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Congenital Left Atrial Appendage Aneurysm

Atchison, Fawn W., MD, PhD; Rehfeldt, Kent H., MD

doi: 10.1213/ANE.0b013e318213fbb7
Cardiovascular Anesthesiology: Echo Rounds
Free
SDC
CME

Published ahead of print March 3, 2011

From the Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.

Funding: No funding.

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 Web site (www.anesthesia-analgesia.org).

Address correspondence and reprint requests to Kent H. Rehfeldt, MD, Department of Anesthesiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. Address e-mail to rehfeldt.kent@mayo.edu.

Accepted January 24, 2011

Published ahead of print March 3, 2011

Consent for publication was obtained from the patient. A 45-year-old man presented with symptomatic supraventricular tachycardia. Transthoracic echocardiography showed normal biventricular function without valvular abnormalities. However, a large echolucent space was noted adjacent to the anterolateral walls of the left ventricle (LV). This space was in communication with the circulation as demonstrated by contrast enhancement after the administration of IV perflutren (Definity; Lantheus Medical Imaging, North Billerica, MA), although the location of the communication was not identified. Cardiac magnetic resonance imaging demonstrated this space to be a left atrial appendage (LAA) aneurysm. Resection of the LAA aneurysm and Maze procedure were scheduled.

Prebypass intraoperative transesophageal echocardiography (TEE) demonstrated a large 6.5 × 6.2 cm LAA aneurysm, most prominently in the transgastric 2-chamber (Fig. 1) and midesophageal views (Figs. 2 and 3A) (Supplemental Digital Content 1 and 2; see Video 1, http://links.lww.com/AA/A248 and Video 2, http://links.lww.com/AA/A249; see Appendix for video legends), showing clear communication with the left atrium (LA). The aneurysm exerted mass effect on the LV with inward deformation of the anterolateral wall, most evident in diastole (Fig. 3A). No thrombus was identified within this structure (Fig. 2). The remainder of the LA was of normal size and there was trivial mitral regurgitation. The surgeon excised the aneurysmal LAA and performed a CryoMaze procedure. Postbypass TEE confirmed absence of the LAA aneurysm along with reduced extrinsic mass effect on the anterolateral LV wall (Fig. 3B).

Figure 1

Figure 1

Figure 2

Figure 2

Figure 3

Figure 3

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DISCUSSION

Congenital aneurysm of the LAA is an exceedingly rare cardiac anomaly. According to one review of the literature, only 78 cases were reported between 1922 and 2007.1 The underlying pathology is thought to be congenital dysplasia of the atrial pectinate muscles. Proposed diagnostic criteria include: (1) absence of other cardiac pathology, (2) origination from an otherwise normal LA, (3) a well-defined communication with the LA, and (4) distortion of the LV free wall by the aneurysm.2 Some authors have also proposed that complete containment within the pericardium also characterizes congenital LAA aneurysm2 whereas others have reported rare cases in which the aneurysmal LAA herniated through a pericardial defect.3 Interestingly, few investigators have suggested size as a diagnostic criteria although one group suggested an LAA linear measurement exceeding 3 cm is consistent with aneurysm.4 Aneurysmal dilation may affect other areas of the LA, although the LAA is the most common site.3 Congenital aneurysm of the right atrium is least common.3

LAA aneurysm may be either congenital or, more frequently, acquired. Echocardiographers diagnose acquired LAA aneurysm when it coexists with conditions leading to increased LA pressure and generalized LA dilation such as mitral stenosis or regurgitation.2 In addition, weakening of the LAA wall due to myocarditis may lead to acquired LAA.3 In our case, the absence of mitral valve disease, generalized LA enlargement, or other structural abnormalities suggestive of myocarditis distinguished this as a congenital LAA aneurysm and underscores the need for a comprehensive TEE examination when LAA dilation is noted.

The differential diagnosis of an intrapericardial, echolucent structure adjacent to the left heart chambers includes pericardial cyst, coronary artery aneurysm, LV pseudoaneurysm, or a dilated coronary sinus. TEE is able to distinguish these conditions from LAA aneurysm because, unless fistula formation has occurred, only the latter demonstrates connection with the LA chamber. If communication with the LA is difficult to establish with TEE, the administration of IV contrast agents may help localize any connection with the circulation.

Additionally, TEE can more confidently exclude the presence of thrombus within the appendage. Identification of thrombus within the LAA aneurysm is essential because after arrhythmia, systemic embolism is the next most common clinical presentation in this patient group.3 Imaging artifacts may be seen within the LAA (Fig. 3A) if the ultrasound beam first passes through a prominent ridge between the LAA and left upper pulmonary vein, the mitral annulus, or a portion of the LAA orifice. The use of additional imaging planes such as the transgastric 2-chamber view (Fig. 1) may assist the echocardiographer in distinguishing artifact from thrombus. Along with 2-dimensional (D) imaging, specific techniques using 3-D TEE to interrogate the LAA have been described.5 In fact, 3-D TEE was attempted in this case, but the large size of the LAA and its relative distance from the transducer precluded useful 3-D image generation. Cardiac magnetic resonance imaging may offer the highest resolution imaging of an aneurysmal LAA.4 However, TEE is a more versatile imaging modality, particularly in the intraoperative setting.

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DISCLOSURES

Name: Fawn W. Atchison, MD, PhD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Fawn W. Atchison approved the final manuscript.

Name: Kent H. Rehfeldt, MD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Kent H. Rehfeldt approved the final manuscript.

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REFERENCES

1. Chowdhury UK, Seth S, Govindappa R, Jagia P, Malhotra P. Congenital left atrial appendage aneurysm: a case report and brief review of literature. Heart Lung Circ 2009;18:412–6
2. Culver DL, Bezante GP, Schwarz KQ, Meltzer RS. Transesophageal echocardiography in the diagnosis of acquired aneurysms of the left atrial appendage. Clin Cardiol 1993;16:149–51
3. de la Fuente A, Urchaga A, Sanchez R, Fernandez JL, Moriones I. Congenital aneurysm of the left atrial appendage. Ann Thorac Surg 2008;85:2139–40
4. Ulucam M, Muderrisoglu H, Sezgin A. Giant left atrial appendage aneurysm: the third ventricle! Int J Cardiovasc Imaging 2005;25:225–30
5. Mizuguchi KA, Burch TM, Bulwer BE, Fox AA, Rizzo RJ, Shernan SK. Thrombus or bilobar left atrial appendage? Diagnosis by real-time three-dimensional transesophageal echocardiography. Anesth Analg 2009;108:70–2
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APPENDIX: ONLINE ECHOCARDIOGRAPHIC STILL AND VIDEO IMAGES

Video 1. Midesophageal commissural and transgastric 2-chamber views demonstrating the left atrial appendage (LAA) aneurysm (solid arrow). Image artifact is present in the midesophageal view (open arrow). The left atrium (LA) and left ventricle (LV) are indicated. Video 2. Modified, zoomed, midesophageal long-axis view demonstrating the left atrial appendage (LAA) aneurysm (solid arrow) containing a single pectinate muscle (circle). Color Doppler demonstrates connection with the left atrium (LA).

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Clinician's Key Teaching Points Nikolaos J. Skubas M.D., and Roman M. Sniecinski M.D.
  • Left atrial appendage (LAA) aneurysm appears as an intrapericaridal echolucent space adjacent to the anterolateral walls of the left ventricle (LV) and, if large enough, may exert mass effect on the LV free wall. Most are acquired secondary to elevated left atrium (LA) pressure, but congenital ones do exist. Large LAAs, create a potential space for stagnant blood, and hence thrombus formation.
  • Pericardial cyst, coronary artery aneurysm, LV pseudoaneurysm, and a dilated coronary sinus have similar echolucent appearances and can appear in the same vicinity, but only an LAA aneurysm is in direct communication with the LA cavity. This continuity is best demonstrated with color flow Doppler or administration of IV contrast agents.
  • In this case, the absence of mitral pathology, an LA of normal size and the presence of extrinsic LV compression were suggestive of a congenital LAA aneurysm. Imaging in multiple views (midesophageal 2 chamber and long-axis as well as transgastric 2 chamber) established the diagnosis and correctly identified a large pectinate muscle, initially thought to be thrombus.
  • Intraoperative echocardiographers must have a high index of suspicion when an enlarged intrapericadial “cyst” is imaged. Apart from correct diagnosis, it is important to distinguish clot from normal LAA endocardium and muscle. A LA emptying velocity <20 cm/s, recorded with pulsed wave Doppler inside the LA, is highly suggestive of LA mechanical dysfunction and stagnant flow.

Supplemental Digital Content

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