title: Mapping and ablation of ventricular tachycardia guided by virtual electrograms using a noncontact, computerized mapping system.
abstract: OBJECTIVE
  The purpose of this study was to describe a computerized mapping system that utilizes a noncontact, 64 electrode balloon catheter to compute virtual electrograms simultaneously at 3,360 left ventricular (LV) sites and to assess the clinical utility of this system for mapping and ablating ventricular tachycardia (VT).
  
  
  BACKGROUND
  Mapping VT in the electrophysiology laboratory conventionally is achieved by sequentially positioning an electrode catheter at multiple endocardial sites.
  
  
  METHODS
  Fifteen patients with VT underwent 18 electrophysiology procedures using the noncontact, computerized mapping system. A 9F 64 electrode balloon catheter and a conventional 7F electrode catheter for mapping and ablation were positioned in the LV using a retrograde aortic approach. Using a boundary element inverse solution, 3,360 virtual endocardial electrograms were computed and used to derive isopotential maps. An incorporated locator system was used in conjunction with or instead of fluoroscopy to position the conventional electrode catheter.
  
  
  RESULTS
  A total of 21 VTs, 12 of which were hemodynamically-tolerated and 9 of which were not, were mapped. Isolated diastolic potentials, presystolic areas, zones of slow conduction and exit sites during VT were identified using virtual electrograms and isopotential maps. Among 19 targeted VTs, radiofrequency ablation guided by the computerized mapping system and the locator signal was successful in 15.
  
  
  CONCLUSIONS
  The computerized mapping system described in this study computes accurate isopotential maps that are a useful guide for ablation of hemodynamically stable or unstable VT.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0022, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Strickberger
authors.forename: B P
authors.initials: BP
authors.lastname: Knight
authors.forename: G F
authors.initials: GF
authors.lastname: Michaud
authors.forename: F
authors.initials: F
authors.lastname: Pelosi
authors.forename: F
authors.initials: F
authors.lastname: Morady
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018780:Body Surface Potential Mapping / Q000379:methods*; D006328:Cardiac Catheterization; D017115:Catheter Ablation / Q000379:methods*; D004594:Electrophysiology; D005260:Female; D006339:Heart Rate; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D015203:Reproducibility of Results; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome; D014584:User-Computer Interface