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Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size
BACKGROUND: Many studies have shown that when hypothermia is started after coronary artery reperfusion (CAR), it is ineffective at reducing necrosis. However, some suggest that hypothermia may preferentially reduce no‐reflow. Our aim was to test the effects of hypothermia on no‐reflow when initiated...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Blackwell Publishing Ltd
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603258/ https://www.ncbi.nlm.nih.gov/pubmed/23525431 http://dx.doi.org/10.1161/JAHA.112.004234 |
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author | Hale, Sharon L. Herring, Michael J. Kloner, Robert A. |
author_facet | Hale, Sharon L. Herring, Michael J. Kloner, Robert A. |
author_sort | Hale, Sharon L. |
collection | PubMed |
description | BACKGROUND: Many studies have shown that when hypothermia is started after coronary artery reperfusion (CAR), it is ineffective at reducing necrosis. However, some suggest that hypothermia may preferentially reduce no‐reflow. Our aim was to test the effects of hypothermia on no‐reflow when initiated close to reperfusion and 30 minutes after reperfusion, times not associated with a protective effect on myocardial infarct size. METHODS AND RESULTS: Rabbits received 30 minutes coronary artery occlusion/3 hours CAR. In protocol 1, hearts were treated for 1 hour with topical hypothermia (myocardial temperature ≈32°C) initiated at 5 minutes before or 5 minutes after CAR, and the results were compared with a normothermic group. In protocol 2, hypothermia was delayed until 30 minutes after CAR and control hearts remained normothermic. In protocol 1, risk zones were similar and infarct size was not significantly reduced by hypothermia initiated close to CAR. However, the no‐reflow defect was significantly reduced by 43% (5 minutes before CAR) and 38% (5 minutes after CAR) in hypothermic compared with normothermic hearts (P=0.004, ANOVA, P=ns between the 2 treated groups). In protocol 2, risk zones and infarct sizes were similar, but delayed hypothermia significantly reduced no‐reflow in hypothermic hearts by 30% (55±6% of the necrotic region in hypothermia group versus 79±6% with normothermia, P=0.008). CONCLUSION: These studies suggest that treatment with hypothermia reduces no‐reflow even when initiated too late to reduce infarct size and that the microvasculature is especially receptive to the protective properties of hypothermia and confirm that microvascular damage is in large part a form of true reperfusion injury. |
format | Online Article Text |
id | pubmed-3603258 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | Blackwell Publishing Ltd |
record_format | MEDLINE/PubMed |
spelling | pubmed-36032582013-03-27 Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size Hale, Sharon L. Herring, Michael J. Kloner, Robert A. J Am Heart Assoc Original Research BACKGROUND: Many studies have shown that when hypothermia is started after coronary artery reperfusion (CAR), it is ineffective at reducing necrosis. However, some suggest that hypothermia may preferentially reduce no‐reflow. Our aim was to test the effects of hypothermia on no‐reflow when initiated close to reperfusion and 30 minutes after reperfusion, times not associated with a protective effect on myocardial infarct size. METHODS AND RESULTS: Rabbits received 30 minutes coronary artery occlusion/3 hours CAR. In protocol 1, hearts were treated for 1 hour with topical hypothermia (myocardial temperature ≈32°C) initiated at 5 minutes before or 5 minutes after CAR, and the results were compared with a normothermic group. In protocol 2, hypothermia was delayed until 30 minutes after CAR and control hearts remained normothermic. In protocol 1, risk zones were similar and infarct size was not significantly reduced by hypothermia initiated close to CAR. However, the no‐reflow defect was significantly reduced by 43% (5 minutes before CAR) and 38% (5 minutes after CAR) in hypothermic compared with normothermic hearts (P=0.004, ANOVA, P=ns between the 2 treated groups). In protocol 2, risk zones and infarct sizes were similar, but delayed hypothermia significantly reduced no‐reflow in hypothermic hearts by 30% (55±6% of the necrotic region in hypothermia group versus 79±6% with normothermia, P=0.008). CONCLUSION: These studies suggest that treatment with hypothermia reduces no‐reflow even when initiated too late to reduce infarct size and that the microvasculature is especially receptive to the protective properties of hypothermia and confirm that microvascular damage is in large part a form of true reperfusion injury. Blackwell Publishing Ltd 2013-02-22 /pmc/articles/PMC3603258/ /pubmed/23525431 http://dx.doi.org/10.1161/JAHA.112.004234 Text en © 2013 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley-Blackwell. http://creativecommons.org/licenses/by/2.5/ This is an Open Access article under the terms of the Creative Commons Attribution Noncommercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. |
spellingShingle | Original Research Hale, Sharon L. Herring, Michael J. Kloner, Robert A. Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size |
title | Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size |
title_full | Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size |
title_fullStr | Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size |
title_full_unstemmed | Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size |
title_short | Delayed Treatment With Hypothermia Protects Against the No‐Reflow Phenomenon Despite Failure to Reduce Infarct Size |
title_sort | delayed treatment with hypothermia protects against the no‐reflow phenomenon despite failure to reduce infarct size |
topic | Original Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603258/ https://www.ncbi.nlm.nih.gov/pubmed/23525431 http://dx.doi.org/10.1161/JAHA.112.004234 |
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