Secundum Atrial Septal Defect

This type involves septum primum and/or septum secundum. In both cases the result is a patent foramen ovale.

There may be excessive resorbtion of septum primum where very little septum remains or it has been completely resorbed. The short septum primum does not overlap the foramen ovale leaving a communication between right and left atrium. If the septum secundum is involved it is because it did not reach its full growth and thus results in a large foramen ovale. You may wish to review atrial partitioning at this time.

Figure

• FO = Foramen ovale
• S1 = Septum primum
• S2 = Septum secundum