Supravalvular stenosing ring of the left atrium.

Two patients with supravalvular stenosing ring of the left atrium are described. In 1 patient with an associated ventricular septal defect and Wolff-Parkinson-White syndrome, the diagnosis of supravalvular stenosing ring was only suspected. This patient underwent correction but died 34 days after the operation because of pulmonary embolism. In the second patient a preoperative diagnosis was not made, and this contributed to his death following correction of tetralogy of Fallot. The association of these two anomalies is very rare. Differential diagnosis from other congenital anomalies producing obstruction of left atrial flow is discussed. The divergent microscopical features of the membrane in supravalvular stenosing ring of the left atrium and in cor triatriatum are described. The value of cardiac catheterization, angiography, and echocardiography as diagnostic aids is emphasized. The hazards of not recognizing and diagnosing this anomaly when associated with other cardiac malformations are pointed out.