Ultrastructure of human and transplanted canine veins: effects of different preparation media.

Human saphenous veins were studied to determine alterations resulting from preparation by moist gauze wrapping, balanced salt solution immersion, and heparinized whole blood storage at 4 degrees C. Morphologic derangements of endothelial cells, smooth muscle cells, and adventitial tissues were pronounced in the nonblood preparations. In a second study, 20 canine jugular vein segments were interposed into the iliofemoral arterial circulation, with half the grafts prepared in balanced salt solution and half in whole blood. Veins were harvested monthly for 10 months, being subjected to light and electron microscopic examinations. No thromboses or stenoses occurred. Diffuse graft dilatation affected veins three times more often when stored in lactated Ringer's solution than when stored in heparinized blood. Medial thinning, ranging from 20% to 54%, occurred in veins stored in the balanced salt solution. Endothelial regeneration was complete in all grafts within 30 days after implantation. However, medial and adventitial injury to veins prepared in balanced salt solution appeared progressive, with fibrodysplastic tissue replacing smooth muscle cells. Plasmacytosis and neutrophil infiltrates, consistent with chronic active inflammation, often accompanied fibroproliferative changes. Alterations in medial structures, rather than endothelial injury, may have an important influence on the long-term durability of transplanted vein grafts.