Document Detail


Left ventricular output and aortic blood flow in response to changes in preload and afterload in the preterm piglet heart.
MedLine Citation:
PMID:  22895742     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Aims: Low systemic blood flow occurs in up to 30% of infants born at less than 30 weeks 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. Methods: Myocardial and coronary vascular function was assessed using an isolated working heart model in term (115d) and preterm (92d) piglets. Results: Cardiac output /kg body weight in preterm hearts was approximately 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 to term hearts. In preterm hearts, exposure to maternal glucocorticoids resulted in increased aortic flow when afterload was below 25 mmHg. Conclusion: These data suggest the preterm heart lacks the functional capacity to acutely adapt to post-natal afterload. To maximise systemic blood flow in preterm infants, treatments limiting afterload while harnessing significant preload reserve should be further explored.
Authors:
Yvonne Ann Eiby; Eugenie R Lumbers; John P Headrick; Barbara E Lingwood
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-15
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1The University of Queensland.
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