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  • Left ventricular output and aortic blood flow in response to changes in preload and afterload in the preterm piglet heart

    Author(s)
    Eiby, Yvonne Ann
    Lumbers, Eugenie R.
    Headrick, John
    Lingwood, Barbara E.
    Griffith University Author(s)
    Headrick, John P.
    Year published
    2012
    Metadata
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    Abstract
    Low systemic blood flow occurs in up to 30% of infants born at less than 30 wk gestation. It is associated with increased morbidity and mortality, and current treatments are ineffective in 40% of cases. The aim of this study was to assess the ability of the preterm heart to respond to the acute shifts in preload and afterload that occur at the time of birth. Myocardial and coronary vascular function was assessed using an isolated working heart model in term (115 days) and preterm (92 days) piglets. Cardiac output/kg body wt in preterm hearts was ~50% lower than that of term hearts (P = 0.001). Pressure development was similar ...
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    Low systemic blood flow occurs in up to 30% of infants born at less than 30 wk gestation. It is associated with increased morbidity and mortality, and current treatments are ineffective in 40% of cases. The aim of this study was to assess the ability of the preterm heart to respond to the acute shifts in preload and afterload that occur at the time of birth. Myocardial and coronary vascular function was assessed using an isolated working heart model in term (115 days) and preterm (92 days) piglets. Cardiac output/kg body wt in preterm hearts was ~50% lower than that of term hearts (P = 0.001). Pressure development was similar in term and preterm hearts. Elevations in preload increased cardiac output and aortic flow similarly in term and preterm hearts, demonstrating significant preload "reserve". By contrast, elevations in afterload markedly depressed aortic flow, with a greater proportion of cardiac output being distributed to coronary flow in preterm hearts at high afterloads. The demands of increased workload were associated with greater increases in coronary flow in preterm hearts compared with term hearts. In preterm hearts, exposure to maternal glucocorticoids resulted in increased aortic flow when afterload was below 25 mmHg. These data suggest the preterm heart lacks the functional capacity to acutely adapt to postnatal afterload. To maximize systemic blood flow in preterm infants, treatments limiting afterload, while harnessing significant preload reserve, should be further explored.
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    Journal Title
    American Journal of Physiology - Regulatory, Integrative and Comparative Physiology
    Volume
    303
    Issue
    7
    Publisher URI
    http://ajpregu.physiology.org/content/303/7/R769.short
    Copyright Statement
    Self-archiving of the author-manuscript version is not yet supported by this journal. Please refer to the journal link for access to the definitive, published version or contact the authors for more information.
    Subject
    Systems Physiology
    Biological Sciences
    Medical and Health Sciences
    Publication URI
    http://hdl.handle.net/10072/51831
    Collection
    • Journal articles

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