A giant left atrial appendage aneurysm with a large pinball-like thrombus in a 2 year old.

Congenital left atrial appendage aneurysm is very rare. We describe a giant left atrial appendage aneurysm with a pinball-like mobile thrombus in a 2-year-old child with cardioembolic stroke. Patient underwent successful surgical resection of the aneurysm.

CASE REPORT

A 2-year-old male child presented with an episode of seizures followed by left-sided hemiparesis. There were no other abnormal physical findings. The chest radiograph demonstrated prominence of the superior left heart border (the left atrium). There was no past history suggestive of any cardiac disease. The ECG showed normal sinus rhythm without evidence of left atrium enlargement. Transthoracic echocardiography [Figures 1 and 2] revealed a large cavity lateral to the heart within the pericardial space, indenting the anterolateral wall of the left ventricle. Two-dimensional (2-D) and Doppler echocardiograms in the apical four-chamber view showed that this space communicated with a normal-sized left atrial cavity via a narrow neck and was diagnosed as left atrial appendage aneurysm (LAA). The aneurysm size was 5.6 × 5.1 cm and extended laterally toward the cardiac apex. The mitral valve apparatus was normal. Inside this aneurysm, a large thrombus (3 cm diameter) with variegated echo texture and dreadful pinball-like movement was seen [Videos 1 and 2] Each of these “pinball-like attempts” of the thrombus to escape from the aneurysmal cavity into the left atrium was halted by a relatively narrow neck of 1.3 cm diameter. Another smaller thrombus was seen attached to the lateral wall of the aneurysm. The diagnosis was further confirmed by cardiac magnetic resonance imaging (MRI). Resection of the aneurysm was done with median sternotomy approach under cardiopulmonary bypass. Postoperative period was uneventful.

Figure 1

Transthoracic echocardiography showing large left atrial appendage aneurysm (with a relatively narrow neck of 1.3 cm diameter) lateral to the heart within the pericardial space, indenting the anterolateral wall of the left ventricle. A large thrombus (3 cm diameter) is seen inside the aneurysm

Figure 2

Transthoracic echocardiogram (subcostal view) showing large left atrial appendage aneurysm (5.6 × 5.1 cm)

DISCUSSION

Aneurysms of the left atrium may be congenital or acquired.[12] They are considered to be congenital if they arise as a primary lesion from an otherwise normal atrial chamber[3] and acquired if they develop secondary to raised left atrial pressure.[1] Congenital aneurysm of the left atrium is a very rare entity. Only a few cases are reported in the world literature. These aneurysms most frequently involve the atrial appendage. Victor and Nayak[4] attributed the aneurysm to congenital dysplasia of the musculi pectinati in the left atrial appendage and of the bands of atrial muscle from which they arise. In their patient, the neck of the sac was wide, and they attributed it to the failure of lax inner and outer bands to constrict the base of the appendage. In our patient, the neck of the sac was narrow. So, there may be some other mechanism in addition to congenital dysplasia of these muscles. Although congenital, the majority of the patients are asymptomatic until adult age, when complications such as cardiac arrhythmias and systemic embolization may occur.[2] Clinical presentation in childhood as in our case is even rarer. Atrial thrombi occur, especially in patients with atrial arrhythmias. Even in the absence of arrhythmias, emboli have occurred in patients with LAAs as in our patient. Stasis of blood within the aneurysm probably predisposes to thrombus formation.[5] Some patients complain of angina pectoris. A chest X-ray showing prominent left cardiac border should raise the suspension of left atrial aneurysm. A 2-D echocardiography imaging with color and pulsed-wave Doppler is the most useful noninvasive diagnostic modality which typically shows the cyst-like structure connected to the left atrium and demonstrates the flow through the communication between the aneurysm and the body of the left atrium as in our case. The body of the aneurysm typically causes indentation of the left ventricular wall. Differential diagnosis on echocardiography imaging involves acquired left atrial “aneurysms,” extra pericardial herniations of portions of the heart, solid or cystic paracardiac tumors and pericardial or extracardiac fluid collections, and an enlarged coronary sinus lying behind the heart.[1] Transesophageal echocardiography is a useful additional diagnostic tool, particularly for the detection of thrombus. Magnetic resonance imaging is also helpful for establishing the diagnosis and delineating the relation to the surrounding structures.[6] The complications associated with this abnormality can be devastating. Hence, surgical resection is recommended even in an asymptomatic patient.[7] Some surgeons approach the left atrium via left thoracotomy. In view of the large thrombus in our patient, median sternotomy with cardiopulmonary bypass was done for the complete removal of the aneurysm and clot. Surgery is an effective therapeutic measure and there are no reported operative mortalities.