title: Impact of local ablation on interconnected channels within ventricular scar: mechanistic implications for substrate modification.
abstract: BACKGROUND
  The extent to which channels within scar are interconnected is not known. The objective of the study was to evaluate the impact of local ablation of late potentials (LPs) on adjacent and remote areas of slow conduction with simultaneous multipolar mapping.
  
  
  RESULTS
  Analysis was performed on consecutive patients referred for ablation of scar-mediated ventricular tachycardia with double ventricular access. Ablation was performed targeting the earliest of LPs visualized on the multipolar catheter, and the impact on later LPs was recorded. In 21 patients, a multipolar catheter placed within scar visualized spatially distinct LPs. Among 39 radiofrequency applications, ablation at earlier LPs had an effect on neighboring and remote LPs in 31 (80%), with delay in 8 (21%), partial elimination in 9 (23%), and complete elimination in 14 (36%). The mean distance where an ablation impact was detected was 17.6±14.7 mm (range, 2-50 mm). Among all patients, 9.7±7.8 radiofrequency applications were delivered to homogenize the targeted scar region with a mean number of 23±12 LPs targeted.
  
  
  CONCLUSIONS
  Ablation can eliminate neighboring and remote areas of slow conduction, suggesting that channels within scar are frequently interconnected. This is the first mechanistic demonstration to show that ablation can modify electrical activity in regions of scar outside of the known radius of an radiofrequency lesion. The targeting of relatively earlier LPs can expedite scar homogenization without the need for extensive ablation of all LPs.
authors.affiliation: University of California, Los Angeles Cardiac Arrhythmia Center, University of California, Los Angeles Health System, David Geffen School of Medicine at University of California, Los Angeles.
authors.forename: Roderick
authors.initials: R
authors.lastname: Tung
authors.forename: Nilesh S
authors.initials: NS
authors.lastname: Mathuria
authors.forename: Rich
authors.initials: R
authors.lastname: Nagel
authors.forename: Ravi
authors.initials: R
authors.lastname: Mandapati
authors.forename: Eric F
authors.initials: EF
authors.lastname: Buch
authors.forename: Jason S
authors.initials: JS
authors.lastname: Bradfield
authors.forename: Marmar
authors.initials: M
authors.lastname: Vaseghi
authors.forename: Noel G
authors.initials: NG
authors.lastname: Boyle
authors.forename: Kalyanam
authors.initials: K
authors.lastname: Shivkumar
mesh_terms: D000368:Aged; D017115:Catheter Ablation / Q000379:methods; D002921:Cicatrix / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D055502:Secondary Prevention; D017180:Tachycardia, Ventricular / Q000601:surgery
keywords: catheter ablation; tachycardia; ventricular