Postnatal congenital heart disease diagnosis

Cyanosis:

While babies with cyanotic heart disease may present blue at birth, in many is less obvious. The oxygen saturation has to be below 80% before cyanoses becomes clinically obvious. In some cyanotic conditions, the resting saturations will be in the 80's and so will not be obvious. Ductal dependent lessions eventually present with  rapidly progressive  cyanosis as the duct closes but the mixing situations may take some time to present. If there is any doubt about a baby, put a saturation monitor on the foot. If it is persistently less than 90%, further investigations should be initiated. The commonest condition presenting with neonatal cyanosis is transposition of the great vessels but any cyanotic congenital heart disease lesions can present in the newborn period.

Heart failure / respiratory distress:

It is unusual for the common left to right shunts to present in the newborn period because pulmonary pressure take longer to fall in the presence of a large left to right shunts. Typically, large ventricle septal defect   don't produce symptoms or signs in the neonatal period but present in failure at 2-4 weeks of age after the pulmonary pressures have fallen. Occasionally babies with left to right shunts will present with respiratory sign (usually tachypnoea), particularly if there is shunting at more than one site such as ventricle septal defect and patent ductus arteriosus or patent foramen ovale.

Shock / cardiovascular collapse:

This is the classic presentation of the ductal dependent obstructive left ventricle conditions (hypoplastic left heart, critical aortic stenosis and coarctation). In these conditions, the only way blood can reach the systemic circulation is via the ductus. They are often asymptomatic while the duct is patent and then collapse any time during the first week when it closes. They present pale and shocked with respiratory distress and weak pulses.


INVESTIGATIONS

Echocardiography:

This is the definitive test and in situations where there is early access to these skills, most of the other investigations become superfluous. Early echocardiography to exclude congenital heart disease should be arranged in the following situations.

Chest Xray and electrocardiogram:

The traditional cardiac investigations of chest Xray and electrocardiogram are still useful in situations where there is limited access to echocardiography although both are limited use in excluding heart disease.

Hyperoxia test:

This is used for differentiating cardiac from non cardiac causes of cyanosis. Most babies with cyanotic heart conditions will not increase O2 pressure  significantly if placed in 100% oxygen.

Upper and lower limb blood pressure:

This maybe  useful in suspected coarctation although the accuracy of non-invasive blood pressure measures in babies is open to question. The difference between upper and lower limb blood pressures should be less than 15 mmHg.