Interatrial septal aneurysm or atrial septal aneurysm (ASA) is defined as an abnormal protrusion of the interatrial septum. The exact length of the protrusion that defines an interatrial septal aneurysm varies in the literature, ranging from >11 mm to >15 mm beyond normal excursion in adults 4,5 and 5 mm in children.
It can be limited to the fossa ovale or involve the entire inter-atrial septum.
It is encountered in approximately 1% of the pediatric population.
Interatrial septal aneurysm is associated with an increased incidence of peripheral arterial embolism and increased stroke risk.
It is known to be associated with the following:
Several classification systems have been proposed, on system is as 1:
- type 1R: bulging is in the right atrium only
- type 2L: bulging is in the left atrium only
- type 3RL: major excursion bulges to the right atrium and the lesser excursion bulges toward the left
- type 4LR: maximal excursion of the atrial septal aneurysm is toward the left atrium with a lesser excursion toward the right atrium
- type 5: atrial septal aneurysm movement is bidirectional and equidistant to both atria during the cardiorespiratory cycle
- some consider an aneurysm of more than 10 mm excursion to be associated with markedly increased risk (odds ratio 8) 8
- the concurrent presence of a patent foramen ovale is thought to have a synergistic effect on stroke 8
On imaging consider:
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- 2. Demirkol S, Balta S, Unlü M et-al. Case Images: Huge interatrial septal aneurysm associated with a multiple atrial septal defect evaluated by transesophageal echocardiography. Turk Kardiyol Dern Ars. 2013;41 (1): 88. Turk Kardiyol Dern Ars (link) - Pubmed citation
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- 5. Mas JL, Arquizan C, Lamy C et-al. Recurrent cerebrovascular events associated with patent foramen ovale, atrial septal aneurysm, or both. N. Engl. J. Med. 2001;345 (24): 1740-6. doi:10.1056/NEJMoa011503 - Pubmed citation
- 7. Mügge A, Daniel WG, Angermann C et-al. Atrial septal aneurysm in adult patients. A multicenter study using transthoracic and transesophageal echocardiography. Circulation. 1995;91 (11): 2785-92. doi:10.1161/01.CIR.91.11.2785 - Pubmed citation
- 8. Cabanes L, Mas JL, Cohen A et-al. Atrial septal aneurysm and patent foramen ovale as risk factors for cryptogenic stroke in patients less than 55 years of age. A study using transesophageal echocardiography. Stroke. 1994;24 (12): 1865-73. Pubmed citation
- 9. Wahl A, Krumsdorf U, Meier B et-al. Transcatheter treatment of atrial septal aneurysm associated with patent foramen ovale for prevention of recurrent paradoxical embolism in high-risk patients. J. Am. Coll. Cardiol. 2005;45 (3): 377-80. doi:10.1016/j.jacc.2004.10.043 - Pubmed citation
- 10. Olivares-Reyes A, Chan S, Lazar EJ, Bandlamudi K, Narla V, Ong K. Atrial septal aneurysm: a new classification in two hundred five adults. (1997) Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. 10 (6): 644-56. Pubmed