An unusual case of cor triatriatum sinister presenting as pulmonary oedema during labor.

A 35 years old second gravida was admitted to our department with acute pulmonary oedema after labor. Echocardiography disclosed an intra-atrial membrane prolapsing through the mitral valve in diastole, with two small orifices creating a mean pressure gradient of 7.9 mm Hg. However the membrane clearly originated away from the mitral valve ring, proximal to the left atrial appendage, consistent with cor triatriatum sinister. Cor triatriatum sinister rarely presents in adulthood and although forward movement of the membrane towards the mitral valve funnel has been described, such a degree of prolapse through the valve has never been reported.