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Critical Congenital Heart
Disease:Extent of the Problem
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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.
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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.
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Presentation of Congenital
Heart Disease: An Overview
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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 ...