title: Direct imaging of transvenous radiofrequency cardiac ablation using a steerable fiberoptic infrared endoscope.
abstract: BACKGROUND
  Direct imaging through blood has been achieved in vivo using fiberoptics and infrared wavelength technology.
  
  
  OBJECTIVE
  The purpose of this study was to determine the feasibility of using a percutaneous, steerable, fiberoptic infrared endoscope to identify and characterize the electrode-tissue interface during transvenous cardiac ablation.
  
  
  METHODS
  Infrared endoscopy was performed during 24 catheter ablation attempts in 10 mongrel dogs. Infrared imaging was performed through a transparent dome located at the tip of a 7Fr steerable endoscope using an imaging wavelength of 1,620 nm. Radiofrequency ablation was performed using a 4-mm-tip electrode catheter. Attempts were made to identify the electrode-endocardial interface at each ablation site and to characterize any signal changes during ablation.
  
  
  RESULTS
  The electrode-tissue interface could be identified at 19 of the 24 ablation sites. Changes at the electrode-tissue interface were observed during ablation at 14 sites, which included a gradual increase in the tissue signal intensity at 12 sites. Small lucencies near the ablation electrode were observed at six sites. There was no interference during energy delivery. Endocardial features identified by endoscopy correlated with the postmortem appearance.
  
  
  CONCLUSIONS
  Direct imaging of intracardiac structures and the electrode-tissue interface can be achieved through blood during transvenous catheter ablation with infrared endoscopy using a steerable, fiberoptic, infrared endoscopic catheter. Ablation lesion formation can be seen as a gradual increase in signal intensity. Fiberoptic infrared endoscopy appears to be a promising new tool for guiding catheter ablation.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, University of Chicago, Chicago, Illinois, USA. bknight@medicine.bsd.uchicago.edu
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Knight
authors.forename: Martin C
authors.initials: MC
authors.lastname: Burke
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hong
authors.forename: Al
authors.initials: A
authors.lastname: McAuley
authors.forename: David
authors.initials: D
authors.lastname: Amundson
authors.forename: John
authors.initials: J
authors.lastname: Hanlin
authors.forename: Larry
authors.initials: L
authors.lastname: Blankenship
authors.forename: T Bruce
authors.initials: TB
authors.lastname: Ferguson
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000628:therapy; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D004285:Dogs; D004567:Electrodes, Implanted; D004699:Endocardium / Q000473:pathology / Q000601:surgery; D004724:Endoscopy; D004867:Equipment Design; D006325:Heart Atria / Q000473:pathology / Q000601:surgery; D006352:Heart Ventricles / Q000473:pathology / Q000601:surgery; D000078702:Radiofrequency Therapy