Persistent foramen ovale
The atrial septum separates the right atrium from the left atrium. Some people are born with defects of the atrial septum. It is called persistent foramen ovale (PFO) and occurs in approximately 20% of people. It usually has no consequences. The PFO can, however, let small blood clots pass from the right to the left atrium. As the result some neurological defects can occur. If such a neurological event took place, it can be wise to close the PFO.
Larger atrial septal defects (ASD) cause big amounts of blood to flow from the left to the right atrium. The relevant shunt volume represents the load on the right heart. The closure of the ASD in case of relevant atrial septal defect is usually performed interventionally.