title: Real-time atrial wall imaging during radiofrequency ablation in a porcine model.
abstract: BACKGROUND
  Real-time monitoring of radiofrequency (RF) ablation remains challenging.
  
  
  OBJECTIVE
  We used intravascular ultrasound (IVUS) to describe atrial wall changes during RF ablation and to assess the extent of RF-induced lesions.
  
  
  METHODS
  In 9 piglets, RF and IVUS catheters were coupled and introduced into the right atrium. RF applications were performed along the intercaval line. Corresponding IVUS images were analyzed. Wall thickness was correlated with electrogram (EGM) changes (n = 9) and histology (n = 5).
  
  
  RESULTS
  There were 66 RF applications performed in 57 sites. IVUS provided real-time imaging of the atrial wall during RF application in all but 2 sites. IVUS demonstrated significant (>20%) and immediate increase in atrial wall thickness in 71.4% of RF applications. It showed epicardial or intramyocardial effusion in 30% of cases, 2 steam pops, 1 intramural hematoma, and 1 thrombus. EGM amplitude decreased and thickness increased after RF application than at baseline (2.20 ± 1.11 to 0.99 ± 0.62 mV and 1.34 ± 0.53 to 1.93 ± 0.80 mm, respectively; P < .001 for each). However, EGM and thickness changes were poorly correlated (r = 0.43; P < .05). Histologically and echographically measured thicknesses were correlated (r = 0.71; P = .004), but echographic thickness change was not related to histological lesion transmurality.
  
  
  CONCLUSIONS
  An IVUS probe coupled to an RF catheter can provide relevant real-time imaging of the atrial wall during ablation. Although thickness change does not appear as a good predictor of the transmural extent, direct visualization and monitoring of RF application may provide new information to guide and secure RF ablation.
authors: Cardiology Department, Nimes University Hospital, Nimes, France. Electronic address: mathieu.granier@chu-nimes.fr.
authors: Mathieu
authors: M
authors: Granier
authors: Cardiology Department, Nimes University Hospital, Nimes, France.
authors: Pierre François
authors: PF
authors: Winum
authors: Pathology Department, Montpellier University Hospital, Montpellier, France.
authors: Mireille
authors: M
authors: Granier
authors: EA 2992: Dysfunction of Vascular Interfaces, Faculty of Medicine, Montpellier University, Nimes, France.
authors: Pierre
authors: P
authors: Liaud
authors: Cardiology Department, Nimes University Hospital, Nimes, France; Montpellier University, Nimes, France.
authors: Guillaume
authors: G
authors: Cayla
authors: Cardiology Department, Nimes University Hospital, Nimes, France; Montpellier University, Nimes, France.
authors: Patrick
authors: P
authors: Messner
authors: Cardiology Department, Montpellier University Hospital; INSERM U1046 Montpellier University, Montpellier,France.
authors: Jean-Luc
authors: JL
authors: Pasquie
authors: Cardiology Department, Nimes University Hospital, Nimes, France; EA 2992: Dysfunction of Vascular Interfaces, Faculty of Medicine, Montpellier University, Nimes, France.
authors: Iris
authors: I
authors: Schuster
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D003952:Diagnostic Imaging / Q000379:methods*; D004195:Disease Models, Animal; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D013552:Swine; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000379:methods*
keywords: Atrial fibrillation; IVUS imaging of atrial wall; RF ablation; RF lesion extent; Radiofrequency ablation; Radiofrequency ablation in a porcine model; Transmural extent of RF lesions; Transmural lesion extent