Antiplatelet therapy for shunt thrombosis

The antithrombotic effects of dipyridamole and ticlopidine were compared retrospectively in 36 E-PTFE grafts and 27 external fistulas in patients who underwent maintenance hemodialysis. Further, plasma β-thromboglobulin (β-TG) and platelet factor 4 (PF 4) levels were measured before and after hemodialysis in these patients starting 10 to 14 days after treatment with the antiplatelet agents. The patients received 150-300mg of dipyridamole or 200-300mg of ticlopidine a day orally. The present study revealed that neither antiplatelet agent significantly reduced the frequency of thrombotic problems with E-PTFE grafts. But this result may be interpreted by the facts that the antithrombotic effects of these drugs were not shown clearly because many factors are involved in the patency of E-PTFE grafts and that we tended to administer them to patients with frequent shunt troubles. On the other hand, significant antithrombotic effects on external fistulas wear observed during ticlopidine treatment, but not during dipyridamole treatment. The hemodialysis-induced increases of plasma β-TG and PF 4 were significantly prevented by ticlopidine, but not by dipyridamole. This result was supported in that only ticlopidine significantly inhibited platelet aggregation by ADP addition. From the above results, it is concluded that ticlopidine might be a useful antithrombotic agent in patients on maintenance hemodialysis, not only by preventing shunt thrombotic difficulties, but also by inhibiting platelet activation in the dialyzer or circuit.