Persistent ductus arteriosus: most probably a primary congenital malformation.

This study was undertaken in an attempt to determini whether there is a distinct histological difference between the human normally closing ductus arteriosus and a pe.rsistent ductus arteriosus. The microscopical investigation was done in 42 specimens ofhuman ductus arteriosusfrom subjects ranging in agefrom 12 hours after premature delivery to 32 years. The ducts derived from hearts with various congenital malformations, in some of which patency of the ductus was essentialfor survival, as well as from hearts without other congenital malformations. Because no histological differences werefound between the isolated patent ductus arteriosus and those associated with other congenital heart anomalies, the specimers were classified according to age. Stages of a normal anatomical closing process were not encountered in patients over 4 months of age with a patent duct. Younger material showed either a histologically normal stage of anatomical closure or an abnormality ofthe ductus wall. This abnormal histology is mainly characterised by an aberrant distribution of elastic material, the most conspicuous feature being a thick, wavy, unfragmenteI subendothelial elastic lamina. In respect of the question as to whether the observed histological abnormality forms part of a primary anomaly of the ductus arteriosus or is secondary to the prolonged patency, it appears that most of the evidence provides support for the view that a primary anatomical defect of the ductus wall is responsible for persistence qf the ductus arteriosus.