Document Detail


Functional uncoupling of the mitral annulus and left ventricle with mitral regurgitation and dopamine.
MedLine Citation:
PMID:  18512487     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: The mitral annulus and left ventricle are generally thought to be functionally coupled, in the sense that increases in left ventricular (LV) size, as seen in ischemic mitral regurgitation (MR), or decreases in LV size, as seen with inotropic stimulation, are thought to increase or decrease annular dimensions in similar manner. The study aim was to elucidate the functional relationship between the mitral annulus and left ventricle during acute MR and inotrope-induced MR reduction. METHODS: Radiopaque markers were implanted on the left ventricle and mitral annulus of five adult sheep. A suture was placed on the central scallop of the posterior mitral leaflet and exteriorized through the atrial-ventricular groove. Open-chest animals were studied at baseline (CTRL), at seconds after pulling on the suture to create moderate-severe 'pure' MR (PULL), and after titration of dopamine until the MR grade was maximally reduced (PULL+DOPA). This process was repeated two to three times for each animal. RESULTS: The MR grade was increased with PULL (from 0.5 +/- 0.01 to 3.4 +/- 0.4, p < 0.01) and decreased after PULL+DOPA (from 3.4 +/- 0.4 to 1.5 +/- 0.9, p < 0.001). PULL resulted in an increase in mitral annular (MA) area, predominantly by an increase in the muscular mitral annulus. PULL+DOPA caused a decrease in MA area, but the LV volume and dimensions were not altered with either PULL or PULL+DOPA. CONCLUSION: The acute geometric response to 'pure' MR and inotrope-induced MR reduction was limited to the mitral annulus. Surprisingly, the LV volume and dimensions did not change with acute MR or with inotrope-induced MR reduction. This suggests that, under these two conditions in an ovine model, the mitral annulus and left ventricle are functionally uncoupled.
Authors:
Tom C Nguyen; Akinobu Itoh; Carl J Carlhäll; Robert A Oakes; David Liang; Neil B Ingels; D Craig Miller
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of heart valve disease     Volume:  17     ISSN:  0966-8519     ISO Abbreviation:  J. Heart Valve Dis.     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-06-02     Completed Date:  2008-09-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9312096     Medline TA:  J Heart Valve Dis     Country:  England    
Other Details:
Languages:  eng     Pagination:  168-77; discussion 178     Citation Subset:  IM    
Affiliation:
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California 94305-5247, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cardiotonic Agents / pharmacology
Disease Models, Animal
Dopamine / pharmacology
Heart Ventricles / pathology*
Hemodynamics
Mitral Valve Insufficiency / chemically induced,  pathology*,  physiopathology
Models, Cardiovascular*
Sheep
Suture Techniques
Grant Support
ID/Acronym/Agency:
HL-29589/HL/NHLBI NIH HHS; HL-67025/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Cardiotonic Agents

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