Interatrial Septal Aneurysms

Echocardiographic Spectrum of Interatrial Septal Aneurysms



Interatrial septal aneurysm (IASA) and patent foramen ovale (PFO)—either alone or coexisting—are a frequent cause of cryptogenic cerebral and/or peripheral thromboemboli. The IASA plus PFO combination has been shown to confer higher risk,1 particularly in adults aged 45 years or younger.2Therefore, recognition and documentation of these 2 abnormalities during an echocardiographic (transthoracic or transesophageal) study, when performed for other indications, is essential.

Most patients with PFO are asymptomatic. PFO may manifest as cryptogenic stroke, transient ischemic attack, decompression sickness (in divers and aviators), and platypnea-orthodeoxia (dyspnea and oxygen desaturation that occurs when standing but is relieved in the supine position).3

These images illustrate the transthoracic echocardiographic spectrum of IASA, with and without PFO. For comparison, a transthoracic, 2-dimensional, apical, 4-chamber view (A) shows normal interatrial septa in a 45-year-old woman who has a mass on the posterior mitral leaflet (unrelated). View B shows a typical IASA bulging into the right atrium in an asymptomatic 58-year-old man; there is no detectable PFO. View C shows a typical IASA with echo dropout (arrow) in its middle portion indicating a PFO in an asymptomatic 40-year-old woman. A color-encoded Doppler flow study confirms a small left to right shunt in the same patient (D).

Both the 58-year-old man and the 40-year-old woman with IASA take aspirin (325 mg/d) and have remained asymptomatic for the past 3 years. Percutaneous PFO closure— a catheter-based technique using atrial septum occlusion devices—has shown promise, with low morbidity and long-term durability; however, no randomized comparative study with medical therapy has been performed as yet.4 One nonrandomized study of 308 patients with PFO and recurrent cryptogenic stroke found percutaneous PFO closure to be at least as effective as medical treatment. It might be more effective than medical treatment in patients with complete closure and recurrent cryptogenic stroke.5


1. Mas JL, Zuber M. Recurrent cerebrovascular events in patients with patent foramen ovale, atrial septal aneurysm, or both and cryptogenic stroke on transient ischemic attack. French Study on Patent Foramen Ovale and Atrial Septal Aneurysm. Am Heart J. 1995;130:1083-1088.
2. Homma S, Sacco RL, Di Tullio MR, et al. Atrial anatomy in non-cardioembolic stroke patients. Effect of medical therapy. J Am Coll Cardiol. 2003;42: 1066-1072.
3.Kerut EK, Norfleet WT, Plotnick GD, Giles TD. Patent foramen ovale: a review of associated conditions and the impact of physiological size. J Am Coll Cardiol. 2001;38:613-623.
4. Meier B, Lock JE. Contemporary management of patent foramen ovale. Circulation. 2003;107:5-9.
5.Windecker S, Wahl A, Nedeltchev K, et al. Comparison of medical treatment with percutaneous closure of patent foramen ovale in patients with cryptogenic stroke. J Am Coll Cardiol. 2004;44:750-758.