The foramen secundum (from Latin 'second opening') is formed from small perforations that develop in the septum primum.

[4] Newborns with small foramen secundum atrial septal defects have been shown to spontaneously correct by the third or fourth year of life.

[7] Surgical intervention should result in full closure of the foramen secundum, and mortality rates are similar to those for general anesthesia.

[9] Inserting a catheter has proven to be a safe and successful method for closing the foramen secundum in children.

Transesophageal echocardiography is accepted as the method to monitor this procedure which, when performed correctly, has shorter recovery times than surgical intervention.

[11] Complications of catheter insertion often include nausea and vomiting, blood vessel obstruction, pain, and hemorrhage.

[12] There is at present no drug therapy for foramen secundum atrial septal defects, although infective endocarditis is a postoperative concern.

[15] Operative closure of atrial septal defects after age 40, and the ability to diminish symptoms at all remains controversial.

Some data does suggest that even after that age, symptoms can be alleviated via surgical intervention, including prevention of Arrhythmogenic right ventricular dysplasia and other associated cardiac abnormalities.