• Lesions are being increasingly identified on antenatal ultrasound screening

• Most lesions are diagnosed by echocardiography, the mainstay of diagnostic imaging

• MRI allows three-dimensional reconstruction of complex cardiac disorders, assessment of haemodynamics and flow patterns and assists interventional cardiology, reducing the need for cardiac catheterisation

• Most defects can be corrected by definitive surgery at the initial operation

• An increasing number of defects (60%) are treated non-invasively, e.g. persistent ductus arteriosus

• New therapies are available to treat pulmonary hypertension and delay transplantation

• The overall infant cardiac surgical mortality has been reduced from approximately 20% in 1970 to 2% in 2010.

Epidemiology

Heart disease in children is mostly congenital. It is the most common single group of structural malformations in infants:

The nine most common anomalies account for 80% of all lesions (Box 17.1), but:

Aetiology

Genetic causes are increasingly recognised in the aetiology of congenital heart disease, now in more than 10%. These might affect whole chromosomes, point mutations or microdeletions (Table 17.1). Polygenic abnormalities probably explain why having a child with congenital heart disease doubles the risk for subsequent children and the risk is higher still if either parent has congenital heart disease. A small proportion are related to external teratogens.

Circulatory changes at birth

In the fetus, the left atrial pressure is low, as relatively little blood returns from the lungs. The pressure in the right atrium is higher than in the left, as it receives all the systemic venous return including blood from the placenta. The flap valve of the foramen ovale is held open, blood flows across the atrial septum into the left atrium and then into the left ventricle, which in turn pumps it to the upper body (Fig. 17.1).

With the first breaths, resistance to pulmonary blood flow falls and the volume of blood flowing through the lungs increases six-fold. This results in a rise in the left atrial pressure. Meanwhile, the volume of blood returning to the right atrium falls as the placenta is excluded from the circulation. The change in the pressure difference causes the flap valve of the foramen ovale to be closed. The ductus arteriosus, which connects the pulmonary artery to the aorta in fetal life, will normally close within the first few hours or days. Some babies with congenital heart lesions rely on blood flow through the duct (duct-dependent circulation). Their clinical condition will deteriorate dramatically when the duct closes, which is usually at 1–2 days of age but occasionally later.

Presentation

Congenital heart disease presents with:

Heart failure

Symptoms

• Breathlessness (particularly on feeding or exertion)

• Sweating

• Poor feeding

• Recurrent chest infections.

Signs

• Poor weight gain or ‘faltering growth’

• Tachypnoea

• Tachycardia

• Heart murmur, gallop rhythm

• Enlarged heart

• Hepatomegaly

• Cool peripheries.

Signs of right heart failure (ankle oedema, sacral oedema and ascites) are rare in developed countries, but may be seen with long-standing rheumatic fever or pulmonary hypertension, with tricuspid regurgitation and right atrial dilatation.

In the first week of life, heart failure (Box 17.2) usually results from left heart obstruction, e.g. coarctation of the aorta. If the obstructive lesion is very severe then arterial perfusion may be predominantly by right-to-left flow of blood via the arterial duct, so-called duct-dependent systemic circulation (Fig. 17.2). Closure of the duct under these circumstances rapidly leads to severe acidosis, collapse and death unless ductal patency is restored (Case History 17.1).

Box 17.2   Causes of heart failure

1 Neonates – obstructed (duct-dependent) systemic circulation

• Hypoplastic left heart syndrome

• Critical aortic valve stenosis

• Severe coarctation of the aorta

• Interruption of the aortic arch

2 Infants (high pulmonary blood flow)

• Ventricular septal defect

• Atrioventricular septal defect

• Large persistent ductus arteriosus

3 Older children and adolescents (right or left heart failure)

• Eisenmenger syndrome (right heart failure only)

• Rheumatic heart disease

• Cardiomyopathy.

After the first week of life, progressive heart failure is most likely due to a left-to-right shunt (Case History 17.2). During the subsequent weeks, as the pulmonary vascular resistance falls, there is a progressive increase in left-to-right shunt and increasing pulmonary blood flow. This causes pulmonary oedema and breathlessness.

Such symptoms of heart failure will increase up to the age of about 3 months, but may subsequently improve as the pulmonary vascular resistance rises in response to the left-to-right shunt. If left untreated, these children will develop Eisenmenger syndrome, which is irreversibly raised pulmonary vascular resistance resulting from chronically raised pulmonary arterial pressure and flow. Now the shunt is from right to left and the teenager is blue. If this develops, the only surgical option is a heart-lung transplant, if available, although medication is now available to palliate the symptoms.

Cyanosis

• Peripheral cyanosis (blueness of the hands and feet) may occur when a child is cold or unwell from any cause or with polycythaemia

• Central cyanosis, seen on the tongue as a slate blue colour, is associated with a fall in arterial blood oxygen tension. It can only be recognised clinically if the concentration of reduced haemoglobin in the blood exceeds 5 g/dl, so it is less pronounced if the child is anaemic

• Check with a pulse oximeter that an infant’s oxygen saturation is normal (≥94%). Persistent cyanosis in an otherwise well infant is nearly always a sign of structural heart disease.

Cyanosis in a newborn infant with respiratory distress (respiratory rate >60 breaths/min) may be due to:

• Cardiac disorders – cyanotic congenital heart disease

• Respiratory disorders, e.g. surfactant deficiency, meconium aspiration, pulmonary hypoplasia, etc.

• Persistent pulmonary hypertension of the newborn (PPHN) – failure of the pulmonary vascular resistance to fall after birth

• Infection – septicaemia from group B streptococcus and other organisms

• Metabolic disease – metabolic acidosis and shock.

Case History

17.1 Shock

A 2-day-old baby had been discharged home the day after delivery following a normal routine examination. He suddenly collapsed and was rushed to hospital. He was pale, with grey lips. The right brachial pulse could just be felt, the femoral pulses were impalpable and his liver was significantly enlarged. Blood gases showed a severe metabolic acidosis. The differential diagnosis was:

• Congenital heart disease

• Septicaemia

• Inherited disorder of metabolism.

He was ventilated and treated with volume support. Blood cultures were taken and antibiotics started for possible sepsis. Blood and urine samples were taken for an amino acid screen and urine for organic acids. As the femoral pulses remained impalpable, a prostaglandin infusion was started. Within 2 hours, he was pink and well perfused and the acidosis was resolving. Severe coarctation of the aorta (Fig. 17.3) was diagnosed on echocardiography. He had developed shock from a left heart outflow tract obstruction once the arterial duct had closed.

Maintaining ductal patency is the key to early survival in neonates with a duct-dependent circulation.

Case History

17.2 Heart failure

A 5-week-old female infant was referred to hospital because of wheezing, poor feeding and poor weight gain during the previous 2 weeks. Before this, she had been well. Her routine neonatal examination had been normal. She was tachypnoeic (50–60 breaths/min) and there was some sternal and intercostal recession. The pulses were normal. There was a thrill, a pansystolic murmur at the lower left sternal edge and a slightly accentuated pulmonary component to the second heart sound. There were scattered wheezes. The liver was enlarged, palpable at two fingerbreadths below the costal margin. The ECG was unremarkable. The chest radiograph showed cardiomegaly and increased pulmonary vascular markings. An echocardiogram showed a moderate-sized ventricular septal defect (VSD) (Fig. 17.4). Treatment was medical with diuretics and captopril. The VSD closed spontaneously at 18 months.

This infant developed heart failure from a moderate VSD presenting at several weeks of age when the pulmonary resistance fell, causing increased left-to-right shunting of blood. The defect closed spontaneously.

Summary

Presentation of congenital heart disease

• Antenatal ultrasound screening – increasing proportion detected

• Detection of a heart murmur – need to differentiate innocent from pathological murmur

• Cyanosis – if duct dependent, prostaglandin to maintain ductal patency is vital for initial survival

• Heart failure – usually from left-to-right shunt when pulmonary vascular resistance falls

• Shock – when duct closes in severe left heart obstruction.

Whether the presentation of congenital heart disease is with a heart murmur, heart failure, cyanosis or shock depends on the underlying anatomic lesion causing:

• left to right shunt

• right to left shunt

• common mixing

• outflow obstruction in the well or sick child.

This is summarised in Table 17.2.

Table 17.2

Types of presentation with congenital heart disease

Type of lesion	Left-to-right shunt	Right-to-left shunt	Common mixing	Well children with obstruction	Sick neonates with obstruction
Symptoms	Breathless or asymptomatic	Blue	Breathless and blue	Asymptomatic	Collapsed with shock
Examples	ASD	Tetralogy of Fallot	AVSD	AS	Coarctation
	VSD	TGA	Complex congenital heart disease	PS	HLHS
	PDA			Adult-type CoA

ASD, atrial septal defect; VSD, ventricular septal defect; PDA, patent ductus arteriosus; TGA, transposition of the great arteries; AVSD, atrioventricular; AS, aortic stenosis; PS, pulmonary stenosis; CoA, coarctation of the aorta; HLHS, hypoplastic left heart syndrome.

Diagnosis

If congenital heart disease is suspected, a chest radiograph and ECG (Box 17.3) should be performed. Although rarely diagnostic, they may be helpful in establishing that there is an abnormality of the cardiovascular system and as a baseline for assessing future changes. Echocardiography, combined with Doppler ultrasound, enables almost all causes of congenital heart disease to be diagnosed. Even when a paediatric cardiologist is not available locally a specialist echocardiography opinion may be available via telemedicine, or else transfer to the cardiac centre will be necessary. A specialist opinion is required if the child is haemodynamically unstable, if there is heart failure, if there is cyanosis, when the oxygen saturations are <94% due to heart disease and when there are reduced volume pulses.

Nomenclature

The European (as opposed to American) system for naming congenital heart disease is referred to as sequential segmental arrangement. The advantage is that it is not necessary to remember the pattern of an eponymous syndrome, e.g. tetralogy of Fallot. The disadvantage is that it is longwinded. The idea is that each component is described in turn, naming the way the atria, then the ventricles and then the great arteries are connected. Hence, a normal heart will be described as situs solitus (i.e. the atria are in the correct orientation), concordant atrioventricular connection and concordant ventriculo–arterial connection. Therefore a heart of any complexity can be described in a logical step-by-step process. This system is not described here, as it is beyond the scope of this book.

Left-to-right shunts

These are:

Atrial septal defect

There are two main types of atrial septal defect (ASD):

• Secundum ASD (80% of ASDs) (Fig. 17.5a)

• Partial atrioventricular septal defect (primum ASD, pAVSD) (Fig 17.5b).

Both present with similar symptoms and signs, but their anatomy is quite different. The secundum ASD is a defect in the centre of the atrial septum involving the foramen ovale.

Partial AVSD is a defect of the atrioventricular septum and is characterised by:

• An inter-atrial communication between the bottom end of the atrial septum and the atrioventricular valves (primum ASD)

• Abnormal atrioventricular valves, with a left atrioventricular valve which has three leaflets and tends to leak (regurgitant valve).

Clinical features

Symptoms

• None (commonly)

• Recurrent chest infections/wheeze

• Arrhythmias (fourth decade onwards).

Physical signs (Fig. 17.5c)

• An ejection systolic murmur best heard at the upper left sternal edge – due to increased flow across the pulmonary valve because of the left-to-right shunt

• A fixed and widely split second heart sound (often difficult to hear) – due to the right ventricular stroke volume being equal in both inspiration and expiration

• With a partial AVSD, an apical pansystolic murmur from atrioventricular valve regurgitation.

Atrial septal defect

Investigations

Chest radiograph (Fig. 17.5d)

Cardiomegaly, enlarged pulmonary arteries and increased pulmonary vascular markings.

ECG

• Secundum ASD – partial right bundle branch block is common (but may occur in normal children), right axis deviation due to right ventricular enlargement (Fig. 17.5e)

• Partial AVSD – a ‘superior’ QRS axis (mainly negative in AVF) (Fig 17.5f

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