🧠 Aneurysmal Interatrial Septum (IAS) – Echo Focus 🔍 What Is It? An aneurysmal IAS is an exaggerated bulging or excursion of the interatrial septum (typically the fossa ovalis) into either the right or left atrium, often associated with a PFO or ASD. It may be isolated or occur with shunts, stroke, or atrial arrhythmias. 📸 Echocardiographic Definition: 🔹 Aneurysmal motion is defined as: ➡️ IAS excursion > 10–15 mm from the midline ➡️ Bulging into RA, LA, or both directions 🖥️ Best views: Su