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Logo of thijTexas Heart Institute JournalSee also Cardiovascular Diseases Journal in PMCSubscribeSubmissionsTHI Journal Website
Tex Heart Inst J. 2006; 33(3): 410–411.
PMCID: PMC1592278

A Closed Interatrial Septal Aneurysm Mimicking a Tumor in the Left Atrium

Raymond F. Stainback, MD, Section Editor
Department of Adult Cardiology, Texas Heart Institute and St.Luke's Episcopal Hospital, 6624 Fannin Street, Suite 2480, Houston, TX 77030

A 56-year-old woman presented with a congenital atrial septal aneurysm (ASA) that was found incidentally on routine echocardiographic evaluation. The echocardiographic images mimicked a left atrial tumor. She had hypertension, and she had been taking amlodipine for 5 years. There was no audible murmur. The chest radiograph and electrocardiogram were normal. Two-dimensional echocardiography showed rheumatic valvular disease and a mobile mass in the left atrium that resembled a cyst or cor triatriatum sinister. Further evaluation by other echocardiographic views confirmed the ASA. The presence of a left-to-right shunt was excluded by 2-dimensional, color-flow Doppler and contrast echocardiography (Figs. 1A and 1B). Multiple parasternal long- and short-axis, apical 4-chamber, and modified echocardiographic evaluations revealed that the circular cyst-like image was a cross-section of an interatrial septal aneurysm (Figs. 1B and 1C). Color-flow Doppler echocardiography showed moderate tricuspid regurgitation, mild mitral stenosis, and mild aortic regurgitation. The mitral valve area was 2.5 cm2. Systolic pulmonary artery pressure was calculated by continuous-wave Doppler echocardiography as 55 mmHg. It appeared that elevated right atrial pressure was causing continuous right-to-left bowing of the atrial septal aneurysm into the left atrium. To the best of our knowledge, this is the 1st report of an interatrial septal aneurysm mimicking a left atrial tumor.

figure 33FF1
Fig. 1 A,B)Parasternal long-axis,2-dimensional echocardiographic images show a mobile and cyst-like mass (arrows)in the left atrium. C,D) Apical 4-chamber echocardiographic views show the interatrial septal aneurysm (arrows).

An ASA is a localized segment of the atrial septum that bulges into the right or left atrium. It can be found as an isolated lesion or in association with other cardiac anomalies, such as patent foramen ovale, atrial septal defect, or mitral valve prolapse.1–5 Such aneurysms are readily detected by 2-dimensional and transesophageal echocardiography. They are occasionally mobile, in which instance they can be seen moving between the atria during the cardiac cycle.3 Most ASAs are clinically silent, and they are an incidental finding in 1% of the general population.6 Although an ASA is considered clinically benign, there can be clinical consequences, such as cardiogenic embolism.3 Embolism can result from left-atrial thrombus formation within the aneurysm, or it can occur as a paradoxical embolism.7–9 Another complication is a right-to-left interatrial shunt, which occurs in 90% of ASAs.3 Rarely, some ASAs mimic a right atrial cyst or tumor.8


Address for reprints: Ramazan Akdemir, MD, Health Ministry, Department of Cardiology, Diskapi Educational and Research Hospital, 06110 Ankara, Turkey. E-mail: moc.oohay@rimedkar

Dr. Ramazan Akdemir is now affiliated with the Health Ministry, Department of Cardiology, Diskapi Educational and Research Hospital, Ankara.


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