Increased prevalence of ventricular septal defect: epidemic or improved diagnosis.

The Baltimore-Washington Infant Study is an ongoing case-control study of congenital cardiovascular malformations in infants in whom the clinical diagnoses have been confirmed by echocardiography, catheterization, surgery, or autopsy. An increase in the prevalence of ventricular septal defects was detected in 1,494 infants with congenital cardiovascular malformations between 1981 and 1984. The prevalence of congenital cardiovascular malformations increased from 3.6 to 4.5 per 1,000 live births (P less than .025) and the prevalence of ventricular septal defect increased from 1.0 to 1.6 per 1,000 live births (P less than .001). The increase in ventricular septal defects accounted for the total increase in congenital cardiovascular malformations. The prevalence of isolated ventricular septal defect increased from 0.67 to 1.17 per 1,000 live births (P less than .001). The prevalence of ventricular septal defect with associated coarctation of the aorta, patent ductus arteriosus, atrial septal defect, and pulmonic stenosis did not change. The prevalence of ventricular septal defect diagnosed by catheterization, surgery, and autopsy did not change; however, defects diagnosed by echocardiography increased from 0.30 to 0.70 per 1,000 live births (P less than .001). It is concluded that the reported increase in prevalence of ventricular septal defect is due to improved detection of small, isolated ventricular septal defects and that there is no evidence of an "epidemic."