[Stenosis of left coronary artery ostium by a hypoplastic cusp].

Occlusion of a coronary ostium due to fusion of the aortic cusp to the aortic wall is a rare but noteworthy anomaly, because it may cause a sudden death. We report a 9-year-old girl with severe stenosis of the left coronary ostium by the aortic cusp that fused to the aortic wall. The left coronary flow was restored by excision of the adherent left aortic cusp, and aortic valve replacement was performed with the technique of bilateral enlargement of the aortic valve ring (Yamaguchi's method) to prevent prosthesis-patient mismatch in the future. The patient had an uneventful recovery and was discharged 14th postoperative day (POD). Postoperative angiography showed no coronary ostial stenosis.