Lung-to-lung circulation times during exercise in heart failure

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Title Lung-to-lung circulation times during exercise in heart failure
Author Morris, Norman; Snyder, Eric M.; Beck, Kenneth C.; Johnson, Bruce D.
Journal Name European Journal of Applied Physiology
Year Published 2009
Place of publication Germany
Publisher Springer
Abstract Circulation time (the transit time for a bolus of blood through the circulatory system) is a potential index of cardiac dysfunction in chronic heart failure (HF). In healthy subjects, circulation time falls as cardiac output (Q) rises during exercise, however little is known about this index in HF. In this study we examined the relationship between lung-to-lung circulation time (LLCT) during exercise in ten HF (53 ± 14 year, resting ejection fraction = 23 ± 8%) and control subjects (51 ± 18 year). We hypothesized that HF patients would have slower LLCT times during exercise when compared to control subjects. Each subject completed two identical incremental exercise tests during which LLCT was measured in one test and Q measured in the other. Q was measured using the open circuit C2H2 washin technique and circulation time measured using an inert gas technique. In HF patients and control subjects, LLCT decreased and Q increased from rest (HF:LLCT = 53.6 ± 8.2 s, Q = 4.3 ± 1.1 l min−1; control: LLCT = 55.3 ± 10.9 s, Q = 4.5 ± 0.5 l min−1) to peak exercise (HF:LLCT = 20.6 ± 3.9* s, Q = 8.8 ± 2.5* l min−1; control:LLCT = 14.9 ± 2.4 s, Q = 16.5 ± 1.2 l min−1; *P < 0.05 vs control). LLCT was significantly (P < 0.05) slower for the HF group when compared to the control group during submaximal exercise and at peak exercise. However, at a fixed Q the HF subjects had a faster LLCT. We hypothesize that the faster LLCT at a fixed Q for HF patients, may be the result of a more intensive peripheral vasoconstriction of non-active beds and a better redistribution of blood flow.
Peer Reviewed Yes
Published Yes
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Copyright Statement Copyright 2009 Springer Berlin / Heidelberg. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. The original publication is available at
Volume 106
Issue Number 4
Page from 621
Page to 627
ISSN 1439-6319
Date Accessioned 2010-03-05
Language en_AU
Research Centre Menzies Health Institute Qld; Heart Foundation Research Centre
Faculty Griffith Health Faculty
Subject Exercise Physiology
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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