| Local and global geometric influence on steady flow in distal anastomoses of peripheral bypass grafts. | |
| | |
MedLine Citation:
|
PMID: 16502651 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
We consider the effect of geometrical configuration on the steady flow field of representative geometries from an in vivo anatomical data set of end-to-side distal anastomoses constructed as part of a peripheral bypass graft. Using a geometrical classification technique, we select the anastomoses of three representative patients according to the angle between the graft and proximal host vessels (GPA) and the planarity of the anastomotic configuration. The geometries considered include two surgically tunneled grafts with shallow GPAs which are relatively planar but have different lumen characteristics, one case exhibiting a local restriction at the perianastomotic graft and proximal host whilst the other case has a relatively uniform cross section. The third case is nonplanar and characterized by a wide GPA resulting from the graft being constructed superficially from an in situ vein. In all three models the same peripheral resistance was imposed at the computational outflows of the distal and proximal host vessels and this condition, combined with the effect of the anastomotic geometry, has been observed to reasonably reproduce the in vivo flow split. By analyzing the flow fields we demonstrate how the local and global geometric characteristics influences the distribution of wall shear stress and the steady transport of fluid particles. Specifically, in vessels that have a global geometric characteristic we observe that the wall shear stress depends on large scale geometrical factors, e.g., the curvature and planarity of blood vessels. In contrast, the wall shear stress distribution and local mixing is significantly influenced by morphology and location of restrictions, particular when there is a shallow GPA. A combination of local and global effects are also possible as demonstrated in our third study of an anastomosis with a larger GPA. These relatively simple observations highlight the need to distinguish between local and global geometric influences for a given reconstruction. We further present the geometrical evolution of the anastomoses over a series of follow-up studies and observe how the lumen progresses towards the faster bulk flow of the velocity in the original geometry. This mechanism is consistent with the luminal changes in recirculation regions that experience low wall shear stress. In the shallow GPA anastomoses the proximal part of the native host vessel occludes or stenoses earlier than in the case with wide GPA. A potential contribution to this behavior is suggested by the stronger mixing that characterizes anastomoses with large GPA. |
| | |
Authors:
|
S Giordana; S J Sherwin; J Peiró; D J Doorly; J S Crane; K E Lee; N J W Cheshire; C G Caro |
Publication Detail:
|
Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
|
Title: Journal of biomechanical engineering Volume: 127 ISSN: 0148-0731 ISO Abbreviation: J Biomech Eng Publication Date: 2005 Dec |
Date Detail:
|
Created Date: 2006-02-28 Completed Date: 2006-05-23 Revised Date: 2006-11-15 |
Medline Journal Info:
|
Nlm Unique ID: 7909584 Medline TA: J Biomech Eng Country: United States |
Other Details:
|
Languages: eng Pagination: 1087-98 Citation Subset: IM |
Affiliation:
|
Department of Aeronautics, Department of Bioengineering and Regional Vascular Unit, St Mary's Hospital, Imperial College London, London, UK. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Anastomosis, Surgical
/
instrumentation,
methods* Arteries / physiology*, surgery* Blood Flow Velocity / physiology* Blood Pressure / physiology Blood Vessel Prosthesis* Computer Simulation Humans Models, Cardiovascular* Prognosis Surgery, Computer-Assisted / methods Treatment Outcome Veins / transplantation* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Cellular response of adipose derived passage-4 adult stem cells to freezing stress.
Next Document: The origins of syringomyelia: numerical models of fluid/structure interactions in the spinal cord.