Cor triatriatum sinister
Cor triatriatum sinister is a rare congenital defect in which the left atrium is divided by a fibromuscular membrane into two distinct chambers. Classically, patients present in infancy although in some cases they remain asymptomatic until adulthood. The clinical features on presentation can mimic those of mitral stenosis due to the obstructive properties of the membrane.
Cor triatriatum sinister is a rare congenital defect first described by Church in 1868. It is found in only 0.1% of cases of congenital heart disease. In the classical form of cor triatriatum the left atrium is divided by a fibromuscular membrane into two chambers: a posterosuperior chamber receiving the pulmonary veins, and an anteroinferior chamber (true left atrium) communicating with the mitral orifice. Embryologically this condition is thought to arise from the failure of inclusion of the pulmonary veins into the left posterior atrial wall. The clinical features on presentation can mimic those of mitral stenosis. Classically, patients present during the neonatal period or early infancy although in some instances cases remain undetected until the patient is an adult.
