| Response of the intact canine left ventricle to increased afterload and increased coronary perfusion pressure in the presence of coronary flow autoregulation. | |
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MedLine Citation:
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PMID: 10510061 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Increased left ventricular (LV) contractile force or oxygen consumption has been documented with increased coronary arterial pressure (CAP) and flow (Gregg phenomenon). We investigated whether the increase in contractile force with increased LV afterload might be mediated by the concomitant increase in CAP when coronary autoregulation is intact. METHODS AND RESULTS: The LV of 6 autonomically blocked open-chest dogs was perfused through the left main coronary artery by a cannula with a side gate to the aortic root. With the gate open, CAP increased from 77+/-20 to 93+/-20 mm Hg (P<0.05) with aortic constriction (AC). With the gate closed, CAP was maintained at a constant level of 100 mm Hg. A small reduction in the slope of the preload recruitable stroke work (PRSW) relationship was observed with AC, but this response was not altered by the coronary perfusion gate position. The end-systolic pressure-volume (ESPV) relationship shifted upward significantly with AC (P<0.001), but this shift was not greater with open-gate perfusion than with closed-gate perfusion. Furthermore, with coronary autoregulation intact, wide changes in CAP (between 60 and 180 mm Hg, n=5) did not alter either the PRSW or ESPV relationship. In contrast, when autoregulation was abolished with intracoronary adenosine (n=6), both indexes of contractility increased progressively with increased CAP. CONCLUSIONS: The concomitant increase in CAP with increased afterload in the intact canine LV does not contribute to the afterload-induced increase in contractile force. Coronary perfusion pressure per se does not influence LV contractile function. Coronary perfusion pressure influences contractility only when coronary flow changes. |
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Authors:
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M K Karunanithi; J A Young; W Kalnins; S Kesteven; M P Feneley |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Circulation Volume: 100 ISSN: 1524-4539 ISO Abbreviation: Circulation Publication Date: 1999 Oct |
Date Detail:
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Created Date: 1999-10-21 Completed Date: 1999-10-21 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0147763 Medline TA: Circulation Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1562-8 Citation Subset: AIM; IM |
Affiliation:
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Victor Chang Cardiac Research Institute and Cardiology Department, St. Vincent's Hospital, Sydney, Australia. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blood Pressure* Coronary Circulation* Dogs Homeostasis Myocardial Contraction* Ventricular Function, Left* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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