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[Aortic subvalvular stenosis caused by accessory mitral tissue].

Three cases of subaortic stenosis due to accessory mitral tissue are presented. The diagnosis of the cause of obstruction was correctly established in each child before surgery, by 2D echocardiography and cineangiography. Resection of the accessory mitral tissue through a simple aortotomy gave excellent results. The eight previously published cases are discussed, emphasising the importance of accurate preoperative diagnosis. The cause of obstruction is difficult to determine at surgery, which may have disastrous consequences, whilst simple resection of the abnormal tissues leads to a complete and definitive cure.