Document Detail

Site-specific differences in latency intervals during biventricular pacing: impact on paced QRS morphology and echo-optimized V-V interval.
MedLine Citation:
PMID:  20735713     Owner:  NLM     Status:  In-Process    
OBJECTIVE: To investigate differences in latency intervals during right ventricular (RV) pacing and left ventricular (LV) pacing from the (postero-)lateral cardiac vein in cardiac resynchronization therapy (CRT) patients and their relationship to echo-optimized interventricular (V-V) intervals and paced QRS morphology.
METHODS: We recorded digital 12-lead electrocardiograms in 40 CRT patients during RV, LV, and biventricular pacing at three output settings. Stimulus-to-earliest QRS deflection (latency) intervals were measured in all leads. Echocardiographic atrioventricular (AV) and V-V optimization was performed using aortic velocity time integrals.
RESULTS: Latency intervals were longer during LV (34 ± 17, 29 ± 15, 28 ± 15 ms) versus RV apical pacing (17 ± 8, 15 ± 8, 13 ± 7 ms) for threshold, threshold ×3, and maximal output, respectively (P < 0.001), and shortened with increased stimulus strength (P < 0.05). The echo-optimized V-V interval was 58 ± 31 ms in five of 40 (12%) patients with LV latency ≥ 40 ms compared to 29 ± 20 ms in 35 patients with LV latency < 40 ms (P < 0.01). During simultaneous biventricular pacing, four of five (80%) patients with LV latency ≥ 40 ms exhibited a left bundle branch block (LBBB) pattern in lead V(1) compared to three of 35 (9%) patients with LV latency < 40 ms (P < 0.01). After optimization, all five patients with LV latency ≥ 40 ms registered a dominant R wave in lead V(1) .
CONCLUSIONS: LV pacing from the lateral cardiac vein is associated with longer latency intervals than endocardial RV pacing. LV latency causes delayed LV activation and requires V-V interval adjustment to improve hemodynamic response to CRT. Patients with LV latency ≥ 40 ms most often display an LBBB pattern in lead V(1) during simultaneous biventricular pacing, but a right bundle branch block after V-V interval optimization.
Bengt Herweg; Rias Ali; Arzu Ilercil; Chris Madramootoo; Ray Cutro; Mark W Weston; S Serge Barold
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-08-24
Journal Detail:
Title:  Pacing and clinical electrophysiology : PACE     Volume:  33     ISSN:  1540-8159     ISO Abbreviation:  Pacing Clin Electrophysiol     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7803944     Medline TA:  Pacing Clin Electrophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1382-91     Citation Subset:  IM    
Copyright Information:
©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.
Arrhythmia Service and Division of Cardiology, Tampa General Hospital and University of South Florida, Tampa, Florida 33606, USA.
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