RAA is an extremely rare congenital cardiac condition that can present anytime between fetal life and old age1,2. Most right atrial aneurysm manifested no obvious symptoms3. However, atrial fibrillation, supraventricular arrhythmias(in this case) and intracardiac thrombus may occur2,4−5. Our report details a 6-years disease progression with a single RAA who was symptomatic with supraventricular tachycardia and no history of embolic event.
The etiology of RAA is still unclear, it has been speculated that an intrinsic structural protein defect, dysplastic pectinate muscle or abnomal collagen were prone to dilate the right atrial6.
Histological changes of resected aneurysmal tissue had revealed a variety of changes adjacent to entirely normal findings, including fibrosis, focal lymphocytic infiltration and focal myxoid changes1.
Abnormal enlargement of the RA was often confused with other more common conditions such as Ebstein’s anomaly7, diverticulum and idiopathic right atrial enlargement. As in our case, it is diffcult to distinguish Ebstein's anomaly from idiopathic right atrial enlargement, when the whole right atrium was enlarged. But when the right atrium side wall locally expanded and pushed the corresponding anterior tricuspid valve ring, resulting in the false downward movement of the anterior leaflet, it was easily misdiagnosed for Ebstein's anomaly, especially the insertion points of mitral and tricuspid valves in the apical four-chamber view as the distance between these two points greater than 15 cm. However, differential diagnosis can be made by carefully observing the structure of the right atrial wall and the relationship between the out pouching of right atrial and tricuspid valve.
The natural course of RAA remains unclear, but reported complications included thrombus formation in the RA cavity, predisposing to thromboembolic complications such as stroke and pulmonary embolism. Arrhythmias and atrial rupture are the other potential complications.
Most authorities recommended surgical resection in the patients with marked RA enlargement complicated by atrial fibrillation, evident thrombus formation or signs of pulmonary embolization. At present, there is no unified recommended treatment standard in the world. In general, conservative treatment is recommended for asymptomatic patients8. Patients with congenital heart defects, or large and symptomatic tumors were recommended surgery. But some patients with small and symptomatic tumors, radiofrequency ablation can be tried, and the effect is also acceptable. However, the current histological findings showed right atrial wall of right atrial aneurysm was thin and degenerative, so the risk of perforation is higher than normal ventricle or atrium during ablation. According to these recommendations, he had received radiofrequency ablation to maintain his sinus rhythm five-year ago, now the best therapy of choice was to reduce the size of RA surgically, but he was received a long-term regular anticoagulation therapy, because she did not accept surgery.