Mital Desai1, Maqsood Ahmed2, Achala de Mel2, Janice Tsui1, Alexander M. Seifalian2, George Hamilton1
1Royal Free Hampstead NHS Trust, London, United Kingdom; 2University College London, London, United Kingdom.
OBJECTIVES: To evaluate in vivo performance of small diameter grafts (5 mm) made from a compliant, thrombo-resistant, bio-durable POSS-PCU polymer in a challenging ovine model.
METHODS: POSS-PCU grafts were implanted in 12 sheep as interposition grafts in left common carotid artery (LCA) (GLP Regulations; all had daily 75 mg aspirin). Duplex imaging was performed on days 1, 7, 14 and then monthly. Comparison was made with 5mm ePTFE grafts as control (n=6 sheep) and in all animals with the unoperated right common carotid artery (RCA). Flow rates and graft compliance were measured in all target vessels/grafts. Patent grafts were explanted after 9 months. Following explantation, all grafts were assessed independently by histological analysis.
RESULTS: Animal 8 did not survive the anaesthetic and grafts 1 and 9 thrombosed immediately; these two carotids exhibited irreversible spasm during surgery. Animal 7 had tortuous LCA with gross diameter mismatch and thrombosed on day 14. Graft 4 blocked on day 15 and Graft 3 on day 59. Six grafts were patent for 9 months. Patency rates were 67% at 9 months and 78% at 6 weeks. The ePTFE grafts in comparison had all occluded by 1 month. On explantation patent POSS-PCU grafts showed no significant difference in diameters, dimensions, biostability, flow or compliance as compared to native LCA or RCA. On histology, graft wall was free of any significant degenerative change, or cellular ingrowth; only very minimal intimal hyperplasia at distal anastomosis was found in 3 grafts.
CONCLUSIONS: The POSS-PCU small diameter bypass graft had an impressive 9-month patency rate of 67% in this sheep carotid model recognized as having high occlusion and intimal hyperplasia rates in PTFE and Dacron. These results confirm that small diameter POSS-PCU grafts should now be investigated as a realistic alternative to current grafts in patients who do not have suitable autologous conduits.
AUTHOR DISCLOSURES: M. Ahmed, Nothing to disclose; A. de Mel, Nothing to disclose; M. Desai, Nothing to disclose; G. Hamilton, Nothing to disclose; A. M. Seifalian, Nothing to disclose; J. Tsui, Nothing to disclose.
Posted April 2012