Backgrounds: Localization of the esophagus and the left atrium (LA) posterior wall thickness (LAPWT) should be taken into account when delivering radiofrequency energy. Intracardiac echo (ICE) advanced into the LA is useful in visualizing LA and surrounding structure by its high and real-time resolution. Methods: In 73 patients (mean age, 68±12; paroxysmal AF in 45), 3-dimensional (3D) esophagus image was created with CARTO Soundstar® and its location was compared with contrast esophagography saved in Carto UNIVU™. LAPWT adjacent to the esophagus was measured at 4 levels: left superior PV (LSPV), intervenous carina (IC), left inferior PV (LIPV), and LIPV bottom. A target AI value was 260 (25W power) on the esophagus region. Results: All patients had the esophagus posterior to the left PV antrum. Creating 3D esophagus and measurement of LAPWT with ICE was done without any complications. ICE esophagus image was completely overlapped with contrast esophagography. LAPWT (mm) was 2.8 (interquartile range, 2.5-3.2), 2.2 (1.9-2.5), 1.9 (1.8-2.1), and 2.1 (1.9-2.4) for LSPV, IC, LIPV and LIPV bottom, respectively, while LA roof thickness 3.2 (2.9-3.6) (P<0.0001 by ANOVA). No residual conduction gap on the esophagus after the first circumferential PV isolation was found in 64 of 73 (88%) patients. Conclusions: ICE inserted into the LA can reliably locate and display the esophagus and its relationship to the LA. LAPWT was thinnest at LIPV level. AI-guide ablation targeting a relatively low target AI value 260 on the esophagus seemed to be effective.

Backgrounds. Fusion of the left and right inferior pulmonary veins (PV) (confluent inferior PV, CIPV) is a rare variation. Using intracardiac echocardiography (ICE) from the left atrium (LA), we measured the posterior wall thickness (PWT) of CIPV adjacent to the esophagus and compared it with LA posterior wall thickness (LAPWT) in non-CIPV cases. Methods. Of the consecutive 986 patients undergoing atrial fibrillation (AF) ablation from July 2020 to June 2022, seven (0.7%) had CIPV with a common trunk connecting to the LA diagnosed by 3-dimentinal contrast-enhanced computed tomography. Twenty-five AF patients without CIPV served as control. ICE was done from LA to measure PWT of CIPV and LAPWT of non-CIPV cases at the level of the left inferior PV. For ablation in CIPV patients, each superior PV was individually isolated, and BOX isolation of CIPV without ablating CIPV posterior wall was added. Results. CIPV PWT was 0.7±0.1 mm, while LAPWT of non-CIPV was 2.0±0.4 mm (P<0.001). In CIPV group, the upper and lower portions of CIPV were both apart from the esophagus (mean distances, 6.7±3.4 mm and 7.9±2.7 mm, respectively). Individual superior PV isolation and BOX CIPV isolation resulted in complete isolation of all PVs. There were no complications. All CIPV patients but one remained free from AF recurrence for 376±52 days. Conclusions. Although CIPV frequency is low (0.7%), CIPV PWT is very thin and a special care is needed in ablation. The present ablation strategy is effective for complete PV isolation with a less risk of the esophageal injury.