Early detection of congenital heart disease

Congenital heart disease is one of the commonest human malformation.  It is  a clinical paradox that the most benign lesions such as small ventricle septal defect or mild pulmonary stenosis, are more likely to be detected on routine newborn examination. Of the major structural lesions, the cyanotic conditions will usually present with symptoms or signs and so also will be detected early. There remains however an important group with major structural lesions, particularly those with ductal dependent systemic circulations, who are well in the period shortly after birth and then collapse in a critical state once the ductus closes.

Risk factors of congenital heart disease:

• Family history
• Maternal diabetes
• Other fetal abnormalities on  prenatal screening, including malformations of other systems, fetal arrythmia's and non-immune hydrops
• Syndromes and other structural malformations diagnosed postnatally. Any baby with dysmorphic features or a structural malformation should be considered as at high risk for congenital heart disease. Congenital heart disease is a common in most chromosomal abnormalities and in many other non chromosomal syndromes, including fetal alcohol syndrome and congenital infection such as rubella.
• Down syndrome

Antenatal diagnosis:

Babies will have had an ultrasound screening for malformations. This examinations usually includes a four chamber heart view. The use of the four chamber view also influences the type of lesions detected antenatally. Condition with major impact on chamber size  such as the hypoplastic left heart syndrome are more likely to be detected while conditions with little impact on chamber size such transposition or coarctation are less likely to be detected. Detection rates in high risk pregnancies are  much higher than for general screening and reflect the fact that referal is ussually made to a centre with expertise in fetal echocardiography.
Postnatal diagnosis:

• An abnormal examination in an asymptomatic baby, usually a murmur
• Cyanosis
• Heart failure/respiratory distress
• Shock/cardiovascular collapse

Abnormal clinical examination in an asymptomatic baby:

• Assessement of colour

Many babies with cyanotic heart disease will be obviously blue from birth but some can be quite subtle, particularly with common mixing situations or ductal dependent pulmonary circulations before ductal constriction.  This is further confused by babies often having blue lips and extremities in the first day or two of birth. Look at the tongue can be helpful in babies with blue lips but, if in doubt, put an oxygen saturation monitor on the baby's foot.

• Assessment of peripheral pulses including femorals

In post-ductal coarctation or preductal coarctation with a constricting  duct, weak femoral pulsess maybe the only clinical pointer. Unfortunately in the latter condition, while duct is still patent, the femorals maybe easily palpable. Feeling the femorals can be difficult in vigourous baby. One useful technique is to hold the leg in your hand and run your thumb up the medial border of the quadriceps muscle, your thumb will usually fall on the femoral pulse while your hand can limit the leg movement.

• Assessment of the praecordial impulses

While there is no rigorous study of the accuracy of this sign, many major congenital heart disease lessions will produce an increased right and/or left venticular load well before a murmur appears. So an easily palpable or visible praecordial impulse in a quite baby should always be taken seriously as a possible sign of congenital heart disease.

• Ausculation for normal heart sounds and murmurs