| Diastolic time fraction as a determinant of subendocardial perfusion. | |
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MedLine Citation:
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PMID: 15615846 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Diastolic time fraction (DTF) has been recognized as an important determinant for subendocardial perfusion, but microsphere studies in which DTF was the independent variable are practically absent. In 21 anesthetized goats, the left coronary main stem was artificially perfused at controlled pressure. DTF was varied by pacing the heart, vagus stimulation, or administration of dobutamine. Regional coronary flow was measured with fluorescent microspheres under full adenosine dilation. Perfusion pressure (P(c)) was defined as mean coronary arterial pressure minus minimal left ventricular pressure. Regional flow conductances (flow/P(c)) were as follows: for the subendocardium, C(endo) = -0.103 + 0.197 DTF + 0.00074 P(c) (P < 0.001); for the midmyocardium, conductance = -0.048 + 0.126 DTF + 0.00049 P(c) (P < 0.001); and for the subepicardium, C(epi) was not significant. C(endo)-DTF relations demonstrated a finite value for DTF at which flow is zero, implying that, at physiological pressures, systolic subendocardial flow limitation extends into diastole. The DTF corresponding to an equal conductance in subendocardium and subepicardium (DTF1) was inversely related to P(c): DTF1 = 0.78 - 0.003 P(c) (P < 0.01). When heart rate and P(c) were held constant and dobutamine was administered (5 goats), contractility doubled and DTF increased by 39%, resulting in an increase of C(endo) of 40%. It is concluded that 1) DTF is a determinant of subendocardial perfusion, 2) systolic compression exerts a flow-limiting effect into diastole, and 3) corresponding to clinical findings on inducible ischemia we predict that, under hyperemic conditions, C(endo) < C(epi) if P(c) is lower than approximately 75% of a normal aortic pressure and heart rate >80 beats/min. |
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Authors:
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Dirk S Fokkema; Jurgen W G E VanTeeffelen; Simone Dekker; Isabelle Vergroesen; Johannes B Reitsma; Jos A E Spaan |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2004-12-22 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: 288 ISSN: 0363-6135 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2005 May |
Date Detail:
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Created Date: 2005-04-20 Completed Date: 2005-05-31 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: United States |
Other Details:
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Languages: eng Pagination: H2450-6 Citation Subset: IM |
Affiliation:
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Department of Medical Physics, Cardiovascular Research Institute Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blood Pressure / physiology Cardiotonic Agents / pharmacology Coronary Circulation / physiology* Diastole / drug effects, physiology* Dobutamine / pharmacology Endocardium / physiology* Goats Heart Rate / physiology Microspheres Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Cardiotonic Agents; 34368-04-2/Dobutamine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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