Cor triatriatum sinister with severe obstruction: a rare presentation in an adult.

Cor triatriatum sinister is a rare congenital anomaly usually presenting in infancy or childhood. Most cases reported in adulthood have minimal obstruction. A case of critically obstructed cor triatriatum sinister presenting for the first time in adulthood is described here. The characteristic ECG, radiological and echocardiographic findings of this rare anomaly are demonstrated in this case report. The clinical features closely mimic mitral stenosis. The clues to differentiate cor triatriatum from other causes of left ventricular inflow obstruction are described.