ISUOG consensus statement: what constitutes a fetal echocardiogram?

Cardiac function in trisomy 21 fetuses

OBJECTIVES

Trisomy 21 is associated with an increased nuchal translucency thickness (NT), abnormal ductus venosus (DV) flow at 11-14 weeks' gestation and congenital heart defects (CHD), and cardiac dysfunction has been hypothesized as the link between them. We therefore aimed to investigate whether cardiac function is altered in trisomy 21 fetuses.

METHODS

Between December 2003 and June 2009, we performed echocardiography on 46 trisomy 21 fetuses (28 with structurally normal heart and 18 with CHD) and on 191 chromosomally/phenotypically normal fetuses with a confirmed normal heart (87 with normal NT and 104 with NT ≥ 95(th) percentile), between 11 and 35 weeks' gestation. Measurements included: E- and A-wave peak velocity, E/A velocity ratio and E/time velocity integral (TVI) ratio over atrioventricular valves; myocardial performance index (MPI); semilunar valve peak velocity and acceleration time; stroke volume (SV); cardiac output; and DV pulsatility index for veins (PIV) at 11-14 weeks' gestation. Data were categorized into three different age groups for analysis (11 to 13 + 6, 14 to 21 + 6 and 22 to 35 weeks' gestation).

RESULTS

The tricuspid valve (TV) A-wave velocity and aortic valve peak velocity were significantly reduced in trisomy 21 compared with normal fetuses. Other highly significant differences found in trisomy 21 fetuses at 11-14 weeks' were increased TV-E/A ratio and DV-PIV, and decreased pulmonary valve peak velocity. We also observed evidence of left ventricular (LV) systolic dysfunction, reduced SV and increased MPI. After 14 weeks' gestation, the mitral valve A-wave peak velocity and E/TVI ratio were significantly reduced in the trisomy 21 fetuses with normal hearts compared with the controls with increased NT.

CONCLUSIONS

In comparison with controls with normal or increased NT, cardiac function in trisomy 21 fetuses is abnormal irrespective of the presence of CHD. Evidence for cardiac loading (increased preload and afterload) and LV systolic (in the first trimester) and later diastolic dysfunction was observed.

Fetal cardiac function between 11 and 35 weeks' gestation and nuchal translucency thickness

OBJECTIVES

The pathophysiological background of an increased nuchal translucency (NT) is still poorly understood. Cardiac dysfunction has been proposed as a cause. The aim of this study was to determine if, in fetuses with normal hearts, the NT thickness is related to cardiac function throughout gestation.

METHODS

The NT was measured in 191 karyotypically/phenotypically normal fetuses with structurally normal hearts and was increased (≥ 95(th) centile) in 104. All fetuses had been referred for fetal echocardiography and were prospectively included between October 1 2003 and April 1 2009. Three-hundred and ten echocardiograms were performed between 11 and 35 weeks' gestation. The E- and A-wave velocity, E/A velocity ratio, E/time velocity integral (TVI) ratio over the atrioventricular (AV) valves, myocardial performance index, acceleration time (AT) and peak velocity over the semilunar valves, stroke volume (SV) and cardiac output (CO) as well as the ductus venosus pulsatility index for veins at 11-14 weeks' gestation (DV-PIV), were measured. A multilevel analysis was performed using the NT multiples of the median (MoM) as a continuous variable.

RESULTS

AV-E- and A-wave velocities, E/A velocity ratios, semilunar valve peak velocity, SV, CO and aortic valve (AoV) AT increased significantly with advancing gestation. At 11-14 weeks' gestation, the AoV-AT, tricuspid valve (TV)-E/A, TV-E/TVI ratios and DV-PIV increased, and the pulmonary valve (PV) AT decreased, with increasing NT-MoMs. After midgestation, the PV-AT increased and the AoV-AT, TV-E/A and TV-E/TVI ratios decreased with increasing NT-MoMs.

CONCLUSIONS

NT thickness is related to right ventricular diastolic function and semilunar valve AT. Our findings suggest improved first-trimester, but later reduced, right ventricular relaxation and discordant ventricular afterload in fetuses with an increased NT.

Antenatal diagnosis of pompe disease by fetal echocardiography: impact on outcome after early initiation of enzyme replacement therapy

Hypertrophic cardiomyopathy (HCM) affects most infants with Pompe disease (PD), and may serve as a marker for its antenatal diagnosis (ANDx) by fetal echocardiography (FE). Fetuses diagnosed with HCM between 2006 and 2009 were included in this study. HCM, defined as Z-score of mean left ventricular wall thickness (LVWT) and/or mass (LVM) above 2, was detected in 5/1,268 fetuses (0.39%) carried by 1,137 pregnant women referred for FE. Three fetuses (0.24%) had postnatal confirmation of PD. Their gestational age and fetal weight at diagnosis was (mean ± standard deviation) 31 ± 3.6 weeks and 1.9 ± 0.2 kg, respectively. Fetal Z-score of LVM and LVWT was 3.8 ± 0.9 and 3.1 ± 0.6, respectively. Postnatally, acid α-glucosidase (GAA) enzyme activity was nearly absent in all patients, 2 were homozygous for the mutation 1327-2A>G in the GAA gene, and 1 was homozygous for 340insT. Enzyme replacement therapy (ERT) was initiated 4.9 ± 7.8 days after birth (range 2 h-14 days), and continued every 2 weeks. Two infants are alive at 4 and 31 months, and one died of aspiration pneumonia at 19 months. Cardiac hypertrophy resolved after 10-12 weeks of ERT in all patients, and none required any respiratory support. One patient had normal neurodevelopmental assessment at 25 months, and one had severe global delay at 15 months before death. ANDx of PD by FE is feasible based on fetal HCM. It promotes early initiation of ERT which may improve outcome in some patients. However, larger studies and longer follow-ups are required.

Eleven fetal echocardiographic planes using 4-dimensional ultrasound with spatio-temporal image correlation (STIC): a logical approach to fetal heart volume analysis

BACKGROUND

Theoretically, a cross-sectional image of any cardiac planes can be obtained from a STIC fetal heart volume dataset. We described a method to display 11 fetal echocardiographic planes from STIC volumes.

METHODS

Fetal heart volume datasets were acquired by transverse acquisition from 200 normal fetuses at 15 to 40 weeks of gestation. Analysis of the volume datasets using the described technique to display 11 echocardiographic planes in the multiplanar display mode were performed offline.

RESULTS

Volume datasets from 18 fetuses were excluded due to poor image resolution. The mean visualization rates for all echocardiographic planes at 15-17, 18-22, 23-27, 28-32 and 33-40 weeks of gestation fetuses were 85.6% (range 45.2-96.8%, N = 31), 92.9% (range 64.0-100%, N = 64), 93.4% (range 51.4-100%, N = 37), 88.7%(range 54.5-100%, N = 33) and 81.8% (range 23.5-100%, N = 17) respectively.

CONCLUSIONS

Overall, the applied technique can favorably display the pertinent echocardiographic planes. Description of the presented method provides a logical approach to explore the fetal heart volumes.

Perinatal diagnosis of heart defects

IMPORTANCE OF THE FIELD

Heart defects are the most frequent congenital malformations, affecting 8 in every 1000 neonates. As 90% of infants born with a congenital heart defects (CHD) have no known risk factor, screening for heart defects in every routine obstetric ultrasound is essential for antenatal diagnosis.

AREAS COVERED IN THIS REVIEW

Two-dimensional echocardiography allied with three- and four-dimensional technologies such as spatio-temporal image correlation offer means for thoroughly evaluating fetal cardiac anatomy.

WHAT THE READER WILL GAIN

This article reviews the most relevant aspects of antenatal screening and diagnosis of CHD using sonography and echocardiography. It includes first trimester diagnosis and three- and four-dimensional techniques.

TAKE HOME MESSAGE

These antenatal diagnostic tools play an important role in optimization of obstetric care and neonatal management, thus potentially reducing perinatal mortality.

Color Doppler twinkling artifact in fetuses with echogenic intracardiac foci: echocardiographic observation and clinical significance

OBJECTIVE

To evaluate echocardiographic characteristics and clinical relevance of color Doppler twinkling artifacts in fetuses with isolated echogenic intracardiac foci (EIF).

METHODS

This study included 50 fetuses with EIF, at 18-38 weeks of gestation. Echocardiographic examination, which was performed using a 1.0-5.0-MHz phased array probe, included gray-scale, color and spectral Doppler imaging. Twinkling artifacts were assessed using fetal color Doppler echocardiography on isolated EIF situated in the left and/or right ventricles. The prevalence, appearance and clinical relevance of the color Doppler twinkling artifacts were analyzed.

RESULTS

Eight of 50 fetuses with EIF (16%) showed color Doppler twinkling artifacts, which appeared as a rapidly changing color complex seen persistently behind the EIF. The spectra obtained in all eight with color Doppler artifacts were composed of straight vertical bands occurring in mid to late systole and early diastole. After birth, none of 50 fetuses with EIF had structural heart diseases or showed clinical signs of cardiac failure.

CONCLUSIONS

Color Doppler twinkling artifacts from isolated EIF occur in some fetuses and may be considered as an additional echocardiographic feature of EIF. Attention should be paid to the identification and interpretation of these artifacts so that they may be accurately distinguished from true color flow generated by atrioventricular valvular regurgitation jets.

Fetal echocardiography: z-score reference ranges for a large patient population

OBJECTIVES

The main goal was to develop new z-score reference ranges for common fetal echocardiographic measurements from a large referral population.

METHODS

A retrospective cross-sectional study of 2735 fetuses was performed for standard biometry (biparietal diameter (BPD) and femoral diaphysis length (FDL)) and an assessment of menstrual age (MA). Standardized fetal echocardiographic measurements included aortic valve annulus and pulmonary valve annulus diameters at end-systole, right and left ventricular diameters at end-diastole, and cardiac circumference from a four-chamber view of the heart during end-diastole. Normal z-score ranges were developed for these echocardiographic measurements using MA, BPD and FDL as independent variables. This was accomplished by using first standard regression analysis and then weighted regression of absolute residual values for each parameter in order to adjust for inconstant variance.

RESULTS

A simple, linear regression model was the best description of the data in each case and correlations between fetal cardiac measurements and the independent variables were excellent. There was significant heteroscedasticity of standard deviation with increasing gestational age, which also could be modeled with simple linear regression. After this adjustment, the residuals conformed to a normal distribution, validating the calculation and interpretation of z-scores.

CONCLUSION

Development of reliable z-scores is possible for common fetal echocardiographic parameters by applying statistical methods that are based on a large sample size and weighted regression of absolute residuals in order to minimize the effect of heteroscedasticity. These normative ranges should be especially useful for the detection and monitoring of suspected fetal cardiac size and growth abnormalities.

The nuchal translucency and the fetal heart: a literature review

In this overview the current knowledge of the relationship between an increased nuchal translucency (NT) measurement and fetal heart structure and function in chromosomally normal fetuses is reviewed. Relevant pathophysiological theories behind the increased NT are discussed. Fetuses with an increased NT have an increased risk for congenital heart disease (CHD) with no particular bias for one form of CHD over another. This risk increases with increasing NT measurement. Although the NT measurement is only a modestly effective screening tool for all CHD when used alone, it may indeed be effective in identifying specific CHD "likely to benefit" from prenatal diagnosis. The combination of an increased NT, tricuspid regurgitation and an abnormal ductus venosus (DV) Doppler flow profile, is a strong marker for CHD. A fetal echocardiogram should be performed at 20 weeks' gestation in fetuses with an NT > or = 95th percentile but < 99th percentile. When the NT measurement is > or = 99th percentile, or when tricuspid regurgitation and/or an abnormal DV flow pattern is found along with the increased NT, an earlier echocardiogram is indicated, followed by a repeat scan at around 20 weeks' gestation. The resultant increased demand for early fetal echocardiography and sonographers with this special expertise needs to be planned and provided for.