Elsevier

Heart Rhythm

Volume 5, Issue 7, July 2008, Pages 975-980
Heart Rhythm

Original-clinical
Comparison of computed tomography imaging with intraprocedural contrast esophagram: Implications for catheter ablation of atrial fibrillation

https://doi.org/10.1016/j.hrthm.2008.03.058Get rights and content

Background

Computed tomography (CT) has been used to localize the esophagus before radiofrequency ablation (RFA) of atrial fibrillation (AF).

Objective

The purpose of this study was to compare esophageal imaging by CT versus esophagram.

Methods

CT imaging of the left atrium was performed in 57 patients 1 week before RFA and was imported into the CARTO mapping system. The electrophysiologist created a virtual shell of the left atrium and pulmonary veins (PVs) that was merged with the CT image; however, the CT-defined location of the esophagus was not displayed. The patient was then given 10 mL of oral contrast. Using fluoroscopy, an electroanatomic catheter tagged the esophageal borders outlined by esophagram. The CT-defined esophagus was then imported, and the borders were tagged on the merged map. In this manner, the esophagus borders by esophagram versus those by CT were compared.

Results

The maximum diameter of the esophagus by esophagram versus CT was not different (16.3 ± 3.4 vs. 16.5 ± 3.1 mm; P = .7). The esophagus was near the left PVs in 34 (62%), center in 13 (24%), and near the right PVs in eight (15%) patients. There was concordance between CT and esophagram in 48 of 55 patients (87%; P = .2). Ye, in 21 (44%) of 48 patients with concordant location, the CT-defined esophageal borders were separated from the esophagram-defined borders by ≥50% of the esophagus diameter.

Conclusions

Reliance on remotely acquired CT images does not ensure adequate intraprocedural localization of the esophagus or enhance recognition of esophageal motility.

Introduction

A common strategy for radiofrequency ablation (RFA) of atrial fibrillation (AF) is to deliver radiofrequency lesions in a circumferential manner around the pulmonary veins (PVs). A rare but often fatal complication of this strategy is an atrioesophageal fistula.1, 2 This complication is due to delivery of RF current in a region of the left atrium that is in close proximity to the esophagus. Accurate identification of the course of the esophagus during RFA of AF is an important tool to minimize the risk of thermal injury. Previous studies3, 4, 5, 6, 7, 8 have suggested that computed tomography (CT) imaging of the esophagus performed before the procedure accurately predicts the location of the esophagus at the time of the procedure. Other studies have defined the esophagus position by use of an electroanatomic catheter.9, 10 In addition, studies have noted movement of the esophagus.11 The purpose of this study was to assess the accuracy of a preprocedural CT scan in predicting the location of the esophagus at the time of the RFA procedure and to assess the extent of esophageal mobility during the procedure.

Section snippets

Study population

The subjects of this study were 57 patients undergoing curative RFA of symptomatic paroxysmal, persistent, or long-standing persistent AF. Inclusion criteria were completion of CT imaging of the chest within 1 week of planned RFA of AF and adequate imaging of the esophagus by contrast at the time of RFA procedure. Clinical characteristics of the study population are summarized in Table 1. The Institutional Review Board approved the study protocol.

CT imaging

All patients underwent electrocardiographically

Location of esophagus

The course of the esophagus was categorized as left, center, or right relative to the ostia of the PVs. By esophagography, the esophagus was located near the left PVs in 34 patients (62%), in the center in 13 patients (24%), and near the right PVs in eight patients (15%). The CT prediction of the location of the esophagus was concordant with the esophagram in 48 (87%) of 55 patients. This did not represent a statistical difference (P = .2). However, even among the 48 patients in whom the CT and

Main findings

There are several main findings of this study. First, by statistical analysis, a CT performed 1 week before RFA predicted the location of the esophagus at the time of the procedure. However, even though there was no statistical difference, the prediction of the esophagus location relative to the PVs by CT was inaccurate in 13% of the patients. This degree of error seems unacceptable when trying to carefully avoid delivering RF lesions adjacent to the esophagus. It is notable that a similar

Limitations

The limitations of this study are that the findings are limited to patients who undergo RFA with conscious sedation. Movement of the esophagus may not be as significant in patients who receive general anesthesia. A second limitation is the possibility that the mere administration of barium contrast in this setting may act as a stimulant for esophageal motility, although this phenomenon is not noted when esophagography is performed to evaluate esophageal motility.18 A third limitation is that

Conclusions

A common practice of identifying the esophagus during curative RFA of AF is a CT image performed preprocedure or creation of a virtual esophagus with use of an electroanatomical catheter during the procedure. However, the findings of the current study highlight that these imaging techniques may offer false assurance that RFA lesions are being applied in a safe position. Esophagography not only defines the general location of the esophagus relative to the PVs but also identifies subtle but

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