title: Bipolar ablation for deep intra-myocardial circuits: human ex vivo development and in vivo experience.
abstract: OBJECTIVE
  Current conventional ablation strategies for ventricular tachycardia (VT) aim to interrupt reentrant circuits by creating ablation lesions. However, the critical components of reentrant VT circuits may be located at deep intramural sites. We hypothesized that bipolar ablations would create deeper lesions than unipolar ablation in human hearts.
  
  
  RESULTS
  Ablation was performed on nine explanted human hearts at the time of transplantation. Following explant, the hearts were perfused by using a Langendorff perfusion setup. For bipolar ablation, the endocardial catheter was connected to the generator as the active electrode and the epicardial catheter as the return electrode. Unipolar ablation was performed at 50 W with irrigation of 25 mL/min, with temperature limit of 50°C. Bipolar ablation was performed with the same settings. Subsequently, in a patient with an incessant septal VT, catheters were positioned on the septum from both the ventricles and radiofrequency was delivered with 40 W. In the explanted hearts, there were a total of nine unipolar ablations and four bipolar ablations. The lesion depth was greater with bipolar ablation, 14.8 vs. 6.1 mm (P < 0.01), but the width was not different (9.8 vs. 7.8 mm). All bipolar lesions achieved transmurality in contrast to the unipolar ablations. In the patient with a septal focus, bipolar ablation resulted in termination of VT with no inducible VTs.
  
  
  CONCLUSIONS
  By using a bipolar ablation technique, we have demonstrated the creation of significantly deeper lesions without increasing the lesion width, compared with standard ablation. Further clinical trials are warranted to detail the risks of this technique.
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Sigfus
authors.initials: S
authors.lastname: Gizurarson
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Danna
authors.initials: D
authors.lastname: Spears
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Gopal
authors.initials: G
authors.lastname: Sivagangabalan
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Canada.
authors.forename: Talha
authors.initials: T
authors.lastname: Farid
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Andrew C T
authors.initials: AC
authors.lastname: Ha
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Massé
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Canada.
authors.forename: Marjan
authors.initials: M
authors.lastname: Kusha
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Vijay S
authors.initials: VS
authors.lastname: Chauhan
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Krishnakumar
authors.initials: K
authors.lastname: Nair
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Louise
authors.initials: L
authors.lastname: Harris
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada.
authors.forename: Eugene
authors.initials: E
authors.lastname: Downar
authors.affiliation: Division of Cardiology, Toronto General Hospital, Toronto, ON, Canada The Hull Family Cardiac Fibrillation Management Laboratory, Toronto General Hospital, Toronto, Canada k.nanthakumar@uhn.on.ca.
authors.forename: Kumaraswamy
authors.initials: K
authors.lastname: Nanthakumar
mesh_terms: D062906:Cardiac Catheters; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D007507:Therapeutic Irrigation; D016896:Treatment Outcome
keywords: Bipolar ablation; Langendorff perfusion; Ventricular tachycardia