Evaluation of cryopreserved arteries as alternative small vessel prostheses

Biologic or synthetic grafts have had limited success in small vessel applications. Studies were initiated to assess the potential use of cryopreserved (CP) arteries as coronary artery bypass conduits. Sheep carotid arteries (internal diameter: 4 mm; length: 10 cm) were cryopreserved in a nutrient media containing 10% DMSO and were stored in a nitrogen vapor at -150 degrees C. After thawing, histological, enzyme-histochemical and functional studies showed slight histological alterations, preservation of enzymal activities and an abolition of the contractile response. In a sheep model, arterial substitution of a 10 cm segment of carotid artery was realised by implantation of fresh autografts ( n = 4); fresh allografts (n = 9) and CP allografts (n = 9). After 3 months, all autografts were patent with slight histological alterations. Fresh and CP allografts showed similar modifications: patency rate was 7/9 in both groups. Intimal thickening with cell proliferation was seen in fresh (3/7) and CP (4/8) arteries; loss of smooth muscle medial cells was constant. Adventitia was always involved by a marked inflammatory reaction. One characteristic of CP allografts was the frequent presence of large dystrophic calcifications. In conclusion, morphologic and functional arterial changes occurred after freezing and thawing. In spite of vascular rejection, the patency rate of allografts after 3 months of implantation in arterial circulation remained high and does not seem influenced by cryopreservation.