title: Development of Time- and Voltage-Domain Mapping (V-T-Mapping) to Localize Ventricular Tachycardia Channels During Sinus Rhythm.
abstract: In ventricular scar, impulse spread is slow because it traverses split and zigzag channels of surviving muscle. We aimed to evaluate scar electrograms to determine their local delay (activation time) and inequality in voltage splitting (entropy), and their relationship to channels. We reasoned that unlike innocuous channels, which are often short with multiple side branches, ventricular tachycardia (VT) supporting channels have very slow impulse spread and possess low entropy because of their longer protected length and relative lack of side-branching.
  
  
  
  Patients with ischemic cardiomyopathy and multiple VT were studied. In initial mapping stage (16 patients and 58 VTs), left ventricular endocardial mapping was performed in sinus rhythm. Detailed pace mapping was used to identify VT channels and confirmed, when feasible, by entrainment. Scar electrograms were analyzed in time and voltage domains to determine mean activation time, dispersion in activation time, and entropy. Predictive performances of these properties to detect VT channels were tested. In the application stage (7 patients and 20 VTs), these properties were prospectively tested to guide catheter ablation. A mean number of 763±203 sampling points were taken. From 1770 pace maps, 47 channels corresponded to VTs. A combination of scar electrograms with the latest mean activation time and minimum entropy, in a high activation dispersion region, accurately recognized regions containing VT channels (κ=0.89, sensitivity=86%, specificity=100%, positive predictive value=93%, and negative predictive value=100%). Finally, focused ablation within 5-mm rim of the prospective channel regions eliminated 18 of 20 inducible VTs.
  
  
  
  Activation time and entropy mapping in the scar accurately identify VT channels during sinus rhythm. The method integrates principles of reentry formation to recognize VT channels without pace mapping or mapping during VT.
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Sachin
authors.initials: S
authors.lastname: Nayyar
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Pawel
authors.initials: P
authors.lastname: Kuklik
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Anand N
authors.initials: AN
authors.lastname: Ganesan
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Sullivan
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Lauren
authors.initials: L
authors.lastname: Wilson
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Young
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.).
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
authors.affiliation: From the Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Australia (S.N., P.K., A.N.G., L.W., G.D.Y., P.S., K.C.R.-T.); and School of Public Health, University of Adelaide, Australia (T.R.S.). kurt.roberts-thomson@adelaide.edu.au.
authors.forename: Kurt C
authors.initials: KC
authors.lastname: Roberts-Thomson
mesh_terms: D000368:Aged; D009202:Cardiomyopathies / Q000503:physiopathology* / Q000601:surgery; D017115:Catheter Ablation; D002921:Cicatrix / Q000209:etiology / Q000503:physiopathology*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000601:surgery
keywords: catheter ablation; entropy; humans; mapping; ventricular tachycardia