title: Quantitative evaluation of atrial radio frequency ablation using intracardiac shear-wave elastography.
abstract: OBJECTIVE
  Radio frequency catheter ablation (RFCA) is a well-established clinical procedure for the treatment of atrial fibrillation (AF) but suffers from a low single-procedure success rate. Recurrence of AF is most likely attributable to discontinuous or nontransmural ablation lesions. Yet, despite this urgent clinical need, there is no clinically available imaging modality that can reliably map the lesion transmural extent in real time. In this study, the authors demonstrated the feasibility of shear-wave elastography (SWE) to map quantitatively the stiffness of RFCA-induced thermal lesions in cardiac tissues in vitro and in vivo using an intracardiac transducer array.
  
  
  METHODS
  SWE was first validated in ex vivo porcine ventricular samples (N = 5). Both B-mode imaging and SWE were performed on normal cardiac tissue before and after RFCA. Areas of the lesions were determined by tissue color change with gross pathology and compared against the SWE stiffness maps. SWE was then performed in vivo in three sheep (N = 3). First, the stiffness of normal atrial tissues was assessed quantitatively as well as its variation during the cardiac cycle. SWE was then performed in atrial tissue after RFCA.
  
  
  RESULTS
  A large increase in stiffness was observed in ablated ex vivo regions (average shear modulus across samples in normal tissue: 22 ± 5 kPa, average shear-wave speed (ct): 4.5 ± 0.4 m s(-1) and in determined ablated zones: 99 ± 17 kPa, average ct: 9.0 ± 0.5 m s(-1) for a mean shear modulus increase ratio of 4.5 ± 0.9). In vivo, a threefold increase of the shear modulus was measured in the ablated regions, and the lesion extension was clearly visible on the stiffness maps.
  
  
  CONCLUSIONS
  By its quantitative and real-time capabilities, Intracardiac SWE is a promising intraoperative imaging technique for the evaluation of thermal ablation during RFCA.
authors.affiliation: Institut Langevin ESPCI ParisTech, CNRS UMR7587, INSERM U797, Paris 75005, France.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kwiecinski
authors.affiliation: Institut Langevin ESPCI ParisTech, CNRS UMR7587, INSERM U797, Paris 75005, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Provost
authors.affiliation: LIRYC Institute, INSERM 1045, Université de Bordeaux, Bordeaux 33400, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Dubois
authors.affiliation: LIRYC Institute, INSERM 1045, Université de Bordeaux, Bordeaux 33400, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sacher
authors.affiliation: LIRYC Institute, INSERM 1045, Université de Bordeaux, Bordeaux 33400, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
authors.affiliation: Vermon, Tours 37000, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Legros
authors.affiliation: Vermon, Tours 37000, France.
authors.forename: An
authors.initials: A
authors.lastname: Nguyen-Dinh
authors.affiliation: Vermon, Tours 37000, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Dufait
authors.affiliation: Institut Langevin ESPCI ParisTech, CNRS UMR7587, INSERM U797, Paris 75005, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Tanter
authors.affiliation: Institut Langevin ESPCI ParisTech, CNRS UMR7587, INSERM U797, Paris 75005, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Pernot
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D017115:Catheter Ablation / Q000379:methods*; D057785:Catheters; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006321:Heart / Q000502:physiology; D006325:Heart Atria / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009206:Myocardium / Q000473:pathology; D011312:Pressure; D011846:Radio Waves; D033081:Shear Strength; D012756:Sheep; D012815:Signal Processing, Computer-Assisted; D013314:Stress, Mechanical; D014159:Transducers; D014463:Ultrasonography