冠動脈左室瘻の心筋虚血に対する冠拡張剤治療の有効性

Effect of Vasodilation Therapy for Myocardial Ischemia in Patients with a Fistula from the Left Coronary Artery to the Left Ventricle

　冠動脈瘻は冠動脈造影中0.2％で，そのうち左室瘻は2％と極めて少ない．また，冠動脈左室瘻は心筋虚血を伴うことが多く，その治療に対する有効性は明らかでない．そこで心筋虚血を有する冠動脈左室瘻2症例を対象に心筋虚血の状態と冠拡張剤治療の有効性を検討した．2症例とも運動負荷心電図で明らかなST低下を示し，冠動脈造影で症例1は左前下行枝と回旋枝から，症例2では左前下行枝と右冠動脈から多数の網状血管を通じ造影剤の左室腔内流入がみられ，冠拡張剤（亜硝酸剤）の冠動脈内投与後，左室腔内流入量は増大した．運動負荷心筋シンチでは2症例とも負荷時，安静時を通して左室下壁領域に虚血を認め冠拡張剤（Ca拮抗剤）投与下でも改善はみられなかった．2症例とも瘻孔を通じて冠血流の左室腔内stealによる心筋虚血を有したが，冠拡張剤治療の有効性は認められず，冠動脈左室瘻において冠拡張剤はsteal量を増加させても心筋虚血の改善にはならない可能性が示唆された．

The incidence of coronary artery fistulas has been reported to be only 0.2% of all coronary arteriograms, and left ventricular fistulas account for only 2% of them, thus making it extremely rare. We studied the extent of myocardial ischemia and the efficacy of coronary vasodilation therapy in two patients (a 56-year-old woman and a 70-year-old man) with fistulas from coronary arteries to the left ventricle and myocardial ischemia. Both patients showed marked depression of ST segment on exercise electrocardiograms. The coro-nary arteriography showed flow of contrast medium into the left ventricular chamber via many reticular blood vessels which extended from the middle to the distal portions of the left anterior descending artery and left circumflex artery in case 1, and from the left ante-rior descending artery and right coronary artery in case 2. The flow into the left ventricular chamber was in-creased by the intracoronary administration of a coro-nary vasodilator (isosorbide dinitrate). On exercise myocardial scintigraphy, myocardial ischemia was seen in the inferior wall of the left ventricule in both patients during exercise and at rest, and there was no improve-ment of this ischemia when a coronary vasodilator (calcium entry Mocker) was administered.

These two patients revealed that myocardial ischemia can be due to the steal effect of the fistula on coronary blood flow. There was no benefit to be gained by coro-nary vasodilation therapy. This suggests that myocar-dial ischemia will not improve even if the steal effect is increased by vasodilation therapy.