Elsevier

Current Paediatrics

Volume 14, Issue 1, February 2004, Pages 39-44
Current Paediatrics

Review
Antenatal detection of congenital heart disease

https://doi.org/10.1016/j.cupe.2003.10.001Get rights and content

Abstract

Congenital heart disease is an important cause of mortality in infancy. Most lesions detected antenatally are identified because of an abnormal 18–20-week scan, approximately 10% being found on a specialist scan for a known risk factor. Conditions that can be seen in the four-chamber view are most likely to be detected. The spectrum of heart disease is therefore different from that diagnosed postnatally. Atrioventricular septal defects and hypoplastic left heart syndrome are the most commonly diagnosed conditions. There is conflicting evidence regarding whether the antenatal diagnosis of duct-dependent lesions improves survival. Analysis is complicated as this represents the severe end of the clinical spectrum. These infants also have a higher incidence of chromosomal and extracardiac abnormalities, which adversely affects outcome. An early recognition of heart disease allows the parents time to consider the options available to them and make decisions based on information of the condition and its implications.

Introduction

Heart defects are the most common major congenital malformation, severe congenital heart disease occurring in almost 2 in every 1000 pregnancies.1 The mid-trimester scan provides the best opportunity to identify anomalies in the developing fetus. Echocardiography allows an evaluation of the structure and function of the fetal heart.

Section snippets

The routine 18–20-week anomaly scan

This includes examination of the heart in the four-chamber view. The heart is identified with the apex to the left, a cardiothoracic ratio of less than 50%, two atria and two ventricles of equal size, and normal atrioventricular valves with the tricuspid valve inserted a little lower in the interventricular septum than the mitral valve. This identifies fetuses with asymmetry of the cardiac chambers. It can diagnose lesions such as:

  • hypoplastic left or right ventricle;

  • atrioventricular septal

Indications for specialist fetal echocardiography

Maternal and familial factors may be present:

  • 1.

    Mother, mother's partner or sibling with congenital heart disease (excluding atrial septal defect and patent arterial duct). The risk varies from 2% for a previous child with heart disease to 15% if the mother is affected.7 This risk also depends on the type of cardiac lesion. Some forms of dilated and hypertrophic cardiomyopathy are familial.

  • 2.

    Mother or her partner with a chromosome 22q11 deletion. This is inherited in an autosomal dominant manner and

Referral to a specialist centre

When congenital heart disease is suspected, or when risk factors exist, the mother is referred to a specialist fetal centre for further evaluation. The timing of this specialist scan is usually within a week of a routine scan that has identified an abnormality, or at 18–20 weeks when a risk factor exists. Earlier fetal echocardiography, between 12 and 15 weeks’ gestation, can provide good views of the heart.9 If this shows a severe cardiac abnormality, it can help in a decision regarding

Arrhythmias

Atrial ectopic beats detected during pregnancy are usually benign but can occasionally progress to supraventricular tachycardia or another significant arrhythmia.10 Supraventricular tachycardia and atrial flutter can cause severe heart failure in utero. Maternal digoxin or flecainide is used to control the arrhythmia, and other drugs have been used if these are unsuccessful.11 congenital complete heart block produces bradycardia and is usually associated with maternal autoimmune antibodies. The

Initial counselling

This includes a detailed description of the cardiac and any other abnormalities found, in language that the parents can understand. Diagrams and leaflets are helpful for partents to take away, along with contact telephone numbers for the cardiac and obstetric support services. Amniocentesis is offered as this can provide additional information on which parents can base their decisions. It may also give information on the causes of congenital heart disease and the risk of recurrence.

Information

Termination of pregnancy rate

Antenatal diagnosis allows parents to consider termination among their options. The rate of termination of the pregnancy is between 30% and 60% in various studies.6., 13. This has become lower as results of surgery have improved.

Follow-up during the pregnancy

Review during the pregnancy allows further evaluation of the cardiac lesion and the monitoring of fetal growth. It also provides additional opportunities for discussion with the family and may be a chance for families to visit the cardiology unit where the baby will be cared for. The incidence of intrauterine death is in the region of 10%.6., 13.

Poor prognostic indicators

These include multiple fetal abnormalities, trisomy 13 and 18, fetal hydrops, and tachy or bradyarrhythmia associated with congenital heart disease. Infants with Down syndrome, a cardiac lesion and growth retardation have a 1-year survival of only 60%; if intrauterine death is included, this falls to 40%. Prematurity also increases the risk for infants with complex congenital heart disease, particularly those with a single functioning ventricle. Complete heart block with an atrial rate of less

Outcome of antenatal diagnosis

Operative mortality for most congenital heart disease, other than hypoplastic left heart syndrome, is less than 5%, but this is not reflected in the outcome of antenatally diagnosed lesions.6., 13. There is conflicting evidence regarding whether the antenatal diagnosis of duct-dependent lesions significantly improves survival.14 Analysis is complicated by fact that the more severe end of the spectrum of congenital heart disease is diagnosed antenatally, and these infants have a much higher

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