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Peter Mortier

Peter Mortier. Bifurcation stenting simulation: the vessel 1 IBiTech - bioMMeda Ghent University, Belgium 2 FEops, Gent, Belgium. Virtual stent implantation in a patient-based bifurcation model. Stents induce different stress levels. 0.4. 0.3. 0.2. 0.1. 0.0.

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Peter Mortier

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  1. Peter Mortier Bifurcation stenting simulation: the vessel 1 IBiTech - bioMMeda Ghent University, Belgium 2 FEops, Gent, Belgium

  2. Virtual stent implantation in a patient-based bifurcation model

  3. Stents induce different stress levels 0.4 0.3 0.2 0.1 0.0 Circumferential stresses [MPa] Taxus Liberté Endeavor Cypher Select

  4. How to … ? … create a virtual bifurcation model based on patient data? … incorporate realistic material properties for the vessel?

  5. Step 1: 3D-CA Images are illustrative Allura 3D-CA (Philips) Possibility to export geometrical information (circles)

  6. Step 2: Luminal surface generation Circles describing the lumen can be exported • Idealised (cross-sections often have a much more complex shape) • Limited geometrical information in the bifurcation region Mathematical surfaces were created (NURBS)

  7. Step 3: Outer surface generation A wall thickness was assigned based on anatomical data * • Varying wall thickness • Alternative approach: using IVUS information (ANGUS**) * Holzapfel et al., 2005, Am J Physiol Heart Circ Physiol ** Slager et al., 2000, Circulation

  8. Step 4: Discretization + layers The continuous model has to be split in discrete regions (or elements) • Finite Element Analysis (FEA) • Calculation of the displacements of the nodes

  9. Step 4: Discretization + layers The continuous model has to be split in discrete regions (or elements) • Finite Element Analysis (FEA) • Calculation of the displacements of the nodes A structured grid or mesh can easily be divided in different layers

  10. Alternative approach

  11. Vessel wall mechanics Each of the arterial layers has a different composition, which leads to important differences in their mechanical behavior. Characterization of the mechanical behavior requires experimental testing of each tissue layer Courtesy Prof. G. Holzapfel

  12. Experimental testing Courtesy Prof. G. Holzapfel The mechanical behavior can be quantified by imposing a displacement and measuring the reaction forces

  13. Experimental testing Force Courtesy Prof. G. Holzapfel Displacement The mechanical behavior can be quantified by imposing a displacement and measuring the reaction forces Vascular tissue behaves non linear

  14. Experimental testing Force Circumferential Axial Courtesy Prof. G. Holzapfel Displacement The mechanical behavior can be quantified by imposing a displacement and measuring the reaction forces Vascular tissue behaves non linear Mechanical behavior is direction-dependent (i.e. anisotropic)

  15. Material model The experimentally measured behavior is then translated into a material model which is used by the simulation software:

  16. Patient-based bifurcation model

  17. Simulated insertion

  18. Conclusions Patient-based bifurcation models • We need to automate some time-consuming steps in order to use these simulations for a large series of patients • The better the imaging techniques, the better the models Material modelling • Not all real-life phenomena are included (e.g. dissections) • Imaging might play a crucial role (accurate in-vivo determination of mechanical properties?)

  19. Thank you! • Acknowledgements • Matthieu De Beule • Denis Van Loo • Benedict Verhegghe • Yves Taeymans • Patrick Segers • Pascal Verdonck • Email: • peter.mortier@feops.com

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