title: Response to pacing at sites of isolated diastolic potentials during ventricular tachycardia in patients with previous myocardial infarction.
abstract: OBJECTIVE
  The goal of this study was to determine whether isolated diastolic potentials (IDPs) recorded during ventricular tachycardia (VT) are generated in zones of slow conduction and whether the arcs of block that bound these zones of slow conduction are functional or anatomic in nature.
  
  
  BACKGROUND
  No previous studies have systematically investigated the response to pacing during VT and sinus rhythm at sites where IDPs are recorded.
  
  
  METHODS
  The study included 11 patients with a previous infarction who underwent radiofrequency catheter ablation of 15 hemodynamically stable, sustained VTs and in whom an IDP that could not be dissociated from the VT was detected during mapping.
  
  
  RESULTS
  Pacing during VT at the site where the IDP was recorded resulted in concealed entrainment in each of the 15 VTs. In 10 of the 15 VTs, an IDP was present during sinus rhythm at the same site at which a diastolic potential was recorded during VT. In nine VTs, the isolated potential occurred early in diastole; in these cases, the QRS configuration during pacing in the setting of sinus rhythm was different from that during VT. In six VTs, the isolated potential occurred later in diastole, and in these cases, the QRS configuration during pacing in the setting of sinus rhythm was the same as that during VT.
  
  
  CONCLUSIONS
  Isolated diastolic potentials may often be generated in an area of slow conduction bounded by arcs of block that are anatomically determined and present during sinus rhythm.
authors.affiliation: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0022, USA.
authors.forename: F
authors.initials: F
authors.lastname: Bogun
authors.forename: M
authors.initials: M
authors.lastname: Bahu
authors.forename: B P
authors.initials: BP
authors.lastname: Knight
authors.forename: R
authors.initials: R
authors.lastname: Weiss
authors.forename: R
authors.initials: R
authors.lastname: Goyal
authors.forename: E
authors.initials: E
authors.lastname: Daoud
authors.forename: K C
authors.initials: KC
authors.lastname: Man
authors.forename: S A
authors.initials: SA
authors.lastname: Strickberger
authors.forename: F
authors.initials: F
authors.lastname: Morady
mesh_terms: D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D003971:Diastole / Q000502:physiology; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications*; D017180:Tachycardia, Ventricular / Q000503:physiopathology*