title: Isthmus characteristics of reentrant ventricular tachycardia after myocardial infarction.
abstract: BACKGROUND
  The reentrant mechanism of postinfarct ventricular tachycardia (VT) has been documented by surgical mapping analysis, but little is known about postinfarct VT circuits and the characteristics of their related protected isthmus with the use of 3D catheter mapping systems.
  
  
  RESULTS
  A 3D electroanatomic mapping was performed in 21 patients with well-tolerated, postinfarct, sustained VT. In total, 33 episodes of tachycardia (mean cycle length 432+/-74 ms) were induced and mapped. Complete maps demonstrated macroreentrant circuits with 1 loop (n=8) or 2 loops (n=25) rotating around a protected isthmus bounded by 2 approximately parallel conduction barriers that consisted of a line of double potentials, a scar area, or the mitral annulus. A total of 26 critical isthmi were identified for the 33 VTs mapped, with the same isthmus being shared by 2 to 4 different tachycardic morphologies in 5 patients. On average, isthmi were 31+/-7 mm long (ranging from 18 to 41 mm) and 16+/-8 mm wide (ranging from 6 to 36 mm) and harbored diastolic electrograms. The isthmus axis was oriented parallel to the mitral annulus plane in perimitral circuits and perpendicular to the mitral annulus plane in all other circuits. Linear radiofrequency ablation performed across the most accessible part of the isthmus prevented the recurrence of tachycardia in 19 patients (90%) with a follow-up at 16+/-8 months.
  
  
  CONCLUSIONS
  Detailed 3D electroanatomic mapping is helpful in reconstructing postinfarct VT circuits and in defining the characteristics of their related protected isthmi. The wide range of isthmus width values supports the need of linear radiofrequency lesions to eliminate the reentrant substrate of postinfarct VTs.
authors.affiliation: Department of Cardiology, University Hospital Nancy, Nancy, France. c.dechillou@chu-nancy.fr
authors.forename: Christian
authors.initials: C
authors.lastname: de Chillou
authors.forename: Dominique
authors.initials: D
authors.lastname: Lacroix
authors.forename: Didier
authors.initials: D
authors.lastname: Klug
authors.forename: Isabelle
authors.initials: I
authors.lastname: Magnin-Poull
authors.forename: Christelle
authors.initials: C
authors.lastname: Marquié
authors.forename: Marc
authors.initials: M
authors.lastname: Messier
authors.forename: Marius
authors.initials: M
authors.lastname: Andronache
authors.forename: Claude
authors.initials: C
authors.lastname: Kouakam
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sadoul
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.forename: Etienne
authors.initials: E
authors.lastname: Aliot
authors.forename: Salem
authors.initials: S
authors.lastname: Kacet
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping; D017115:Catheter Ablation; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D011237:Predictive Value of Tests; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery; D016896:Treatment Outcome