| Left ventricular systolic and diastolic function during tilt table positioning and passive heat stress in humans. | |
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MedLine Citation:
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PMID: 21536844 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The ventricular response to passive heat stress has predominately been studied in the supine position. It is presently unclear how acute changes in venous return influence ventricular function during heat stress. To address this question, left ventricular (LV) systolic and diastolic function were studied in seventeen healthy men (24.3 ± 4.0 yrs; mean ± SD), using two-dimensional transthoracic echocardiography with Doppler ultrasound, during tilt table positioning (supine, 30° head-up tilt, HUT; and 30° head-down tilt, HDT), under normothermic and passive heat stress (core temperature 0.8 ± 0.1°C above baseline) conditions. The supine heat stress LV volumetric and functional response was consistent with previous reports. Combining HUT with heat stress reduced end-diastolic (25.2 ± 4.1%) and end-systolic (65.4 ± 10.5%) volume from baseline, while heart rate (37.7 ± 2.0%), ejection fraction (9.4 ± 2.4%), and LV elastance (37.7 ± 3.6%) increased, and stroke volume (-28.6 ± 9.4%) and early diastolic inflow (-17.5 ± 6.5%) and annular tissue (-35.6 ± 7.0%) velocities were reduced. Combining HDT with heat stress restored end-diastolic volume, while LV elastance (16.8 ± 3.2%), ejection fraction (7.2 ± 2.1%), and systolic annular tissue velocities (22.4 ± 5.0%) remained elevated above baseline, and end-systolic volume was reduced (-15.3 ± 3.9%). Stroke volume, and the early and late diastolic inflow and annular tissue velocities were unchanged from baseline. This investigation extends previous work by demonstrating increased LV systolic function with heat stress, under varied levels of venous return, and highlights the preload dependency of early diastolic function during passive heat stress. |
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Authors:
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Michael D Nelson; Luis A Altamirano-Diaz; Stewart R Petersen; Darren S Delorey; Michael K Stickland; Richard B Thompson; Mark J Haykowsky |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-2 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: - ISSN: 1522-1539 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-5-3 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1University of Alberta. |
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