We describe the clinical history of a nine years old girl with Shone's syndrome. She underwent balloon angioplasty of the aortic coarctation in infancy, and later developed severe sub-aortic stenosis and moderate mitral valvar stenosis. The mitral valve was therefore replaced with a mechanical prosthesis, and the sub-aortic shelf was resected. Immediately after the operation, she developed signs of myocardial ischemia. Coronary angiography showed compression of the middle part of the circumflex artery by the mechanical prosthesis, the obstructed segment being successfully dilated using a coronary arterial stent.