© 2014, Wiley Periodicals, Inc. DOI: 10.1111/echo.12852
Echocardiography
Obstructive Membrane at the Base of the Left Atrial Appendage, a Multi-Imaging Approach Demian Chejtman, M.D., Matıas Failo, M.D., Valeria Richarte Rueda, M.D., Emilio Logarzo, M.D., Luis Barja, M.D., Alejandro Benticuaga, M.D., Maria Laura Ayerdi, M.D., Domingo Turri, M.D., Sergio Baratta, M.D., Pablo Aguirre, M.D., and Alejandro Hita, M.D. Cardiology Department, Hospital Universitario Austral, Buenos Aires, Argentina
The left atrial appendage (LAA) is a small muscular extension that grows from the anterolateral wall of the left atrium, in the proximity of the left pulmonary veins. The presence of a membrane in the LAA is a rare clinical entity whose origin is not known. Its clinical implication in the genesis of atrial arrhythmias and thromboembolic risk remains unknown. We report a case of an obstructive membrane located at the base of the LAA, found incidentally in a young patient who was initially undergoing a transesophageal echocardiogram prior to an invasive treatment for atrial fibrillation. (Echocardiography 2015; 32: 864–867) Key words: left atrial appendage function, membrane, transesophageal echocardiogram The left atrial appendage (LAA) is a small muscular extension that grows from the anterolateral wall of the left atrium (LA), in the proximity of the left pulmonary veins.1 The presence of a membrane in the body or at the base of the LAA is an entity described in the last decade, due to its discovery with transesophageal echocardiography. It is infrequent and with unknown origin and clinical implications. We report a case of a patient with a membrane at the base of the LAA.
a thin membrane at the base of the LAA with interior color Doppler signal and pulsing (Figs. 2A,B and 3; movie clips S1 and S2) but no evidence of acceleration in it. It was decided to complete the evaluation with contrast-enhanced cardiac nuclear magnetic resonance (NMR) in which contrast of the LAA could be observed only after 2 minutes, which confirmed the presence of LAA with an incomplete obstruction which delayed contrast in 2 minutes (Fig. 4A,B). Finally
Case Presentation: Our patient was a 35-year-old man, with a history of symptomatic persistent paroxysmal atrial fibrillation episodes from age 23, with no other known pathological history. To treat his condition an electrophysiological treatment with radiofrequency ablation was decided on. To study the anatomy of the pulmonary veins, a cardiac computed tomography (CT) was performed, which reported absence of contrast filling in the LAA, estimating that it could be due to the presence of thrombus in it (Fig. 1). The transthoracic echocardiogram showed preserved cavity diameters and good left ventricular systolic function. To complete the study of the possible thrombus, a transesophageal echocardiography was performed in which the presence of a thrombus was ruled out. However, it evidenced the presence of Address for correspondence and reprint requests: Demian Chejtman, M.D., Peron 1500 Derqui-Pilar, Buenos Aires B1629HJ, Argentina. Fax: 54-230-448-2190; E-mail: [email protected]
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Figure 1. Image of chest CT scan with contrast, evidencing lack of left atrial appendage filling.
Membrane of the Left Atrial Appendage
A
A
B
B
Figure 2. A.,B. Images of transesophageal echocardiography in which the membrane at the base of the left atrial appendage can be observed.
Figure 4. Image of NMR in axial slices: A. in arterial phase that shows the early lack of filling with contrast. B. Image that shows the presence of the left atrial appendage 2 minutes after the injection of the contrast dye.
One year after the pulmonary vein isolation, the paroxysmal atrial fibrillation persisted. To date, the patient is still anticoagulated, awaiting a new procedure. A follow-up three-dimensional transesophageal echocardiography was performed (Fig. 6A,B; movie clips S3 and S4).
Figure 3. Pulsed Doppler Image showing the characteristic flow-pattern of sinus rhythm in the left atrial appendage.
the ablation of atrial fibrillation was carried out without complications. In the image of the LA anatomical reconstruction obtained during the ablation using EnSite St. Jude Medical system (St. Paul, MN, USA), (Fig. 5), the LAA was not observed in characteristic form, confirming the partial exclusion of that structure.
Discussion: The membrane of the LAA is a rare entity, with no clear etiology and whose clinical significance remains unknown due to the small number of cases reported.2,3 The membranes may or may not obstruct the flow (functional stenosis) and are located in the body or at the base of the appendage.4 It is believed that its origin could be due to a congenital anomaly or anatomical variant.5 It is also known that the LA and the LAA have different embriological origins, which results in significant morphological and structural differences. The LA would derive from the pulmonary vein, being a smooth walled chamber with a large diameter and fine muscle fibers. In contrast, the small and lobulated LAA with thick muscular walls 865
Chejtman, et al.
A
B
Figure 5. Image of the anatomical reconstruction obtained during the ablation of atrial fibrillation using EnSite St. Jude Medical system of the LA from the left lateral view. In it, the left pulmonary veins (PV) are shown. The left superior PV in light blue, the left inferior PV in yellow. Characteristically, the left atrium appendage was not observed.
would have its origin in the primitive atrium.6,7 This would lead to suspect that the presence of a membrane in the body or base of the LAA is due to a disturbance in the morphogenesis of the primitive atrium. The cardioembolic risk has not been documented, but the formation of thrombi in the appendage is due to blood stasis.8 In the majority of the reported cases no thrombi were found in the LAA, but there are reports of spontaneous contrast. The presence of spontaneous contrast or thrombus indicates abnormality in the structure or function of LAA.9 Its association with atrial arrhythmias is not clear.5 LAA is believed to modulate the volumes and pressures in the LA. The loss of this cavity could be associated to an overload of volume and pressure of LA,10 increasing the incidence of atrial arrhythmias. While the majority of the patients had a history of atrial arrhythmia, this could be due to bias in the sample. The differential diagnosis should be made with linear structures that appear within the LAA, which may include pectinate muscles, side lobe 866
Figure 6. A. Images of the three-dimensional transesophageal echocardiography showing the membrane of the left atrial appendage. B. The same image with less gain.
artifacts, localized pericardial effusion, and partial resolution of thrombi.4 Conclusion: The presence of a membrane in the LAA is an uncommon entity and its clinical relevance remains unknown. Our case was a finding in a young patient with a history of atrial fibrillation with several years of evolution, in treatment toward radiofrequency ablation. The membrane was evidenced in the CT images, cardiac NMR, transesophageal echocardiography, and in the anatomical reconstruction during the ablation. References 1. Veinot JP, Harrity PJ, Gentile F, et al: Anatomy of the normal left atrial appendage: A quantitative study of age related changes in 500 autopsy hearts: Implications for echocardiographic examination. Circ Res 1997;96:3112– 3115. 2. Mallisho M, Hwang I, Alsafwah S, et al: A rare case of a non obstructive membrane of the left atrial appendage. Echocardiography 2014;31:E58–E59. 3. Stern J, Skolnick A, Freedberg R, et al: Isolated left atrial appendage ostial stenosis. Eur J of Echocardiogr 2009;10:702–703.
Membrane of the Left Atrial Appendage
4. Correale M, Ieva R, Deluca G, et al: Membranes of left atrial appendage: Real appearance or “pitfall”. Echocardiography 2008;25:334–336. 5. Smith C, Hunt M, Geimer- Flanders J: An incidentally discovered left atrial appendage membrane: Case report and literature review. Hawaii J Med Public Health 2012;71:4. 6. Franco D, Campione M, Kelly R, et al: Multiple transcriptional domains, with distinct left and right components, in the atrial chambers of the developing heart. Circ Res 2000;87:984–991. 7. Moorman A, Christoffels V: Cardiac chamber formation: Development, genes, and evolution. Physiol Rev 2003;83:1223–1267. 8. Postacı N, Yesßil M, _Isßci A, et al: Nonobstructive membrane of the left atrial appendage. Ana do lu Kar di yol Derg 2009;9:423–429. 9. Yao S, Meisner J, Factor S, et al: Assessment of left atrial appendage structure and function by trans-
esophageal echocardiography. Echocardiography 1998; 15:243–256. 10. Agmon Y, Khandheria D, Gentile F, et al: Echocardiographic assessment of the left atrial appendage. J Am Coll Cardiol 1999;34:1867–1877.
Supporting Information Additional Supporting Information may be found in the online version of this article: Movie clips S1–S2. Two-dimensional transesophageal echocardiography video showing the membrane at the base of the left atrial appendage. Movie clips S3–S4. Three-dimensional transesophageal echocardiography.
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Copyright of Echocardiography is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Echocardiography
Obstructive Membrane at the Base of the Left Atrial Appendage, a Multi-Imaging Approach Demian Chejtman, M.D., Matıas Failo, M.D., Valeria Richarte Rueda, M.D., Emilio Logarzo, M.D., Luis Barja, M.D., Alejandro Benticuaga, M.D., Maria Laura Ayerdi, M.D., Domingo Turri, M.D., Sergio Baratta, M.D., Pablo Aguirre, M.D., and Alejandro Hita, M.D. Cardiology Department, Hospital Universitario Austral, Buenos Aires, Argentina
The left atrial appendage (LAA) is a small muscular extension that grows from the anterolateral wall of the left atrium, in the proximity of the left pulmonary veins. The presence of a membrane in the LAA is a rare clinical entity whose origin is not known. Its clinical implication in the genesis of atrial arrhythmias and thromboembolic risk remains unknown. We report a case of an obstructive membrane located at the base of the LAA, found incidentally in a young patient who was initially undergoing a transesophageal echocardiogram prior to an invasive treatment for atrial fibrillation. (Echocardiography 2015; 32: 864–867) Key words: left atrial appendage function, membrane, transesophageal echocardiogram The left atrial appendage (LAA) is a small muscular extension that grows from the anterolateral wall of the left atrium (LA), in the proximity of the left pulmonary veins.1 The presence of a membrane in the body or at the base of the LAA is an entity described in the last decade, due to its discovery with transesophageal echocardiography. It is infrequent and with unknown origin and clinical implications. We report a case of a patient with a membrane at the base of the LAA.
a thin membrane at the base of the LAA with interior color Doppler signal and pulsing (Figs. 2A,B and 3; movie clips S1 and S2) but no evidence of acceleration in it. It was decided to complete the evaluation with contrast-enhanced cardiac nuclear magnetic resonance (NMR) in which contrast of the LAA could be observed only after 2 minutes, which confirmed the presence of LAA with an incomplete obstruction which delayed contrast in 2 minutes (Fig. 4A,B). Finally
Case Presentation: Our patient was a 35-year-old man, with a history of symptomatic persistent paroxysmal atrial fibrillation episodes from age 23, with no other known pathological history. To treat his condition an electrophysiological treatment with radiofrequency ablation was decided on. To study the anatomy of the pulmonary veins, a cardiac computed tomography (CT) was performed, which reported absence of contrast filling in the LAA, estimating that it could be due to the presence of thrombus in it (Fig. 1). The transthoracic echocardiogram showed preserved cavity diameters and good left ventricular systolic function. To complete the study of the possible thrombus, a transesophageal echocardiography was performed in which the presence of a thrombus was ruled out. However, it evidenced the presence of Address for correspondence and reprint requests: Demian Chejtman, M.D., Peron 1500 Derqui-Pilar, Buenos Aires B1629HJ, Argentina. Fax: 54-230-448-2190; E-mail: [email protected]
864
Figure 1. Image of chest CT scan with contrast, evidencing lack of left atrial appendage filling.
Membrane of the Left Atrial Appendage
A
A
B
B
Figure 2. A.,B. Images of transesophageal echocardiography in which the membrane at the base of the left atrial appendage can be observed.
Figure 4. Image of NMR in axial slices: A. in arterial phase that shows the early lack of filling with contrast. B. Image that shows the presence of the left atrial appendage 2 minutes after the injection of the contrast dye.
One year after the pulmonary vein isolation, the paroxysmal atrial fibrillation persisted. To date, the patient is still anticoagulated, awaiting a new procedure. A follow-up three-dimensional transesophageal echocardiography was performed (Fig. 6A,B; movie clips S3 and S4).
Figure 3. Pulsed Doppler Image showing the characteristic flow-pattern of sinus rhythm in the left atrial appendage.
the ablation of atrial fibrillation was carried out without complications. In the image of the LA anatomical reconstruction obtained during the ablation using EnSite St. Jude Medical system (St. Paul, MN, USA), (Fig. 5), the LAA was not observed in characteristic form, confirming the partial exclusion of that structure.
Discussion: The membrane of the LAA is a rare entity, with no clear etiology and whose clinical significance remains unknown due to the small number of cases reported.2,3 The membranes may or may not obstruct the flow (functional stenosis) and are located in the body or at the base of the appendage.4 It is believed that its origin could be due to a congenital anomaly or anatomical variant.5 It is also known that the LA and the LAA have different embriological origins, which results in significant morphological and structural differences. The LA would derive from the pulmonary vein, being a smooth walled chamber with a large diameter and fine muscle fibers. In contrast, the small and lobulated LAA with thick muscular walls 865
Chejtman, et al.
A
B
Figure 5. Image of the anatomical reconstruction obtained during the ablation of atrial fibrillation using EnSite St. Jude Medical system of the LA from the left lateral view. In it, the left pulmonary veins (PV) are shown. The left superior PV in light blue, the left inferior PV in yellow. Characteristically, the left atrium appendage was not observed.
would have its origin in the primitive atrium.6,7 This would lead to suspect that the presence of a membrane in the body or base of the LAA is due to a disturbance in the morphogenesis of the primitive atrium. The cardioembolic risk has not been documented, but the formation of thrombi in the appendage is due to blood stasis.8 In the majority of the reported cases no thrombi were found in the LAA, but there are reports of spontaneous contrast. The presence of spontaneous contrast or thrombus indicates abnormality in the structure or function of LAA.9 Its association with atrial arrhythmias is not clear.5 LAA is believed to modulate the volumes and pressures in the LA. The loss of this cavity could be associated to an overload of volume and pressure of LA,10 increasing the incidence of atrial arrhythmias. While the majority of the patients had a history of atrial arrhythmia, this could be due to bias in the sample. The differential diagnosis should be made with linear structures that appear within the LAA, which may include pectinate muscles, side lobe 866
Figure 6. A. Images of the three-dimensional transesophageal echocardiography showing the membrane of the left atrial appendage. B. The same image with less gain.
artifacts, localized pericardial effusion, and partial resolution of thrombi.4 Conclusion: The presence of a membrane in the LAA is an uncommon entity and its clinical relevance remains unknown. Our case was a finding in a young patient with a history of atrial fibrillation with several years of evolution, in treatment toward radiofrequency ablation. The membrane was evidenced in the CT images, cardiac NMR, transesophageal echocardiography, and in the anatomical reconstruction during the ablation. References 1. Veinot JP, Harrity PJ, Gentile F, et al: Anatomy of the normal left atrial appendage: A quantitative study of age related changes in 500 autopsy hearts: Implications for echocardiographic examination. Circ Res 1997;96:3112– 3115. 2. Mallisho M, Hwang I, Alsafwah S, et al: A rare case of a non obstructive membrane of the left atrial appendage. Echocardiography 2014;31:E58–E59. 3. Stern J, Skolnick A, Freedberg R, et al: Isolated left atrial appendage ostial stenosis. Eur J of Echocardiogr 2009;10:702–703.
Membrane of the Left Atrial Appendage
4. Correale M, Ieva R, Deluca G, et al: Membranes of left atrial appendage: Real appearance or “pitfall”. Echocardiography 2008;25:334–336. 5. Smith C, Hunt M, Geimer- Flanders J: An incidentally discovered left atrial appendage membrane: Case report and literature review. Hawaii J Med Public Health 2012;71:4. 6. Franco D, Campione M, Kelly R, et al: Multiple transcriptional domains, with distinct left and right components, in the atrial chambers of the developing heart. Circ Res 2000;87:984–991. 7. Moorman A, Christoffels V: Cardiac chamber formation: Development, genes, and evolution. Physiol Rev 2003;83:1223–1267. 8. Postacı N, Yesßil M, _Isßci A, et al: Nonobstructive membrane of the left atrial appendage. Ana do lu Kar di yol Derg 2009;9:423–429. 9. Yao S, Meisner J, Factor S, et al: Assessment of left atrial appendage structure and function by trans-
esophageal echocardiography. Echocardiography 1998; 15:243–256. 10. Agmon Y, Khandheria D, Gentile F, et al: Echocardiographic assessment of the left atrial appendage. J Am Coll Cardiol 1999;34:1867–1877.
Supporting Information Additional Supporting Information may be found in the online version of this article: Movie clips S1–S2. Two-dimensional transesophageal echocardiography video showing the membrane at the base of the left atrial appendage. Movie clips S3–S4. Three-dimensional transesophageal echocardiography.
867
Copyright of Echocardiography is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
