Congenital Heart Disease (CHD) in Children

Congenital heart disease (CHD) describes the presence of a cardiac anomaly from birth. It is unfortunate that the initials CHD may stand for congenital heart disease or coronary heart as this can cause confusion. In this article, CHD will always mean the former.

The management of congenital heart disease has improved so much over the years that many affected children are now adults. This is sometimes called GUCHD (grown up congenital heart disease). Congenital heart disease in adults will not be considered here as it has its own article.

The incidence of congenital heart disease in full term live born infants is between 4 and 9 per 1,000 and each year there are in the region of 1.5 million new cases worldwide.¹ It is the most common congenital condition diagnosed in newborns.

Risk factors

As children with CHD are now surviving to have children of their own there are problems of the extra cardiovascular burden of pregnancy as discussed in grown up congenital heart disease and pregnancy. In addition, the incidence of mothers with CHD having affected children is between 2.5 and 18%, and the incidence of fathers with CHD having affected children is between 1.5 and 3.0%. Both figures are significantly higher than for the general population.² It is unusual for more than one child in the same family to have CHD.

A fetus may be affected during cardiac development by intrauterine infection such as rubella, or drugs and toxins taken by the mother including lithium and alcohol. Some genetic conditions are also associated with a higher incidence of CHD including Down's syndrome and Turner's syndrome.

Some maternal chronic diseases are also associated with an increased incidence of CHD including diabetes mellitus³ and phenylketonuria (PKU). Close control of diabetes is required and in PKU a diet free of phenylalanine should be started before conception to reduce the risk of brain damage and CHD in the fetus.⁴ Lack of folic acid during the first trimester is certainly associated with neural tube defects but any predisposition to CHD is rather more dubious.⁵

Some of these anomalies will have been diagnosed before delivery by ante-natal scans, but many will present at, or after birth. CHD covers a wide spectrum from small ventricular septal defects (VSD), called Maladie de Roger, which may be totally asymptomatic and compatible with a normal life span, to more severe forms such as Fallot's tetralogy. Routine screening of all infants, and regular screening of small children in the UK and other developed countries has ensured that the majority of children with significant disease are diagnosed at a very early stage.

The cardiovascular system is complex as the circulation changes from fetal to infant and there may be transient problems such as patent ductus arteriosus or patent foramen ovale, especially in premature babies. Not all murmurs are pathological. Murmurs heard in the first week to months of life are more likely to be due to CHD than those discovered in later childhood years.⁶ Murmurs may not appear until an infant has left hospital, as the pulmonary vascular resistance changes with the closure of the ductus arteriosus. Hence a child with a VSD may have no signs for the first 24 hours, and a child with a hypoplastic left heart may appear healthy until the ductus closes.⁷ Many defects are possible, but most defects either obstruct flow of blood in the heart or in vessels near to it or cause blood to take an abnormal route through the heart. More rarely only one ventricle may be present, or the right or left side of the heart has failed to form properly (hypoplastic heart). If a significant amount of blood shunts from right to left without traversing the lungs, this is called cyanotic congenital heart disease.

Nowadays, many children will be diagnosed by a detailed antenatal scan and provision can be made for treatment if required after delivery.

Children who have not been diagnosed before birth may present with:

• Murmurs on routine screening
• Tachycardia
• Heart failure
• Difficulty feeding and failure to thrive
• Shortness of breath
• Cyanotic episodes, especially during feeding
• Sudden collapse
• Slightly older children tend to squat when they become tired or breathless. This is especially true with cyanotic congenital heart disease.

Investigation should be preceded by a thorough history of the pregnancy and the mother's health and drug use during the pregnancy, together with any history of cardiac abnormalities.

• Murmurs arising during the first days or weeks of life should be referred to a paediatrician for assessment
• The initial investigation of choice is echocardiography. It is non-invasive. There is no radiation. It can elucidate both anatomy and flow and will give some indication of the underlying abnormality.
• Cardiac catheterisation may be required in more severe cases to assess the extent of the problem, and prepare for correction of the problem.

• Some children with CHD will require no specific treatment, but will be at risk of endocarditis for their entire life, and should be given antibiotic prophylaxis for any interventional procedure.
• If the disorder is severe enough to compromise the circulation, the oxygenation of the blood or to put a strain on the heart or lungs, then surgical correction or non surgical intervention such as balloon valvotomy may be required.
• In the most severe cases, especially hypoplastic heart, a heart transplant may be required.
• The type and extent of the correction required will depend on the underlying anomaly.

• All form of CHD except for atrial septal defect, carry a risk of subacute bacterial endocarditis and so prophylaxis should be given at appropriate times. Even if the risk is very small, this is a small price to pay to protect against such a serious complication.
• There may be failure to thrive or just difficulty in joining in games and sports with other children
• A right to left shunt can permit paradoxical embolism that may present with a systemic embolism such as a stroke
• A left to right shunt does not cause cyanosis but the high volume pumped by the right side may result in pulmonary hypertension and if this builds up and exceeds systemic pressure the shunt may reverse from right to left. This is called the Eisenmenger complex and it may not develop until the child is an adolescent or adult.
• Cyanosis results in polycythaemia and a haemoglobin value as high as 20g/100ml may cause additional difficulty as the blood is so viscous.

The prognosis for children with congenital heart disease has improved dramatically over the last 20 years.⁸ In 1986 60% of deaths from congenital heart disease occurred in the first year of life, whereas in the 1990s the majority of deaths occurred in adults over the age of 20.⁹ It is predicted that 78% of the babies born with congenital heart disease today will survive into adulthood.²

Although many forms of CHD are not currently preventable, the avoidance of known risk factors such as drugs and alcohol during pregnancy will help to reduce the risk.
Vaccination against rubella has reduced the number of children born with rubella syndrome in the last two decades but foolishness about the MMR vaccine could allow congenital rubella to return.