Background: Functional closure and subsequent remodeling of the ductus arteriosus (DA) are essential for postnatal adaptation. Very preterm infants often fail to accomplish this process spontaneously. Histologic studies on human DA have shown that the closing ductus exhibits progressive intimal thickening and cell death of muscle media, which was verified by recent animal studies.
Aims: To analyze the histologic findings of preterm infants' DA in relation to their clinical parameters and to investigate the histologic difference between preterm and term DAs.
Methods: Histology of 14 preterm DAs and 13 term DAs obtained from surgery was analyzed. We examined hematoxylin and eosin staining and van Gieson staining for the elastic tissue. Cell death was determined with the in situ apoptosis detection technique.
Results: The histologic findings of preterm DAs showed apparent correlations with clinical parameters, especially birth weight. Preterm DA histology was significantly different from that of term DAs in the extent and degree of intimal thickening. Cytolytic necrosis where TUNEL-positive cell deaths were prominent was observed mainly in term DAs.
Conclusions: The results of this study indicate that insufficient intimal thickening and scarcity of cell deaths in the DA may play a significant role in the pathogenesis of the persistently patent DA in preterm infants.