title: New endpoint for ablation of ventricular tachycardia: change in QRS morphology with pacing at protected isthmus as index of isthmus block.
abstract: BACKGROUND
  Endpoints confirming block in the critical isthmus in sinus rhythm and with pace mapping have not been established.
  
  
  RESULTS
  A 44-year-old man with a history of Tetralogy of Fallot presented with recurrent ventricular tachycardia (VT). Entrainment mapping was consistent with a macroreentrant circuit rotating in a clockwise fashion under the pulmonic valve. After termination of the VT in a critical isthmus located on the conal free wall, a pace map proximal to the site of successful ablation was consistent with a change in QRS morphology. This change in QRS morphology suggested critical isthmus block and successful ablation, which was confirmed by noninducibility with programmed stimulation.
  
  
  CONCLUSIONS
  Evidence of conduction block can be used as an additional endpoint for successful ablation of VT.
authors.affiliation: Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. balar@uphs.upenn.edu
authors.forename: Rupa
authors.initials: R
authors.lastname: Bala
authors.forename: Sandhya
authors.initials: S
authors.lastname: Dhruvakumar
authors.forename: Shuaib A
authors.initials: SA
authors.lastname: Latif
authors.forename: Francis E
authors.initials: FE
authors.lastname: Marchlinski
mesh_terms: D000328:Adult; D018780:Body Surface Potential Mapping / Q000379:methods*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D023381:Endpoint Determination / Q000379:methods*; D006327:Heart Block / Q000175:diagnosis; D006801:Humans; D008297:Male; D017180:Tachycardia, Ventricular / Q000175:diagnosis*