title: Visualization of epicardial cryoablation lesions using endogenous tissue fluorescence.
abstract: BACKGROUND
  Percutaneous cryoballoon ablation is a commonly used procedure to treat atrial fibrillation. One of the major limitations of the procedure is the inability to directly visualize tissue damage and functional gaps between the lesions. We seek to develop an approach that will enable real-time visualization of tissue necrosis during cryo- or radiofrequency ablation procedures.
  
  
  RESULTS
  Cryoablation of either blood-perfused or saline-perfused hearts was associated with a marked decrease in nicotinamide adenine dinucleotide (NADH) fluorescence, leading to a 60% to 70% loss of signal intensity at the lesion site. The total lesion area observed on the NADH channel exhibited a strong correlation with the area identified by triphenyl tetrazolium staining (r=0.89, P<0.001). At physiological temperatures, loss of NADH became visually apparent within 26±8 s after detachment of the cryoprobe from the epicardial surface and plateaued within minutes after which the boundaries of the lesions remained stable for several hours. The loss of electrical activity within the cryoablation site exhibited a close spatial correlation with the loss of NADH (r=0.84±0.06, P<0.001). Cryoablation led to a decrease in diffuse reflectance across the entire visible spectrum, which was in stark contrast to radiofrequency ablation that markedly increased the intensity of reflected light at the lesion sites.
  
  
  CONCLUSIONS
  We confirmed the feasibility of using endogenous NADH fluorescence for the real-time visualization of cryoablation lesions in blood-perfused cardiac muscle preparations and revealed similarities and differences between imaging cryo- and radiofrequency ablation lesions when using ultraviolet and visible light illumination.
authors.affiliation: From the Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC (L.S., D.A.B.G., M.K., N.S.); Department of Electrical and Computer Engineering, George Washington School of Engineering and Applied Science, Washington, DC (D.A.B.G., R.J., M.K.); and Division of Cardiology, George Washington University School of Medicine and Health Sciences and Medical Faculty Associates, Washington, DC (M.M.).
authors.forename: Luther
authors.initials: L
authors.lastname: Swift
authors.affiliation: From the Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC (L.S., D.A.B.G., M.K., N.S.); Department of Electrical and Computer Engineering, George Washington School of Engineering and Applied Science, Washington, DC (D.A.B.G., R.J., M.K.); and Division of Cardiology, George Washington University School of Medicine and Health Sciences and Medical Faculty Associates, Washington, DC (M.M.).
authors.forename: Daniel A B
authors.initials: DA
authors.lastname: Gil
authors.affiliation: From the Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC (L.S., D.A.B.G., M.K., N.S.); Department of Electrical and Computer Engineering, George Washington School of Engineering and Applied Science, Washington, DC (D.A.B.G., R.J., M.K.); and Division of Cardiology, George Washington University School of Medicine and Health Sciences and Medical Faculty Associates, Washington, DC (M.M.).
authors.forename: Rafael
authors.initials: R
authors.lastname: Jaimes
authors.affiliation: From the Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC (L.S., D.A.B.G., M.K., N.S.); Department of Electrical and Computer Engineering, George Washington School of Engineering and Applied Science, Washington, DC (D.A.B.G., R.J., M.K.); and Division of Cardiology, George Washington University School of Medicine and Health Sciences and Medical Faculty Associates, Washington, DC (M.M.).
authors.forename: Matthew
authors.initials: M
authors.lastname: Kay
authors.affiliation: From the Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC (L.S., D.A.B.G., M.K., N.S.); Department of Electrical and Computer Engineering, George Washington School of Engineering and Applied Science, Washington, DC (D.A.B.G., R.J., M.K.); and Division of Cardiology, George Washington University School of Medicine and Health Sciences and Medical Faculty Associates, Washington, DC (M.M.).
authors.forename: Marco
authors.initials: M
authors.lastname: Mercader
authors.affiliation: From the Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC (L.S., D.A.B.G., M.K., N.S.); Department of Electrical and Computer Engineering, George Washington School of Engineering and Applied Science, Washington, DC (D.A.B.G., R.J., M.K.); and Division of Cardiology, George Washington University School of Medicine and Health Sciences and Medical Faculty Associates, Washington, DC (M.M.). phynas@gwu.edu.
authors.forename: Narine
authors.initials: N
authors.lastname: Sarvazyan
mesh_terms: D000200:Action Potentials; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D017115:Catheter Ablation; D003452:Cryosurgery; D015536:Down-Regulation; D005240:Feasibility Studies; D005260:Female; D008297:Male; D023421:Models, Animal; D009243:NAD / Q000378:metabolism*; D009336:Necrosis; D061848:Optical Imaging; D010496:Pericardium / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D011237:Predictive Value of Tests; D017207:Rats, Sprague-Dawley; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D015415:Biomarkers; D009243:NAD
keywords: ablation; atrial fibrillation arrhythmia