Chapter 5

### Critical Congenital Heart Disease:Extent of the Problem

Congenital heart disease occurs in about 1% of live births (excluding bicuspid aortic valve and hemodynamically insignificant lesions such as small atrial and ventricular septal defects). Critical congenital heart disease consists of a group of defects which will result in death or severe morbidity if unrecognized in early infancy. Such defects often depend on patency of the ductus arteriosus to maintain either pulmonary or systemic blood flow. Signs of rapidly progressive heart failure and cardiovascular collapse develop as the ductus arteriosus constricts during the first few days after birth. It is important to recognize that a newborn with critical congenital heart disease may show little evidence of cardiovascular compromise on physical examination in the first 24 to 48 hours of life. Cardiovascular instability may not occur until after the infant is discharged from the hospital.

Approximately 4,300,000 children were born in the United States in 2006, which means that about 43,000 infants were born with heart defects. Of all such infants, almost one-third are predicted to have critical heart disease, defined as a heart defect that is likely to cause death within 2 months of age if undiagnosed. Thus, it is estimated that over 14,000 infants are born with critical congenital heart disease in the United States each year. Diagnosis before the onset of cardiovascular decompensation is essential for optimal outcome. However, of those not diagnosed as a fetus, about 70% of infants with critical heart disease are not diagnosed before 2 days of age and about 20% are discharged from hospital undiagnosed. This leads to severe morbidity and mortality in many hundreds of newborns each year in the United States alone, at a large social and economic cost. Thus, it is incumbent upon all physicians and other health care professionals who care for newborns to rigorously evaluate every newborn for the possibility of critical heart disease. Furthermore, if there is any indication that such disease might exist, the infant must be referred for further evaluation without delay.

### Presentation of Congenital Heart Disease: An Overview

The evaluation of the infant to exclude critical heart disease should focus on the three cardinal signs of neonatal cardiovascular distress: cyanosis, decreased systemic perfusion, and tachypnea. Cyanosis may be appreciated by careful visual inspection and pulse oximetry, decreased systemic perfusion is identified by examination of the extremities, and tachypnea is noted by observing the respiratory rate and pattern. The presence of a congenital heart defect (or less commonly, a cardiomyopathy or arrhythmia) must be considered in the differential diagnosis of any infant with one or more of these findings. A cyanotic infant likely has underlying heart disease, and almost certainly does in the absence of significant respiratory distress. An infant with decreased systemic perfusion may be septic or have a primary metabolic abnormality, but about one-half of such infants have symptomatic heart disease. An infant who has tachypnea without ...

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