Abstract
Left atrial appendage aneurysm is an infrequent abnormality presenting as atrial tachyarrhythmias, progressive dyspnoea, atypical chest pain and systemic thromboembolism. Surgical excision is considered to prevent fatal complications, even in asymptomatic cases. We describe the case of a 44-year-old woman with a history of acute cerebral infarction caused by emboli from a giant left atrial appendage aneurysm, which is the largest one reported to date. Histopathology and Masson staining confirmed the final diagnosis.
INTRODUCTION
Left atrial appendage aneurysm (LAAA) is a rare abnormality with potentially fatal complications. Herein, we present a case of a 44-year-old woman with a history of acute cerebral infarction caused by emboli from a giant LAAA, which is the largest one reported to date. Written patient informed consent was obtained to submit and publish this report.
CASE REPORT
A 44-year-old woman with right-sided paralysis was admitted to our institution because of acute cerebral infarction and suspected cardiac thrombosis. Physical examination was unremarkable. The chest roentgenogram showed a marked prominence of the left cardiac border with a cardiothoracic ratio of 0.78. Transthoracic echocardiography demonstrated a giant echo-free space adjacent to the posterolateral wall of the left ventricle, communicating with the left atrium through a 2-cm wide neck. She had normal left ventricle function and cardiac valves. A multislice computed tomography (CT) scan revealed a giant chamber arising from the left atrium with thrombus and indentations of the ribs (Fig. 1). A twelve-lead electrocardiogram confirmed normal sinus rhythm.
Computed tomography (CT) revealed a giant chamber with a thrombus arising from left atrial appendage, which is larger than the original heart (A and B). The indentations of the ribs on the aneurysmal wall were found in a 3-dimensional CT reconstruction (C). LAAA: left atrial appendage aneurysm.
Considering the size of the aneurysm and history of systemic thromboembolism, aneurysmectomy and intracardiac thrombectomy were performed through median sternotomy with cardiopulmonary bypass and mild hypothermia. Intraoperatively, an 18 cm × 10 cm × 8 cm intrapericardial aneurysm was visualized (Fig. 2A). After cardiac arrest, the aneurysm was incised and some thrombi were found inside the cavity of the aneurysm which was originating from the orifice of the left atrial appendage (Fig. 2B). After resecting the aneurysm, the remnant of the left atrial appendage was closed with ‘Sandwich’ suture using 4-0 prolene reinforced by Teflon patches.
A giant 18 cm × 10 cm × 8 cm aneurysm, originating from the orifice of the left atrial appendage, was visualized (A). Some thrombi were found inside the cavity of the aneurysm (B). Haematoxylin–eosin staining and Masson staining of the aneurysmal wall showed extensive fibrosis in myocardium layer with sporadic lymphocyte infiltration (C).
The patient had an uneventful postoperative course and was discharged home on the seventh postoperative day. Histopathology reported loss of myocardial cross striations and myocardial steatosis together with fibrosis. Masson staining confirmed significant myocardial fibrosis in the aneurysm tissue (Fig. 2C).
DISCUSSION
LAAA is an extremely rare anomaly. Morphologically, the genesis of LAAA has been attributed to congenital dysplasia of musculi pectinati. The anomaly is usually diagnosed in the second to fourth decade of life due to symptoms such as palpitations, progressive dyspnoea, atypical chest pain and stroke [1].
LAAA could be detected by an unusual prominent left heart border on chest X-ray, especially in asymptomatic patients. Transthoracic or transoesophageal echocardiography provides great value in the initial evaluation of a suspected cardiac lesion. The distinction from paracardiac tumours or fluid collections can be demonstrated by the exchange of blood between the structure and the left atrium. Other investigations such as CT, magnetic resonance imaging and computed tomographic angiography can provide the anatomical detail of the extracardiac or intracardiac structure.
To prevent the occurrence of severe complications, such as myocardial dysfunction, atrial fibrillation and systemic embolism, early surgical intervention is recommended once the diagnosis is established even in asymptomatic cases. Various successful approaches to aneurysmectomy with or without cardiopulmonary bypass have been described, including median sternotomy, left thoracotomy, mini-thoracotomy and endoscope [2, 3]. In our case, the large size of this LAAA made us choose resection via median sternotomy and cardiopulmonary bypass. This approach provides a clear and motionless field so that we can have complete and accurate resection of the aneurysm to prevent the recurrence of thrombotic events, coronary artery injury and obstruction of the left superior pulmonary vein. A concomitant Cox-maze IV procedure along with resection of the aneurysm is considered in the case of LAAA with atrial fibrillation and biatrial enlargement [4].
On histological examination, transmural fibrosis without well-differentiated myocardial layers, and a paradoxal contraction with the ventricular mass is the typical characteristic of the aneurysm [5]. In our case, red thrombus cells were adherent to the endocardial layer, and increased distance between elongated myocytes mimick a ‘kinky hair’ appearance. Myocardium layer showed extensive fibrosis with sporadic lymphocyte infiltration. For the above-mentioned reasons, our patient was classified as LAAA, which is clearly distinct from atrial diverticulum or pseudoaneurysm.
CONCLUSION
In conclusion, we presented the largest LAAA ever reported with sinus rhythm. Because of its potentially fatal complications, early surgical intervention is reasonable once diagnosed. The use of the cardiopulmonary bypass via median sternotomy is the widely accepted approach, uniformly considered safe and successful.
Conflict of interest: none declared.
