Ann Thorac Surg 2001;71:719-722
© 2001 The Society of Thoracic Surgeons
Case report
Left atrial aneurysm
J. Mark Morales, MDa,
Sanjeet G. Patela,
Joseph H. Jackson, MDa,
James A. Duff, MDa,
James W. Simpson, MDa
a Driscoll Children’s Hospital, Corpus Christi, Texas, USA
Accepted for publication March 31, 2000.
Address reprint requests to Dr Morales, PO Box 30104, Corpus Christi, TX 78463-0104
e-mail: moralej{at}driscollchildrens.org
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Abstract
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Aneurysms of the left atrium are rare abnormalities. They can be congenital or acquired. Whereas a true congenital aneurysm presents as isolated pathology, inflammatory or degenerative processes involving the endocardium are associated with the acquired type. The clinical records of 2 patients with the diagnosis of left atrial aneurysm were reviewed, along with the surgical strategies, current literature, and patient outcomes. Because of the risk of life-threatening complications, surgery is recommended even in asymptomatic cases. Resection and mitral valvuloplasty should be the treatment of choice.
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Introduction
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Isolated aneurysm of the left or right atrium is a rare congenital abnormality, first described by Semans and Taussig [1] in 1938. There have been isolated reports in the surgical literature; the age of presentation varies widely, from 1 month to 66 years. The appearance of an aneurysm as an isolated pathology, without evidence of predisposing, inflammatory, or degenerative processes, indicates a congenital origin. Acquired aneurysmal dilatation of the left atrium is seen secondary to inflammatory processes.
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Case reports
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Patient 1
An 11-month-old Hispanic boy, born full term, 10 lbs weight at birth, sustained a cardiorespiratory arrest shortly after birth. He was resuscitated and placed on mechanical ventilation, and after several weeks of hospitalization he was discharged home. At the age of 1 month he was found to have a murmur; 11 months later he was transferred to our institution exhibiting cardiomegaly. Chest auscultation demonstrated 2/6 holosystolic murmur throughout the precordium, hepatomegaly, and bibasilar rales. Chest roentgenogram showed significant cardiomegaly. Magnetic resonance imaging of the chest demonstrated a large mass displacing the heart (Fig 1). An echocardiogram demonstrated mitral insufficiency and a giant left atrium. Cardiac catheterization revealed a large aneurysm of the left atrium (Fig 2).
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Fig 1. Magnetic resonance imaging scan revealing large left atrial aneurysm displacing the heart anteriorly.
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At the time of surgery, through a median sternotomy, on cardiopulmonary bypass, moderate hypothermia, and aortic cross-clamp, the heart was displaced superiorly and anteriorly, and the posterior aspect of the heart was exposed, revealing a large aneurysm of the left atrium that projected posteroinferiorly, displacing the left ventricle anteriorly. The neck of the sac extended to the level of the posteromedial commissure without directly involving it. The aneurysmal sac was resected to the base of the commissure and closed with a double running layer of 5-0 Prolene. A standard atriotomy was performed, and the valve was tested, yielding no significant insufficiency. The patient was asymptomatic at the 2-year follow-up. Pathologic examination demonstrated a true aneurysmal sac of 6 by 4.2 cm, with endocardial lining. All layers of the atrial wall were present, indicating a true atrial aneurysm (Fig 3).
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Fig 3. Histologic section of left atrial aneurysm wall (x50). The top section shows the endocardial surface, the middle area is collagenous atrial substance, and the lower section shows the cardiac atrial muscle.
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Patient 2
This child is a 7-year-old African American with a medical history significant for cardiomegaly and congestive heart failure. Positive clinical findings included a holosystolic murmur with a diastolic rumble, hepatomegaly, and cardiac cachexia. The child was evaluated in the clinic, where the echocardiogram demonstrated severe mitral insufficiency, mild mitral stenosis, and an aneurysmal left atrium. Chest roentgenogram showed significant cardiomegaly; electrocardiogram displayed left atrial hypertrophy and left ventricular enlargement. The patient was scheduled for elective mitral valve repair and aneurysmal excision. A week later he decompensated, requiring hospitalization. Cardiac catheterization demonstrated moderate to severe mitral regurgitation, with mild mitral stenosis along with a large left atrial aneurysm. At surgery, through a median sternotomy under cardiopulmonary bypass, the left atrium was approached through a standard incision. The aneurysm was identified extending posteriorly and involving the posteromedial commissure of the mitral valve (Fig 4). The valve leaflets and the subvalvular apparatus were fibrosed. The aneurysm was repaired from the inside of the left atrium by excising the abnormal sac and approximating the fibrous neck with a double layer of 5-0 Prolene, and the appendage was plicated. A valvuloplasty was attempted but unfortunately proved to be unsuccessful. The mitral valve was replaced with a 3l-mm Carbomedics mechanical prosthesis. The pathologic section demonstrated myxomatous changes in the valve and endocardium of the left atrium. Postoperatively, the patient is doing well, remaining in junctional rhythm 1 year after surgery.
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Comment
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Congenital aneurysm of the left atrium is a rare condition that usually presents as an isolated roentgenogram finding or with symptoms related to cardiac arrhythmia and systemic embolism. The mean age of presentation in a previously reported review was 23.5 years [3]. Although there is some discrepancy in the literature in regards to what constitutes a congenital aneurysm and which aneurysmal dilatations of the left atrium are secondary to congenital mitral regurgitation, this difference carries only academic value, because the clinical approach is the same: resection of the aneurysm and repair or replacement of the valve as needed [4, 5, 6]. Left atrial aneurysms are most commonly found in the left atrial appendage, but they can present in the atrial wall, as was the case in both of our patients. Such aneurysms can be found with an intact pericardium [6] or with a pericardial defect [7], in which case the aneurysmal protrusions resemble dog’s ears [8]. The aneurysms can be classified as congenital or acquired, the latter being more common and associated with conditions such as rheumatic heart disease, tuberculosis, or syphilitic myocarditis. The absence of anatomic abnormalities of the mitral valve as well as the lack of degenerative or inflammatory processes in the histologic section support a congenital etiology.
Mitral regurgitation can occur primarily or as a consequence of the atrial enlargement and the asymmetric annular deformity. Whereas older patients are usually asymptomatic, newborns and infants present with cardiac decompensation [4, 9]. Congestive heart failure may be related to an anatomic obstruction of the pulmonary venous drainage [4]. Respiratory distress, especially in the neonate, can be secondary to displacement of the relatively flexible mediastinum and airway obstruction (as one may observe in Fig 1). Cardiac tamponade due to the limitation of diastolic expansion of the left ventricle has been described in the literature [9]. Other symptoms, prevalent in the older patients, include systemic embolization or supraventricular arrhythmias, which probably result from an abnormal atrial wall [10].
In asymptomatic patients, the diagnosis can be suspected by the enlarged heart silhouette of the chest roentgenogram. A mediastinal mass can be ruled out by computed tomography of the chest or magnetic resonance imaging. Transthoracic echocardiogram may reveal the enlarged left atrium and mitral insufficiency; however, the point of communication of the aneurysm with the left atrium can be difficult to image. A transesophageal echocardiogram is much better for evaluating this area of the heart; moreover, the atrial appendage can be imaged for the presence of thrombus [11]. Foale and colleagues [12] characterized the echocardiographic findings of left atrial aneurysms as: (1) origin from an otherwise normal left atrium, (2) a well-defined communication with the atrium, (3) a position within the pericardium, and (4) distortion of the left ventricular free wall by the aneurysm. Cardiac catheterization with cineangiocardiography is probably still recommended in order to evaluate pressures, shunts, and biopsy tumors if necessary.
Because of the risk of life-threatening complications, including tamponade (patient 1), tachyarrhythmia, systemic embolization, congestive heart failure, or the potential theoretical risk of rupture, surgery is recommended even in asymptomatic cases. The principles of surgery should emphasize minimal manipulation of the aneurysm until cardiopulmonary bypass is established, in order to avoid embolization, especially if a transesophageal echocardiogram has shown thrombus within the heart. In neonates or infants, the aneurysm is best approached posteriorly after displacing the apex of the heart superiorly. The aneurysmal sac is resected to the neck, and the left atrium is closed. The mitral valve can be tested with cold saline infusion through a standard left atriotomy, or by placing a vent in the apex of the left ventricle. In older patients, aneurysms can be approached through the left atrium, and the sac can be resected and the valve repaired or replaced as needed. It is important to assess the relationship of the neck of the aneurysm with the posterolateral mitral commissure, because on occasion the aneurysm extends into the commissure, requiring a partial annuloplasty (De Vega) in order to reestablish mitral competence. Aneurysms involving the atrial appendage can be resected by a left thoracotomy without the use of cardiopulmonary support [12].
In conclusion, early diagnosis and prompt surgical therapy will obviate the risk of devastating complications of this rare problem [2, 13].
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References
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Abstract
Introduction
