The Use of Finite Element Methods and Genetic Algorithms in Search of an Optimal Fabric Reinforced Porous Graft System
- 161 Downloads
The mechanics of arteries result from the properties of the soft tissue constituents and the interaction of the wall layers, predominantly media and adventitia. This concept was adopted in this study for the design of a tissue regenerative vascular graft. To achieve the desired structural properties of the graft, most importantly a diametric compliance of 6%/100 mmHg, finite element methods and genetic algorithms were used in an integrated approach to identify the mechanical properties of an adventitial fabric layer that were required to optimally complement an intimal/medial polyurethane layer with interconnected porosity of three different size classes. The models predicted a compliance of 16.0, 19.2, and 31.5%/100 mmHg for the non-reinforced grafts and 5.3, 5.5, and 6.0%/100 mmHg for the fabric-reinforced grafts. The latter, featuring fabrics manufactured according to the required non-linear mechanical characteristics numerically predicted, exhibited an in vitro compliance of 2.1 ± 0.8, 3.0 ± 2.4, and 4.0 ± 0.7% /100 mmHg. The combination of finite element methods and genetic algorithms was shown to be able to successfully optimize the mechanical design of the composite graft. The method offers potential for the application to alternative concepts of modular vascular grafts and the incorporation of tissue ingrowth and biodegradation.
KeywordsAdventitial reinforcement Constitutive model Diametric compliance Numerical modeling Optimization Vascular mechanics Vascular prosthesis
This work was mainly funded through a research collaboration grant by Medtronic Inc. (Minneapolis, MN, USA) to the University of Cape Town. The authors acknowledge the assistance of Richard Steventon with the GA coding.
- 1.Bezuidenhout, D. Porous Polymeric Superstructures as In-Growth Scaffolds for Tissue-Engineered Vascular Prosthesis. PhD Thesis, Stellenbosch University, 2001.Google Scholar
- 6.Faires, J. D., and R. L. Burden. Numerical Methods. Boston, MA: PWS Publishing, 1993.Google Scholar
- 7.Fung, Y. C. Biomechanics: Mechanical Properties of Living Tissue, 2nd ed. New York: Springer-Verlag, 1984.Google Scholar
- 12.Hess, F., C. Jerusalem, and B. Braun. The endothelialisation of a fibrous polyurethane microvascular prosthesis after implantation in the abdominal aorta of the rat. J. Cardiovasc. Surg. 24:516–524, 1983.Google Scholar
- 16.Kim, J. H. Fabric Mechanics Analysis Using Large Deformation Orthotropic Shell Theory. PhD Thesis, North Carolina State University, 1991.Google Scholar
- 17.NN. Cardiovascular Implants—Vascular Prosthesis. American National Standard Association for the Advancement of Medical Instrumentation, AAMI Standard Edition, 1994.Google Scholar
- 18.NN. Cardiovascular Implants-Tubular Vascular Prosthesis. ISO International Standard 7198, 1998.Google Scholar
- 30.Yeoman, M. S. The Design and Optimisation of Fabric Reinforced Porous Prosthetic Grafts Using Finite Element Methods and Genetic Algorithms. PhD Thesis, University of Cape Town, 2004.Google Scholar