[Heparin-induced thrombocytopenia as the cause of persistent bleeding after pacemaker implantation]

A cardiac pacemaker was to be implanted in a 74-year-old man, known for many years to have cardiac arrhythmias. Lown type IVb, because of the onset of severe bradycardic episodes. After appropriate preoperative preparation the patient's anticoagulant medication was changed over 5 days from phenprocoumon (Marcumar) to heparin. The procedure and the immediate postoperative period were without complication. But two days later he had to be admitted to the intensive care unit because of cardiac failure and bleeding into the operation site.

One week after starting heparin the platelet count had fallen from 154 x 10(9)/l preoperatively to 92 x 10(9)/l. Haemoglobin concentration was 8.9 g/dl, haematocrit 26.7%. The Quick value of 51%, partial thromboplastin time of 54.1 s, thrombin time of 17.6 s and plasma antithrombin level of 61% provided no further diagnostic pointers. An HIPA test and a PF4/heparin immunoassay, performed as heparin-induced type II thrombocytopenia was suspected, subsequently confirmed the diagnosis.

After the cardiac status had stabilized the operative wound was explored, but no bleeding site found. Other causes having been excluded (liver failure, disseminated intravascular coagulopathy, septicemia, dilution thrombocytopenia), heparin was discontinued 2 days later. Recombinant hirudin infusion, 0.025 mg/kg per hour, was begun. After 4 days the platelet count had improved, the other clotting parameters were stable within the therapeutic anticoagulant range and the diffuse bleeding had stopped.

When changing from phenprocoumon to heparin preoperatively one must be aware of the rare risk of acquired heparin-induced thrombocytopenia. Intravenous recombinant hirudin proved to be a safe treatment until oral anticoagulation had been established, quickly normalizing the platelet count.