From the Guidelines
Echocardiographic criteria for an aneurysmal interatrial septum include a bulging or protrusion of the septum into either atrium with an excursion of at least 10-15 mm beyond the plane of the atrial septum, and a base width of at least 15 mm, as defined by the American College of Cardiology/American Heart Association Task Force on Clinical Data Standards 1. The diagnosis of an aneurysmal interatrial septum requires visualization in multiple echocardiographic views, particularly the subcostal and apical four-chamber views, to confirm the abnormal septal motion and morphology. Some key features of an aneurysmal interatrial septum include:
- Excessive mobility during the cardiac cycle, with phasic excursions that follow atrial pressure changes
- Thinning of the septal tissue at the site of the aneurysm
- Sometimes multiple fenestrations or perforations within the aneurysmal portion Color Doppler assessment should be performed to evaluate for any associated shunting through patent foramen ovale or atrial septal defects, which are present in approximately 70% of cases, as reported in a study on patent foramen ovale and atrial septal aneurysm 1. Transesophageal echocardiography may be necessary for definitive diagnosis in cases where transthoracic imaging is suboptimal, as it provides superior resolution of the interatrial septum and can better characterize the aneurysm's morphology and any associated defects. It is essential to note that the presence of an atrial septal aneurysm is often associated with other cardiac abnormalities, such as patent foramen ovale, and a comprehensive echocardiographic evaluation is necessary to identify any potential defects or shunts 1.
From the Research
Echocardiographic Criteria for Aneurysmal Interatrial Septum
The echocardiographic criteria for aneurysmal interatrial septum include:
- A linear echo in the left atrial cavity in early and mid systole on M-mode recordings 2
- A hemispherical bulge in the mid portion of the interatrial septum on 2D echo, which is mobile and has a to-and-fro motion between the two atria in relation to the different phases of the cardiac cycle 2
- An isolated aneurysm of the interatrial septum on 2D echocardiography 3
- Mobile intra-right atrial echos on M-mode examination, which can be distinguished from other conditions such as Chiari's malformation, tricuspid valve vegetations, intraatrial tumour or thrombus, or Eustachian valve using 2D examination with different incidences and contrast injections 3
Associated Echocardiographic Findings
Associated echocardiographic findings in patients with aneurysmal interatrial septum include:
- Aortic valve regurgitation and mitral valve regurgitation 4
- Ascending aortic aneurysm (AAA) 4
- Patent foramen ovale (PFO) 4
- Atrial septal defect (ASD) 4
- Larger aortic root diameter and ascending aorta diameter compared to patients without aneurysmal interatrial septum 4
Diagnostic Considerations
The diagnosis of aneurysmal interatrial septum can be confirmed by: