title: Changes in local wall thickness correlate with pathologic lesion size following radiofrequency catheter ablation: an intracardiac echocardiographic imaging study.
abstract: BACKGROUND
  High-resolution intracardiac echocardiographic (ICE) imaging can accurately assess wall thickness during radiofrequency (RF) catheter ablation procedures. This study investigated the correlation of changes in wall thickness at the ablation site with pathologic lesion size.
  
  
  RESULTS
  ICE image-guided 31 RF applications (30-50 W, up to 120 sec) were performed in five anesthetized closed chest swine (n = 5, body weight 35-60 kg). Twenty-four lesions were delivered in the right and left atria with standard RF; seven lesions were delivered in the left ventricle (LV) with irrigated (30-40 ml/min) RF. Wall thickness and tissue echo density measured by ICE imaging (pre- and 1-minute post-RF delivery) with increased focal echo density following RF deployment in the atria (4.5 +/- 1.5 vs 2.3 +/- 1.0 mm pre-RF) and the LV (9.8 +/- 2.3 vs 6.8 +/- 2.2 mm pre-RF; P < 0.01). The observed changes in wall thickness (DeltaWT) following ablation in the LV were greater than in the atria (3.0 +/- 1.4 vs 2.2 +/- 1.2 mm; P < 0.05). A significant correlation between DeltaWT and lesion depth (ventricular: r = 0.85, P < 0.05; atrial: r = 0.82, P < 0.01) was demonstrated at all ablation sites. Local wall thickness measured post-RF also significantly correlated with lesion depth (r = 0.89, P < 0.01), especially with that of transmural lesions (r = 0.95, n = 23, P < 0.001) at atrial and LV sites.
  
  
  CONCLUSIONS
  Therapeutic RF ablation results in mural swelling and increased echo density. These changes can be detected by ICE imaging and correlate with pathologic lesion size. ICE imaging may be useful in online quantification of lesion size, especially for transmural lesions during clinical catheter ablation procedures.
authors.affiliation: Cardiac Electrophysiology Research Laboratory, University of Pennsylvania, MSRL Building at Presbyterian Medical Center, Mail Box 225, 39th and Market Streets, Philadelphia, PA 19104-2692, USA. jfren@mail.med.upenn.edu
authors.forename: J F
authors.initials: JF
authors.lastname: Ren
authors.forename: D J
authors.initials: DJ
authors.lastname: Callans
authors.forename: D
authors.initials: D
authors.lastname: Schwartzman
authors.forename: J J
authors.initials: JJ
authors.lastname: Michele
authors.forename: F E
authors.initials: FE
authors.lastname: Marchlinski
mesh_terms: D000818:Animals; D001344:Autopsy; D013504:Cardiovascular Surgical Procedures / Q000295:instrumentation; D017115:Catheter Ablation; D002404:Catheterization; D004452:Echocardiography; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000601:surgery; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008955:Models, Cardiovascular; D013552:Swine