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Two- and Three-Dimensional Transesophageal Echocardiographic Interrogation of an Atrial Septal Pouch Thrombosis

Williams, Emily MD; Anthony, David MD; Duncan, Andra MD

doi: 10.1213/XAA.0000000000000803
Echo Rounds

From the Department of Cardiothoracic Anesthesiology, Cleveland Clinic, Cleveland Ohio.

Accepted for publication February 9, 2018.

Funding: None.

The authors declare no conflicts of interest.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website.

Address correspondence to Emily Williams, MD, 640 Jackson St, St. Paul, MN 55101. Address e-mail to

A 60-year-old man with stenosis of a native bicuspid aortic valve presented for aortic valve replacement. His medical history was significant for ischemic cardiomyopathy and previous coronary artery bypass grafting. He was in normal sinus rhythm. In the operating room, standard American Society of Anesthesiologists monitors were supplemented with arterial and pulmonary artery catheters. After an uneventful anesthetic induction, an intraoperative transesophageal echocardiogram (TEE) confirmed low-flow, low-gradient aortic stenosis (peak/mean gradient 46/26 mm Hg, aortic valve area 0.9 cm2 by continuity equation) and moderate left ventricular dysfunction (ejection fraction, 32%) with spontaneous echo contrast seen in the left atrium. Incidentally, a 1.7 × 1.0 cm hyperechoic, nonmobile, ovoid mass was adherent to the left side of the interatrial septum (Figure 1A, B; Supplemental Digital Content, Video,

Figure 1.

Figure 1.

The unclear etiology of the interatrial mass prompted alteration of the surgical plan to include a right atriotomy and bicaval venous cannulation. During the interatrial septal mass extraction, the surgeon confirmed the presence of a left atrial septal pouch without a patent foramen ovale. The mass was removed (Figure 1C) and later identified as thrombus by light microscopy. Postoperative evaluation found no evidence of systemic embolization; thus, anticoagulation was deferred. His postoperative course was uneventful, and he was discharged to home 7 days later. The patient provided consent to publish this case report.

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An atrial septal pouch is a normal anatomical variant found in up to 50% of the general population that results from incomplete fusion of the septum primum and secundum.1,2 It is often undetected by TEE because of normal close apposition of the septum primum and septum secundum. The location of the interatrial septal fusion determines pouch classification. Fusion of the caudal septum (near the inferior vena cava) results in the more common left-sided septal pouch.1,2 Fusion of the cranial portion (near the superior vena cava) leads to a right septal pouch and central fusion leads to a double pouch (Figure 2).1,2

Figure 2.

Figure 2.

In situ thrombus formation occurs more often in a left atrial septal pouch due to its downward orientation (see Figure 2, left atrial septal pouch) and presence of secondary diverticula. However, thrombus formation is rare due to the protective, brisk, laminar blood flow of the right pulmonary veins.3 With left ventricular dysfunction or atrial fibrillation, this protective function is lost promoting thrombus formation and embolism.3 Identifying an atrial septal pouch thrombus may have significant clinical implications, including need for surgery or change in the surgical approach (requiring atrial incision or change in cannulation strategy), evaluation for systemic embolic events, and initiation of anticoagulation. No investigations have evaluated the benefits of medical versus surgical treatment of an atrial septal pouch thrombus.

Echocardiographic interrogation of the interatrial septum to evaluate for an atrial septal pouch and presence of a thrombus should occur in patients at risk for atrial clots (and subsequent embolization) including those with mitral stenosis, left ventricular dysfunction, and atrial fibrillation.3 Five basic views (upper esophageal ascending aorta short axis, midesophageal aortic valve, 4 chamber, bicaval, and long axis) with progressive multiplane angle adjustments are used to assess the interatrial septum, both atria, and surrounding structures for the presence of abnormalities.4 Each view evaluates a different portion of the interatrial septum. The majority of interatrial septal pouches are visualized in the midesophageal 4-chamber, bicaval, and aortic valve short-axis views.2

Thorough evaluation of an atrial septal pouch includes location, size, and presence of a thrombus or atrial communication (such as a patent foramen ovale or atrial septal defect). An atrial communication can be identified using agitated saline or color Doppler (if a left-to-right shunt is present) and further evaluated with spectral Doppler to determine velocity, direction, and timing of flow through the defect.4 If a mass is present, contrast echocardiography may be helpful by differentiating a thrombus (lack of enhancement) from a myxoma (partial or incomplete enhancement) and intracardiac tumor (complete enhancement).5 Unfortunately, some myxomas or tumors may not show enhancement either.5

The interatrial septum is a 3-dimensional (3D) structure that makes atrial septal pouch visualization difficult. 3D echocardiography can capture the entire interatrial septum and with processing (en face view) can improve detection and size measurements of the atrial septal pouch.4,6,7 A 2-dimensional midesophageal bicaval view is used to acquire a zoomed 3D data set of the interatrial septum. A 90° up-down rotation of the data set allows the interatrial septum to be visualized in an en face perspective from the left atrium.4,7 Proper left atrium en face positioning is with the right upper pulmonary vein at the 1-o’clock position.4,6 From the left atrium en face view, a 180° counterclockwise rotation produces the en face perspective from the right atrium with placement of the superior vena cava at the 12-o’clock position (Figure 3).4,6,7 Limitations of 3D echocardiography include (1) acquisition time: data sets with higher spatial and temporal resolution may necessitate multibeat acquisition, and (2) presence of artifact: dropout and reconstruction (“stitch”) artifacts.7

Figure 3.

Figure 3.

In our case, this incidental finding by TEE determined the size and location of the atrial septal pouch, identified the presence of a thrombus, impacted the operative course, and confirmed adequate resection (Figure 1C).

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Name: Emily Williams, MD.

Contribution: This author helped collect the transesophageal echocardiogram images, create the manuscript’s concept, and write the manuscript.

Name: David Anthony, MD.

Contribution: This author helped collect the transesophageal echocardiogram images and create the manuscript’s concept.

Name: Andra Duncan, MD.

Contribution: This author helped collect the transesophageal echocardiogram images, create the manuscript’s concept, and write the manuscript.

This manuscript was handled by: Nikolaos J. Skubas, MD, DSc, FACC, FASE.

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1. Krishnan SC, Salazar MSeptal pouch in the left atrium: a new anatomical entity with potential for embolic complications. JACC Cardiovasc Interv. 2010;3:98104.
2. Bandyopadhyay S, Mandana KLeft atrial septal pouch: a potential source of systemic thromboembolism: incidental transesophageal echocardiogram findings. Anesth Analg. 2015;121:5961.
3. Hołda MK, Koziej M, Hołda JAtrial septal pouch - morphological features and clinical considerations. Int J Cardiol. 2016;220:337342.
4. Silvestry FE, Cohen MS, Armsby LBAmerican Society of Echocardiography; Society for Cardiac Angiography and Interventions. Guidelines for the echocardiographic assessment of atrial septal defect and patent foramen ovale: from the American Society of Echocardiography and Society for Cardiac Angiography and Interventions. J Am Soc Echocardiogr. 2015;28:910958.
5. Porter TR, Abdelmoneim S, Belcik JTGuidelines for the cardiac sonographer in the performance of contrast echocardiography: a focused update from the American Society of Echocardiography. J Am Soc Echocardiogr. 2014;27:797810.
6. Elsayed M, Hsiung MC, Meggo-Quiroz LDIncremental value of live/ real time three-dimensional over two-dimensional transesophageal echocardiography in the assessment of atrial septal pouch. Echocardiography. 2015;32:18581867.
7. Lang RM, Badano LP, Tsang WAmerican Society of Echocardiography; European Association of Echocardiography. EAE/ASE recommendations for image acquisition and display using three-dimensional echocardiography. J Am Soc Echocardiogr. 2012;25:346.

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