Document Detail

Energetically optimal left ventricular pressure for the failing human heart.
MedLine Citation:
PMID:  8616943     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: An energy-starved failing heart would benefit from more effective transfer of the mechanical energy of ventricular contraction to blood propulsion. However, the energetically optimal loading conditions for the failing heart are difficult to establish. In the present study, we analyzed the optimal left ventricular pressure to achieve maximal mechanical efficiency of the failing heart in humans. METHODS AND RESULTS: We determined the relation between left ventricular pressure-volume area and myocardial oxygen consumption per beat (VO2), stoke work, and mechanical efficiency (stroke work/VO2) in 13 patients with different contractile states. We also calculated the optimal end-systolic pressure that would theoretically maximize mechanical efficiency for a given end-diastolic volume and contractility. Left ventricular pressure-volume loops were constructed by plotting the instantaneous left ventricular pressure against the left ventricular volume at baseline and during pressure loading. The contractile properties of the ventricle were defined by the slope of the end-systolic pressure-volume relation. In patients with less compromised ventricular function, the operating end-systolic pressure was close to the optimal pressure, achieving nearly maximal mechanical efficiency. As the heart deteriorated, however, the optimal end-systolic pressure became significantly lower than normal, whereas the actual pressure remained within the normal range. This discrepancy resulted in worsening of ventriculoarterial coupling and decreased mechanical efficiency compared with theoretically maximal efficiency. CONCLUSIONS: Homeostatic mechanisms to maintain arterial blood pressure within the normal range cause the failing heart to deviate from energetically optimal conditions.
H Asanoi; T Kameyama; S Ishizaka; T Nozawa; H Inoue
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Circulation     Volume:  93     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1996 Jan 
Date Detail:
Created Date:  1996-06-10     Completed Date:  1996-06-10     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  67-73     Citation Subset:  AIM; IM    
Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Japan.
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MeSH Terms
Blood Pressure
Energy Metabolism
Heart Failure / physiopathology*
Middle Aged
Oxygen Consumption
Ventricular Function, Left*

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