Heart size in newborn infants with birth asphyxia.

Cardiomegaly is believed to be an important and relatively common radiographic finding in infants asphyxiated at birth. However, the true incidence of cardiomegaly in such infants has not been previously assessed. Accordingly, heart size was estimated using the cardiothoracic ratio (CTR) in 67 consecutive neonates with birth asphyxia (Apgar score below 6 at 1 and 5 min). The average CTR on the first postnatal film was 52.8%, significantly higher than that of unasphyxiated infants published previously. Subsequent CTR values did not differ significantly from the initial value. Of the 67 patients studied, 13 (19%) had significant cardiomegaly (CTR more than 2 SD above normal). Of these, 10 had conditions other than asphyxia that probably contributed to the cardiomegaly observed. Although relative heart enlargement is common in asphyxiated infants, absolute cardiomegaly is relatively uncommon, and in such infants causes other than asphyxia should be sought.