Experimental comparative study of thrombogenicity of two differently luminal heparinized ePTFE vascular prosthetics

Introduction: Heparin bonded grafts have proven to improve patency, at least transiently. Two different heparin bonded expanded polytetrafluoroethylene (ePTFE) grafts produced by different technologies are currently available. This pilot primary goal was to test these commonly used, but differently heparinized ePTFE grafts for differences in primary patency after a 6-months follow-up in a sheep model. Secondly, the aim was to establish a large animal model to enable future translational studies and further graft development. Method: End-to-side bypass of the common carotid artery was performed bilaterally in sheep. Either a Gore^® Propaten heparinized graft or a Jotec^® Flowline Bipore heparinized graft was used, both 5 mm in diameter. Following graft implantation, the sheep were kept on pasture for 6 months, with monthly duplex scans to determine patency. At termination, the grafts were duplex scanned a final time, with the animals sedated, and the grafts were removed for heparin activity analysis. Results: 14 sheep were operated, 11 survived total follow-up time. At final follow-up, 4 patent Gore^® grafts, and 6 Jotec^® remained. Mean patency time was 106.7 ± 21.9(SD) days and 96.2 ± 25.9(SD) days for Gore^® and Jotec^®, respectively. Log-rank test showed no significant difference at final follow-up after 6 months. Post mortem heparin analysis showed no significant difference in mean activity. Conclusion: Based on patency data alone, no significant difference between these grafts were found. In accordance, heparin activity analysis showed no difference between the grafts. The model itself, proved easily implementable, and provides many possibilities for future studies, though some adjustments should be made to improve survival.