非リウマチ性僧帽弁閉鎖不全症に合併した左房内球状血栓の1例

A Case of Free-floating Ball Thrombi in the Left Atrium with Non-rheumatic Mitral Regurgitation

　心房細動に伴う僧帽弁狭窄症に左房内球状血栓が形成されることはこれまでに報告があるが，それ以外の症例に球状血栓が形成された症例の報告は少ない．今回，われわれは，非リウマチ性の軽度の僧帽弁閉鎖不全症に合併した左房内球状血栓を経験した．症例は70歳，男性で，心房細動，軽度の僧帽弁閉鎖不全で外来で経過をみていた．定期で施行した心エコー検査で左房内に浮遊する47×32mmの類円形の腫瘤を認めたため緊急入院となった．緊急手術を施行し，腫瘤を摘出した．腫瘤は左房天蓋部に茎を介して付着しており，組織学的には茎を含めて新鮮な血栓であった．非リウマチ性の僧帽弁閉鎖不全症に球状血栓が形成されたことは，きわめて稀なことと考えられ，球状血栓の形成過程を考察するうえでも興味深い症例と考えられた．

Left atrial ball thrombi have been reported associated with mitral stenosis. Thrombi, however, are rarely for-med in the left atrium if mitral regurgitation coexists with stenosis. We describe a case of free floating ball thrombi in the left atrium without mitral stenosis, but with non-rheumatic mitral regurgitation.

A 70-year-old man with non-rheumatic mitral regur-gitation and atrial fibrillation, who had been treated with digitalis and diuretics was admitted to our hospital because a floating mass (47×32 mm) had been inciden-tally detected in the left atrium by routine follow-up echocardiogram. An emergency operation was perfor-med because there was a risk that the mass might obstruct the left atrial outflow. The mass stuck to the top side of the left atrium with a stalk but was easily resected. Histologically the mass and stalk were proved to he a fresh thrombus. Some injury of the atrial wall by the jet of mitral regurgitation, in addition to atrial fibrillation, may contribute to the process of thrombus formation.