Accessory mitral valve tissue: a case report and an updated review of literature.

Accessory mitral valve tissue is an unusual congenital cardiac anomaly and a rare cause responsible for left ventricular outflow tract obstruction. An 18-year-old patient was referred to this hospital due to an occasionally noted heart murmur in a medical examination. Echocardiography facilitated the diagnosis of accessory mitral valve tissue. To relieve the left ventricular outflow tract obstruction, an operation including resection of the accessory mitral valve tissue, implantation of artificial chordae tendineae, and mitral valve annuloplasty was performed successfully. Postoperative echocardiography showed a complete relief of the mitral valve leaflets and a wide patent left ventricular outflow tract. However, transient ischemic attack and Horner's syndrome complicated the patient early postoperatively. He was administered with a high dose of aspirin, and he recovered shortly. Surgical removal is in so much mandatory as a definite diagnosis of accessory mitral valve tissue with left ventricular outflow tract obstruction is established. A prophylactic treatment should be applied to the patients with accessory mitral valve tissue in virtue of their susceptibility to neurological events.