title: Assessment of ventricular tachycardia scar substrate by intracardiac echocardiography.
abstract: BACKGROUND
  Intracardiac echocardiography (ICE) is increasingly used to guide complex ablation procedures. This study aimed to assess the scar substrate of ventricular tachycardia (VT) by ICE in patients undergoing VT ablation.
  
  
  METHODS
  In 22 patients undergoing VT ablation (10 ischemic, 12 nonischemic), the Biosense CARTOSOUND module (Biosense Webster, Diamond Bar, CA, USA) was used for three-dimensional reconstruction of the ventricles. The characteristics and appearance with ICE imaging of voltage-defined scar zones (bipolar voltage <0.5 mV), border zones (0.5-1.5 mV), and normal myocardium (>1.5 mV) on electroanatomic maps were evaluated. The standard image analysis software Image J (National Institutes of Health, Bethesda, MD, USA) was used to analyze signal intensity (mean pixel signal intensity unit [SIU]) and heterogeneity (standard deviation of signal intensity in analyzed area) on ICE images.
  
  
  RESULTS
  A total of 83 myocardial areas were analyzed from two-dimensional ICE images (15 scars, 31 border zones, and 37 normal). Voltage-defined scar zones had increased signal intensities compared to border zones (149 SIU vs 104 SIU, P < 0.0001) and normal myocardium (88 SIU, P < 0.0001). Border zones were more likely to have heterogeneous densities compared to normal myocardium (standard deviation of signal intensity 20 SIU vs 12 SIU, P < 0.0001). In receiver-operator characteristic analyses, signal intensity ≥ 137 SIU differentiated scar from nonscar zones (area under curve 0.91, P < 0.0001). Software-based color enhancement of areas with signal intensity ≥ 137 SIU allowed identification of the VT substrate in all 15 patients with voltage-defined scar zones.
  
  
  CONCLUSIONS
  ICE provides important information about the VT anatomical substrate and may have potential to identify areas of scarred myocardium.
authors.affiliation: From the Division of Cardiology, Maryland Arrhythmia and Cardiology Imaging Group (MACIG), University of Maryland, Baltimore, Maryland.
authors.forename: Ayman
authors.initials: A
authors.lastname: Hussein
authors.forename: Alejandro
authors.initials: A
authors.lastname: Jimenez
authors.forename: Ghada
authors.initials: G
authors.lastname: Ahmad
authors.forename: Olurotimi
authors.initials: O
authors.lastname: Mesubi
authors.forename: Thomas
authors.initials: T
authors.lastname: Klein
authors.forename: Gagandeep
authors.initials: G
authors.lastname: Gurm
authors.forename: Hiroko
authors.initials: H
authors.lastname: Beck
authors.forename: Omar
authors.initials: O
authors.lastname: Shams
authors.forename: Vincent
authors.initials: V
authors.lastname: See
authors.forename: Anastasios
authors.initials: A
authors.lastname: Saliaris
authors.forename: Stephen
authors.initials: S
authors.lastname: Shorofsky
authors.forename: Timm
authors.initials: T
authors.lastname: Dickfeld
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006328:Cardiac Catheterization / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D002921:Cicatrix / Q000150:complications / Q000000981:diagnostic imaging*; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D025321:Surgery, Computer-Assisted / Q000379:methods*; D017180:Tachycardia, Ventricular / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery*; D016896:Treatment Outcome
keywords: ablation; intracardiac echocardiography; ventricular tachycardia