Surgical Treatment of Left Atrial Appendage Aneurysm: A Case Report

Background

Left atrial appendage aneurysm (LAAA) is a rare cardiac anomaly that was first reported in 1960 [1]. Since severe complications of LAAA have appeared, such as symptomatic thromboembolic events, arrhythmias, and congestive heart failure, surgical treatment is generally recommended [2]. The authors describe an asymptomatic 31-year-old woman who was hospitalized because of an LAAA that was incidentally detected via echocardiography. The patient was scheduled to undergo an operation to remove the aneurysm on cardiopulmonary bypass.

Case Presentation

A 31-year-old female patient was hospitalized without any particular antecedent. She underwent a thoracic x-ray and left ventricular hypertrophy was found, despite no signs of clinical symptoms or an abnormal electrocardiogram. The echocardiography revealed a large 66 x 54 mm LAAA expanded and partially compressed to the left side of the left ventricle (LV). However, the LV ejection fraction was normal (66%) as long as the pulmonary artery pressure. Computed tomography (CT) was performed to precisely assess the dimension of the LAAA and the communication with the LV, as well as the condition of the pulmonary veins and other surrounding structures (Figure 1). The patient was scheduled to undergo surgery in 2017.

A full median sternotomy was performed. Cardiopulmonary bypass was established with aortic and bicaval cannulations. The giant thin-wall LAAA was exposed with intact overlying pericardium. Aneurysmectomy was performed and no thrombus was found inside (Figure 2). Then, the base of the LAAA was sutured using 5/0 polypropylene (Figure 3). There was no evidence of left circumflex coronary artery injury visualized on intraoperative monitors nor evidence of other cardiac anomalies during the operation.

The postoperative course was uneventful. At the one-year follow-up visit, the patient remained asymptomatic with sinus rhythm. The echocardiography confirmed a normal size of the LA and no evidence of any residual leak or blood clot (Figure 4).

Discussion

Atrial appendage aneurysms may occur in either the left heart, the right heart, or both [2, 3]. To date, nearly 90 cases were individually reported in the literature since the first case in 1960 [1, 4]. Nevertheless, the actual rate of the LAAA has not yet been documented. The LAAA is associated with other cardiac anomalies, such as tricuspid atresia [4]. A “giant” LAAA is generally identified to be longer than 50 mm [5].

An aneurysm frequently arises in the third decade of life, and a quickly enlarging aneurysm can compress the adjacent cardiac structures and cause clinical symptoms, including palpitation, dyspnea, arrhythmia, and thromboembolic events [2]. The origin of LAAA has been attributed to dysplasia of the pectinate muscles and of the related bundles of muscles of the LA [6]. Neonates and infants are more likely to develop congestive heart failure and respiratory distress because of a large aneurysm that compresses the pulmonary veins and causes airway obstruction [7, 8].

Transthoracic echocardiography is commonly used for the investigation of the LAAA as well as the thrombosis or other cardiac abnormalities. However, transesophageal echocardiography allows a more detailed evaluation of the structure and the function of the left appendage, including blood flow across the orifice or the presentation of any small blood clots, and it is currently the modality of choice [9]. Various imaging techniques, including CT scan and magnetic resonance imaging (MRI), should be considered for more accurate anatomic definition of the LAAA, especially in the differential diagnosis. Diagnostic criteria for LAAA include: (1) origin from an otherwise normal-sized LA; (2) well-defined communication with the LA; (3) location within the pericardium; and (4) distortion of the LV by the aneurysmal body [10].

Early surgical intervention is recommended, even in asymptomatic cases, for preventing potentially fatal cardiovascular events, such as stroke [11]. Conversely, a conservative treatment strategy has been reported in some giant LAAA cases. Plonska-Gosciniak and colleagues reported the case of a 45-year-old patient presenting with palpitation and exercise intolerance with a massive LAAA (112 x 49 x 80 mm) who refused the operation. After the 20-year follow-up, this patient occasionally acquired a supra-ventricular arrhythmia [12]. Sharma reported the case of a 35-year-old patient with an LAAA (51 x 66 mm) presenting with significant shortness of breath. The patient was monitored for medical treatment for six months with single oral anticoagulation treatment to prevent any future thromboembolic events [13]. Generally, even when there are no symptomatic thromboembolic events, further imaging techniques, including MRI [5], need to be performed to detect any thromboembolic consequences.

Although some authors have demonstrated that an asymptomatic patient with LAAA may be safely managed conservatively over several years with appropriate drugs and frequent follow-up [12-14], surgical management is highly recommended in the case of an LAAA with serious complications or other coexisting abnormalities. There are no gold standard surgical method options including neck-ligation, purse-string techniques, and stapling, with or without aneurysmal excision [15]. Standard median sternotomy is more favorable than other approaches in many situations requiring other surgical procedures, such as surgical thrombectomy, the Maze procedure in the case of persistent atrial fibrillation [16], and in patients who are secondary to mitral regurgitation requiring the valvuloplasty [7]. Otherwise, many authors have successfully reported the minimally invasive approach as an alternative to median sternotomy for LAAA surgery with many potential advantages [17, 18]. However, despite the good surgical outcome, the optimal strategies for the LAAA are still under debate.

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