Tricuspid valve dysplasia or displacement in intrauterine life.

In 450 cases of structural heart disease diagnosed prenatally, 38 fetuses (8.5%) had either a dysplastic or a displaced tricuspid valve. The tricuspid valve was dysplastic in 22 fetuses, all of which had evidence of tricuspid regurgitation resulting in right atrial dilation and increased cardiothoracic ratio. An associated abnormality of the pulmonary valve occurred in 16 fetuses. The remaining 16 fetuses had Ebstein's malformation, 14 with evidence of tricuspid incompetence at presentation and 10 with an associated abnormality of the pulmonary valve. Of the 38 cases, the pregnancy was interrupted in 17, spontaneous intrauterine fetal death occurred in 8, 11 infants died postnatally and 2 infants are still alive; additional abnormalities were found in 8 cases (chromosomal anomalies in 2, ventricular septal defects in 2, corrected transposition in 2, the Chiari malformation in 2, supraventricular tachycardia in 1 case and coarctation of the aorta in 1). Fetuses with severe abnormalities are selected for fetal echocardiography by the four chamber screening program and a high rate of natural loss both in intrauterine life and immediately after birth was observed in the 21 cases in which pregnancy was continued. This would explain the higher incidence of tricuspid valve disease in our prenatal compared with postnatal series. Although increased cardiothoracic ratio and associated lesions of the right ventricular outflow tract contribute to the poor outcome in the cases detected prenatally, the absence of these features does not always indicate a good prognosis because progression of disease can occur with advancing gestational age. No absolute measurement or single echocardiographic feature emerged as a consistent predictive factor of prognosis.

Atrioventricular septal defects diagnosed in fetal life: associated cardiac and extra-cardiac abnormalities and outcome.

OBJECTIVES: We sought to establish the outlook for fetuses diagnosed with atrioventricular septal defect (AVSD) prenatally and its relation to additional cardiac, extracardiac and chromosomal abnormalities. BACKGROUND: Prediction of likely outcome of AVSD presenting prenatally is complicated by the wide variation in associated features. METHODS: Computerized records from 14,726 pregnancies referred to a fetal cardiology center were reviewed retrospectively. Pathological reports, postnatal records, follow-up inquiries and review of echocardiographic video recordings supplemented analysis of the records for all those with AVSD. RESULTS: Atrioventricular septal defect was confirmed in 301 fetuses. Eighty-six (39%) of the 218 with known karyotype had trisomy 21, and 21/218 (10%) had other chromosome abnormalities. Right isomerism occurred in 37/301 (12%) fetuses, left isomerism in 62 (20%), mirror image atrial arrangement in 2 (1%), and 200 (67%) had usual arrangement. Atrioventricular septal defect occurred without any other intracardiac abnormality in 155 fetuses (51%). Extracardiac abnormalities and nonkaryotypic syndromes were evident in 40 fetuses (13%, confidence interval [CI] 9.5-17.1%). Uncomplicated cardiac anatomy was significantly associated with the presence of karyotype abnormality (p < 0.0001). Parents opted for termination of pregnancy in 175/298 (58.5%). For the continuing pregnancies, Kaplan-Meier estimates for live birth, survival past the neonatal period and survival to three years were 82% (CI 75.3-88.9%), 55% (CI 46.0%-0/64.3%) and 38% (CI 27.1-48.6%), respectively. Fetal hydrops and earlier year of diagnosis were independent variables with adverse influence on survival. CONCLUSIONS: Despite some improvements in the outlook for AVSD diagnosed prenatally, the overall prognosis remains considerably poorer than that implied from surgical series. The detection of associated cardiac and extracardiac abnormalities is important in order to give the best indication of the likely outcome when counseling parents.

Prospective diagnosis of 1,006 consecutive cases of congenital heart disease in the fetus.

OBJECTIVE: This report describes our experience with fetal congenital heart disease since 1980. BACKGROUND: Knowledge and expertise in the diagnosis, management and natural history of fetal congenital heart disease is increasingly demanded by both obstetricians and parents. The analysis of a large series should help the pediatric cardiologist to provide this service. METHODS: The notes of 1,006 patients, where a prospective diagnosis of fetal congenital heart disease was made, were reviewed. The reason for referral, the diagnosis made, the accuracy of diagnosis, the fetal karyotype and the outcome of the pregnancy were noted. The cases were grouped into malformation categories, and the spectrum of disease seen was compared with that found in infants. RESULTS: Most fetal cardiac anomalies are now suspected by the ultrasonographer during obstetric scanning. A different incidence of abnormalities is seen compared with that expected in infants. Chromosomal anomalies were more frequent in the fetus than in live births. The accuracy of diagnosis was good. The survival rate after diagnosis was poor because of frequent parental choice to interrupt pregnancy and the complexity of disease. CONCLUSIONS: A large experience with fetal congenital heart disease allows the spectrum of disease to be described with accuracy and compared with that in infancy. Knowledge of the natural history of heart malformations when they present in the fetus allows accurate counseling to be offered to the parents. If the trend in parental decisions found in this series continues, a smaller number of infants and children with complex cardiac lesions will present in postnatal life.

Echocardiographic features and outcome of truncus arteriosus diagnosed during fetal life.

There are few data on the outcome of truncus arteriosus when this diagnosis is made during fetal life. Such prognostic information is important to assist parental counseling during pregnancy. This study aimed to analyze, retrospectively, the echocardiographic features and outcome of fetuses with truncus arteriosus. A database of those presenting to a tertiary center for fetal cardiology between 1990 and 1999 was reviewed. Cases in which truncus arteriosus was identified as a firm or differential diagnosis were selected. Outcome data were derived from clinical records, and fetal echocardiograms were reviewed retrospectively. At presentation, truncus arteriosus was firmly diagnosed in 16 patients and was a differential diagnosis in 12. Fourteen of 16 (87%) of the firm diagnoses were correct. There were 17 confirmed cases of truncus arteriosus. Pregnancy was terminated in 4 patients (24%) and there were 13 live births. One child was not actively treated, 4 (31%) died preoperatively, and 8 (61%) underwent surgery. Thirty-day surgical mortality was 2 of 8 (25%). There was 1 late death after cardiac catheterization, and overall survival on an intention-to-treat basis was 5 of 12 (42%). Five of 6 patients with a prenatal truncal valve Doppler velocity above the normal aortic range were found to have postnatal truncal valve stenosis. Two fetuses with stenotic valves died preoperatively with sudden cardiovascular collapse. Counseling of parents for fetuses with truncus arteriosus should include the relatively high nonsurgical mortality as well as surgical results. Elevated prenatal truncal valve Doppler velocity predicts postnatal truncal valve stenosis. Fetuses with truncal valve stenosis may be at risk of early sudden death.

Natural history and outcome of aortic stenosis diagnosed prenatally.

OBJECTIVE: To document the growth of the left heart structures and outcome of fetuses with aortic stenosis. DESIGN: Retrospective echocardiographic and clinical study. SETTING: Tertiary centre for fetal cardiology. PATIENTS: 27 consecutive fetuses with aortic stenosis. MAIN OUTCOME MEASURES: Survival of affected fetuses. Measurement of left ventricular end diastolic volume (LVEDV), aortic root diameter, and ejection fraction. RESULTS: Before 25 weeks' gestation, the LVEDV was normal or increased in all cases. In six of eight fetuses studied sequentially, the LVEDV fell across normal centiles. Initial ejection fraction was reduced in 23 fetuses (88%). Before 28 weeks' gestation, the aortic root was normal in all but one case, but after 29 weeks, 11 of 13 fetuses had values below the 50th centile. In two fetuses prenatal aortic valvoplasty was attempted, 10 babies had postnatal interventions, and there were six survivors. Biventricular repair was attempted in eight cases, of whom five survived. A first stage Norwood operation was performed in three babies, of whom one survived. The four fetuses with the highest aortic root z scores had successful biventricular repair. The two fetuses with initially normal ejection fractions survived. Successful biventricular repair was achieved even where the LVEDV was below the 5th centile. CONCLUSIONS: In aortic stenosis diagnosed prenatally, failure of growth of the left ventricle and aortic root often occurs. The outcome of affected fetuses is better than previously reported. Prenatal echocardiography may assist selection of suitable candidates for biventricular versus Norwood repair.

Fetal tachycardias: management and outcome of 127 consecutive cases.

OBJECTIVE: To review the management and outcome of fetal tachycardia, and to determine the problems encountered with various treatment protocols. STUDY DESIGN: Retrospective analysis. SUBJECTS: 127 consecutive fetuses with a tachycardia presenting between 1980 and 1996 to a single tertiary centre for fetal cardiology. The median gestational age at presentation was 32 weeks (range 18 to 42). RESULTS: 105 fetuses had a supraventricular tachycardia and 22 had atrial flutter. Overall, 52 fetuses were hydropic and 75 non-hydropic. Prenatal control of the tachycardia was achieved in 83% of treated non-hydropic fetuses compared with 66% of the treated hydropic fetuses. Digoxin monotherapy converted most (62%) of the treated non-hydropic fetuses, and 96% survived through the neonatal period. First line drug treatment for hydropic fetuses was more diverse, including digoxin (n = 5), digoxin plus verapamil (n = 14), and flecainide (n = 27). The response rates to these drugs were 20%, 57%, and 59%, respectively, confirming that digoxin monotherapy is a poor choice for the hydropic fetus. Response to flecainide was faster than to the other drugs. Direct fetal treatment was used in four fetuses, of whom two survived. Overall, 73% (n = 38) of the hydropic fetuses survived. Postnatally, 4% of the non-hydropic group had ECG evidence of pre-excitation, compared with 16% of the hydropic group; 57% of non-hydropic fetuses were treated with long term anti-arrhythmics compared with 79% of hydropic fetuses. CONCLUSIONS: Non-hydropic fetuses with tachycardias have a very good prognosis with transplacental treatment. Most arrhythmias associated with fetal hydrops can be controlled with transplacental treatment, but the mortality in this group is 27%. At present, there is no ideal treatment protocol for these fetuses and a large prospective multicentre trial is required to optimise treatment of both hydropic and non-hydropic fetuses.

Prenatal detection and progression of right coronary artery to right ventricle fistula.

Prenatal diagnosis of a congenital coronary artery fistula between the right coronary artery and right ventricle was made by colour Doppler echocardiography at 20 weeks of gestation. Its progression was monitored by serial echocardiography throughout pregnancy and postnatally.

Isomerism of the atrial appendages associated with 22q11 deletion in a fetus.

There is a strong association between prenatally diagnosed structural heart disease and fetal chromosomal abnormalities. Isomerism of the atrial appendages is an exception to this because the fetal karyotype is usually normal in this condition. A case of atrial isomerism diagnosed antenatally with a normal female karyotype but with a microdeletion of chromosome 22q11 is reported.

The use of colour Doppler in fetal echocardiography.

Doppler colour flow mapping provides a non-invasive method for studying patterns of blood flow in the cardiovascular system. We undertook a prospective study using this technique in order to document normal and abnormal patterns in the human fetus. A group of 50 consecutive normal fetuses were examined with colour flow mapping. Patterns of flow that could be readily identified in the majority included inflow at the atrioventricular valves, outflow through the arterial valves and flow in the aortic arch and arterial duct. Flow across the oval foramen and in the pulmonary veins was identified in approximately half the patients. Colour Doppler also proved helpful in the detection and definition of cardiac anomalies. A series of 74 cardiac malformations, seen during 1988, were examined with colour flow mapping. The presence or absence of flow across valves could be confirmed, valvar incompetence demonstrated and the direction of blood flow displayed across both normal and abnormal communications. Colour Doppler studies in the human fetus can thus improve the understanding of the characteristics of flow of blood and add to the accuracy of antenatal diagnosis of congenital heart disease.

The accuracy of fetal echocardiography in the diagnosis of congenital heart disease.

The accuracy of the echocardiographic diagnosis of fetal heart disease in an experienced centre was evaluated by analysing the results achieved during 1987 at the Perinatal Cardiology Unit, Guy's Hospital. In this one year, 978 high-risk patients were referred for fetal echocardiography. Of these, 74 cases were found to have cardiac malformation, 69 of which were predicted from the prenatal study. Of the 69, the autopsy specimen was available for correlative purposes in 41 cases. A postnatal echocardiogram was performed by us in a further 15 cases. The result of autopsy or of a postnatal echocardiogram was obtained from another hospital in 7 cases. Postmortem was refused in 5 cases, while one further case remains alive but has not had a postnatal echocardiogram. Close correlation was achieved between the predicted echocardiographic diagnosis and the anatomical results. Some minor errors in the complete interpretation of a defect were found, particularly in those fetuses in whom image quality was poor, due to early (less than 20 weeks) or late (greater than 34 weeks) gestation or to maternal obesity. Difficulty in echocardiographic interpretation was also experienced in unusual defects. There was one false positive prediction of coarctation of the aorta. One major (total anomalous pulmonary venous drainage) and 5 minor abnormalities (two atrial and three ventricular septal defects) detected after birth were overlooked on the fetal study. Although the echocardiogram in prenatal life is not as accurate as it can be postnatally, with suitable experience a high degree of precision can now be achieved.

Prenatally diagnosed pulmonary atresia with ventricular septal defect: echocardiography, genetics, associated anomalies and outcome.

OBJECTIVE: To assess the accuracy of prenatal diagnosis, the association with genetic and extracardiac anomalies, and outcome in fetuses with isolated pulmonary atresia with ventricular septal defect (PA-VSD). DESIGN AND SETTING: Retrospective study in a tertiary centre for fetal cardiology. PATIENTS AND OUTCOME MEASURES: Echocardiographic video recordings of 27 consecutive fetuses with PA-VSD were reviewed for: (1) intracardiac anatomy; (2) presence of confluence and size of the branch pulmonary arteries; (3) source of pulmonary blood supply; and (4) side of the aortic arch. Postmortem and postnatal data were added. Karyotyping was performed in 25 patients and, in 23 of these, fluorescent in situ hybridisation to identify 22q11.2 deletion. RESULTS: PA-VSD was correctly diagnosed in 19 of 21 patients (90%) with postnatal or autopsy confirmation of diagnosis. Central pulmonary arteries were correctly identified in 79% (15/19), the source of pulmonary blood supply in 62% (13/21) and major aortopulmonary collateral arteries in 44% (4/9). Aneuploidy was detected in 4 of 25 patients (16%) and 22q11.2 deletion in 6 of 23 patients (26%). Five of 27 patients (19%) had extracardiac anomalies. Eleven pregnancies were interrupted. Eleven of 16 liveborn babies survived. Neonatal survival was 15 of 16 (94%, 95% confidence interval (CI) 70 to 100), one-year survival was 9 of 12 (75%, 95% CI 43 to 95) and two-year survival was 5 of 9 (56%, 95% CI 21 to 86). CONCLUSION: PA-VSD can be diagnosed by fetal echocardiography with a high degree of accuracy. However, it can be difficult to determine the morphology of the central pulmonary arteries and to locate the source of pulmonary blood supply. In most liveborn infants, complete surgical repair can be achieved.

Outcome after preterm delivery of infants antenatally diagnosed with congenital heart disease.

OBJECTIVE: To determine outcome of delivery before 36 weeks gestation in babies diagnosed antenatally with serious congenital heart disease (CHD). STUDY DESIGN: A retrospective database review at 2 tertiary care fetal cardiology centers. Details of neonatal course and outcome were obtained for those antenatally diagnosed with serious CHD who were live born before 36 weeks gestation. RESULTS: Between January 1998 and December 2002, 9918 women were referred for fetal echocardiography. Serious CHD was diagnosed in 1191 fetuses (12%), of which 46 (4%) delivered prematurely. Median gestation was 33 (range 24-35) weeks, and median birth weight 1.56 (0.50-3.59) kg. Extracardiac/karyotypic anomalies occurred in 23 (50%). Twenty-six babies (57%) underwent neonatal surgery: 16 a cardiac procedure, 5 a general surgical procedure, and 5 both. Eight died during or after operation (31%). Two babies underwent interventional heart catheterization; both died. The overall mortality rate was 72%. Extracardiac/karyotypic anomalies increased the relative risk of death by a factor of 1.36. Mean hospital stay for those surviving to initial discharge was 46 (2-137) days. CONCLUSIONS: There is a very high morbidity and mortality rate in this group, particularly for those with extracardiac/karyotypic anomalies. This should be reflected in decisions over elective preterm delivery and when counseling parents.

The low oxygen-carrying capacity of Krebs buffer causes a doubling in ventricular wall thickness in the isolated heart.

The buffer-perfused Langendorff heart is significantly vasodilated compared with the in vivo heart. In this study, we employed ultrasound to determine if this vasodilation translated into changes in left ventricular wall thickness (LVWT), and if this effect persisted when these hearts were switched to the "working" mode. To investigate the effects of perfusion pressure, vascular tone, and oxygen availability on cardiac dimensions, we perfused hearts (from male Wistar rats) in the Langendorff mode at 80, 60, and 40 cm H2O pressure, and infused further groups of hearts with either the vasoconstrictor endothelin-1 (ET-1) or the blood substitute FC-43. Buffer perfusion induced a doubling in diastolic LVWT compared with the same hearts in vivo (5.4 +/- 0.2 mm vs. 2.6 +/- 0.2 mm, p < 0.05) that was not reversed by switching hearts to "working" mode. Perfusion pressures of 60 and 40 cm H2O resulted in an increase in diastolic LVWT. ET-1 infusion caused a dose-dependent decrease in diastolic LVWT (6.6 +/- 0.4 to 4.8 +/- 0.4 mm at a concentration of 10(-9) mol/L, p < 0.05), with a concurrent decrease in coronary flow. FC-43 decreased diastolic LVWT from 6.7 +/- 0.5 to 3.8 +/- 0.7 mm (p < 0.05), with coronary flow falling from 16.1 +/- 0.4 to 8.1 +/- 0.4 mL/min (p < 0.05). We conclude that the increased diastolic LVWT observed in buffer-perfused hearts is due to vasodilation induced by the low oxygen-carrying capacity of buffer compared with blood in vivo, and that the inotropic effect of ET-1 in the Langendorff heart may be the result of a reversal of this wall thickening. The implications of these findings are discussed.

Timing of presentation and postnatal outcome of infants suspected of having coarctation of the aorta during fetal life.

OBJECTIVE: To report the timing of presentation and clinical profile of a cohort of fetuses with normal main cardiac connections but fetal echocardiographic signs suggestive of coarctation of the aorta. DESIGN: Retrospective observational study. SETTING: Tertiary fetal and paediatric cardiology centre. PATIENTS: Between 1 January 1998 and 31 December 2002, 174 fetuses were studied, of whom 144 infants were born alive. MAIN OUTCOME MEASURES: Of the 144 liveborn infants, 43 had coarctation of the aorta, four had interruption of the aortic arch, and one was managed as having hypoplastic left heart syndrome. Hemianomalous pulmonary venous drainage was diagnosed in two infants. Three infants with coarctation presented late at 7-13 weeks of age, 6-12 weeks after closure of the arterial duct. Fetuses with cardiac asymmetry had a higher incidence of left superior vena cava than a control group. For fetuses with cardiac asymmetry, the incidence of left superior vena cava and ventricular septal defects was similar in infants who proved to have coarctation postnatally and in those who did not. The 30 day and one year surgical mortality of infants having repair of coarctation of the aorta was two of 41 (4.9%, 95% confidence interval (CI) 0.6 to 16.0). All cause mortality of liveborn infants with any abnormality of the aortic arch was five of 48 (10.4%, 95% CI 3.5 to 22.7) at 30 days and one year, which was heavily influenced by prematurity and extracardiac abnormalities. CONCLUSIONS: Precise diagnosis of coarctation of the aorta during fetal life remains difficult. Coarctation of the aorta may present several weeks after closure of the arterial duct and sequential echocardiography is recommended.

Fetal dextrocardia: diagnosis and outcome in two tertiary centres.

OBJECTIVE: To evaluate the incidence of fetal dextrocardia, associated cardiac and extracardiac malformations, and outcome. DESIGN: Retrospective echocardiographic study. SETTING: Two tertiary centres for fetal cardiology. PATIENTS: 81 consecutive fetuses with a fetal dextrocardia presenting at Guy's Hospital, London, between 1983 and 2003 and at Hôpital Robert Debré, Paris, between 1988 and 2003. Fetal dextrocardia was defined as a condition in which the major axis of the heart points to the right. RESULTS: The incidence was 0.22%. There were 38 fetuses (47%) with situs solitus (SS), 24 (30%) with situs ambiguus (SA), and 19 (23%) with situs inversus (SI). Structural cardiac malformations were found in 25 cases (66%) of SS, 23 cases (96%) of SA, and 12 cases (63%) of SI. Extracardiac malformations were identified in 12 cases (31%) of SS, in five cases (21%) of SA, and in two cases (10%) of SI. Of the 81 cases of fetal dextrocardia, there were 27 interrupted pregnancies (15 of 24 SA, 10 of 38 SS, and 2 of 19 SI), six intrauterine deaths (3 of 38 SS, 2 of 24 SA, and 1 of 19 SI), and five neonatal deaths (3 of 24 SA, 1 of 19 SI, and 1 of 38 SS). There were 43 survivors (24 of 38 SS, 15 of 19 SI, and 4 of 24 SA). CONCLUSION: The majority of fetuses with dextrocardia referred for fetal echocardiography have associated congenital heart disease. There is a broad spectrum of cardiac malformation and the incidence varies according to the atrial situs. Fetal echocardiography enables detection of complex congenital heart disease so that parents can be appropriately counselled.

Normal fetal cardiac measurements derived by cross-sectional echocardiography.

Cardiac structures have been measured in normal fetuses by cross-sectional echocardiography to establish a range of normal values. Gestational ages varied from 16 weeks to term. The cardiac structures measured were left and right ventricular width (n = 337), aortic root diameter (n = 296), pulmonary artery diameter (n = 312), mitral valve orifice (n = 159), and tricuspid valve orifice (n = 161). The lengths of the left and right ventricles were measured in 100 fetuses. Normal ranges were constructed using real-time ultrasound images which can be readily used in routine practice. Measurement of cardiac structures is an aid to the study of cardiac abnormalities and the availability of normal ranges of measurements of fetal cardiac structures may help to confirm and define suspected cardiac malformation during routine screening.

Screening for congenital heart disease prenatally. Results of a 2 1/2-year study in the South East Thames Region.

OBJECTIVE: To assess the efficacy of four chamber view examination, during routine obstetric scanning, in the prenatal detection of fetuses with congenital heart disease. DESIGN: Prospective observational study. SETTING: Ten obstetric ultrasound units in the South East Thames Region. SUBJECTS: All pregnant women attending for routine obstetric ultrasound examination. INTERVENTION: Ultrasonographers performing routine ultrasound examinations were taught to obtain, and correctly interpret, the four chamber view of the fetal heart. When this view could not be achieved adequately, an attempt was made to identify a reason for failure and, if possible, to arrange a repeat scan. All suspected abnormalities were referred to a specialized unit. MAIN OUTCOME MEASURES: Numbers of true abnormalities detected or overlooked, and the number in whom abnormality was suspected incorrectly. RESULTS: Over a 2.5-year period, 69% of the known number of cardiac lesions associated with an abnormality of the four chamber view were detected prenatally during the routine obstetric scan, 10% were identified as a result of referal for other high-risk factors and 21% were overlooked. The overall positive predictive value in the 10 obstetric units was 36%. CONCLUSIONS: Prenatal screening for some forms of major congenital heart disease is possible by including examination of the four chamber view of the fetal heart in routine obstetric scans. However, there are important limiting factors that will influence the success of abnormality detection and must be taken into account if screening is to be effective nationwide.

Prognosis in fetal tetralogy of Fallot.

The outcome in a series of 23 cases of tetralogy of Fallot diagnosed prenatally was compared to published figures for this condition when (a) identified postnatally or (b) treated surgically. There was a marked difference in the survival between these groups, with the highest mortality (75%) occurring when the diagnosis had been made prenatally. The high incidence of chromosomal and extracardiac anomalies in this group (60%) largely accounted for the discrepancy. This, and the potential for progressive changes in the anatomy of the defect during pregnancy, must be taken into account by the pediatric cardiologist offering prognosis in early pregnancy.

Nuchal translucency and congenital heart defects: heart failure or not?

OBJECTIVE: To determine whether heart failure is the mechanism underlying the association between increased fetal nuchal translucency and congenital heart defects. METHODS: Retrospective analysis of the types of congenital heart defect observed in fetuses with increased nuchal translucency and those with normal nuchal scans. Retrospective quantitative analysis of cardiac size and left ventricular ejection fraction in fetuses with ventricular septal defects or the hypoplastic left heart syndrome. RESULTS: Eighty-three fetuses with congenital heart defects had undergone nuchal screening of which 51 had increased nuchal translucency and 32 had normal nuchal translucency. A wide variety of different congenital cardiac lesions with different hemodynamic effects were observed in fetuses with increased nuchal translucency and those with normal nuchal scans. Defects primarily characterized by left heart obstruction, right heart obstruction and septal defects occurred in both groups. All measurements of cardiothoracic ratio and left ventricular ejection fraction fell within the normal range and there was no significant difference between fetuses with increased nuchal translucency and those with normal nuchal scans. CONCLUSIONS: No specific type of congenital heart lesion is associated with increased nuchal translucency. The contention that heart failure explains the association between congenital heart defects and increased nuchal translucency is not supported by this study.