These are not as common as the VSD in children, but are proportionately more
significant in adults and more frequent in females. An isolated patent foramen ovale is
of no clinical significance and not considered to be an ASD. Even an extremely large
ASD rarely produces heart failure in children, but symptoms usually appear in the
third decade. Surgery is usually carried out before school age.
Pulmonary stenosis
With mild to moderate stenosis of the pulmonary valve there are usually no
symptoms, but exercise intolerance and cyanosis may occur if this is severe.
Treatment is required for the moderate to severe forms; relief of this obstruction is
now carried out in majority of children by balloon dilatation rather than surgery.
Patent ductus arteriosus
During fetal life most of the pulmonary arterial blood is shunted through the ductus
arteriosus into the aorta, thus bypassing the lungs. Functional closure of the ductus
arteriosus usually occurs at birth. Virtually all preterm babies weighing less than 1.75
kg have a patent ductus arteriosus in the first 24 h of life but this usually closes
spontaneously. Ductus arteriosus patency is mediated by prostaglandins, and the
administration of inhibitors of prostaglandin synthesis, such as indomethacin, is
effective in closing the ductus in a significant number of babies. Surgical ligation,
however, is a safe and effective back-up if indomethacin is contraindicated or has not
been successful.
Tetralogy of Fallot
This classically consists of the combination of:
(1) an obstruction to right ventricular outflow (pulmonary stenosis);
(2) VSD;
(3) dextroposition of the aorta;
(4) right ventricular hypertrophy.
Cyanosis is one of the most obvious signs of this condition but it may not be present
at birth. As the child grows, however, the obstruction to blood flow is further
exaggerated. The oral mucous membranes and nail-beds are often the first places to
show signs of cyanosis. Growth and development may be markedly delayed in severe
untreated tetralogy of Fallot and puberty is delayed. Early medical management
involves the use of prostaglandins so that adequate pulmonary blood flow can occur
until surgical intervention can be carried out. Initially, a shunt procedure (usually the
Blalock-Taussig shunt) is performed to anastomose the subclavian artery to the
homolateral branch of the pulmonary artery. Later in childhood, total surgical
correction is undertaken but the mortality rate from this procedure is 5-10%.