Figure 6. Morphologic attributes of a patent foramen ovale that contribute to its complexity.

The red striped area designates the tunnel between the septum primum on the left atrial side and the septum secundum on the right atrial side. The green striped area demonstrates the potential excursion and mobility of an atrial septal aneurysm. The thickness of the septum secundum has also been associated with increased complexity. See text for expanded discussion. ASA, atrial septal aneurysm; LA, left atrium; RA, right atrium.