| Longitudinal impedance is independent of outflow resistance. | |
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MedLine Citation:
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PMID: 12505041 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Many investigators have measured outflow resistance (R) following peripheral bypass procedures, but correlations with graft patency have been weak. This is because the primary determinants of graft patency are the size and quality of the conduit, not its outflow bed. Efforts at separating conduit resistance from outflow resistance have been unsuccessful. Recently, the concept of longitudinal impedance ( integral Z(L)) has been suggested as a measure of conduit resistance independent of outflow resistance. The purpose of this in vitro experiment was to test the hypothesis that integral Z(L) is independent of R within physiologically relevant ranges. METHODS: Rigid polyethylene tubing of known internal diameter and length (4.3 mm, 375 cm) was perfused with a glycerin/saline mixture mimicking the viscosity of blood (4.1 cp), utilizing a variable pulsatile pump and Windkessel, with outflow into multiply branched tubes of decreasing diameter simulating the hemodynamic conditions of arterial bypass. Flow and pressure were measured using ultrasonic transit time and catheter transduction, respectively, and waveforms digitized at 200 Hz. Flow was varied while maintaining "systemic" pressure and resistance. After Fourier transformation, integral Z(L) was calculated as deltaP/Q at each harmonic and integrated over 4 Hz. RESULTS: integral Z(L) calculations were remarkably reproducible within the same day with a coefficient of variation (CV) = 4.0% (at 100 dyne. s/cm(5); n = 4) or over 4 successive days (CV = 4.3%). Furthermore, integral Z(L) was largely independent of R over the physiologic range tested, with integral Z(L) remaining relatively constant as R was increased sixfold. CONCLUSION: integral Z(L) is a consistent and reproducible measure of conduit resistance independent of R over a wide physiologic range. It may be useful for measuring the adequacy of bypass graft conduits. |
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Authors:
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Michael A Curi; Christopher L Skelly; Clay Quint; Shari L Meyerson; Amy J Farmer; Umar M Shakur; Francis Loth; Lewis B Schwartz |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of surgical research Volume: 108 ISSN: 0022-4804 ISO Abbreviation: J. Surg. Res. Publication Date: 2002 Dec |
Date Detail:
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Created Date: 2002-12-30 Completed Date: 2003-01-22 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0376340 Medline TA: J Surg Res Country: United States |
Other Details:
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Languages: eng Pagination: 191-7 Citation Subset: IM |
Affiliation:
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Section of Vascular Surgery, University of Chicago, Illinois 60637, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Blood Circulation* Hemodynamics Humans Models, Cardiovascular* Pressure Rheology Vascular Resistance* |
| Grant Support | |
ID/Acronym/Agency:
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5T32 HL07237/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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