ABSTRACT
Cor triatriatum is a rare cardiac malformation in which the left atrium is subdivided into two chambers by a fibromuscular septum, one locates posterosuperiorly, which is connects with the pulmonary veins, and the other locates anteroinferiorly connecting with the mitral valves and left ventricie. It is often lethal in children with cor triatriatum due to congestive heart faliure which develops abruptly and rapidly. So, the most important thing is early detection of the disease. We experienced a case of cor triatriatum in 20 month-old female. She had severe symptoms related to congestive heart faliure, and the conditions showed dangerous. Echocardiography was used for correct diagnosis. The patients was improved dramatically after proper surgery. So, We reported this case and review literatures briefly.