[Severe aneurysmal dilatation of the left atrium. Apropos of a case].

The authors report the case of an eleven year old child with aneurysmal dilatation of the left atrial appendage and underline the diagnostic value of Doppler echocardiography in this affectation. The two signs which led to investigation of the patient and the diagnosis of this rare congenital abnormality were bulging of the left heart border on chest X-ray and atrial fibrillation. In addition to visualising a left para-cardiac chamber communicating with the left atrium on transthoracic and transoesophageal echocardiography, colour Doppler confirmed an exchange of blood between the two chambers. This aneurysm was particularly voluminous and contained echos of spontaneous contrast, a possible source of thrombosis. Thoracic CT scan and angiocardiography did not provide any further useful information. The surgical findings confirmed the presence of a large aneurysm of the left atrial appendage and excluded partial agenesis of the pericardium, the main differential diagnosis. The aneurysm was excised under cardiopulmonary bypass, and, in particular, atrial fibrillation did not recur after surgery.