Perioperative suppression of platelet adherence to small-diameter polytetrafluoroethylene (PTFE) grafts

Abstract

The perioperative effect of platelet antagonists on small-diameter polytetrafluoroethylene (PTFE) grafts was evaluated in forty-six New Zealand white male rabbits receiving either dipyridamole (DPM) 100 mg/kg/day ( n = 10; group 1), aspirin (ASA) 10 mg/kg/day ( n = 10; group 2), a combination of ASA 10 mg/kg/day and DPM 10 mg/kg/day ( n = 9; group 3) or 100 mg/kg/day ( n = 10; group 4), or placebo ( n = 7) as single daily doses. All regimens began 72 hr prior to insertion of a 20 × 3-mm internal diameter PTFE interposition aortic graft. Autologous indium-111 labeled platelets were injected immediately after implantation. Graft and an equivalent segment of aorta were harvested after 48 hr. Graft platelet adherence index (GPAI) was calculated as the graft:reference aorta ratio of emissions. The GPAI in the control group was 238 ± 46 (mean ± SD). Single regimen antiplatelet agents in groups 1 and 2 reduced mean GPAI to 47 ± 38 and 40 ± 12, respectively. The combination regimen in group 3 lowered mean GPAI to 43 ± 8 and in group 4 to 21 ± 7. Platelet uptake in PTFE grafts at 48 hr is significantly lowered to 8.8 to 19.7% of control by perioperative antiplatelet agents given as a single daily oral dose ( P < 0.001). ASA alone and DPM alone provided similar suppression of platelet uptake, but combination ASA + low dose or high dose DPM gave significantly greater ( P < 0.001) suppression of early platelet deposition than the single agent regimens. These results support perioperative administration of combination oral antiplatelet agents as adjunctive therapy in small diameter prosthetic graft implantation.