FIGURE 1 The relationship between the esophageal route and the CPL, as well as the MPL from three-dimensional (3D) volume rendering computed tomography (CT) images. The CPL (blue) and the MPL (green) were both shown on LAPW. The CPL or the MPL segment that touched the esophagus was divided into two equal parts by 3 points, respectively (a, b, c and d, e, f). A: Type A esophageal route covered the start portion of MPL (only descending branch of this line) B: The left lateral view of the same patient of panel A showed the start portion of MPL was separated from the esophagus by LIPV. C: Type B esophageal route covered mid part of MPL (both descending and ascending branches of this line). D: Type C esophageal route covered the end portion of MPL (only ascending branch of this line). We measured the shortest distance from every point to the anterior border of the esophagus. The esophagus in panel A and panel C were also categorized into esophageal route type 1, while the esophagus in panel D was categorized into esophageal route type 2. DA, descending aorta; ESO, esophagus; LA, left atrium; LAA, left atrial appendage; LIPV, left inferior pulmonary vein; LL, left lateral; LPVI, left pulmonary vein isolation; LSPV, left superior pulmonary vein; LV, left ventricle; MA, mitral annulus; MPL, modified posterior-inferior line; CPL, conventional posterior line; RIPV, right inferior pulmonary vein; RPVI, right pulmonary vein isolation; RSPV, right superior pulmonary vein.