Haemodynamic production of lipid deposition, intimal tears, mural dissection and thrombosis in the blood vessel wall

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Abstract
Arteriovenous aneurysms between the common carotid artery and external jugular vein were produced unilaterally in 20 sheep. Control arteriotomy and phlebotomy operations were performed on contralateral vessels. The vessels were examined histologically from 2 to 56 months postoperatively. Bilateral control operations were performed on three additional sheep sacrificed 50 to 51 months postoperatively. There were pronounced degenerative changes in the common carotid arteries and dilated external jugular veins involved in the shunt. The phlebosclerosis, progressive and similar to that in man, was complicated by intimal tears of varying duration, mural dissection and thrombosis. Lipid deposits closely resembling spontaneous atherosclerosis were present in the walls of the anastomosed veins in seven animals. The results indicate that the vibrations produced by the arteriovenous shunt induce: (1) phlebosclerosis in the venous wall; (2) fatigue failure of the connective tissues with a loss of tensile strength resulting in dilatation, intimal tears, mural dissection and thrombosis; and (3) intimal lipid deposits similar to those of human atherosclerosis, without physical injury, an atherogenic diet or the administration of pharmacological agents. The striking similarity of the haemodynamically induced lesions to those occurring in the human aorta suggests that haemodynamic stress plays a major role in the pathogenesis of atherosclerosis, dissecting aneurysm and arterial ulceration with thrombosis, and that ingestion of an atherogenic diet is not a prerequisite for the development of atherosclerosis.