Thromboembolic potential of synthetic vascular grafts in baboons

We have compared in baboons the capacity of two types of synthetic vascular grafts to accumulate thrombus, activate circulating platelets, and generate occlusive platelet microemboli. Grafts were incorporated into femoral arterial-arterial shunts placed unilaterally in 10 baboons; the unoperated contralateral limbs served as controls. The accumulation of indium 111 (111In)-labeled platelets onto the grafts (expanded polytetrafluoroethylene [ePTFE] or knitted Dacron, 4 mm inner diameter) and the appearance of 111In radioactivity in distal microcirculatory beds (calf and foot) were quantified by dynamic scintillation camera imaging. After 1 hour total platelet deposition per graft was higher with Dacron (49.0 +/- 8.0 x 10(9) platelets) than with ePTFE (3.7 +/- 0.6 x 10(9) platelets, p less than 0.01). Platelet counts decreased and beta-thromboglobulin levels increased with Dacron graft placement but were unaffected by ePTFE graft placement (p less than 0.05 and p less than 0.01, respectively). Emboli shed from Dacron grafts were detected as multifocal, irregular, and changing deposits in the calves and feet. Indium 111 platelet activity in the feet distal to the Dacron grafts increased 81.1% +/- 21.4% from baseline values over 1 hour, whereas the activities in the feet distal to the ePTFE grafts were unchanged (p less than 0.05). The increase 111In-platelet radioactivity above the control limb values (excess radioactivity) was higher for the Dacron graft group than for the ePTFE group in both the feet (139.6% +/- 46.9% vs 6.2%, p less than 0.05) and the calves (86.7% +/- 21.7% vs 7.3% +/- 3.6%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)