title: Variability in postpacing intervals predicts global ventricular activation pattern during tachycardia.
abstract: BACKGROUND
  Assessment of ventricular activation pattern is critical to the successful ablation of ventricular tachycardia (VT). We have previously shown that the global atrial activation pattern during tachycardia can be rapidly and accurately assessed by calculating the postpacing interval variability (PPIV); PPIV was minimal in circuitous tachycardias and highly variable in centrifugal tachycardias. In the present study, we use the PPIV to determine the ventricular global activation pattern during VT.
  
  
  METHODS
  Patients with mappable VT were included. We defined global ventricular activation as either centrifugal (arising from a focus with radial expansion) or circuitous (gross macro-reentrant circuit), based on the findings of electroanatomic mapping. PPIV was calculated as the difference in postpacing interval with right ventricular apical overdrive pacing during tachycardia at cycle lengths (CL) 10 ms and 30-ms shorter than tachycardia, regardless of the origin of the tachycardia. We studied 20 patients with 23 VTs (11 centrifugal, mean CL 390 +/- 36.1 ms; 12 circuitous, mean CL 418 +/- 75.7 ms).
  
  
  RESULTS
  The mean PPIV was 45 +/- 16 ms for patients with centrifugal VT and 6.7 +/- 4.1 ms for patients with circuitous VT. Rank sum analysis of PPIV showed a significant difference between the two groups (P < 0.05).
  
  
  CONCLUSIONS
  Our data suggest that the global ventricular activation pattern during VT can be rapidly and accurately defined by assessing the PPIV. This technique allows for a rapid confirmation of the tachycardia activation and significantly facilitates mapping and ablation.
authors.affiliation: Texas Heart Institute, St. Luke's Episcopal Hospital, Houston, TX 77060, USA.
authors.forename: Ilyas K
authors.initials: IK
authors.lastname: Colombowala
authors.forename: Ali
authors.initials: A
authors.lastname: Massumi
authors.forename: Abdi
authors.initials: A
authors.lastname: Rasekh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Saeed
authors.forename: Jie
authors.initials: J
authors.lastname: Cheng
authors.forename: Bita
authors.initials: B
authors.lastname: Fakhri
authors.forename: Mossaab
authors.initials: M
authors.lastname: Shuraih
authors.forename: Mehdi
authors.initials: M
authors.lastname: Razavi
mesh_terms: D000328:Adult; D000368:Aged; D022062:Electrophysiologic Techniques, Cardiac; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult