Congenital heart anomalies in the trisomy 18 syndrome, with reference to congenital polyvalvular disease.

Congenital polyvalvular disease (CPVD) is seen in trisomy 18 and other aneuploidy syndromes. However, its extent and nature have not been studied. Gross pathologic and histologic aspects of the heart were studied in 15 autopsied cases of trisomy 18. All had CPVD; other congenital defects included membranous ventricular septal defect (87%), patent ductus arteriosus (73%), and high takeoff of the right coronary ostium (80%). With a scoring system, histologic findings of the valves of all trisomy 18 cases were compared with those of 30 normal hearts of comparable age in order to determine the degree of morphologic abnormality. This included the presence of blood cysts, derangement of the spongiosa and fibrosa, vascular degeneration of the spongiosa, and defective elastic fibers. There were distinct differences between the changes seen in CPVD with trisomy 18 syndrome and those seen in the normal individuals. The most severe changes were present in the tricuspid and mitral valves with derangement of the spongiosa and fibrosa and defective elastic fibers. The valve tissue had a similar histologic appearance and structure to that of low birth weight infants (gestational age, 25 weeks). The valvular changes observed therefore are of fetal type and represent errors in tissue differentiation occurring as last as the third trimester.