Electron microscopic studies on the alveolar-capillary barrier in the patients of chronic pulmonary edema.

Electron microscopic studies on the alveolar-capillary barrier were carried out in 13 patients of chronic pulmonary edema and/or congestion resulting from heart disease of various etiologies. The characteristic findings are tremendous proliferation of type II granular pneumocyte and irregular thickening of alveolar epithelial and capillary basement membrane. These ultrastructural changes correlated to the duration of heart failure and mean pulmonary arterial wedge pressure despite of disease groups and the age of the patients. In particular, lamination of capillary basement membrane with fragmentation was more specific finding which was observed only in patients with mean pulmonary arterial wedge pressure above 35 mmHg and duration of heart failure over 6 hears. There was no apparent relationship existed between the ultrastructural changes and pulmonary arterial pressure. In addition to these characteristic changes the remaining ultrastructural changes of the alveolar-capillary barrier were difficult to make a correlation to clinical course and cardio-pulmonary hemodynamics.