The diagnostic dilemma of the newborn with congenital heart disease (CHD) must be resolved quickly because therapy may prove lifesaving for many of these infants. CHD occurs in approximately 1% of live-born infants. Nearly half of all cases of CHD are diagnosed during the first week of life, or now that fetal echocardiogram is becoming so widespread and available, diagnosis is made in utero (up to 70%). In patients with complex CHD, neonatal hospital mortality can be as high as 7%. These patients have a high frequency of multiple congenital anomalies, genetic syndromes, low birthweight, and prolonged length of stay. The most frequently occurring anomalies seen during this first week are patent ductus arteriosus, dextro-transposition of the great arteries, hypoplastic left heart syndrome (HLHS), tetralogy of Fallot, and pulmonary atresia.
Symptoms and signs in newborns with heart disease permit grouping according to levels of arterial oxygen saturation based on the hyperoxia test (see later in this chapter). Further classification (based on other physical findings, laboratory testing) facilitates delineation of the exact cardiac lesion present.
Cyanotic heart disease. Infants with cyanotic heart disease are usually unable to achieve a partial pressure of oxygen (PaO2) of >100 mm Hg after breathing 100% inspired oxygen for 10 to 20 minutes (hyperoxia test).
Acyanotic heart disease. Infants with acyanotic heart disease achieve PaO2 levels of >100 mm Hg under the same conditions as noted in Section I.A.
II. CYANOTIC HEART DISEASE
See Figure 94–1. (See also Chapter 56, “Cyanosis.”)
Hyperoxia test. (See Chapter 56, Imaging and other studies.) Because of obligate total mixing, the newborn with cyanotic CHD (in contrast to the infant with pulmonary disease) is unable to raise the arterial saturation, even in the presence of increased ambient oxygen.
Determine partial pressure of oxygen while the infant is on room air by arterial blood gas.
Give 100% oxygen for 10 to 20 minutes by mask, hood, or endotracheal tube.
Obtain an arterial blood gas level while the infant is breathing 100% oxygen.
Interpret results. See hyperoxia test interpretation.
Pulse oximetry screen. See also Chapter 7 and Figure 7–1. This is the test to screen for critical CHD that will require early intervention. It was endorsed by the US Department of Health and Human Services and American Academy of Pediatrics in 2011 as part of routine universal screening.
Determine pulse oximetry in right hand and foot in infants 24 to 48 hours of age.
If pulse oximetry is <90% in right hand or foot, this is a positive screen and further evaluation is needed.
If pulse oximetry is >95% in right hand or foot or there is a ≤3% difference between right hand and foot, this is a negative screen.
If pulse oximetry is between 90% and 95% in right hand ...