title: Formation of thermal coagulum on multielectrode catheters during phased radiofrequency energy ablation of persistent atrial fibrillation.
abstract: BACKGROUND
  Radiofrequency ablation (RFA) can unfavorably cause coagulum on the ablation electrode. The aim of this study was to assess this phenomenon on three different multielectrode catheters used to treat persistent atrial fibrillation with duty-cycled RFA.
  
  
  RESULTS
  Twenty-six consecutive patients have been treated with the pulmonary vein ablation catheter (PVAC) and the multiarray ablation catheter (MAAC). In 13 patients, additional ablation with the multiarray septal catheter (MASC) has been performed. The multichannel RF generator GENius™ (Medtronic Inc., Minneapolis, MN, USA) independently delivered energy in a bipolar and unipolar mode (ratio of 4/1, 2/1, or 1/1) to any of the electrodes. Versions 14.2, 14.3, and 14.4 of the generator were used. Coagulum presence was determined postablation by careful visual inspection of the catheter electrodes. No coagulum formation was visualized on the PVACs. Coagulum formation was visualized in 59% of the electrodes of the MAACs using a 2/1 mode and the 14.2 software version versus 69% using the 14.4 version and a 2/1 mode (P = 0.7) versus 14% of the electrodes applying a 1/1 ratio and the 14.4 software version (P < 0.001).
  
  
  CONCLUSIONS
  Duty-cycled RFA in 2/1 bipolar/unipolar ratio generates a substantial frequency of coagulum formation on the multielectrode catheters MAAC and MASC. The use of the 14.4 version of the software to drive the RF generator and the use of energy in the default 1/1 bipolar/unipolar ratio could significantly reduce the frequency of coagulum formation, but so far, could not completely overcome it. The PVAC did not form coagulum, regardless of generator version or energy ratio used.
authors.affiliation: Imelda Hospital, Bonheiden, Belgium.
authors.forename: Philippe
authors.initials: P
authors.lastname: Debruyne
authors.forename: Tom
authors.initials: T
authors.lastname: Rossenbacker
authors.forename: Bart
authors.initials: B
authors.lastname: Vankelecom
authors.forename: Filip
authors.initials: F
authors.lastname: Charlier
authors.forename: John
authors.initials: J
authors.lastname: Roosen
authors.forename: Bavo
authors.initials: B
authors.lastname: Ector
authors.forename: Luc
authors.initials: L
authors.lastname: Janssens
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000097:blood* / Q000601:surgery*; D001777:Blood Coagulation / Q000528:radiation effects*; D017115:Catheter Ablation / Q000009:adverse effects* / Q000295:instrumentation*; D002908:Chronic Disease; D004566:Electrodes / Q000009:adverse effects*; D004617:Embolism / Q000209:etiology*; D004867:Equipment Design; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011846:Radio Waves; D016896:Treatment Outcome
keywords: ablation; atrial fibrillation; clinical trials