Nephropathy in cyanotic congenital heart disease.

Three children with cyanotic congenital heart disease who developed transient proteinuria and edema are described. One died of an intercurrent illness but the other two are now well. Renal biopsy findings in all three children demonstrated a mesangial proliferative glomerulonephritis on light microscopy. An unusual ultrastructural appearance of localized electron-dense thickening of the basement membrane of the capillary loops was seen in all three and collagen fibers were present in the mesangium of two. There was slight fusion of foot processes in two specimens and marked fusion in the third. Immunofluorescence in two patients demonstrated IgM staining in both and fibrin in one. The cause of the glomerular lesions is unknown but, among the many possible factors involved, anoxia and increased venous pressure may be important.