Document Detail

Alterations in endocardial activation of the canine papillary muscle early and late after myocardial infarction.
MedLine Citation:
PMID:  3652425     Owner:  NLM     Status:  MEDLINE    
Permanent coronary occlusion produces time-dependent changes in surviving subendocardial cellular properties. We compared the functional alterations in Purkinje (P) and ventricular muscle (VM) activation early (24 hr) and late (4 weeks or greater) after permanent coronary occlusion in an in vitro preparation of canine papillary muscle. High-density extracellular (1 to 2 mm resolution) and selected intracellular recordings were made in five animals early and seven animals late during stimulation of a free-running P strand. Activation patterns of P and VM layers from ischemic and unaffected papillary muscles were compared in the same animal. Average P layer conduction velocity was determined in normal and ischemic regions with the use of a linear array of recording and stimulating electrodes. Purkinje activation was altered little in the early phase of infarction, while healing was associated with a generalized 25% reduction in P layer conduction velocity and localized block and fragmentation of P waveforms. Intracellular recordings at sites of nonsynchronous P activation revealed electrotonic interaction between cell groups. At 24 hr, small groups of VM were present but with abnormal activation patterns in regions of necrosis with fragmented and delayed extracellular waveforms produced by partially uncoupled groups of cells. Local delay and block could be modulated by rate and site of stimulation. After healing, VM activation abruptly stopped at the visual infarct border, marked by a characteristic "end potential." These studies demonstrate important differences in the functional attributes of the P and VM layers studied early and late after coronary occlusion. Alterations in cell-to-cell relationships are likely very important in determining abnormalities of activation in both settings.
M G Kienzle; R C Tan; B M Ramza; M L Young; R W Joyner
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  76     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1987 Oct 
Date Detail:
Created Date:  1987-11-19     Completed Date:  1987-11-19     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  860-74     Citation Subset:  AIM; IM    
Department of Internal Medicine, University of Iowa, Iowa City.
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MeSH Terms
Endocardium / physiopathology
Heart Ventricles / physiopathology
Myocardial Infarction / pathology,  physiopathology*
Papillary Muscles / pathology,  physiopathology*
Purkinje Fibers / physiopathology
Time Factors
Grant Support

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

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