Surgical Treatment of Accessory Mitral Valve Tissue in a Toddler

Accessory mitral valve tissue causing left ventricular outflow tract obstruction is exceedingly rare in children.We present the surgical treatment of a toddler with severe obstruction due to type IIa accessory mitral valve tissue.Intraoperatively, the accessory tissue resembled a duplicated mature mitral valve leaflet.Surgical treatment included a septal myectomy and imbrication of the accessory tissue without leaflet resection, which successfully relieved the obstruction and preserved valve function.This case emphasizes the importance of awareness of this diagnosis and classification system as standard mitral repair techniques may not be appropriate or effective, depending on the anatomic subtype.