Persistent left superior vena cava causing subdivided left atrium: diagnosis, embryological implications, and surgical management.

A 3-month-old infant is described in whom a persistent left superior vena cava impinged on the posterior wall of the left atrium, producing a subdivided left atrium with left-to-right shunting and congestive heart failure. To our knowledge, this anomaly has not previously been reported. The preoperative diagnosis, surgical management, and embryological implications are discussed.