Differential Diagnosis for 2D Echo Suggestive of IAS Aneurysmal

• Single most likely diagnosis
  • Aneurysm of the Interatrial Septum (IAS): This is the most direct diagnosis based on the echo findings, suggesting a bulge or outpouching in the interatrial septum, which could be due to various causes including congenital defects, increased pressure, or weakening of the septal wall.
• Other Likely diagnoses
  • Atrial Septal Defect (ASD): An ASD could present with similar echo findings, especially if it's a large defect that might appear as an aneurysmal bulge in the interatrial septum.
  • Patent Foramen Ovale (PFO): While typically smaller than an ASD, a large PFO could potentially be misinterpreted as an aneurysm, especially if there's significant shunting or if the PFO is associated with an aneurysmal septum.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sinus Venosus Atrial Septal Defect: Though less common, this type of ASD is located at the junction of the superior vena cava into the right atrium and can be associated with anomalous pulmonary venous return, making it critical to diagnose due to its implications for surgical repair.
  • Coronary Sinus Aneurysm or Diverticulum: An aneurysm or diverticulum of the coronary sinus could potentially be visualized on echo and might be confused with an IAS aneurysm, especially if it's large and protrudes into the left atrium.
• Rare diagnoses
  • Interatrial Septal Pseudaneurysm: This could occur post-myocardial infarction or due to other causes of septal wall weakening, presenting as a false aneurysm of the interatrial septum.
  • Tumors (e.g., myxoma) of the Interatrial Septum: Though rare, a tumor could potentially cause an aneurysmal appearance on echo due to its growth pattern and location.