Subaortic stenosis caused by an accessory tissue of the mitral valve

A case of a three years old boy with subaortic stenosis caused by accessory tissue of the mitral valve is presented. We can find only four similar cases in the literature. In surgery of this anomaly, it is a peculiar problem that the most of stenotic tissues can not be identified through the aortotomy only. We opened the left atrium and pulled up the mitral valve with threads, so that we could distinguish the stenotic tissue from true mitral valve through the aortotomy.