Ultrastructure of the alveolar-capillary membrane in children with patent ducts arteriosus at different age groups

ABSTRACT

The ultrastructure of the alveolar-capillary membrane [ACM] was studied in twelve children with patent ductus arteriosus [PDA], divided into three subgroups according to their ages, and in three control children complaining of non cardiac localised chest lesions. Lung biopsies were obtained at the time of thoracotomy. The results revealed definite thickening of the air-blood barrier in the study biopsies. The degree of thickness increased with age. The causal factors for thickening of ACM in children younger than two years, were mainly due to interstitial oedema and mesenchymal cellular deposition. Some degree of elastic and collagen proliferation was noticed as well. In biopsies of old children, the main factor was the massive collagen deposition. The basement membranes of both endothelial and epithelial cells were thin and did not share in membrane thickness. The endothelial cells revealed no changes at age younger than two years, while in old children they exhibited excessive pinocytosis, cytoplasmic bleb formations filled with plasma exudate and abnormal lipid deposition. The alveolar epithelium revealed, in old children, predominance of pneumocyte type II cells to replace the injured type I cells. The findings of the present study constituted a strong motive for early interference to close the ductus whenever its diagnosis becomes certain