2.4 Measurements
Measurements of the parameters were made using a digital caliper on each posterior line under predefined points (CPL = a, b, c and MPL = d, e, f), which are segments that touched the esophagus, with their related esophageal routes are as follows: (1) the shortest distance from the endocardium of LAPW to the anterior border of the esophagus. (2) The thickness of the fat pad, if it existed. (3) The thickness of LAPW myocardium. (4) The distance between the esophagus and ipsilateral inferior PV ostia and the shortest distance from LA to the spine at the left inferior PV level. The distance from the endocardium of LAPW to the esophagus was measured from the density of the intra-cavitary contrast that filled the LA to the anterior border of the esophagus (Figure 2). The presence of a fat pad between the LAPW and the esophagus was identified by an abrupt change in the signal density. The thickness of the LAPW myocardium was measured from the density of the contrast agent in the LA to the fat pad or the outline of the anterior esophageal wall if no fat pad was present. All parameters were determined independently by two cardiologists using axial planes and 3D CT images. If there were discrepancies between those results, they were adjudicated by a third investigator.