A congenital cardiac malformation occurs in about 1% of live births. There is an overall male predominance, although some individual lesions (e.g. atrial septal defect and persistent ductus arteriosus) occur more commonlyin females. The aetiology of congenital cardiac disease is often unknown but involves:
MATERNAL RUBELLA INFECTION (persistent ductus arteriosus, and pulmonary valvular and arterial stenosis)
MATERNAL ALCOHOL ABUSE (septal defects)
MATERNAL DRUG TREATMENT AND RADIATION
GENETIC ABNORMALITIES, e.g. the familial form of atrial septal defect and congenital heart block
CHROMOSOMAL ABNORMALITIES, e.g. septal defects and mitral and tricuspid valve defects associated with Down’s syndrome (trisomy 21) or coarctation of the aorta in Turner’s syndrome.
Some symptoms and signs are common in congenital heart disease:
CENTRAL CYANOSIS occurs because of right-to-left shunting of blood or because of complete mixing of systemic and pulmonary blood flow.
PULMONARY HYPERTENSION results from large left-toright shunts. The persistently raised pulmonary flow leads to the development of increased pulmonary artery vascular resistance and consequent pulmonary hypertension. This is known as the Eisenmenger reaction (or the Eisenmenger syndrome when due specifically to a ventricular septal defect). The development of pulmonary hypertension significantly worsens the prognosis.
CLUBBING OF THE FINGERS may occur in congenital cardiac conditions associated with prolonged cyanosis.
PARADOXICAL EMBOLISM of thrombus from the systemic veins to the systemic arterial system may occur when a communication exists between the right and left heart.
REDUCED GROWTH is common in children with cyanotic heart disease.
SYNCOPE is common when severe right or left ventricular outflow tract obstruction is present. Exertional syncope, associated with deepening central cyanosis, may occur in Fallot’s tetralogy. Exercise results in increased resistance to pulmonary blood flow but reduced systemic vascular resistance. Thus, the right-to-left shunt increases and cerebral oxygenation falls. SQUATTING is the posture adopted by children with Fallot’s tetralogy. It results in obstruction of venous return of desaturated blood and an increase in the peripheral systemic vascular resistance. This leads to a reduced right-to-left shunt and improved cerebral oxygenation. The most common congenital lesions are shown as well as their occurrence in first-degree relatives. Genetic factors should be considered in all patients presenting with congenital heart disease, e.g. parents with a child suffering from Fallot’s tetralogy stand a 4% chance of conceiving another child with the disease and fetal ultrasound screening of the mother during pregnancy is essential .
Ventricular septal defect (VSD)
VSD is the most common congenital cardiac malformation (1 in 500 live births). It may occur as an isolated abnormality or in association with other anomalies. Left ventricular pressure is higher than right ventricular pressure; blood therefore moves from left to right and pulmonary blood flow increases. When pulmonary blood flow is very large, obliterative pulmonary vascular changes may cause the pulmonary arterial pressure to equal the systemic pressure (Eisenmenger’s syndrome). Consequently, the shunt is reduced or reversed (becoming right-to-left) and central cyanosis may develop.
A small VSD (maladie de Roger) presents with a loud and sometimes long systolic murmur in an asymptomatic patient. Such VSDs usually close spontaneously. Moderate VSDs produce some fatigue and dyspnoea. Physical signs include cardiac enlargement and a prominent apex beat. There is often a palpable systolic thrill at the lower left sternal edge. A loud ‘tearing’ pan-systolic murmur is heard at the same position. Large VSDs are associated with increasing pulmonary hypertension (right ventricular parasternal heave and a loud, pulmonary component of the second heart sound).
The murmur may be soft because the increased right ventricular pressure may be nearly equal to the left ventricular pressure, so that flow across the VSD is small.
A small VSD produces no abnormal X-ray or ECG findings. On the chest X-ray, larger defects show a prominent pulmonary artery owing to increased pulmonary blood flow. In Eisenmenger’s syndrome the radiological signs of pulmonary hypertension (i.e. ‘pruned’ pulmonary arteries) can be seen. Cardiomegaly occurs when a moderate or a large VSD is present. The ECG shows features
of both left and right ventricular hypertrophy. The size and location of the VSD, and its haemodynamic consequences, can be assessed by 2-D echocardiography and CW Doppler.
Moderate and large VSDs should be surgically repaired before the development of severe pulmonary hypertension. Infective endocarditis prophylaxis should be advised.
Atrial septal defect (ASD)
This congenital condition is often first diagnosed in adults. It is more common in women than in men. There are two types of ASD-ostium secundum and ostium primum. The common form of ASD is ostium secundum. Communication at the level of the atria allows left-toright shunting of blood. Because the pulmonary vascular resistance is low and the right ventricle is easily distended (i.e. it is compliant), there is a considerable increase in right heart output. Above the age of 30 years there may be an increase in pulmonary vascular resistance, which gives rise to pulmonary hypertension. Atrial arrhythmias, particularly atrial fibrillation, are common at this stage.
Most children with ASDs are asymptomatic, although they are prone to pulmonary infection. Some complain of dyspnoea and weakness. Palpitations due to atrial arrhythmias are not uncommon. Right heart failure may develop in later life.
The physical signs of ASD reflect the volume overloading of the right ventricle. Therefore, the splitting of the second sound is wide and fixed. The increased flow through the right heart produces a loud ejection systolic pulmonary flow murmur, and sometimes a diastolic tricuspid flow murmur may be heard. A right ventricular impulse can usually be felt.
THE CHEST X-RAY shows a prominent pulmonary artery and pulmonary plethora. shows a more severe case with pulmonary hypertension. There may be noticeable right ventricular enlargement.
THE ECG usually shows some degree of right bundle branch block (because of dilatation of the right ventricle) and right axis deviation.
THE ECHOCARDIOGRAM demonstrates right ventricular hypertrophy and pulmonary arterial dilatation. The interventricular septum moves abnormally. Sometimes the ASD is part of a major developmental abnormality and may also involve the ventricular septum and the mitral and tricuspid valves. In this case there is left axis deviation on the ECG. Two-dimensional cardiography will define the site and size of the defect.
FLOW DISTURBANCE can be assessed by Doppler. CARDIAC CATHETERIZATION is not always necessary with the advent of echocardiography.