Document Detail

Assessment of aortic pressure power components and their link to overall elastic and resistive arterial properties.
MedLine Citation:
PMID:  10505389     Owner:  NLM     Status:  MEDLINE    
This paper reviews the analytical expressions for in-phase and quadrature aortic power components associated with the real and imaginary parts of aortic input admittance, respectively. It is shown that active power Wact, and its steady, Wstdy, and pulsatile, Wpuls, components logically follow from in-phase power. Reactive power follows from quadrature power only for sinusoidal signals. The definition of reactive power indexes for real aortic pressures and flows requires extreme care. The link between overall arterial properties and pressure power components (and indexes) is investigated, making use of a three-element windkessel model and ascending aortic pressure and flow data taken from eight anaesthetised dogs, under basal state and after treatment with a vasoconstrictor (methoxamine). Seven dogs are normotensive in the baseline state (NBA cases, n = 7), the average (+/- SE) of mean pressure being 86.5 +/- 5.2 mmHg. The eighth dog has a baseline mean pressure of 134 mmHg and is considered to be hypertensive. The two experimental cases from this dog are grouped with those from the other seven dogs after vasoconstriction, to form the NVC + H group (n = 9). On average, fitting the model to the experimental data yields a 100% increase (p < 0.05) in total peripheral resistance, a 63% decrease (p < 0.01) in total arterial compliance and a 10% decrease (p > 0.05) in aortic characteristic impedance, from the NBA group to the NVC + H. Correspondingly, the peak-to-peak amplitude of quadrature power shows a 69% increase (p < 0.02). Wact, Wstdy, and Wpuls show a 28% increase (p > 0.05), a 40% increase (p < 0.02) and a 43% decrease (p > 0.05), respectively. Energetic efficiency of the arterial system, Eart = 1 - (Wpuls/Wact), increases by 8% (p < 0.02). From analysis of the estimates of power components and arterial parameters in relation to low-frequency phase angles of aortic impedance, it is concluded that the decrease in total arterial compliance with increasing pressure reduces the power lost in pulsation. This happens at the expense of an increase in quadrature power and absolute values of related reactive power indexes.
R Burattini; K B Campbell
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medical & biological engineering & computing     Volume:  37     ISSN:  0140-0118     ISO Abbreviation:  Med Biol Eng Comput     Publication Date:  1999 May 
Date Detail:
Created Date:  1999-10-22     Completed Date:  1999-10-22     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7704869     Medline TA:  Med Biol Eng Comput     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  366-76     Citation Subset:  IM    
Department of Electronics & Automatica, University of Ancona, Italy.
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MeSH Terms
Aorta / physiology*
Blood Pressure / physiology*
Fourier Analysis
Models, Cardiovascular*
Regional Blood Flow / physiology
Vascular Resistance

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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