[Successful removal of a giant ball thrombus in the left atrium in an aged patient with unusual course].

A case of left atrial ball thrombus associated with severe mitral stenosis was reported. This male patient, aged 78, came in the chief complaint of leg and facial edema. An echocardiographic examination revealed the presence of mitral stenosis and floating giant ball thrombus in the atrium. He suffered from acute thromboembolism in his right leg six years ago and had been treated with anticoagulant since then. Despite this a floating giant ball thrombus was observed. Emergency operation including mitral valve replacement and thrombectomy was successfully performed. Thrombus formation in the left atrium is not uncommon but it is very rare to encounter in patients receiving anticoagulant therapy. To manage these patients well, meticulous attention must be paid during induction of anesthesia, intra-operative procedures, perioperative care, and operative position.