An unusual case of cor triatriatum: clinical presentation and the haemodynamics of a rare anomaly.

The case of a 24-year-old woman with cor triatriatum sinister and a persistent left superior vena cava connected to the junction of the left upper pulmonary vein and left atrium is reported. A diagnosis of partial anomalous pulmonary venous return had been made and the patient underwent surgery. Inspection of the left atrium revealed a complex form of left triatrial heart. The general haemodynamics of the malformation are discussed, with particular emphasis on the features accounting for variation in the clinical presentation. This rare anomaly often remains undiagnosed before surgery and should be considered whenever obstruction of pulmonary venous flow above the mitral valve is not explained by pulmonary vein stenosis, mitral or mitral valve-linked abnormalities, atrial tumours or anomalous pulmonary venous drainage with high resistance to flow.