High output heart failure due to congenital arteriovenous fistula is a rare disease and is difficult to treat. A 27 year old man, suffering from dyspnea, palpitation, lower extremity edema, and abdominal distension admitted May, 1987. At admission there were continuous thrill and bruit at left supraclavicular and infraclavicular area. The heart sound was irregular and rapid, and grade IV/VI pansystolic murmur was audible at the apex. Chest PA showed marked cardiomegaly with pleural effusion and notching at superior aspect of left 2nd rib. Selective left subclavian artery angiogram showed extensive congenital arteriovenous fistula at the area of left subclavian artery and its branches. After setrial feeding artery embolization and palliative operation, the fistula size decreased much with clinical improvement.