4.5 The impact of the esophageal route and periesophageal structures on the distance between the endocardium of LA and the esophagus
Tsao et al16 and Maeda et al15 classified the esophageal route into two major types according to the inferior PVs. Most of the esophageal route (88% to 90%) was categorized into type 1, which was similar in our study (91.2%). MPL ran much inferior to CPL when it touched the LAPW. In our study, a thicker myocardium and higher presence of fat pad were identified in the course of MPL than in all the 3 types of esophageal routes below CPL. We also focused on the esophagus compressed in a triangle space at the left inferior PV level because the esophagus vulnerability to injury when LAPW ablation is performed11 possibly, in part, attributable to the short distance from the LAPW to the esophagus and the confinement by periesophageal structures. Reports have shown that higher peak esophageal luminal temperatures were noted with ablation in AF patients whose esophagus were confined by LA, aorta, and the vertebral body. Thus, esophageal confinement might also be a risk factor for the development of AEF.24 Our results show that 38% of the AF patients were among the confined group, which indicated that this kind of topological esophagus location is not rare. However, none of the esophagus was enclosed by LA, aorta, and vertebral body at the MPL level. Thereby, the longer the distance of the MPL from the esophagus, the better it is to avoid ablation at such a vulnerable area, and the subsequent chance to reduce the risk of esophageal injury. However, we still need to pay more attention to the shorter distance from MPL to the esophagus displayed by the confined group, compared with the unconfined group, as it was relatively more accessible and safer when we perform MPL in the unconfined group than in the confined group.