左冠動脈主幹部に生じた動脈硬化性嚢状冠動脈瘤の1例

A Case of Atherosclerotic Saccular Aneurysm Involving the Left Main Coronary Artery

　症例は70歳，男性．冠危険因子は高血圧症と肥満．狭心症症状は明らかでなかったが，心電図異常の指摘をうけ心精査が行われた．運動負荷心電図および心筋シンチで無症候性心筋虚血が疑われた．冠動脈造影では左冠動脈主幹部（LMT）に嚢状動脈瘤および対角枝に小動脈瘤，さらに回旋枝に50％狭窄を認めたが他に有意な狭窄はなかった．動脈瘤がLMTに存在したため，塞栓症による心筋梗塞と瘤破裂の危険性を考慮して外科的に瘤切除術と冠動脈バイパス術を行った．病理組織学的には動脈硬化性冠動脈瘤であった．LMTの冠動脈瘤は非常に稀であり，予後に関してはほとんど不明であり，保存的に加療するか外科的に瘤切除および冠動脈バイパス手術を行うか一定の見解はない．本症例は，LMTに動脈硬化性嚢状動脈瘤を伴った例であったが，外科的手術を行い良好に経過した．

We report a rare case of atherosclerotic aneurysminvolving the left main coronary artery. The patient was a 70-year-old man who underwent cardiac exami-nation when informed of abnormal findings during an ECG check-up. Exercise stress test and myocardial scintigram showed silent myocardial ischemia. Coro-nary angiography demonstrated a large saccular aneur-ysm involving the left main coronary artery and a small aneurysm on a diagonal branch. The circumflex artery showed 50% stenosis in its proximal segment. No narr-owings of the other coronary arteries were observed. Because of the potential risk for extension of the aneur-ysm, coronary arterial embolization, or aneurysmal rupture with sudden death, aneurysmectomy and coro-nary artery bypass surgery (CABG) utilizing the left internal mammary artery (LIMA) and saphenous vein grafts (SVG) were successfully performed. LIMA was bypassed to the mid left anterior descending artery and reversed SVG were placed to the left circumflex artery and the diagonal branch. Histopathology showed typical findings of severe atherosclerotic changes. The decision regarding medical or surgical treatment in patients who have an aneurysm of the left main coronary artery without significant occlusive disease may he more con-troversial. The literature give insufficient data on such patients to warrant a conclusion. We conclude that surgical bypass with resection of the aneurysm was a useful treatment for our patient, who is doing well.