Cor triatriatum sinister: two cases diagnosed in adulthood and a review of literature.

Cor triatriatum sinister is a rare condition caused by a membrane within the left atrium that separates the pulmonary veins from the mitral valve. While the condition is usually diagnosed in childhood, a rare presentation during adulthood is observed when the membrane is incomplete. We report two cases of incomplete cor triatriatum sinister diagnosed during adulthood and review the literature for this rare anomaly.