title: Epicardial ablation with irrigated electrodes: – effect of bipolar vs. unipolar ablation on lesion formation –.
abstract: BACKGROUND
  Ablation of ventricular tachycardia originating from the left ventricular (LV) epicardium is often limited by the radiofrequency power delivery. We compared the effect of bipolar vs. unipolar epicardial ablation on lesion size.
  
  
  RESULTS
  Eleven excised pig hearts were superfused with saline (2 L/min). Unipolar ablation (25 or 30 W for 120 s) was performed between the LV epicardial saline-irrigated electrode and an indifferent electrode (n = 33 lesions). Bipolar ablation (25 or 30 W for 120 s) was performed between a 4-mm saline-irrigated-tip (20 ml/min) electrode on the LV epicardium and an opposing 10-mm non-irrigated-tip electrode on the LV endocardium (n = 38 lesions). Wall thickness did not differ between experiments (15.4 ± 2.4 vs. 15.3 ± 2.1 mm). Impedance was lower at the beginning and end of unipolar ablation than at the beginning and end of bipolar ablation (163.2 ± 20.3Ω and 109.9 ± 16.0Ω vs. 194.6 ± 23.3Ω and 127.1 ± 16.4Ω, respectively) (P<0.001). Epicardial lesion width did not differ between unipolar and bipolar ablation (10.1 ± 2.7 vs. 10.2 ± 2.4 mm), but lesion depth was greater with bipolar ablation (10.6 ± 2.7 vs. 7.5 ± 1.0 mm) (P<0.001). Unipolar ablation produced no transmural lesion, but bipolar ablation produced 15 (46%) (P<0.001). Steam pop occurred in 11 (29%) and 3 (9%) cases, respectively (P = 0.036).
  
  
  CONCLUSIONS
  Bipolar ablation of the LV free wall is highly effective at creating an appropriately deep epicardial lesion.
authors.affiliation: Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Nagashima
authors.forename: Ichiro
authors.initials: I
authors.lastname: Watanabe
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okumura
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Sonoda
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kofune
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mano
authors.forename: Kimie
authors.initials: K
authors.lastname: Ohkubo
authors.forename: Toshiko
authors.initials: T
authors.lastname: Nakai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kunimoto
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kasamaki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hirayama
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*; D017097:Electric Impedance; D004566:Electrodes; D004699:Endocardium / Q000601:surgery*; D006352:Heart Ventricles / Q000473:pathology; D010496:Pericardium / Q000601:surgery*; D012965:Sodium Chloride / Q000494:pharmacology; D013227:Steam / Q000009:adverse effects; D013552:Swine; D017180:Tachycardia, Ventricular / Q000473:pathology / Q000628:therapy*; D007507:Therapeutic Irrigation
chemical_list: D013227:Steam; D012965:Sodium Chloride