Fetal two-dimensional Doppler echocardiography (colour flow mapping) and its place in prenatal diagnosis

Congenital cardiac anomalies: prenatal readings versus neonatal outcomes

OBJECTIVE

The purpose of this study was to determine the variation between prenatal and postnatal diagnosis of congenital cardiac lesions diagnosed by both fetal center primary physicians and fetal pediatric cardiologists at a single tertiary referral center in the United States and evaluate why cases were misdiagnosed.

METHODS

A retrospective review of all cardiac abnormalities identified prenatally by level II sonography at a tertiary referral fetal center between January 2006 and December 2008 was performed to include any patient with a fetal cardiac abnormality and with a documented autopsy or neonatal follow-up. Congenital heart disease diagnoses were classified as correct, incorrect, or incorrect but within the same spectrum of disease. Cases of correct diagnosis by primary physicians and pediatric cardiologists were compared.

RESULTS

Sixty patients with fetal heart abnormalities were identified among 8894 patients who had level II sonography. The combined detection rate for fetal heart abnormalities for both primary physicians and pediatric cardiologists together was 81.7%. The detection rates of congenital heart disease were not statistically different between primary physicians and pediatric cardiologists: 77.9% (46 of 59) versus 85.0% (34 of 40; P = .3). The most common cardiac abnormalities misdiagnosed in our study population included pulmonic stenosis, ventricular septal defect, myxoma, truncus arteriosus, and coarctation of the aorta.

CONCLUSIONS

Congenital heart disease is misdiagnosed in tertiary care centers by both pediatric cardiologists and fetal imaging specialists. We believe that this occurrence is related to multiple factors, including evolution of congenital heart disease, maternal body habitus, associated congenital anomalies, decreased amniotic fluid volume, gestational age at evaluation, imaging techniques, and, most importantly, the experience of the sonographer.

Prenatal diagnosis of congenital heart disease

Owing to the widely different levels of experience of examiners, there is a large discrepancy in study results of second trimester ultrasound screening for fetal malformations, which is a result of varying levels of obstetric scanning expertise prevalent at the reporting centre. This holds particularly true for the prenatal diagnosis of congenital heart disease where detection rates ranging from 0 per cent to 60 per cent are being reported. On the other hand, congenital heart disease affects about 4-8 per 1000 live births and is a leading cause of infant mortality, whereas prenatal diagnosis could possibly prevent death and long-term morbidity in some of these neonates. Various screening concepts for more effective detection of congenital heart diseases are analysed in this article, including the more recent technique of early echocardiography between 13 and 15 weeks of gestation. High-risk groups are defined and the group of fetuses with increased thickness of nuchal translucency seems to be of particular interest.

Congenital heart defects: natural course and in utero development

BACKGROUND

Most congenital heart defects (CHDs) are diagnosed on targeted prenatal transvaginal (TVS) or transabdominal (TAS) ultrasonography during the early second trimester or at midgestation. Nevertheless, delayed diagnosis in some cardiac malformations still remains despite detailed echocardiographic examination. The present study was conducted to evaluate the evolution of fetal cardiac anomalies and assess their development in utero.

METHODS AND RESULTS

We retrospectively reviewed 22,050 pregnant women who were divided into two groups: 6924 who had initial TVSs at 13 to 16 weeks' gestation, followed by TASs at 20 to 22 weeks, and 15,126 who had initial TASs at 20 to 22 weeks. Both groups were subsequently examined in their third trimester. All newborns were examined by certified pediatricians. CHD was diagnosed in 168 babies: 66 in group A and 102 in group B. In group A, 42 malformations (64%) were detected at the first TVS examination, and 11 (17%) were found during the subsequent TAS. Three additional anomalies (4%) were found during the third trimester, and 10 malformations (15%) were detected postnatally. In group B, 80 malformations (78%) were detected in the initial examination at midtrimester, and an additional 7 (7%) were found in the third trimester, whereas 15 (15%) were diagnosed postnatally. The 10 anomalies (group A, n=3; group B, n=7) that were detected only during the third trimester comprised aortic stenosis (n=2), cardiac rhabdomyoma (n=2), subaortic stenosis (n=1), tetralogy of Fallot (n= 1), aortic coarctation (n=1), sealed foramen ovale (n=1), ventricular septal defects (n=1), and hypertrophic cardiomyopathy (n=1).

CONCLUSIONS

Although most fetal cardiac anomalies are detectable early in gestation, some may evolve in utero at different stages of pregnancy.

Effect of detailed fetal echocardiography as part of routine prenatal ultrasonographic screening on detection of congenital heart disease

BACKGROUND

Cardiac abnormalities are frequently not detected by routine ultrasound screening examinations. Although detailed fetal echocardiography is more sensitive in detection of congenital heart disease, it is used only for high-risk cases. The main aim of this study was to assess the prenatal detection of congenital heart disease by detailed fetal echocardiography in an unselected, consecutive group of pregnant women.

METHODS

Between Jan 1, 1993, and Sept 30, 1994, all women who attended our antenatal-care unit were routinely offered a detailed fetal echocardiography examination at 18-28 weeks' gestation. 3085 consecutive women were screened: 2181 were screening cases with no known risk factor for congenital heart disease; 540 had maternal risk factors for congenital heart disease, such as a family history or coexisting maternal disease; 364 had sonographically detected abnormalities. The examination included the four-chamber view, outflow-tract scan, and colour-flow mapping; doppler and M-mode investigations were also done when appropriate.

FINDINGS

46 cases of congenital heart disease were detected prenatally by echocardiography-15 in the group with no risk factors, three in the group with maternal risk factors, and 28 in the group with sonographic abnormalities. Postnatal assessments found six further cases of congenital heart disease that had not been detected prenatally, but these were all minor cases. There were no false-positive diagnoses (sensitivity 85.5%, specificity 100%). The incidence of congenital heart disease in screening cases with no risk factors and in those with maternal risk factors was low (6.9% per 1000, 5.6 per 1000) and similar to the expected overall incidence of 8.0 per 1000 livebirths in the general population. In the group with sonographic abnormalities congenital heart disease was found significantly more often (79.9 per 1000).

INTERPRETATION

Inclusion of detailed fetal echocardiography as a screening examination has a substantial effect on detection of congenital heart disease since a major proportion of prenatally detectable cases occur in a low-risk population.

Reversed shunting across the ductus arteriosus or atrial septum in utero heralds severe congenital heart disease

OBJECTIVES

This study was performed to define the significance of Doppler color flow mapping in demonstrating reversal of the direction of the normal physiologic flow across the atrial septum and ductus arteriosus in the human fetus.

BACKGROUND

Reversal of the physiologic shunting across the ductus arteriosus or atrial septum in utero (i.e., left to right) can be readily identified by Doppler color flow mapping, complemented by pulsed and continuous wave Doppler information.

METHODS

We reviewed echocardiograms recorded at our three institutions from 1988 to 1993, which displayed reversal of flow by Doppler color flow in 53 fetuses of gestational age 18 weeks to term. The diagnoses were confirmed by postnatal echocardiography, operation or autopsy. Reversal of shunting was consistently associated with severe heart disease.

RESULTS

Reversed atrial shunting was found with severe left heart obstructive lesions, including 19 with hypoplastic left heart syndrome, 3 with critical aortic stenosis, 2 with double-outlet right ventricle and 1 each with an interrupted aortic arch, atrioventricular septal defect and severe left ventricular dysfunction due to dilated cardiomyopathy. Reversed ductus arteriosus shunting was found with severe right heart obstructive lesions, including nine fetuses with pulmonary atresia, six with severe obstructive tricuspid valve abnormalities, five with severe tetralogy of Fallot, four with Ebstein's anomaly and two with single ventricle and pulmonary stenosis. Associated cardiac lesions were common in both groups. Only 3 of the 15 infants who were delivered alive from the reverse ductus arteriosus shunt group and 4 of 12 from the reverse atrial shunt group still survive.

CONCLUSIONS

The finding of reversed flow by Doppler color flow mapping during fetal life provides a key to subsequent accurate diagnosis and denotes a spectrum of diseases with a very poor prognosis.

Contributions of color Doppler to the evaluation of cardiovascular abnormalities in the fetus

The applications of color Doppler sonography are reviewed in this article. Color Doppler is an efficient and time-saving means of assessing normal and abnormal flow in the fetus, making it an essential part of the echocardiographic examination for fetal congenital heart disease. In survey mode, color Doppler can be used to quickly evaluate whether flow channels are normal and to detect abnormal flow patterns. These abnormal flow patterns can then be examined further by pulsed or continuous wave Doppler, if needed. Color Doppler, which is subject to less rib shadowing than other Doppler techniques, also can help in assessing the fetal heart when there is less-than-adequate gray scale imaging.

Extended fetal echocardiographic examination for detecting cardiac malformations in low risk pregnancies

OBJECTIVE

To improve the rate of prenatal detection of cardiac malformations in a low risk population.

DESIGN

Comparison of extended fetal echocardiography with the standard four chamber view in detecting abnormalities. Extended echocardiography comprised the four chamber view and visualisation of the left ventricular outflow tract, the right ventricular outflow tract, and the main pulmonary artery and its branches. In cases with abnormal results complete echocardiographic studies were performed by a paediatric cardiologist using M mode, Doppler, and colour flow mapping techniques.

SETTING

Obstetric ultrasonographic unit at Shaare-Zedek Medical Centre, Jerusalem.

SUBJECTS

5400 fetuses in low risk pregnancies between 18 and 24 weeks' gestation (mean 21 weeks); 53 were lost to follow up.

MAIN OUTCOME MEASURES

Detection of abnormality before and after birth.

RESULTS

During the study 23 infants (0.4%) were born with cardiac abnormalities, 21 of whom had major structural and functional heart disease. 18 fetuses had heart disease diagnosed prenatally, 11 by the four chamber view alone (sensitivity 48%) and a further seven by extended echocardiography (sensitivity 78%). Five fetal cardiac defects were missed prenatally (false negative rate 22%). These included coarctation of aorta, persistent truncus arteriosus, tetralogy of Fallot, ventricular septal defect, and pulmonic stenosis. Only one false positive diagnosis (coarctation of aorta) was made (specificity 99.9%, false positive rate 0.1%). The abnormality was correctly identified in 17 out of 18 cases.

CONCLUSIONS

The extended fetal heart examination detected 86% (18/21) of major abnormalities in a low risk population. The examination should be incorporated into routine prenatal ultrasonographic investigations.

Color Doppler flow mapping of fetal heart

Color Doppler flow mapping of fetal heart was performed in 582 fetuses between 16 and 38 weeks of gestation. Congenital heart diseases were excluded in 522 fetuses correctly. In 59 fetuses structural and/or functional cardiac abnormalities were diagnosed. In one fetus small multiple ventricular septal defects were missed. The most important additional information obtained by color Doppler flow mapping was: (1) Diagnosis of insufficiencies of atrioventricular valves; (2) Demonstration of turbulent high velocity jet in stenosis of semilunar valve; (3) Reverse flow in ascending aorta in atresia of aortic valves and on ductus arteriosus and main pulmonary artery in atresia of pulmonary valves; (4) Reverse perfusion of ductus arteriosus and main pulmonary artery as well as an antegrade turbulent high velocity jet in severe pulmonary stenosis as part of tetralogy of Fallot; (5) Bidirectional interventricular shunting of blood in ventricular septal defect. Color Doppler flow mapping allows rapid screening for flow abnormalities of the fetal heart. Exact localisation of sample volume by pulsed wave Doppler in area of abnormal flow pattern is possible, thus significantly reducing the Doppler examination time. The accuracy of prenatal diagnosis of congenital heart diseases is improved by application of color Doppler flow mapping, in particular in presence of complex cardiac defects.

Flow analysis in the pulmonary trunc in fetuses with tetralogy of Fallot by colour Doppler flow mapping; two case reports

Prenatal diagnosis of tetralogy of Fallot by two-dimensional echocardiography, which is based on demonstration of a ventricular septal defect and a large overriding aorta, is difficult. In the majority of cases the main pulmonary artery is small. In utero, there is no pathologically increased degree of the physiological right-ventricular hypertrophy. Colour Doppler flow mapping of reverse flow from the descending aorta via the ductus arteriosus into the main pulmonary artery is easily demonstrated, and provides an indirect sign of severe right-ventricular outlet obstruction. The technique also differentiates between pulmonary stenosis and atresia; the stenotic jet, even small, is identified by demonstration of high velocities and turbulences in the main pulmonary artery.