A 19-year-old girl encountered the symptom of palpitation for 3 months with increased frequency and decrease in exercise duration. The ECG (electrocardiogram) showed atrial fibrillation (Fig.
1B) and several antiarrhythmic drugs were ineffective (including metoprolol, propafenone and amiodarone). Echocardiography showed normal diameter and function in all 4 chambers with mild tricuspid regurgitation (Fig.
1A), and transesophageal echocardiography excluded thrombus in the left atrial appendage. Regular examination ruled out hyperthyroidism and other diseases.
After Circumferential pulmonary venous isolation, there was no potential in the pulmonary vein mapping, but the intracavitary electrogram still showed atrial fibrillation (Fig.
2A). No obvious low voltage area and scar were found in atrial matrix mapping (Fig.
2B). Two hundred joules synchronized electrical cardioversion was performed, we observed 90ms advancement of the CS recording with initiation of the tachycardia, considered right atrial tachycardia, and activation mapping showed that the root of the free wall atrial appendage was first excited, where the catheter induced atrial fibrillation at this location, considered atrial tachycardia and atrial fibrillation originating from the root of the free wall of the right atrial appendage (Fig.
2C). Local site ablation failed to terminate the atrial tachycardia, the activation mapping was the same as before (Fig.
2D), then the right atrial fine mapping was performed and atrial fibrillation was triggered several times during the free wall mapping. Catheter modeling shows a sac-like structure, considering a possible right atrial free wall diverticulum (Fig.
2E). Therefore, a right atrial angiogram was performed, which showed a smooth sac-like abnormal structure in the right atrial free wall, with no commissural muscle showing, and the origin of atrial fibrillation was considered to be there (Fig.
3A). Was it right atrial diverticulum or variant right atrial appendage? Hence, we performed a CTA and TEE (Transesophageal echocardiography) which showed a diverticulum originating from the right atrial appendage (Fig.
3B&C).
Based on the previous findings the patient was referred to cardiac surgery and atrial appendage diverticulum was confirmed. After ligating the base of the right atrial appendage diverticulum and ablated the lateral fibrous ring at the base of the diverticulum and the right atrial appendage, the patient’s rhythm returned to sinus rhythm after 150 J synchronized electrical cardioversion, During the three-month follow-up, the patient had no recurrence of atrial fibrillation (Fig.
1C).