Prenatal detection of congenital heart disease in southern Nevada: the need for universal fetal cardiac evaluation

Fetal cardiac screening and variation in prenatal detection rates of congenital heart disease: why bother with screening at all?

Antenatal screening for fetal cardiac abnormalities was introduced over 25 years ago, yet detection of congenital heart disease before birth remains a challenge. While experienced tertiary centers report a high level of diagnostic accuracy, with most major forms of congenital heart disease being detectable before birth, the overall detection rate remains low. Pregnancies at increased risk of having an affected baby are referred to tertiary centers for fetal ECG, but most cases of congenital heart disease will occur in low-risk pregnancies. These cases will only be detected by screening the low-risk population at the time of routine obstetric scanning. Many obstetric ultrasound units have learnt to successfully obtain, and correctly interpret, views of the heart, including the four-chamber view and outflow tract views. However, standards for doing this are not uniform, nationally or internationally, so there is a significant variation in detection rates across individual countries and between different countries. Early diagnosis of babies with lesions that can result in cardiovascular collapse and death, could improve their survival as well as reducing morbidity. In addition, detection of a cardiac abnormality during pregnancy allows time to prepare parents for the likely course of events after birth. It also facilitates detection of other abnormalities in the baby and gives parents a choice, even if the choice is difficult and unwelcome. As well as providing parents with accurate and up-to-date information regarding the their baby’s abnormality, it is vital to provide continuing support to help them deal with the problem, regardless of what decisions they make. Much work remains to establish a uniform standard for antenatal detection of cardiac abnormalities. More recent national guidelines for examining the fetal heart along with formalized auditing processes should help to achieve this, although considerable time and effort will be required, particularly with regard to the teaching and training required.

Fetal echocardiography

USG performed with a high-end machine, using a good cine-loop facility is extremely helpful in the diagnosis of fetal cardiac anomalies. In fetal echocardiography, the four-chamber view and the outflow-tract view are used to diagnose cardiac anomalies. The most important objective during a targeted anomaly scan is to identify those cases that need a dedicated fetal echocardiogram. Associated truncal and chromosomal anomalies need to be identified. This review shows how fetal echocardiography, apart from identifying structural defects in the fetal heart, can be used to look at rhythm abnormalities and other functional aspects of the fetal heart.

The changing occurrences of tetralogy of Fallot and simple transposition of the great arteries in Southern Nevada

We analysed the occurrence of tetralogy of Fallot and simple transposition in the Hispanic and non-Hispanic populations of Clark County, Nevada, in the United States of America over a 30-year period from 1980 to 2009. We found a downward trend in the incidence of simple transposition of the great arteries in the non-Hispanic population but an upward trend in the incidence in the Hispanic population. For tetralogy of Fallot, we found an upward trend in the incidence in both populations; the trend, however, was more dramatic in the Hispanic population. We also noted differences in the male to female ratios in the different groups. Even though we make no definitive conclusions regarding the causes of these incidence curves or the differences in occurrence between males or females, the data suggest an interplay of genetics and the environment.

Three-dimensional fast acquisition with sonographically based volume computer-aided analysis for imaging of the fetal heart at 18 to 22 weeks' gestation

OBJECTIVE

The purpose of this study was to determine how frequently cardiac images derived from 3-dimensional (3D) volume sets, acquired by fast acquisition and evaluated with sonographically based volume computer-aided analysis (sonoVCAD), were satisfactory for prenatal screening at 18 to 22 weeks' gestation.

METHODS

A prospective study of 100 women with singleton pregnancies was undertaken. Three fast acquisition 3D volume sets were obtained from each patient. Four reviewers independently evaluated the 4-chamber and 5 extracted VCAD views. Factors contributing to unsatisfactory screening were also evaluated.

RESULTS

The frequency with which adequate views for cardiac screening could be obtained varied widely; some single views, such as that of the stomach, were well seen frequently, whereas others, such as the ductal arch, were well seen significantly less frequently (P < .05). A satisfactory screening examination, defined as a visualized 4-chamber, left ventricular outflow tract, right ventricular outflow tract, and axial stomach view, was obtained for 43% to 65% of patients (dependent on reviewer). Logistic regression revealed that obesity (odds ratio, 3.0; 95% confidence interval, 1.7-5.0) and a fetus with the spine toward the maternal abdomen (odds ratio, 1.7; 95% confidence interval, 1.1-2.5) were independently associated with an unsatisfactory screening examination

CONCLUSIONS

Three-dimensional fast acquisition volumes evaluated with sonoVCAD did not allow a satisfactory fetal cardiac screening examination to be obtained a high percentage of the time in a general obstetric population during the second trimester. Certain patient factors, such as body habitus and fetal position, are associated with unsatisfactory 3D imaging.

The challenge of congenital heart disease worldwide: epidemiologic and demographic facts

Congenital heart disease (CHD) afflicts a large number of children every year. The incidence of CHD is generally considered to be 8 per 1,000 live births. However, this estimate is perhaps inaccurate and does not take into consideration regional differences. A large review of the literature was performed to establish the true incidence of CHD and geographical variations. Data on the incidence of specific lesions and their geographical variation, as well as on mortality from CHD, was also reviewed. Taking into consideration the available data on incidence, mortality, and access to care, the global challenge that CHD represents was analyzed. Insight into how to confront this challenge is given.

Satisfactory visualization rates of standard cardiac views at 18 to 22 weeks' gestation using spatiotemporal image correlation

OBJECTIVE

The purpose of this study was to determine the frequency with which 3 standard screening views of the fetal heart (4-chamber, left ventricular outflow tract [LVOT], and right ventricular outflow tract [RVOT]) can be obtained satisfactorily with the spatiotemporal image correlation (STIC) technique.

METHODS

A prospective study of 111 patients undergoing anatomic surveys at 18 to 22 weeks was performed. Two ultrasound machines with fetal cardiac settings were used. The best volume set that could be obtained from each patient during a 45-minute examination was graded by 2 sonologists with regard to whether the 4-chamber, LVOT, and RVOT images were satisfactory for screening.

RESULTS

All 3 views were judged satisfactory for screening in most patients: 1 sonologist graded the views as satisfactory in 70% of the patients, whereas the other found the views to be satisfactory in 83%. The position of the placenta did not alter the probability of achieving a satisfactory view, but a fetus in the spine anterior position was associated with a significantly lower probability that the views were regarded as satisfactory for screening (odds ratio, 0.28; 95% confidence interval, 0.09-0.70; P < .05).

CONCLUSIONS

This study suggests that STIC may assist with screening for cardiac anomalies at 18 to 22 weeks' gestation.

Prenatal screening for major congenital heart disease: superiority of outflow tracts over the 4-chamber view

OBJECTIVE

The purpose of this study was to determine the relative importance of the 4-chamber view (4CV) compared with the outflow tract views (OFTVs) in prenatal screening for major congenital heart disease (CHD).

METHODS

We prospectively evaluated 200 consecutive infants undergoing cardiac surgery at our institution for major CHD. By reviewing the infants' medical records and conducting bedside interviews with their parents or guardians, we evaluated detection rates both prenatally and postnatally (before and after discharge to home), and we noted any prenatally identifiable risk factors for CHD. For each infant, we determined whether the 4CV or OFTVs would be expected to have been normal or abnormal on routine midgestation screening fetal sonography.

RESULTS

A prenatal diagnosis of CHD was made in 65 infants (33%): 30 of 124 low-risk pregnancies (24%) and 35 of 76 high-risk pregnancies (46%). An abnormal screening midgestation 4CV would have been expected in up to 63% of the infants, whereas abnormal midgestation OFTVs would have been expected in up to 91% of the infants. Thus, the potential sensitivity for detecting major CHD was higher with the OFTVs than with the 4CV (91% versus 63%; P < .001). Moreover, the OFTVs were more sensitive than the 4CV for detecting ductal-dependent forms of CHD. Diagnosis after discharge to home occurred in 39 of 135 postnatal diagnoses (29%), including many cases of isolated outflow tract abnormalities requiring early invasive intervention.

CONCLUSIONS

Cases of major neonatal CHD with OFTV abnormalities predominate over cases with 4CV abnormalities, particularly among those forms of CHD requiring early invasive intervention.

Quality of 2- and 3-dimensional fast acquisition fetal cardiac imaging at 18 to 22 weeks: ramifications for screening

OBJECTIVE

The purpose of this study was to evaluate the frequency with which 6 different fetal cardiac views taken during a fetal ultrasound examination at 18 to 22 weeks' gestation can be obtained satisfactorily for cardiac anomaly screening using either a 2-dimensional (2D) static or 3-dimensional (3D) fast acquisition technique.

METHODS

A prospective study of 100 low-risk women undergoing an anatomic survey was performed. Standard static 2D and 3D fast acquisition volumes were obtained on all patients. The 2D and 3D images were assigned, in a random order, to be independently graded by 3 reviewers. The degree of inter-reviewer agreement was assessed through the use of the Cohen kappa statistic. The factors contributing to satisfactory imaging were evaluated by random effects logistic regression.

RESULTS

A significant proportion of both 2D and 3D images were judged unsatisfactory for screening purposes. However, 2D images were significantly more likely, for all cardiac views, to be judged satisfactory (P < .05). The odds ratios for the 2D technique's being more likely than the 3D technique to provide images satisfactory for screening were 2.6 for the 4-chamber view, 2.4 for the right ventricular outflow tract, 4 for the left ventricular outflow tract, 3.2 for the 3-vessel view, 8.6 for the aortic arch, and 2.2 for the ductal arch.

CONCLUSIONS

In this prospective study, static 2D imaging was significantly more likely than fast acquisition 2D imaging to yield cardiac views of high enough quality to satisfactorily screen for anomalies.

Aorta larger than pulmonary artery in the fetal 3-vessel view

OBJECTIVE

Fetal great artery asymmetry may accompany congenital heart disease. The fetal echocardiographic 3-vessel view (3VV) allows assessment of the superior vena cava, ascending aorta (AA), and main pulmonary artery (MPA). Our aim was to determine the association of congenital heart disease in fetuses with an AA/MPA ratio of greater than 1.

METHODS

We electronically searched our fetal echocardiographic database for studies performed between March 2002 and January 2008 that showed 3VVs with AA/MPA ratios of greater than 1 and correlated the findings with the presence of congenital heart disease.

RESULTS

In 2797 fetal echocardiograms, we identified 31 fetuses with normal 4-chamber views showing AA/MPA ratios of greater than 1 in the 3VV. Of 31 fetuses, 25 (81%) had tetralogy of Fallot (ToF) or a ToF variant, and 6 (19%) had an aortic valve abnormality or isolated dilatation of the AA.

CONCLUSIONS

Screening obstetric fetal sonography showing a 3VV AA/MPA ratio of greater than 1 suggests congenital heart disease and indicates the need for comprehensive fetal echocardiography.

Cost implications of introducing a telecardiology service to support fetal ultrasound screening

A district hospital in south-east England used a telecardiology service for fetal cardiac diagnosis alongside an existing arrangement for referring pregnant women directly to perinatal cardiologists in London for detailed fetal echocardiography. Women were identified for referral according to local protocols when having a second trimester anomaly scan. For the telemedicine referrals, the sonographers video-recorded images from the anomaly scans for transmission during monthly videoconferences. The cost of the women's antenatal care was calculated from the specialist assessment until delivery, while family costs were collected in a postal survey. Over 15 months, telemedicine was used in 52 cases, while 24 women were seen in London. The London women were more likely to have had an ultrasound abnormality (29% v 10%, P = 0.047). A telemedicine assessment of 5 min duration was more costly than an examination in London (mean cost per referral of £206 v £74, P < 0.001). However, the telecardiology service was cost neutral after 14 days and for the extended period until delivery. Travel costs for London women averaged £37 compared with £5.50 for the telemedicine referrals. Telemedicine may be useful to support perinatal cardiologists in the UK whose workloads are expanding in response to improved standards in antenatal ultrasound screening.

Evaluation of referral indications for fetal echocardiography in Beijing

OBJECTIVES

This study was conducted to evaluate the referral indications for fetal echocardiography (FE) in a tertiary center and to determine which indications were significantly associated with prenatal detection of congenital heart disease (CHD).

METHODS

The medical records of 1425 consecutive women who underwent second- and third-trimester FE at the Ultrasound Center of Beijing Obstetrics and Gynecology Hospital from March 2003 to December 2007 were reviewed. Referral indications, FE diagnoses, and pregnancy outcomes were collected. Univariate and multivariate logistic regression analyses were performed to identify those referral indications associated with prenatal detection of CHD.

RESULTS

In 126 patients (8.8%), CHD was detected prenatally and confirmed postnatally. Logistic regression analysis showed that abnormal cardiac views and extracardiac malformation findings (especially a single umbilical artery) on second-trimester ultrasound screening were found to have significantly more CHD (P < .001). The adjusted odds ratios were 15.2 (95% confidence interval, 9.85-23.45) and 6.78 (95% confidence interval, 2.38-19.27), respectively.

CONCLUSIONS

Abnormal cardiac views and extracardiac malformation findings on second-trimester ultrasound screening were significantly associated with prenatal detection of CHD.