Cor triatriatum sinister

The cor triatriatum sinister is a rare congenital heart defect, the product of an embryonic defect in the incorporation of the common pulmonary vein to the left atrium, this being divided into two separate chambers by a fibromuscular membrane. We report the case of 5 months old boy with recurrent respiratory infections, who is evaluated by cardiologist suspecting left heart obstruction and heart failure. Echocardiogram study confirmed the presence of a cor triatriatum, being referred to the surgical correction. Key words: Cor triatriatum. Echocardiogram. Surgical correction.