Abstract
Cor triatriatum sinister (CTS) is a rare congenital abnormality. Clinical presentation of patients with CTS mainly depends on the anatomic features of membrane and may vary from mild or moderate symptoms mimicking mitral stenosis to more severe and complicated cardioembolic stroke or a new onset heart failure. We herein have reported on a young male who presented with the signs and symptoms of mitral stenosis and was diagnosed as CTS with gradient on the orifice of the membrane after transthrocacic echocardiography. Computerized tomographic angiography revealed that the patient had unilateral, left sided pulmonary arterial hypoplasia and pulmonary vein atresia, with only the right pulmonary veins draining into the left atrial chamber. Further cardiac imaging by either computed tomography or magnetic resonance imaging is necessary in order to seek accompanying cardiac and vascular abnormalities. Patients with CTS have improved short and long term survival rates if CTS and accompanying abnormalities are surgically treated before the disease is complicated with heart failure, pulmonary hypertension, stroke and etc.