Document Detail

Negative chronotropic effect of beta-blockade therapy reduces myocardial oxygen expenditure for nonmechanical work.
MedLine Citation:
PMID:  8759074     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The negative chronotropic effect of beta-blocking agents is likely to provide hemodynamic and energetic advantages. However, the negative chronotropic effect on cardiac energetics observed on the initiation of beta-blockade therapy has not been fully elucidated. METHODS AND RESULTS: In 18 patients with heart failure, left ventricular pressure and volume, external work (EW), myocardial oxygen consumption per beat (total Vo2), mechanical efficiency (EW/total Vo2), and Vo2 for nonmechanical work (total Vo2-2.EW) were measured with the use of conductance catheter and Webster catheter at the following three states: under control conditions and after beta-blockade (0.15 +/- 0.07 mg/kg propranolol IV) with and without atrial pacing to keep the heart rate at control levels. Heart rate decreased after atrial pacing was stopped. EW decreased during beta-blockade with pacing and returned to the control level after pacing was stopped. Total Vo2 did not change during beta-blockade with or without pacing, whereas Vo2 for nonmechanical work increased with pacing and returned to the control level after pacing was stopped. As a result, mechanical efficiency decreased during beta-blockade with pacing and returned to the control level after pacing was stopped. CONCLUSIONS: The negative chronotropic effect of a beta-blocking agent may offset the mechanoenergetical deterioration resulting from its negative inotropic effect through a reduction in oxygen expenditure for nonmechanical work. These findings suggest that the negative chronotropic effect is an important aspect of beta-blockade therapy.
H Yamakawa; M Takeuchi; H Takaoka; K Hata; M Mori; M Yokoyama
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Circulation     Volume:  94     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1996 Aug 
Date Detail:
Created Date:  1996-12-11     Completed Date:  1996-12-11     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  340-5     Citation Subset:  AIM; IM    
First Department of Internal Medicine, Kobe University School of Medicine, Japan.
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MeSH Terms
Adrenergic beta-Antagonists / pharmacology*
Blood Pressure / drug effects
Blood Volume / drug effects
Cardiac Output, Low / physiopathology
Cardiac Pacing, Artificial
Energy Metabolism / drug effects
Heart Rate / drug effects*
Hemodynamics / drug effects
Myocardium / metabolism*
Oxygen Consumption / drug effects*
Reg. No./Substance:
0/Adrenergic beta-Antagonists

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