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A Computational Study of Structural Designs for a Small-Diameter Composite Vascular Graft Promoting Tissue Regeneration

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Abstract

The structural integrity and arterial mechanics are important aspects for tissue regenerative vascular grafts with ingrowth permissible porous scaffolds. This paper presents a computational study of structural designs for a small-diameter vascular graft comprising porous polyurethane scaffold and knitted reinforcement mesh using Nitinol and polyurethane wire, respectively. Finite element models of the porous scaffold with the knitted mesh as embedded or external reinforcement were generated using validated constitutive models for porous polyurethane and Nitinol. Simulating a luminal pressure of up to 200 mmHg, deformations and stresses were recorded in porous scaffold and knitted mesh. The models predicted compliance between 1.2 and 15.7%/100 mmHg for the reinforced grafts and 65.1 and 106.4%/100 mmHg for the non-reinforced grafts. For the reinforced grafts, maximum stress was 97.0, 28.2, and 0.055 MPa in Nitinol wire, polyurethane wire, and porous polyurethane scaffold, respectively, at 120 mmHg. The corresponding maximum strain was 0.27, 5.0, and 22.5%. Stress and strain remained safe in the Nitinol mesh and the porous polyurethane but became critical in the polyurethane mesh between 120 and 200 mmHg. Despite compression due to luminal pressure load, the porous scaffold remained ingrowth permissible for cells, capillaries, and arterioles up to 200 mmHg. The outcomes of this study provided preliminary concepts for the structural designs for a tissue regenerative composite vascular graft toward improved mechanical performance and structural integrity. The implemented modeling approach can be used in the further development and optimization of small-diameter tissue-regenerating vascular grafts.

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Acknowledgments

This study was supported financially by the National Research Foundation (NRF) of South Africa.

Conflict of interest statement

The authors declare that they do not have conflicts of interest with regard of this manuscript and the data presented therein.

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Authors and Affiliations

  1. Cardiovascular Research Unit, Chris Barnard Division of Cardiothoracic Surgery, Faculty of Health Sciences, University of Cape Town, Private Bag X3, Observatory, Cape Town, 7935, South Africa

    Mazin Salaheldin Sirry, Peter Zilla & Thomas Franz

  2. Centre for Research in Computational and Applied Mechanics, University of Cape Town, Private Bag X3, Rondebosch, Cape Town, 7701, South Africa

    Thomas Franz

Authors
  1. Mazin Salaheldin Sirry
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  2. Peter Zilla
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Correspondence to Thomas Franz.

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Associate Editor John M Tarbell oversaw the review of this article.

Any opinion, findings, and conclusions or recommendations expressed in this publication are those of the authors and therefore the NRF does not accept any liability in regard thereto.

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Sirry, M.S., Zilla, P. & Franz, T. A Computational Study of Structural Designs for a Small-Diameter Composite Vascular Graft Promoting Tissue Regeneration. Cardiovasc Eng Tech 1, 269–281 (2010). https://doi.org/10.1007/s13239-010-0023-5

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