Venous endothelial changes in therapeutic arteriovenous fistulae

Abstract

Specimens of veins of therapeutic arteriovenous fistulae from five patients were examined by an en face immunohistochemical technique to investigate endothelial morphology and the presence of the vasoactive peptide endothelin-1 (ET-1). These were compared with control segments of long saphenous veins from six patients. Venous endothelium from the arteriovenous shunts was mostly intact even overlying phlebosclerotic plaques. Occasional small areas of denudation, with associated platelets, were present in the depressions of ‘jet’ lesion however. The endothelial cells were generally elongated and interspersed with foci of polyhedral cells. The control saphenous veins contained elongated endothelial cells without detectable denudation. Image analysis of histological sections of veins from the shunts indicated significantly less intact elastic tissue than control veins but greater mononucleated endothelial cell density in en face preparations. ET-1 staining was considerably stronger in endothelium from the fistulae than in the control saphenous veins and was most intense over the raised crescentic ridges of jet lesions, stenoses and phlebosclerotic plaques. Endothelial mitoses and cells with hyperchromatic nuclei stained more strongly for ET-1 than surrounding cells. These results indicate that the endothelial cells lining veins associated with arteriovenous fistulae are dynamically altered by the increased haemodynamic stresses associated with these shunts. Furthermore ET-1 may act as a localising factor associated with intimal thickening at sites of ‘jet’ lesions, stenosis and phlebosclerosis.