Atrial septal defects (ASD) and patent foramen ovale (PFO) refer to a defect in the lining of the heart that separates the right atrium from the left atrium (the two upper chambers of the heart).
The vast majority of ASDs are the result of birth defects. PFO are present in every fetuse. It allows blood to bypass the fetus lung, which is not functional until the newborn begins to breath. While the majority of foramen ovale close at this point, up to 25 percent remain open. This is usually not an issue, unless the patient presents with a stroke with no other etiology.
Recent studies have shown that in these instances, PFO should be closed. This can be done through transcatheter techniques.
ASDs are usually more consequential than PFOs, depending on how much blood is shunted between the upper chambers. The heart chambers can dilate, resulting in symptoms if the ASD is large enough. It can also damage the lung vessels. In these cases, ASDs should be repaired before the heart dilates, lung vessels become damaged or symptoms develop.
Depending on the location of the ASD, many can be repaired by transcatheter techniques similar to PFO closure. In certain instances, the location of the ASD makes surgery the only viable option for repair.
While in most cases a routine echo with contrast can point to the presence of a PFO or ASD, transesophageal echocardiography and/or MRI are needed to better delineate the location and characteristics of the defect prior to corrective action.