Document Detail

A computational study of knitted Nitinol meshes for their prospective use as external vein reinforcement.
MedLine Citation:
PMID:  18328487     Owner:  NLM     Status:  MEDLINE    
External reinforcement has been suggested for autologous vein grafts to address the mismatch of mechanical properties and fluid dynamics of graft and host vessel, a main factor for graft failure. A finite-element tool was developed to investigate the mechanical behaviour, in particular radial compliance, of knitted Nitinol meshes (internal diameter: 3.34 mm) with two different knit designs (even versus uneven circumferential loops) and three different wire thicknesses (0.05, 0.0635 and 0.075 mm) under physiological conditions. The Nitinol material parameters were obtained from experimental testing. The compliance predicted for the 80-120 mmHg physiological blood pressure range was 2.5, 0.9 and 0.6%/100 mmHg for the even loop design and 1.2, 0.5 and 0.5%/100 mmHg for the uneven loop design, for wire thicknesses of 0.05, 0.0635 and 0.075 mm. The highest stress, at 120 mmHg, was found in the even loop mesh with the thinnest wire to be 268 MPa, remaining 44.5% below the stress initiating stress-induced phase transformation. The maximum stress decreased to 132 and 91 MPa with increasing wire thickness of the same loop design. The uneven loop design exhibited maximum stress levels of 65.3%, 63.6% and 87.9% of the even loop values at 0.05, 0.0635 and 0.075 mm wire thickness. The maximum strain of 0.7%, at 120 mmHg, remained un-critical considering a typical high-cycle recoverable strain of 2%. It was demonstrated that the numerical approach developed was feasible of effectively evaluating design variations of knitted Nitinol meshes towards vein graft behaviour equivalent to arterial mechanics.
Helena van der Merwe; B Daya Reddy; Peter Zilla; Deon Bezuidenhout; Thomas Franz
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-03-06
Journal Detail:
Title:  Journal of biomechanics     Volume:  41     ISSN:  0021-9290     ISO Abbreviation:  J Biomech     Publication Date:  2008  
Date Detail:
Created Date:  2008-04-14     Completed Date:  2008-09-09     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1302-9     Citation Subset:  IM    
Cardiovascular Research Unit, University of Cape Town, Cape Town, South Africa.
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MeSH Terms
Biocompatible Materials*
Blood Vessel Prosthesis
Computer Simulation
Equipment Design
Stress, Mechanical
Veins / physiology*
Reg. No./Substance:
0/Alloys; 0/Biocompatible Materials; 52013-44-2/nitinol

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

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