Anomalous systemic venous to left atrial connection in tricuspid atresia with severely restrictive interatrial communication.

An adequate interatrial communication is necessary to accommodate right atrial output in patients with tricuspid atresia. We report a patient with a tiny opening in the midportion of the atrial septum, who was found to have an anomalous systemic venous to left atrial communication. This channel was not evident on noninvasive testing, but would likely have caused persistent desaturation following a Fontan procedure had it not been detected. In patients with restrictive interatrial communications, an angiogram of the right atrium may reveal similar anomalous channels.