| Is PA-PWRmax truly a preload-independent index of myocardial contractility in anesthetized humans? | |
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MedLine Citation:
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PMID: 15103176 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study tested the hypothesis that the preload-adjusted maximal power index (PA-PWRmax) is a load-independent index of human myocardial contractility. Based on the ventricular pressure-volume relationship and derived from stroke work, the index is the product of instantaneous ventricular pressure and volume changes, divided by a correction term of end-diastolic volume (EDV2) or end-diastolic area (EDA3/2) to adjust for preload effects. Echocardiographic measures of instantaneous ventricular area change may be used to obtain PA-PWRmax noninvasively. We prospectively evaluated 28 human subjects undergoing cardiac evacuation before cardiopulmonary bypass procedures. Continuous peripheral arterial pressure, pulmonary arterial pressure, and echocardiographic views of the left ventricle in the transgastric short-axis view were recorded. Simultaneously gated instantaneous fractional shortening (FS) and PA-PWRmax indices were calculated, with FS = (EDA - ESA)/EDA and PA-PWRmax = [MAP (EDA - ESA)]/ EDA3/2, where ESA = end-systolic area and MAP = instantaneous mean arterial pressure. FS decreased uniformly with cardiac evacuation and decreasing pulmonary artery diastolic pressure (t = -5.4; 95% confidence interval, -10 to -0.046; p < 0.001), as did PA-PWRmax (t = -5.8; 95% confidence interval, -2.25 to -1.08; p < 0.001). FS and PA-PWRmax showed a strong downward correlation (r = 0.81). Unlike previous studies of autonomically denervated animals, our study did not find PA-PWRmax to be preload independent, perhaps because of the instantaneous homeostatic mechanisms of the human autonomic nervous system linking contractility to loading conditions. |
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Authors:
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Steven J Lester; Henry Shin; A Stephane Lambert; Joseph P Miller; Michael K Cahalan; Manfred D Seeberger; Elyse Foster; Nelson B Schiller |
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Publication Detail:
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Type: Journal Article Date: 2004-04-19 |
Journal Detail:
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Title: Cardiology Volume: 102 ISSN: 0008-6312 ISO Abbreviation: Cardiology Publication Date: 2004 |
Date Detail:
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Created Date: 2004-07-06 Completed Date: 2004-10-05 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 1266406 Medline TA: Cardiology Country: Switzerland |
Other Details:
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Languages: eng Pagination: 77-81 Citation Subset: IM |
Copyright Information:
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Copyright 2004 S. Karger AG, Basel |
Affiliation:
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Adult Echo Laboratory, University of California, San Francisco, San Francisco, Calif, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Anesthesia, General* Cardiac Output / physiology* Hemodynamics Humans Myocardial Contraction / physiology* Prospective Studies Ventricular Function, Left / physiology* Ventricular Pressure / physiology* |
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