title: Endocardial visualization of esophageal-left atrial anatomic relationship by three-dimensional multidetector computed tomography "navigator imaging".
abstract: BACKGROUND
  The close proximity of left atrium (LA) and esophagus during radiofrequency ablation for atrial fibrillation (AF) predisposes to thermal injury resulting in atrio-esophageal fistula. This work proposes to study the anatomic relationship between the esophagus and the LA wall using multidetector computed tomography (MDCT) three-dimensional (3D) "Navigator" reconstruction technique.
  
  
  METHODS
  Forty-five consecutive patients (37 men, mean age 52.7+/-14.1 years) with preradiofrequency ablation MDCT scans of the thorax for AF were recruited. Length and type (continuous or interrupted) of fat pad between esophagus and LA were evaluated. The position, width, and length of the esophagus in contact (without fat pad) with the LA were determined by using "Navigator" software on the endocardial view of LA.
  
  
  RESULTS
  The fat pad was continuous in 4% (2 of 45) and interrupted in 96% (43 of 45) patients. The mean width and length of esophageal-LA contact in 43 cases with interrupted fat pad was 24.0+/-5.8 mm (range 10.5-35.3 mm) and 41.9+/-11.6 mm (5.4-64 mm), respectively. There was an inverse relationship between the lengths of the esophageal-LA contact and the upper fat pad (r=-0.50, P=0.001). The esophagus was located to the left, right, and midline of the LA in 40, 2, and 1 patients, respectively, and the esophagus was in contact with and overrode the PV orifice in 22 and 4 patients, respectively.
  
  
  CONCLUSIONS
  Direct esophageal-LA contact without the intervening fat pad was present in 96% of the cases, with 93% of esophagi lying to the left of the LA and 51% in contact with a PV orifice. Three-dimensional Navigator imaging technique has enhanced the visualization of the anatomical information of the esophagus, LA wall, and PV orifices that may be used to avoid thermal injury to the esophagus during LA ablation procedure.
authors.affiliation: Department of Diagnostic Radiology, The University of Hong Kong, and Department of Radiology, Queen Mary Hospital, Hong Kong.
authors.forename: Si-Lun
authors.initials: SL
authors.lastname: Wang
authors.forename: Clara G C
authors.initials: CG
authors.lastname: Ooi
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
authors.forename: Michael W C
authors.initials: MW
authors.lastname: Yiu
authors.forename: Cby
authors.initials: C
authors.lastname: Pang
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
mesh_terms: D000328:Adult; D000368:Aged; D004699:Endocardium / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D004947:Esophagus / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006325:Heart Atria / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D025321:Surgery, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D014159:Transducers; D014584:User-Computer Interface