Summary
The measurement of platelet deposition in human thrombi is essential for the evaluation
of platelet-inhibitory drugs and prosthetic materials for use in patients. The rate
of 111Indiumlabelled platelet accumulation on Dacron arterial grafts was measured in 27
patients randomised to take either aspirin and dipyridamole (ASA + DPM) or placebo.
Autologous platelets were labelled and re-injected seven days following surgery and
the graft thrombogenidty index calculated as the daily rise in the ratio of emissions
from the graft over a reference site.
The mean (± SD) thrombogenidty index in 12 patients undergoing femoro-popliteal bypass
was 0.25 ± 0.09 on placebo and 0.16 ± 0.07 on ASA + DPM started pre-operatively (p
Ã0.05). Post-operative ASA + DPM therapy started two days following platelet labelling
in 15 patients with aorto-femoral grafts also significantly reduce thrombogenidty
to 0.12 ± 0.05 compared with 0.25 ± 0.08 on placebo (p Ã0.01). In the latter patients
the ratio of emissions from the graft over reference fell significantly on starting
ASA + DPM, suggesting a net loss of platelets from the graft. These results indicate
that the rate of in vivo platelet accumulation on Dacron grafts can be quantitated
and that ASA + DPM reduced this rate in man.
Keywords
Dacron arterial grafts - Thrombosis - Blood platelets - Platelet metabolism - Arterial
occlusive disease - Antiplatelet drugs
