Patent ductus arteriosus and ventricular septal defect: trends in reported frequency.

Nationwide secular increases in the reported frequency of patent ductus arteriosus (PDA) and ventricular septal defect (VSD) are presented. Detailed examination of data from one locality, Metropolitan Atlanta, indicates that the increases were primarily the result of a rise in the reported frequency of these heart defects in isolated form (i.e., without other malformations). During the latter years of the study more Atlanta babies with isolated PDA were of low birth weight and short gestational age, and more cases were diagnosed in the infants' first week of life. The increase in VSD was not as consistent nor as dramatic as that of PDA. Neither were there any changes over time in the demographic characteristics of Atlanta infants affected by isolated VSD. At least part and perhaps all of the increase in PDA may be explained by an increased awareness on the part of physicians who take care of premature infants. While the increase in reported VSD may be explainable on the basis of awareness or secular shifts in diagnostic standards, the problem seems qualitatively different from that of PDA.