Document Detail

Tunnel propagation following defibrillation with ICD shocks: hidden postshock activations in the left ventricular wall underlie isoelectric window.
MedLine Citation:
PMID:  20348028     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: After near-defibrillation threshold (DFT) shocks from an implantable cardioverter-defibrillator (ICD), the first postshock activation that leads to defibrillation failure arises focally after an isoelectric window (IW). The mechanisms underlying the IW remain incompletely understood.
OBJECTIVE: The goal of this study was to provide mechanistic insight into the origins of postshock activations and IW after ICD shocks, and to link shock outcome to the preshock state of the ventricles. We hypothesized that the nonuniform ICD field results in the formation of an intramural excitable area (tunnel) only in the left ventricular (LV) free wall, through which both pre-existing and new shock-induced wavefronts propagate during the IW.
METHODS: Simulations were conducted using a realistic three dimensional (3D) model of defibrillation in the rabbit ventricles. Biphasic ICD shocks of varying strengths were delivered to 27 different fibrillatory states.
RESULTS: After near-DFT shocks, regardless of preshock state, the main postshock excitable area was always located within LV free wall, creating an intramural tunnel. Either pre-existing fibrillatory or shock-induced wavefronts propagated during the IW (duration of up to 74 ms) in this tunnel and emerged as breakthroughs on LV epicardium. Preshock activity within the LV played a significant role in shock outcome: a large number of preshock filaments resulted in an IW associated with tunnel propagation of pre-existing rather than shock-induced wavefronts. Furthermore, shocks were more likely to succeed if the LV excitable area was smaller.
CONCLUSION: The LV intramural excitable area is the primary reason for near-DFT failure. Any intervention that decreases the extent of this area will improve the likelihood of defibrillation success.
Jason Constantino; Yun Long; Takashi Ashihara; Natalia A Trayanova
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-03-25
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  7     ISSN:  1556-3871     ISO Abbreviation:  Heart Rhythm     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-07-15     Completed Date:  2010-11-22     Revised Date:  2011-09-26    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  United States    
Other Details:
Languages:  eng     Pagination:  953-61     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
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MeSH Terms
Body Surface Potential Mapping
Computer Simulation
Defibrillators, Implantable
Electric Countershock / adverse effects*
Heart Conduction System / physiopathology*
Imaging, Three-Dimensional
Models, Animal
Models, Cardiovascular
Pericardium / physiopathology
Ventricular Dysfunction, Left / physiopathology*
Ventricular Fibrillation / etiology,  physiopathology*
Grant Support
R01 HL063195-05/HL/NHLBI NIH HHS; R01 HL082729-04/HL/NHLBI NIH HHS; R01-HL067322/HL/NHLBI NIH HHS; R01-HL082729/HL/NHLBI NIH HHS
Comment In:
Heart Rhythm. 2010 Jul;7(7):962-3   [PMID:  20416400 ]

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

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