2 | CASE REPORT
A 1-year-old infant was first disclosed right atrial enlargement at the 26 weeks of gestation, but the parents were unable to provide detailed prenatal examination data. The infant had been asymptomatic and had not received any echocardiography until he got a prolonged unhealed cold and eventually developed pneumonia accompanying with supraventricular tachycardia and dyspnea at the local hospital. After the infection and arrhythmia were controlled by antibiotics and digoxin, he was transferred to our hospital.
Preoperative chest X-ray showed an enlarged cardiac shadow with a prominent right atrial contour (Figure 1A). Transthoracic echocardiography (TTE) disclosed a giant right atrial aneurysmal structure measured 7.8 × 7.5 cm and a large patent foramen ovale (PFO) (Figure 1B). The anatomical position and structure of the tricuspid valve (TV) were normal. The right ventricle (RV) and left atrium (LA) were compressed by the abnormal cavity, whereas tricuspid regurgitation was minimal. The other valves and left ventricle were normal with good systolic function. An enhanced cardiac computed tomography scan was requested and showed a large aneurysmal dilatation of the right atrial appendage with no internal thrombi (Figure 2). Thus, the infant was diagnosed with a giant right atrial appendage aneurysm complicated with a PFO and was indicated to surgery considering the large size of RAAA, the PFO and the previous episodes of supraventricular tachycardia and dyspnea. After induction of anesthesia, transesophageal echocardiography (TEE) was performed to evaluate the RAAA (Figure 3A) and cardiac structure. It revealed that the free wall of the right ventricle (RV) was compressed by the large aneurysm (Figure 3B). Although blood flow in the right atrium and RAAA was slow, no thrombus was found. Both ventricles and left atrium were of normal size and function (Figure 3B). TEE also revealed a large PFO and mild tricuspid regurgitation with normal RV systolic pressure. Considering the large aneurysm might have higher risks of bleeding and arrhythmia, the surgeons performed the aneurysm resection under cardiopulmonary bypass (CPB). The giant RAAA occupied almost all pericardial space (Figure 4A). The aneurysm sac was opened, an extremely thin atrial wall was observed, no thrombus was found and there were many tube-like structures distributed on the inner wall during surgery (Figure 4B). The aneurysm was resected and the PFO was closed. After weaning of CPB, postoperative TEE showed that the cardiac structure was normal and the tricuspid valve functioned normally without regurgitation or insufficiency (Figure 5A). And the postoperative TTE dimension of the right atrial appendage showed a decrease in right atrial size to 2.0 cm × 2.35 cm (Figure 5B). Later pathological examination confirmed the diagnosis of RAAA (Figure 5C).
The postoperative course was uneventful and the infant was discharged on the 5th day after the surgery. He had a full recovery without any complications at the three-month follow-up.