title: Simultaneous biventricular noncontact mapping and ablation of septal ventricular tachycardia in a chronic ovine infarct model.
abstract: BACKGROUND
  We assessed a novel simultaneous biventricular mapping and ablation approach for septal ventricular tachycardia (VT) in a chronic ovine infarct model.
  
  
  RESULTS
  In 8 sheep with inducible VT, mapping and ablation were performed 9+/-3 months after percutaneously induced myocardial infarction, with left ventricular ejection fraction 23+/-8%. Scar was identified by EnSite Dynamic Substrate Mapping plus CARTO voltage mapping. Thirty VT episodes (cycle length, 235+/-42 ms) were mapped with simultaneous analyses using EnSite arrays deployed in both the left ventricle and the right ventricle. Short ablation lines were created perpendicular to the breakout pathway along the scar border in the ventricle with earliest activity. If septal VT was still inducible, this line was extended before ablation in the second chamber. The end point of noninducibility of VT was achieved in all animals. The mean difference in delay in noncontact breakout timing between the ventricles was shorter for VT with (n=18) than without (n=12) septal breakout (32+/-7.8 ms, P<0.001). In 5 of 6 animals, after ablation in one ventricle, septal VT was still inducible with a common breakout site in the second ventricle. After septal ablation in the second ventricle, VT was no longer inducible. In the 6 animals in which septal VT had been ablated, transmural septal ablation was identified at the scar border, with overlapping left ventricular and right ventricular ablation lesions present in 5 of 6 (septal thickness 8 to 17 mm) and left ventricular endocardial ablation being transmural in 1 of 6 (6 mm).
  
  
  CONCLUSIONS
  Biventricular scar and VT activation mapping correctly localizes septal VT pathways, directing ablation from one or both septal endocardial aspects. Creation of a transmural septal lesion at the scar border interrupting VT exit points is highly effective at ablating septal VT.
authors.affiliation: Cardiology Department, Westmead Hospital, Sydney, Australia.
authors.forename: Gopal
authors.initials: G
authors.lastname: Sivagangabalan
authors.forename: Jim
authors.initials: J
authors.lastname: Pouliopoulos
authors.forename: Kaimin
authors.initials: K
authors.lastname: Huang
authors.forename: Michael A
authors.initials: MA
authors.lastname: Barry
authors.forename: Juntang
authors.initials: J
authors.lastname: Lu
authors.forename: Stuart P
authors.initials: SP
authors.lastname: Thomas
authors.forename: David L
authors.initials: DL
authors.lastname: Ross
authors.forename: Aravinda
authors.initials: A
authors.lastname: Thiagalingam
authors.forename: Pramesh
authors.initials: P
authors.lastname: Kovoor
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D002908:Chronic Disease; D002921:Cicatrix / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D006346:Heart Septum / Q000473:pathology / Q000503:physiopathology; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology*; D011300:Preoperative Care / Q000379:methods; D012756:Sheep; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*