冠攣縮の出現，緩解に伴い一過性側副血行路の出現，消失を認めた中等度器質的狭窄を伴う冠攣縮性狭心症の1例

A Case of Vasospastic Angina Associated with Moderately Organic Stenosis Presented Transient Collateral during Coronary Spasm

　59歳，女性．2000年6月から朝方の安静・軽労作での胸痛を自覚．同年10月，発作頻回となり冠攣縮性狭心症疑いで精査入院．冠動脈造影上，右冠動脈に75％狭窄を認めるのみであったが，冠攣縮誘発試験にて，器質狭窄部位で完全閉塞となる冠攣縮が生じ，同時に左冠動脈から右冠動脈への発達した側副血行路の出現を確認した．胸痛・心電図変化は認めなかった．側副血行路は硝酸薬注入後消失した．本症例にて完全閉塞に至る冠攣縮を生じたにもかかわらず胸痛・心電図変化を認めなかったのは，既に存在する器質狭窄に加え，頻回の発作により発達した側副血行路からの血流により心筋虚血が軽減されたためと思われた．更に，本例は攣縮部位に有意器質狭窄を伴っており，急性冠症候群発症が危惧されたが，冠血管内エコー上，プラーク沈着範囲が造影上の狭窄部位の前後長軸方向に及んでおり，longstentの問題点からインターベンション施行の是非に苦慮した症例であった．

A 59-year-old female was admitted to our hospital due to anginal attacks while resting in the morning. Vasospastic angina was suspected because of these symptoms. Coronary arteriogram revealed a 75% fixed organic stenosis of the middle portion of the right coronary artery (RCA). Provocative coronary angiogra-phy was attempted, using ergonovine maleate (10μg) , to induce coronary artery spasm. The coronary arterio-gram revealed total occlusive spasm in an organic lesion wihtout chest pain and ST segment changes. Simultaneously, the left coronary arteriogram revealed well-developed collateral blood from the left coronary artery (LCA) to the middle portion of the RCA. After intracoronary administration of isosorbide dinitrate, the right coronary arteriogram showed release of the oc-clusive spasm, and the collateral vessels from the LCA had disappeared. By intravascular ultrasound (IVUS), we recognized plaque deposit on the vessel wall, and not only just an organic lesion but also a long lesion nearly. Coronary intervention may be important to prevent acute coronary syndrome in vasospastic angina with organic stenosis. The IVUS findings played an impor-tant role in determining whether we should attempt stent implantation or not. We selected medical treat-ment after considering the IVUS findings in this case. We were able to recognize neither ischemic change on ECG nor anginal symptom, in spite of total occlusive spasm. This suggests that the well-developed transient collateral flow that was augmented by organic stenosis and frequent anginal attacks, was able to prevent myocardial ischemia.