title: High-output pacing in mapping of postinfarction ventricular tachycardia.
abstract: BACKGROUND
  Pace mapping is used to identify critical areas for postinfarction ventricular tachycardia (VT). Unexcitable scar during pacing with standard output can identify borders of the reentry circuit. Unexcitable scar is not thought to contain surviving muscle fibers critical to the circuit. Due to current-to-load mismatch or a deep seated isthmus, higher power might be required in order to obtain capture.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the value of high-output pacing in patients with postinfarction VT.
  
  
  METHODS
  In a consecutive series of 18 patients (15 men, age 62 +/- 9, EF 0.29 +/- 0.15) with postinfarction VT, a voltage map was obtained and bipolar pace mapping was performed in areas with low voltage (<1.5 mV) at an output of 10 mA and 2 ms pulse width (PW). High-output capture was defined as capture that failed at these settings but succeeded at higher pacing output. The pacing output was increased to 20 mA at 2 ms, and the PW was increased to 10 ms as required to achieve capture.
  
  
  RESULTS
  Seventy-seven VTs were induced. Thirty-nine isthmus sites were identified. Focal areas with high-output capture were observed in 12/18 patients (output: 20 mA; mean PW: 7.3 +/- 3.5 ms). In 9/18 patients, this area was critical for the reentry circuit of 10 clinical VTs (23% of isthmus sites). In one third of patients, isthmus sites were identified only by high-output pacing.
  
  
  CONCLUSIONS
  High-output pacing can be helpful in identifying critical areas of postinfarction VT that otherwise may be missed.
authors.affiliation: Department of Cardiology, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Sarrazin
authors.forename: Michael
authors.initials: M
authors.lastname: Kuehne
authors.forename: Darryl
authors.initials: D
authors.lastname: Wells
authors.forename: Nagib
authors.initials: N
authors.lastname: Chalfoun
authors.forename: Thomas
authors.initials: T
authors.lastname: Crawford
authors.forename: Warangkna
authors.initials: W
authors.lastname: Boonyapisit
authors.forename: Eric
authors.initials: E
authors.lastname: Good
authors.forename: Aman
authors.initials: A
authors.lastname: Chugh
authors.forename: Hakan
authors.initials: H
authors.lastname: Oral
authors.forename: Krit
authors.initials: K
authors.lastname: Jongnarangsin
authors.forename: Frank
authors.initials: F
authors.lastname: Pelosi
authors.forename: Fred
authors.initials: F
authors.lastname: Morady
authors.forename: Frank
authors.initials: F
authors.lastname: Bogun
mesh_terms: D018780:Body Surface Potential Mapping / Q000379:methods*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications*; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome