Document Detail

Assessment of Exit block following Pulmonary Vein Isolation: Far-Field Capture Masquerading as Entrance without Exit block.
MedLine Citation:
PMID:  22683746     Owner:  NLM     Status:  Publisher    
BACKGROUND: Complete electrical isolation of pulmonary veins (PV) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block and this may appear as persistent conduction from PV to LA. OBJECTIVE: The aim of our study is to facilitate accurate assessment of exit block. METHODS: Twenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed then pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs. RESULTS: All 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins. Mean age 58±9 yrs; Paroxysmal AF 40%; HTN 70%, DM 30%, CAD 15%; LVEF 55±10%; LA size 42±11 mm. Despite entrance block, exit block was absent in only 16% of PVs suggesting persistent PV to LA conduction. Far-field capture (FFC) of LA appendage was noted in 38% of Left Superior PVs. FFC of superior vena cava (SVC) was noted in 30% of right superior PVs. Mean pacing threshold for FFC was 7±4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block. CONCLUSIONS: FFC of LA appendage or SVC can masquerade as persistent PV to LA conduction. Careful assessment for PV capture at decreasing pacing output is essential to exclude FFC.
Pugazhendhi Vijayaraman; Gopi Dandamudi; Angela Naperkowski; Jess Oren; Randle Storm; Kenneth A Ellenbogen
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-5
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  -     ISSN:  1556-3871     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-6-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier Inc.
Cardiac Electrophysiology, Geisinger Wyoming Valley Medical Center, Wilkes-Barre, PA.
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