Introduction
Pulmonary vein (PV) isolation (PVI) with radiofrequency (RF) catheter
ablation is an established strategy for treating atrial fibrillation
(AF).1 When RF energy is applied to the left atrial
(LA) posterior wall adjacent to or near the esophagus, a special care
needs to be taken because of the thermal injury of the
esophagus2,3, and reducing RF energy and contact force
and shortening application time generally
recommended.4 For localization of the esophagus during
the PVI procedure, an esophageal temperature probe to monitor esophageal
temperature is widely used.5,6 Esophagography by
asking the patient to swallow the contrast medium just before the
procedure is also useful.7,8
Intracardiac echography (ICE) with the use of a Carto
SoundStar® ultrasound catheter (Biosense Webster,
Diamond Bar, CA) is useful for not only transseptal puncture but
creating the LA 3-dimensional (3D) image from the right atrium. This LA
3D echo image can be used for integration with the LA 3D computed
tomography (CT) image with the assist of the
CartoMergeTM module (Biosense Webster) with a high
accuracy.9 In our laboratory, by inserting the Carto
SoundStar® catheter into the LA cavity through the
long sheath advanced to the LA, we have attempted to visualize the LA
posterior wall (LAPW) and the esophagus from the LA. This method seemed
to allow us to create the 3D esophagus image adjacent to the LAPW in a
real-time fashion during the AF ablation procedure and assess the direct
relationship between the esophagus and LAPW. The purpose of the study
was to validate the present method of esophagus visualization and
analyze the LAPW thickness adjacent to the esophagus. We further
assessed the outcome after ablation-index (AI)-guide circumferential PVI
with a relatively low target AI value on the esophagus region confirmed
by the ICE.