering, prominent aortic isthmus and ductus arteriosus diastolic flow, trivial or mild tricuspid regurgitation, and aneurysms of the septum primum are frequently identified after 34 weeks' GA. Their identification suggests that these fetal echocardiographic findings in isolation are likely normal and are results of the physiologic alterations that occur late in the third trimester.

Predictive Models for Normal Fetal Cardiac Structures.

BACKGROUND: Clinicians rely on age- and size-specific measures of cardiac structures to diagnose cardiac disease. No universally accepted normative data exist for fetal cardiac structures, and most fetal cardiac centers do not use the same standards. The aim of this study was to derive predictive models for Z scores for 13 commonly evaluated fetal cardiac structures using a large heterogeneous population of fetuses without structural cardiac defects. METHODS: The study used archived normal fetal echocardiograms in representative fetuses aged 12 to 39 weeks. Thirteen cardiac dimensions were remeasured by a blinded echocardiographer from digitally stored clips. Studies with inadequate imaging views were excluded. Regression models were developed to relate each dimension to estimated gestational age (EGA) by dates, biparietal diameter, femur length, and estimated fetal weight by the Hadlock formula. Dimension outcomes were transformed (e.g., using the logarithm or square root) as necessary to meet the normality assumption. Higher order terms, quadratic or cubic, were added as needed to improve model fit. Information criteria and adjusted R2 values were used to guide final model selection. RESULTS: Each Z-score equation is based on measurements derived from 296 to 414 unique fetuses. EGA yielded the best predictive model for the majority of dimensions; adjusted R2 values ranged from 0.72 to 0.893. However, each of the other highly correlated (r > 0.94) biometric parameters was an acceptable surrogate for EGA. In most cases, the best fitting model included squared and cubic terms to introduce curvilinearity. CONCLUSIONS: For each dimension, models based on EGA provided the best fit for determining normal measurements of fetal cardiac structures. Nevertheless, other biometric parameters, including femur length, biparietal diameter, and estimated fetal weight provided results that were nearly as good. Comprehensive Z-score results are available on the basis of highly predictive models derived from gestational age or other biometrics as preferable for clinical reasons. These results supplant current equations and will provide a foundation for future multicenter collaborations.

Risk-stratified postnatal care of newborns with congenital heart disease determined by fetal echocardiography.

BACKGROUND: Advances in fetal echocardiography have improved recognition of congenital heart disease (CHD). Imaging protocols have been developed that predict delivery room (DR) risk and anticipated postnatal level of care (LOC). The aim of this study was to determine the utility of fetal echocardiography in the perinatal management of CHD. METHODS: A retrospective analysis of fetal and postnatal records was conducted. The anticipated LOC was assigned by fetal echocardiography (LOC 1, nursery consult/outpatient follow-up; LOC 2, stable in DR with transfer to cardiac hospital; LOC 3 or 4, DR instability/urgent intervention needed). Prenatal diagnoses and LOC assignment were compared with postnatal diagnoses, treatment, and short-term outcomes. RESULTS: From 2004 to 2012, 8,101 fetuses were evaluated; 7,405 were normal. Of 696 with CHD, 101 terminated, 40 died in utero, and 37 received palliative care. LOC was assigned in the remaining 518. Of 219 LOC 1, 195 (89%) had postnatal follow-up. Only two required transfer for intervention (LOC 1 sensitivity, 0.9; LOC 1 positive predictive value, 0.99). Of 260 assigned LOC 2, 229 (88%) had follow-up. Of these, 200 (87%) were transferred for surgery or intervention. The median time to admission was 195 min. Twenty-two patients (10%) assigned LOC 2 did not require intervention; however, seven (all with D-transposition of the great arteries) required catheter intervention before surgery. Hospital survival was 86% (LOC 2 sensitivity, 0.97; LOC 2 positive predictive value, 0.87). All LOC 3 and 4 patients had follow-up. Thirty-four (87%) needed urgent intervention, with 100% DR and 87% hospital survival (LOC 3 and 4 sensitivity, 0.83; LOC 3 and 4 positive predictive value, 0.87). CONCLUSIONS: Fetal echocardiography enables accurate postnatal risk stratification in CHD, with the exception of D-transposition of the great arteries. LOC 1 assignment facilitated outpatient follow-up; LOC 2 assignment facilitated transfer for intervention. LOC 3 and 4 patients underwent stabilizing intervention or surgery with good short-term outcomes. Given the inability to predict need for intervention in D-transposition of the great arteries, all such patients should be assigned as LOC 3 or 4. Fetal echocardiography with LOC assignment should be used in the planning of postnatal care in CHD.