Assessment of LAPW and edophagus by ICE
Carto Soundstar® catheter was inserted into the LA through the SL0 sheath. The ICE image by the catheter was created digitally with the use of a VividTM iq imaging console (GE Healthcare, Fairfield, Connecticut). The Soundstar® catheter was rotated so that the imaging plane could see the LAPW and esophagus (Figure 1A ). Gentle clockwise torque was maintained to keep the catheter tip close to but not contact to the posterior wall. The mean distance between the transducer of the catheter and LAPW was 2.4 ± 0.9 cm (n=73). For imaging from the LA, we used a 6 MHz frequency among variable frequencies (4.5, 6, 8, 10, and 11.5 MHz) equipped in Carto Soundstar®. A special care was taken to obtain the image plane as perpendicular as possible toward the LAPW. The esophagus in the ICE imaging was characterized by two echolucent stripes of esophageal muscle separated by a bright echogenic lumen (Figure 1B ). The images of LAPW and esophagus were recorded at 4-6 pre-specified height levels including the left superior pulmonary vein (LSPV), inter venous carina, left inferior pulmonary vein (LIPV), and bottom of LIPV (Figure 1A ), while referring a 3D LA CT image.