Congenital division of the left atrium (cor triatriatum) in the setting of congenitally corrected transposition of the great arteries.

Congenital division of the left atrium (cor triatriatum) and congenitally corrected transposition of the great arteries are both rare congenital cardiac malformations; their coexistence is exceedingly rare with only two previous reports identified in the literature. This combination of lesions is characterized by a pressure-loaded morphologically left ventricle and a propensity for pulmonary edema dependent on the degree of pulmonary venous obstruction caused by the dividing left atrial shelf. The probable impact of this on the natural history and surgical decision making is discussed.