| Polarity reversal lowers activation time during diastolic field stimulation of the rabbit ventricles: insights into mechanisms. | |
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MedLine Citation:
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PMID: 18708441 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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To fully characterize the mechanisms of defibrillation, it is necessary to understand the response, within the three-dimensional (3D) volume of the ventricles, to shocks given in diastole. Studies that have examined diastolic responses conducted measurements on the epicardium or on a transmural surface of the left ventricular (LV) wall only. The goal of this study was to use optical imaging experiments and 3D bidomain simulations, including a model of optical mapping, to ascertain the shock-induced virtual electrode and activation patterns throughout the rabbit ventricles following diastolic shocks. We tested the hypothesis that the locations of shock-induced regions of hyperpolarization govern the different diastolic activation patterns for shocks of reversed polarity. In model and experiment, uniform-field monophasic shocks of reversed polarities (cathode over the right ventricle is RV-, reverse polarity is LV-) were applied to the ventricles in diastole. Experiments and simulations revealed that RV- shocks resulted in longer activation times compared with LV- shocks of the same strength. 3D simulations demonstrated that RV- shocks induced a greater volume of hyperpolarization at shock end compared with LV- shocks; most of these hyperpolarized regions were located in the LV. The results of this study indicate that ventricular geometry plays an important role in both the location and size of the shock-induced virtual anodes that determine activation delay during the shock and subsequently affect shock-induced propagation. If regions of hyperpolarization that develop during the shock are sufficiently large, activation delay may persist until shock end. |
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Authors:
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M M Maleckar; M C Woods; V Y Sidorov; M R Holcomb; D N Mashburn; J P Wikswo; N A Trayanova |
Publication Detail:
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Type: In Vitro; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't Date: 2008-08-15 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: 295 ISSN: 0363-6135 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2008 Oct |
Date Detail:
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Created Date: 2008-10-08 Completed Date: 2008-12-05 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: United States |
Other Details:
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Languages: eng Pagination: H1626-33 Citation Subset: IM |
Affiliation:
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Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, Maryland 21218, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Computer Simulation Diastole* Electric Countershock / methods* Fluorescent Dyes / administration & dosage Heart Conduction System / physiology* Heart Ventricles / anatomy & histology Injections Models, Cardiovascular Pericardium / physiology Pyridinium Compounds / administration & dosage Rabbits Time Factors Ventricular Function* |
| Grant Support | |
ID/Acronym/Agency:
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HL058241/HL/NHLBI NIH HHS; HL063195/HL/NHLBI NIH HHS; HL082729/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Fluorescent Dyes; 0/Pyridinium Compounds; 90134-00-2/1-(3-sulfonatopropyl)-4-(beta)(2-(di-n-butylamino)-6-naphthylvinyl)pyridinium betaine |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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