title: Passive electrode effect reduces defibrillation threshold in bi-filament middle cardiac vein defibrillation.
abstract: OBJECTIVE
  To investigate whether a passive electrode effect decreases defibrillation threshold (DFT) in multi-filament middle cardiac vein (MCV) defibrillation.
  
  
  RESULTS
  Twelve pigs underwent active housing (AH) insertion, with defibrillation coils placed transvenously in right ventricular apex and superior vena cava. The MCV was cannulated, and 1.12F, 50 mm coil electrodes (Ela Medical SA, France) were deployed in its right and left branches. Lead placement was possible in 11 of 12 animals. DFT (J, mean +/- SD) was determined by three-reversal binary search and compared between the MCV monofilament (single filament deployed) and the AH (25.9 +/- 10.9) and the MCV mono + passive filaments (both filaments deployed, one connected) and the AH (19.9 +/- 11.4); 24% DFT reduction P = 0.008.
  
  
  CONCLUSIONS
  A bystander electrode adjacent to a monofilament electrode in the MCV reduces DFT by 24% when compared with monofilament MCV alone. Microfilament electrodes decrease DFT as auxiliary anode but not as sole anode.
authors.affiliation: Wessex Cardiothoracic Centre, Southampton University Hospitals, UK. johnpaisey@doctors.org.uk
authors.forename: John R
authors.initials: JR
authors.lastname: Paisey
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Yue
authors.forename: Frederick
authors.initials: F
authors.lastname: Bessoule
authors.forename: Paul R
authors.initials: PR
authors.lastname: Roberts
authors.forename: John M
authors.initials: JM
authors.lastname: Morgan
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000503:physiopathology*; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000009:adverse effects* / Q000295:instrumentation*; D017097:Electric Impedance; D004567:Electrodes, Implanted; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D013552:Swine; D014693:Ventricular Fibrillation / Q000628:therapy*