[Heparin-induced type II thrombocytopenia as the etiology of severe recurrent pulmonary embolism]

Heparin-induced thrombocytopenia (HIT) is a rare complication of anticoagulative heparin therapy. The more severe HIT type II is defined by peripheral thrombocytopenia combined with thrombotic and thromboembolic events. We report the case of a 24 year old male patient who was admitted to our ICU with thromboembolic obstruction of the right central pulmonary artery, and deep venous thrombosis (DVT) of the right superficial femoral vein. Systemic thrombolytic therapy with urokinase for seven days resulted in nearly complete resolution of the thromboembolic material in the pulmonary arteries. Antithrombotic therapy with intravenous heparin and overlapping oral phenoprocoumon was continued on the regular ward. Six days later, the patient had to be readmitted to the ICU with evidence of hemodynamic compromise due to massive bilateral pulmonary thromboembolism that could be confirmed by CT scan--DVT had extended to the right iliacal vein. Additionally, peripheral thrombocyte counts had markedly declined from 112.000 to 35.000/microliter within 3 days, indicating the presence of a Hit type II. This was verified by positive ELISA testing for antibodies against platelet factor 4 (PF4)-heparin-complex. A filter device was temporarily implanted into the inferior vena cava. The patients condition stabilized upon reinitiated systemic thrombolysis and replacement of heparin therapy against recombinant hirudin. Pulmonary artery pressures normalized. Peripheral thrombocytopenia diminished within three days. HIT type II is a severe complication of anticoagulative therapy with heparin. Here we report a case, and discuss diagnostic procedures as well as differential diagnosis to HIT type I.