Accessory mitral valve tissue causing left ventricular outflow tract obstruction associated with subaortic membrane and aortic sinus aneurysm: A case report and literature review.

Accessory mitral valve tissue is a rare congenital cardiac anomaly that can lead to left ventricular outflow tract obstruction. We present the case of an older female patient with accessory mitral valve tissue, a subaortic membrane, an unruptured aneurysm of the aortic sinus, and left ventricular outflow tract obstruction. Successful excision of the accessory mitral valve tissue and repair of the aortic sinus were performed. Postoperative echocardiography showed complete removal of the subaortic membrane, with a residual accessory mitral valve tissue (5 mm). Color Doppler imaging revealed a significant reduction in mosaic flow signals in the left ventricular outflow tract, with the peak blood flow velocity decreasing to 1.6 m/s. The postoperative course was uneventful, and the patient was followed up with echocardiography at 3 days, 5 days, 1 month, 3 months, and 6 months after the surgery. Accessory mitral valve tissue is a rare congenital defect frequently associated with other cardiovascular congenital malformations. This report also provides a comprehensive clinical review of accessory mitral valve tissue, covering anatomical classification, associated cardiac anomalies, pathophysiology, diagnostic approaches, and treatment strategies to offer an improved clinical understanding of the condition.