Document Detail


Capacitive function of the heart: influence of acute changes in heart volume on mean right atrial pressure.
MedLine Citation:
PMID:  9038978     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Net transfer of blood volume into or out of the cardiac chambers should have the same effect on central venous pressure as does transfer of an equal volume of blood to or from peripheral organs (e.g., spleen, or liver). We studied five pentobarbital sodium-anesthetized open-chest pigs (20-23 kg) to determine whether a reduction in the time-averaged volume of blood contained in the heart, induced by rapid atrial pacing, can raise right atrial pressure. A central premise of our study is that the mean value of right atrial pressure is acutely governed by the volume of blood that distends the central veins, and that atrial contractions primarily determine how atrial pressure varies about its mean value. To prevent changes in cardiac output from altering central blood volume and pressure, cardiac output during rapid pacing (2.36 +/- 0.18 l/min) was made to equal the resting output (2.35 +/- 0.16 l/min). This was achieved by selecting a rate of pacing at which the tendency for more frequent cardiac contractions to raise cardiac output was counterbalanced by the decrease in stroke volume induced by rapid pacing. Autonomic reflex mechanisms were attenuated by pharmacological blockade. Mean arterial pressure was minimally affected in the transition from a normal sinus rhythm (89 +/- 6 beats/min) to rapid atrial pacing (165 +/- 7 beats/min) in four pigs. Mean right atrial pressure rose abruptly from 2.8 +/- 0.5 mmHg during normal sinus rhythm to 3.5 +/- 0.5 mmHg (P = 0.015) at the onset of rapid pacing in these four pigs, presumably owing to decreased cardiac blood volume and a reciprocal expansion of central venous volume. In the fifth pig, a reduction in cardiac output induced by tachycardia led to a larger rise in mean right atrial pressure than did a reduction in cardiac output induced by bradycardia, presumably because tachycardia reduces cardiac blood volume whereas bradycardia raises cardiac volume. We conclude that the heart may play an important role in maintaining or raising its own filling pressure when heart rate rises.
Authors:
D D Sheriff; Z Luo
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  272     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Jan 
Date Detail:
Created Date:  1997-03-31     Completed Date:  1997-03-31     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H553-8     Citation Subset:  IM    
Affiliation:
Division of Cardiovascular Research, St. Elizabeth's Medical Center, Boston, Massachusetts 02135, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Atrial Function, Right*
Blood Volume*
Cardiac Output
Cardiac Pacing, Artificial
Heart / physiology*
Heart Rate
Hemodynamics
Male
Pressure
Swine
Time Factors
Vagus Nerve / physiology
Grant Support
ID/Acronym/Agency:
HL-46314/HL/NHLBI NIH HHS

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


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