HEPARIN-RELATED THROMBOSIS DESPITE NORMAL PLATELET COUNTS IN VASCULAR-SURGERY

BACKGROUND: Acute graft thrombosis is a severe complication in vascula r surgery that may require limb amputation or even cause death, Becaus e nearly all patients undergoing vascular surgery have had previous ex posure to heparin, the presence of heparin-related anti-platelet antib odies typical for heparin-associated thrombocytopenia (HAT) is one und erlying possible mechanism of acute graft thrombosis. Although thrombo cytopenia is a typical finding of HAT, it is not clear whether the occ urrence of clinically important HAT is necessarily associated with thr ombocytopenia. PATIENTS AND METHODS: Ten out of 246 patients undergoin g vascular surgery were diagnosed with HAT because of otherwise unexpl ained acute graft thrombosis that required recurrent surgical interven tions. RESULTS: In all of the 10 patients, heparin-related anti-platel et antibodies were detected although the platelet counts were within t he normal range, When HAT was diagnosed, heparin administration was st opped and, after autoantibody cross-reactivity with the heparinoid Dan aparoid had been excluded, anticoagulation was continued using this an ticoagulant. After heparin therapy was discontinued none of the 10 pat ients developed further thrombotic complications, CONCLUSION: The data presented demonstrate clearly that a normal platelet count does not e xclude the possibility of HAT, As a consequence of this, HAT should be suspected in patients who develop thrombotic complications during hep arin treatment, regardless of the actual platelet counts. (C) 1997 by Excerpta Medica, Inc.