Document Detail


Contracture of the newborn myocardium after prolonged prearrest cooling.
MedLine Citation:
PMID:  8412258     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Profound hypothermic circulatory arrest is frequently used to facilitate the surgical repair of congenital heart defects in neonates. Deep hypothermia is achieved by a period of core systemic cooling during cardiopulmonary bypass before cardioplegic arrest. There have been conflicting reports with respect to the consequence of perfusing a nonarrested newborn heart under hypothermic conditions. This in vitro study was designed to prolong the clinically simulated hypothermic perfusion sequence into an extreme condition and to test the hypothesis that prolonged cold perfusion of the nonarrested newborn myocardium could, in fact, be detrimental. Twenty-four newborn piglets (5 to 7 days old) were randomly assigned to four groups and studied in a crystalloid perfused Langendorff heart model. The first two groups of hearts (n = 6 per group) were subjected to either 30 minutes (group I) or 90 minutes (group II) of cold perfusion at 15 degrees C, followed by 90 minutes of ischemia and then 30 minutes of normothermic reperfusion. In a second experiment, group III hearts subjected to 30 minutes of cold perfusion were compared with group IV (90 minutes of cold perfusion) without ischemic insult in either case. Postischemic recovery of isovolumetric developed pressure was significantly impaired in group II (16.1% +/- 7.4% [II] versus 65.5% +/- 4.8% [I], p < 0.05), and 50% of the hearts had no spontaneous cardiac activity on reperfusion. End-diastolic pressure showed significant contracture with prolonged cold perfusion: group II 57.3 +/- 13.9 mm Hg versus group I 14.8 +/- 1.8 mm Hg, p < 0.05. In the absence of ischemia, a similar relationship was observed between groups IV and III (left ventricular developed pressure 68.5% +/- 3.6% versus 82.4% +/- 4.2%, p < 0.05, and left ventricular end-diastolic pressure 23.5 +/- 6.2 mm Hg versus 13.3 +/- 2.6 mm Hg, p = not significant. Ultrastructural examination revealed severe damage to the myocardial cells and contraction band necrosis in group II (prolonged cooling and ischemia). These results suggest that prolonged cold perfusion of the nonarrested newborn heart impairs functional recovery and is therefore detrimental. When followed by a period of ischemic arrest, it further potentiates the myocardial injury and induces severe contracture. This preceding adverse effect of prolonged myocardial cold perfusion before cardiac arrest may, in part, explain the suboptimal protective effect of cardioplegia in neonates.
Authors:
D Shum-Tim; C I Tchervenkov; T Hosseinzadeh; R C Chiu
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of thoracic and cardiovascular surgery     Volume:  106     ISSN:  0022-5223     ISO Abbreviation:  J. Thorac. Cardiovasc. Surg.     Publication Date:  1993 Oct 
Date Detail:
Created Date:  1993-11-17     Completed Date:  1993-11-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376343     Medline TA:  J Thorac Cardiovasc Surg     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  643-50     Citation Subset:  AIM; IM    
Affiliation:
Division of Cardiovascular and Thoracic Surgery, Montreal General Hospital/The Montreal Children's Hospital McGill University, Quebec, Canada.
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MeSH Terms
Descriptor/Qualifier:
Animals
Animals, Newborn
Contracture / etiology*,  pathology,  physiopathology
Heart / physiology
Heart Arrest, Induced*
Heart Function Tests
Hypothermia, Induced / adverse effects*
Myocardium / pathology*,  ultrastructure
Perfusion / adverse effects
Swine

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


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