Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude

Research output: Contribution to journalArticleResearchpeer review

Authors

  • Mike Stembridge
  • Philip N. Ainslie
  • Michael G. Hughes
  • Eric J. Stöhr
  • James D. Cotter
  • Michael M. Tymko
  • Trevor A. Day
  • Akke Bakker
  • Rob Shave

External Research Organisations

  • Cardiff Metropolitan University
  • University of British Columbia
  • University of Otago
  • Mount Royal University
  • University of Twente
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Details

Original languageEnglish
Pages (from-to)1219-1227
Number of pages9
JournalJournal of applied physiology
Volume119
Issue number10
Early online date15 Nov 2015
Publication statusPublished - Nov 2015
Externally publishedYes

Abstract

Stembridge M, Ainslie PN, Hughes MG, Stöhr EJ, Cotter JD, Tymko MM, Day TA, Bakker A, Shave R. Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude. J Appl Physiol 119: 1219-1227, 2015. First published March 6, 2015; doi:10.1152/japplphysiol.00995.2014.-Impaired myocardial systolic contraction and diastolic relaxation have been suggested as possible mechanisms contributing to the decreased stroke volume (SV) observed at high altitude (HA). To determine whether intrinsic myocardial performance is a limiting factor in the generation of SV at HA, we assessed left ventricular (LV) systolic and diastolic mechanics and volumes in 10 healthy participants (aged 32 ± 7; mean ± SD) at rest and during exercise at sea level (SL; 344 m) and after 10 days at 5,050 m. In contrast to SL, LV end-diastolic volume was ∼19% lower at rest (P = 0.004) and did not increase during exercise despite a greater untwisting velocity. Furthermore, resting SV was lower at HA (∼17%; 60 ± 10 vs. 70 ± 8 ml) despite higher LV twist (43%), apical rotation (115%), and circumferential strain (17%). With exercise at HA, the increase in SV was limited (12 vs. 22 ml at SL), and LV apical rotation failed to augment. For the first time, we have demonstrated that EDV does not increase upon exercise at high altitude despite enhanced in vivo diastolic relaxation. The increase in LV mechanics at rest may represent a mechanism by which SV is defended in the presence of a reduced EDV. However, likely because of the higher LV mechanics at rest, no further increase was observed up to 50% peak power. Consequently, although hypoxia does not suppress systolic function per se, the capacity to increase SV through greater deformation during submaximal exercise at HA is restricted.

Keywords

    Hypoxia, Left ventricular mechanics, Stroke volume

ASJC Scopus subject areas

Cite this

Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude. / Stembridge, Mike; Ainslie, Philip N.; Hughes, Michael G. et al.
In: Journal of applied physiology, Vol. 119, No. 10, 11.2015, p. 1219-1227.

Research output: Contribution to journalArticleResearchpeer review

Stembridge M, Ainslie PN, Hughes MG, Stöhr EJ, Cotter JD, Tymko MM et al. Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude. Journal of applied physiology. 2015 Nov;119(10):1219-1227. Epub 2015 Nov 15. doi: 10.1152/japplphysiol.00995.2014
Stembridge, Mike ; Ainslie, Philip N. ; Hughes, Michael G. et al. / Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude. In: Journal of applied physiology. 2015 ; Vol. 119, No. 10. pp. 1219-1227.
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