Document Detail

Mechanisms for enlarging lesion size during irrigated tip radiofrequency ablation: is there a virtual electrode effect?
MedLine Citation:
PMID:  15209580     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: Irrigated tip radiofrequency ablation of cardiac arrhythmias was developed to increase the size of the radiofrequency-induced lesion, since cooling of the electrode tip allows use of higher power settings. The purpose of this study was to determine if the increased lesion size during irrigated tip ablation is caused by the cooling effect solely or if increased electrical conductivity around the tip also contributes by increasing the "current-delivering size" of the tip: the so-called "virtual electrode effect." METHODS AND RESULTS: In vitro strips of left ventricular porcine myocardium and in vivo canine left ventricles were ablated. In vitro closed loop tip and showerhead irrigated tip catheters were compared. In vitro and in vivo showerhead tip catheters irrigated with solutions having different ionic content were compared. We found no difference in lesion size for closed loop and showerhead-type catheters (998 +/- 345 vs. 811 +/- 313 mm(3) during power-controlled ablation and 227 +/- 76 vs 318 +/- 127 mm(3) during temperature-controlled ablation). For irrigation with liquids having increasing ionic strength we found a decrease in lesion volume in vitro (361 +/- 249 vs. 812 +/- 229 mm(3) (P < 0.001) for power-controlled and 156 +/- 78 vs. 318 +/- 127 mm(3) (P < 0.05) for temperature-controlled ablation and nonsignificant differences in vivo. CONCLUSIONS: The mechanism for enlarging lesion size during radiofrequency irrigated-tip ablation is that higher power levels can be used. There is no virtual electrode effect caused by the highly conductive surroundings of the tip during irrigation. In vitro this effect is shown to be opposite: it decreases lesion size.
Helen Høgh Petersen; Javier Roman-Gonzalez; Susan B Johnson; Jesper Hastrup Svendsen; Stig HaunsØ; Douglas L Packer
Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of interventional cardiology     Volume:  17     ISSN:  0896-4327     ISO Abbreviation:  J Interv Cardiol     Publication Date:  2004 Jun 
Date Detail:
Created Date:  2004-06-22     Completed Date:  2004-10-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8907826     Medline TA:  J Interv Cardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  171-7     Citation Subset:  IM    
Medical Department B, National University Hospital, Copenhagen, Denmark.
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MeSH Terms
Catheter Ablation / instrumentation*,  methods*
Equipment Design
Heart Ventricles / pathology*
Myocardium / pathology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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