Acquired Cor Triatriatum Sinister After the Fontan Operation and Successful Resection in a Child.

Cor triatriatum sinister is a rare congenital lesion encountered in children. It consists of a fibromuscular membrane that separates the left atrium into two chambers resulting in a triatrial heart and often occurs with other structural cardiac anomalies. The acquired form is uncommon and has only been reported after orthotopic heart transplantation or as a complication of infective endocarditis in adults. These cases were mostly because of hypertrophied atrial tissue or suture lines and torsion of the atrium. We describe the first case of acquired cor triatriatum late after the Fontan procedure with successful surgical resection in a child.