Document Detail

Diminished stroke volume during inspiration: a reverse thoracic pump.
MedLine Citation:
PMID:  4017219     Owner:  NLM     Status:  MEDLINE    
In 12 conscious dogs, a three-dimensional array of pulse-transit ultrasonic transducers was used to measure left ventricular anterior-posterior minor, septal-free wall minor, and basal-apical major diameters. Matched micromanometers measured left ventricular, right ventricular, and intrapleural pressures. Electromagnetic ascending aortic blood flow and right ventricular transverse diameter were measured in five of the dogs. A major cause of the inspiratory decline in stroke volume in this preparation appeared to be reflex tachycardia and autonomic changes associated with inspiration. However, when heart rate was controlled by atrial pacing or pharmacologic autonomic attenuation (propranolol and atropine), stroke volume still decreased around 10%, with an inspiratory decrease in pleural pressure of 10 mm Hg. Based on the measurements of ventricular dimension, venous return to the right ventricle appeared to be augmented significantly during inspiration and the transient increase in right ventricular volume was associated with leftward interventricular septal shifting and altered diastolic left ventricular geometry. However, left ventricular end-diastolic volume was changed minimally, implying that alterations in preload were not important. Moreover, transmural left ventricular ejection pressure, calculated as intracavitary minus pleural pressure, was not significantly changed, and it seemed that neither pressure nor geometric components of afterload were altered significantly by inspiration. The inspiratory fall in left ventricular stroke volume correlated best with the decline in intracavitary left ventricular ejection pressure referenced to atmospheric pressure. It is hypothesized that during ejection, left ventricular pressure referenced to atmospheric pressure is the hydraulic force effecting stroke volume and that the decline in this effective left ventricular ejection pressure is responsible for the inspiratory fall in stroke volume through a reverse thoracic pump mechanism.
C O Olsen; G S Tyson; G W Maier; J W Davis; J S Rankin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  72     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1985 Sep 
Date Detail:
Created Date:  1985-09-26     Completed Date:  1985-09-26     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  668-79     Citation Subset:  AIM; IM; S    
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MeSH Terms
Atrial Function
Atropine / pharmacology
Autonomic Nervous System / drug effects,  physiology
Cardiac Output*
Heart Atria / drug effects
Propranolol / pharmacology
Stroke Volume*
Grant Support
2RO1 H109315-17//PHS HHS; R01 H129436-01//PHS HHS
Reg. No./Substance:
51-55-8/Atropine; 525-66-6/Propranolol

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

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