Congenital heart disease is the leading cause of death, excluding prematurity, in infants during the first year of life. The incidence of heart defects also has been found to be high in stillbirths, low-birth-weight or small-for-gestational-age infants, and spontaneous abortions. The use of some drugs during pregnancy is associated with an above-average incidence of congenital heart disease. Examples of these drugs include thalidomide, lithium, phenytoin (Dilantin), and warfarin. The underlying cause of congenital heart disease is known in only 10% of cases. As many as 50% of infants with trisomy 21 have a congenital heart defect, either an atrioventricular (AV) canal defect or a VSD.
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Tricuspid atresia is failure of the tricuspid valve to develop; consequently, there is no communication from right atrium to right ventricle. Blood flows through an atrial septal defect or a patent foramen ovale to the left atrium and through a VSD to the right ventricle, resulting in the complete mixing of unoxygenated and oxygenated blood. A murmur is noted, and cyanosis is usually seen in the newborn period. Children are at risk for bacterial endocarditis, brain abscess, and stroke. Tachycardia, dyspnea, fatigue, and poor feeding may be noted as a result of the excessive pulmonary blood flow.