title: High-density mapping of ventricular scar: a comparison of ventricular tachycardia (VT) supporting channels with channels that do not support VT.
abstract: BACKGROUND
  Surviving myocytes within scar may form channels that support ventricular tachycardia (VT) circuits. There are little data on the properties of channels that comprise VT circuits and those that are non-VT supporting channels.
  
  
  RESULTS
  In 22 patients with ischemic cardiomyopathy and VT, high-density mapping was performed with the PentaRay catheter and Ensite NavX system during sinus rhythm. A channel was defined as a series of matching pace-maps with a stimulus (S) to QRS time of ≥40 ms. Sites were determined to be part of a VT channel if there were matching pace-maps to the VT morphology. This was confirmed with entrainment mapping when possible. Of the 238 channels identified, 57 channels corresponded to an inducible VT. Channels that were part of a VT circuit were more commonly located within dense scar than non-VT channels (97% versus 82%; P=0.036). VT supporting channels were of greater length (mean±SEM, 53±5 versus 33±4 mm), had higher longest S-QRS (130±12 versus 82±12 ms), longer conduction time (103±14 versus 43±13 ms), and slower conduction velocity (0.87±0.23 versus 1.39±0.21 m/s) than non-VT channels (P<0.001). Of all the fractionated, late, and very late potentials located in scar, only 21%, 26%, and 29%, respectively, were recorded within VT channels.
  
  
  CONCLUSIONS
  High-density mapping shows substantial differences among channels in ventricular scar. Channels supporting VT are more commonly located in dense scar, longer than non-VT channels, and have slower conduction velocity. Only a minority of scar-related potentials participate in the VT supporting channels.
authors.affiliation: Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Sachin
authors.initials: S
authors.lastname: Nayyar
authors.forename: Lauren
authors.initials: L
authors.lastname: Wilson
authors.forename: Anand N
authors.initials: AN
authors.lastname: Ganesan
authors.forename: Thomas
authors.initials: T
authors.lastname: Sullivan
authors.forename: Pawel
authors.initials: P
authors.lastname: Kuklik
authors.forename: Darius
authors.initials: D
authors.lastname: Chapman
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Brooks
authors.forename: Rajiv
authors.initials: R
authors.lastname: Mahajan
authors.forename: Mathias
authors.initials: M
authors.lastname: Baumert
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Young
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
authors.forename: Kurt C
authors.initials: KC
authors.lastname: Roberts-Thomson
mesh_terms: D000200:Action Potentials; D000368:Aged; D002304:Cardiac Pacing, Artificial; D009202:Cardiomyopathies / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D017115:Catheter Ablation; D002921:Cicatrix / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D011237:Predictive Value of Tests; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome; D056969:Voltage-Sensitive Dye Imaging
keywords: catheter ablation; ischemic cardiomyopathy; substrate ablation; tachycardia, ventricular