下大静脈フィルターより連続する右房内血栓，肺塞栓症に対して体外循環下に摘出術を施行した1例

Successful Surgery for Intra-Right Atrial Thrombus Attached to IVC Filter and Pulmonary Embolism on a Cardiopulmonary Bypass:A case report

　57歳，男性．右下肢静脈血栓症に起因した肺塞栓症を疑い下大静脈にGreenfield filterを留置した．2日後の心エコーで下大静脈から右室にかけて浮遊する索状の血栓を認め，胸部CTで右肺動脈本幹から一次分枝にかけて血栓が認められた．このため緊急手術を行った．人工心肺下に右房切開し，フィルター留置部から右室まで連続する約27cm長の索状血栓を摘出，上大静脈を切断後右肺動脈本幹から一次分枝まで切り込み肺動脈血栓を可及的に摘出した．フィルターを通過した索状血栓がかろうじてその尾側を捕捉されたまま浮遊し，一部が離断して肺動脈に流入閉塞したものと考えられた．術後経過は順調で，肺動脈造影，胸部CT上遺残血栓を認めなかった．肺塞栓症に対して外科的処置が有効と考えられた．特に肺動脈内血栓に対しても上大静脈を離断することにより容易に摘出できた．またGreenfieldfilterの限界が示された．

A 57-year-old male patient who had a history of leftpulmonary embolism underwent preventive placementof a Greenfield inferior vena caval (IVC) filter becauseof deep vein thrombosis in the right lower limb andsymptoms of pulmonary embolism. Two days afterimplantation of the filter, echocardiography showed acable-like thrombus floating from the inferior vena cavainto the right ventricle through the tricuspid valve andchest CT showed thrombi in the right pulmonary arteryand its branches. Emergency surgical embolectomy onthe cardiopulmonary bypass was performed. The throm-bus in the right atrium was found to he attached to thefilter at its caudal end and was carefully removedthrough right atriotomy. Those in the right pulmonaryartery were resected by transecting the superior vena cava and incising the pulmonary artery. It was supposedthat the cable like thrombus originating from the deepleg vein had passed through the Greenfield IVC filterwith only the caudal end being trapped by the filter, andtorn pieces on the cranial side had flowed into the rightpulmonary artery. Postoperative course was stable andno residual thrombus was found either by pulmonaryarteriography or by chest CT.

Surgical treatment of pulmonary embolism in ourcase was successful. Transection of the superior venacava facilitated removal of the thrombi which had filledthe pulmonary arterial branches. The effectiveness ofthe Greenfield IVC filter to trap thrombi was shown tobe limited in this case.