Case presentation:
A 3-week-old neonate weighing 3400 grams, was brought to the emergency department of a pediatric hospital. The neonate who was delivered with no relevant birth details, has recently suffered from severe respiratory distress symptoms, and was admitted and promptly intubated in that hospital. Chest-x ray (CXR) showed a well-delineated (mass) on the left border of the heart extending to the left hemithorax, and causing complete compression of the left inferior pulmonary lobe (Figure-1). TTE revealed massive dilatation of LA (LA aneurysm) about 8 cm with moderate to severe mitral regurgitation (MR). CTA was performed to precisely evaluate the LA aneurysm, its relation with the left ventricle (LV), and the condition of the pulmonary veins and other surrounding structures (Figure-2-A, Figure-2-B). Depending on the clinical state of the patient, surgical intervention was scheduled on urgent basis. Median sternotomy approach was used. Upon opening the pericardium, the heart protruded outside the chest, and the LA appendage was apparent and intact (it was not part of the aneurysm) (Figure-3). Total cardiopulmonary bypass (CPB) with bicaval cannulation was prepared, and the heart was arrested by antegrade cold blood cardioplegia. The heart was lifted outside the pericardium and rightward (as in the repair of total anomalous pulmonary venous connection), and the aneurysm was found posteriorly and on the left side with very thin wall. The aneurysm was opened, and its communication with LA was confirmed (Figure-4). The left atrial appendage was not the origin of the aneurysm; however, it was originating from the posterior wall of the LA near the posterior mitral annulus. The aneurysm was of sessile nature, and extended to the posterior wall of LV adjacent to marginal arteries. It was completely resected, with special attention to avoid injury to the mitral annulus or any of the marginal arteries. The resulted defect was closed by two layers of running 7/0 prolene suturing (Figure-5). The LA was opened as in mitral surgery, and mitral valve was inspected. The leaflets and subvalvar apparatus were normal. The valve was tested by saline test and was completely competent. Aortic cross clamp was released, and weaning off CPB was uneventful. The patient was discharged from the hospital after 21 days with significant clinical improvement, and normal echocardiography.