重複下大静脈での急性肺動脈血栓塞栓症の治療中にヘパリン起因性血小板減少症を併発した1例

A Case of Heparin-induced Thrombocytopenia associated with Pulmonary Thromboembolism in Double Inferior Vena Cava

要旨　重複下大静脈での急性肺動脈血栓塞栓症を治療中にヘパリン起因性血小板減少症を併発した稀な症例を報告する．患者は42歳，女性，BMI33.3．左下腿の痛み，胸痛，咳嗽のため近医で感冒と診断された．初発から約2週間後，歩行中に胸痛と呼吸困難で救急搬送来院となった．SpO₂低下とエコーで右心系拡大があり，造影CTで急性肺動脈血栓塞栓症と診断した．持続ヘパリンと血栓溶解療法を開始し，一時的下大静脈フィルターを留置した．入院8日目のCTで重複下大静脈が判明，腸骨静脈領域の血栓がないことを確認した．10日目，フィルター先端造影で血栓閉塞が判明，13日目に血小板数が1万まで減少したことからII型ヘパリン起因性血小板減少症と判断，ヘパリンを中止しアルガトロバンの持続投与とした．14日目に永久型下大静脈フィルターを両側腎静脈の中枢に留置し，ワルファリンコントロール後軽快退院となった．

　We report a case of heparin-induced thrombocytopenia associated with pulmonary thromboembolism in double inferior vena cava. A 42-year-old female was admitted to our hospital for dyspnea and chest pain. By echocardiography and enhanced chest CT scan, she was diagnosed as having pulmonary thromboembolism. The CT scan also showed double inferior vena cava. In the acute phase, we implanted a filter device temporarily into the inferior vena cava and administered an anticoagulant(heparin) and applied fibrinolysis therapy. Ten days after anticoagulant therapy with continuous infusion of heparin, the temporary vena cava filter was thrombosed and peripheral thrombocyte counts had markedly declined to 10,000/microliter within 13 days, indicating the presence of a heparin-induced thrombocytopenia(HIT type II). This was verified by positive ELISA testing for antibodies against platelet factor 4(PF4)-heparin-complex. The patient's condition stabilized after systemic thrombolysis was renitiated and heparin therapy against argatroban was replaced. Subsequently, the patient required a permanent filter with supra renal vein position. HIT type II is a severe complication of anticoagulative therapy with heparin.