How is a Patent Foramen Ovale different from an Atrial Septal Defect?
These two defects differ in two main ways. First, a PFO is a defect where two separate sections of septal tissue overlap each other, but are not fused. In an ASD, there is a distinct hole in the septal tissue without any overlap of tissue. A good analogy is to think of a PFO as a large doorway with two doors hinged to it with each door being able to close two thirds of the door opening. The doors, when closed, will overlap each other. An ASD is simply the doorway with no doors attached at all. The second way the two defects differ, using the doors and doorway analogy, is that blood flow through a PFO is obstructed by the two “doors” unless there is a gap between the two doors. Thus, blood flow is transient, meaning it only happens for specific time periods. With an ASD, there is no obstruction. Blood flow through the hole is continuous, and it goes from left atrium to right atrium. Both defects – PFOs and ASDs – can be closed with these occlusion devices in the cardiac catheterization
