[Morphologic study of different types of venous grafts. Correlation trial with parietal fibrinolytic activity]

In this experimental work, morphological aspects of different vein grafts were studied using both light microscopy, transmission electron microscopy and scanning electron microscopy. The correlation was made with their fibrinolytic activity ; 21 dogs were operated on under general anaesthesia ; "venous grafts" (perfusion of the vascular segments with venous blood) were performed by excision of the femoral vein with reanastomosis at the same site (protocol P1). "Arterialised grafts" (perfusion of a segment of vein with arterial blood at arterial pressure) were performed according to two protocols : P2 in which a segment of femoral artery was replaced with a segment of reversed femoral vein ; P3 in which a segment of femoral artery was by passed with the femoral vein left in situ after destroying the valves using a Fogarty balloon without damage of the intima. The factors affected by surgery are, therefore, disconnection of the vasa vasorum by excision of the vessel in protocols P1 and P2 and increased oxygenation and luminal pressure in protocols P2 and P3. In all the cases, endothelial cells retained the morphological characteristics of venous endothelium. However, the vein grafts in the arterial circulation were thickened and the fibrinolytic activity was changed. Pathogenic mechanisms of these changes are discussed.