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J Thorac Cardiovasc Surg 1997;114:278-280
© 1997 Mosby, Inc.

BRIEF COMMUNICATIONS

INVERTED LEFT ATRIAL APPENDAGE: AN UNRECOGNIZED CAUSE OF LEFT ATRIAL MASS

Chicago, Ill.

Received for publication August 8, 1996 Accepted for publication Nov. 5, 1996. Address for reprints: Bradley S. Allen, MD, University of Illinois, Cardiothoracic Surgery, 840 S. Wood St., 515 CSN (M/C 958), Chicago, IL 60612.

When a new left atrial mass is discovered by means of echocardiography, the differential diagnosis is usually between thrombus, vegetation, and tumor. ¹ Moreover, several steps may be necessary to establish an accurate diagnosis. Therapy may be different for each of these conditions and may include anticoagulation, antibiotics, or operation. Recently, however, we were able to document another cause that allowed us to avoid an unnecessary reoperation or therapeutic intervention.

Clinical history

PATIENT 1
A 5-month-old male infant was confirmed to have tetralogy of Fallot by preoperative echocardiogram and cardiac catheterization. With the aid of cardiopulmonary bypass, the ventricular septal defect was patched, infundibular muscle resected, and a pulmonary valvulotomy performed. Because of unfavorable coronary anatomy (left anterior descending originating from the right coronary artery), the right ventricular outflow tract was not patched.

Eighteen hours after the cardiac operation, an echocardiogram was performed to evaluate the adequacy of the right ventricular outflow tract repair. This demonstrated minimal pulmonary stenosis or regurgitation. However, there was a new fingerlike mass in the left atrium measuring approximately 12 x 6 mm (Fig. 1), and color Doppler ultrasonography revealed flow around this lesion with no significant left ventricular inflow obstruction. The mass appeared mobile and was found to be related to the anterolateral wall of the left atrium immediately superior to the left lower pulmonary vein. Because of concern as to the nature of this mass, further studies were performed including another echocardiogram done from unconventional views. This revealed the mass to be an inverted left atrial appendage (Fig. 2). Clinically, the child made a quick recovery and was discharged to his home on the eighth postoperative day. This mass had significantly decreased in size by 6 weeks after the operation and had disappeared at 1 year's follow-up. The PATIENT was free of symptoms during this entire time and continued to have an excellent surgical result.

View larger version (69K): [in this window] [in a new window]   Fig. 1. Parasternal transthoracic echocardiogram demonstrates a new mass in the left atrium 18 hours after repair of tetralogy of Fallot (PATIENT 1). The mass appeared mobile and seemed to arise from the anterior wall of the left atrium near the left superior pulmonary vein.

View larger version (65K): [in this window] [in a new window]   Fig. 2. Transthoracic echocardiogram in the same PATIENT taken from an unconventional view. Note: By tracing the atrial walls, the mass can be easily identified as an inverted left atrial appendage.

Discussion

Typically, a left atrial mass is a tumor, vegetation, or thrombus. With increasing use of echocardiography to assess surgical repair both during and after operations, unusual and previously undiagnosed images may become apparent. ¹ In the first PATIENT, absence of a mass on an immediate preoperative echocardiogram ruled out the possibility of tumor. Full heparinization and postbypass coagulopathy made the development of a large thrombus unlikely. In addition, the lack of any systemic signs of embolization also spoke against this diagnosis. Finally, a vegetation was though to be unlikely because there were no other signs of infection, and the mass seemed to come from the atrial wall and not the mitral valve. This led us to perform more extensive echocardiographic analysis with unconventional views, which confirmed that this mass was an inverted left atrial appendage (Fig. 2). This entity can usually be diagnosed by means of echocardiography without the need for more detailed studies, but only if the diagnosis is suspected.

The most likely cause for postoperative left atrial inversion is the negative pressures created by the left ventricular vent introduced during surgery via the right superior pulmonary vein. It is also possible that the appendage may be inverted as part of the deairing maneuvers. Shorter appendages with a wider base are more likely to become inverted.

To the best of our knowledge, this entity has been reported only once, and the diagnosis was made only during reoperation. ² In contrast, by considering this possibility and determining the cause using unconventional echocardiographic views, we were able to avoid a reoperation. Once the correct diagnosis is ascertained this lesion can be left alone because (1) it is totally endothelialized, (2) it usually gets better with time, and (3) it cannot embolize. Moreover, an inverted left atrial appendage should not induce thrombus formation because it is directly in the path of rapid blood flow and no longer has a long cylindric shape, which can induce blood to stagnate. So long as it does not disturb mitral valve function, the appendage should not be a problem. Therefore, by identifying the etiology of these masses, we avoided further surgery.

In conclusion, an inverted left atrial appendage must be considered as one of the causes for a left atrial mass after surgery. Although the prevalence is unknown, it is probably more common that the other rare causes of left atrial mass, such as septal aneurysm, ³ pulmonary vein remnant, ⁴ diaphragmatic hernia, ⁵ and septal hematoma. ^1,3 Knowledge that such an entity exists should direct surgeons and cardiologists to investigate its possibility and, if confirmed, help avoid an unnecessary reoperation or other inappropriate therapy.

Footnotes

From the Divisions of Cardiothoracic Surgery^a and Pediatric Cardiology,^b the University of Illinois, Chicago, Ill.

References

1. Tallano JV, Gardin JM. Vegetation, tumor, masses & thrombi. In: Tallano JV, Gardin JM, editors. Textbook of two-dimensional echocardiography. New York: Grune & Stratton, 1993:239-70.
   
2. Slavik Z, Salmon AP, Lamb RIC. Unusual left atrial mass following cardiac surgery in an infant. Eur J Cardiothorac Surg 1994;8:566-7.[Abstract]
   
3. Mera F, Patt J, Israel W, Dubin JD. Atrial septal aneurysm simulating a left atrial mass diagnosed by transesophageal echocardiography. Am Heart J 1993;126:1224-5.[Medline]
   
4. Manning WJ, Waksmonski CA, Riley MF. Remnant of the common pulmonary vein mistaken for a left atrial mass: clarification by transoesophageal echocardiography. Br Heart J 1992;68:4-5.[Abstract]
   
5. Movsowitz HD, Jacobs LE, Movsowitz C, Kotler MN. Transesophageal echocardiographic evaluation of a transthoracic echocardiographic pitfall: a diaphragmatic hernia mimicking a left atrial mass. J Am Soc Echocardiogr 1993;6:104-6.[Medline]
   

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This Article Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Bradley S. Allen Michel Ilbawi Renee S. Hartz Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Allen, B. S. Articles by Thoele, D. Search for Related Content PubMed PubMed Citation Articles by Allen, B. S. Articles by Thoele, D.