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International Angiology 2004 September;23(3):276-83

Copyright © 2004 EDIZIONI MINERVA MEDICA

language: English

Non spiral and spiral (helical) flow patterns in stenoses. In vitro observations using spin and gradient echo magnetic resonance imaging (MRI) and computable fluid dynamic modeling

Stonebridge P. A. 1, Buckley C. 2, Thompson A. 3, Dick J. 4, Hunter G. 5, Chudek J. A. 5, Houston J. G. 3, Belch J. J. F. 4

1 Department of Surgery, The Institute of Cardiovascular Research, Ninewells Hospital and Medical School, Dundee, Scotland, UK 2 Magnetic Resonance Research Centre, Department of Chemical Engineering, University of Cambridge, Cambridge, UK 3 Department of Radiology, The Institute of Cardiovascular Research, Ninewells Hospital and Medical School, Dundee, Scotland, UK 4 Department of Vascular Medicine, The Institute of Cardiovascular Research, Ninewells Hospital and Medical School, Dundee, Scotland, UK 5 Department of Chemistry, Dundee University, Dundee, Scotland, UK


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Aim. Phys­io­log­i­cal blood flow pat­terns are them­selves poor­ly under­stood ­despite their ­impact on arte­ri­al dis­ease. ­Stable spi­ral (hel­i­cal) lam­i­nar flow (SLF) has been ­observed in nor­mal sub­jects. The pur­pose of the ­present study is to devel­op a meth­od of mag­net­ic res­o­nance (MR) flow pat­tern vis­u­al­iza­tion and to ana­lyze spi­ral and non-spi­ral flow pat­terns with and with­out lumi­nal nar­row­ing in vitro. The flow con­di­tions were then mod­eled using com­pu­ta­tion­al fluid dynam­ics (Star-CD).
Meth­ods. Lam­i­nar integ­rity was exam­ined in a flow-rig using spin and gra­di­ent echo mag­net­ic res­o­nance imag­ing (MRI) in non-ste­nosed and ste­nosed con­duits in the pres­ence of non-spi­ral and spi­ral flow.
­Results. No dif­fer­ence was ­observed in a non-ste­nosed con­duit ­between non-spi­ral and spi­ral flow. In the pres­ence of a sten­o­sis spi­ral flow pre­serves flow veloc­ity coher­ence where­as non-spi­ral flow increas­ing­ly lost coher­ence begin­ning prox­i­mal to the sten­o­sis. Com­pu­ta­tion­al fluid dynam­ic mod­el­ing of the in vitro experi­ment ­showed ­marked dif­fer­enc­es ­between the 2 flow pat­terns. Non-spi­ral flow pro­duced great­er inward­ly direct­ed forc­es just ­beyond the sten­o­sis and great­er out­ward pres­sures at more dis­tal sites. The near wall tur­bu­lent ener­gy was up to 700% less with spi­ral flow over non-spi­ral flow ­beyond the sten­o­sis.
Con­clu­sion. Spi­ral flow ­appears to offer clear flow pro­file sta­bi­liz­ing advan­tag­es over non-spi­ral flow, by sig­nif­i­cant­ly reduc­ing the tur­bu­lence ­caused by a sten­o­sis. Spi­ral flow also pro­duc­es lower forc­es act­ing on the ves­sel wall.

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