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MODEL STUDIES OF BLOOD FLOW IN BASILAR ARTERY WITH 3D LASER DOPPLER ANEMOMETER

MODEL STUDIES OF BLOOD FLOW IN BASILAR ARTERY WITH 3D LASER DOPPLER ANEMOMETER. Sergey Frolov, Tambov State Technical University, Russia Sergey Sindeev, Tambov State Technical University, Russia Dieter Liepsch, Munich University of Applied Sciences, Germany

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MODEL STUDIES OF BLOOD FLOW IN BASILAR ARTERY WITH 3D LASER DOPPLER ANEMOMETER

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  1. MODEL STUDIES OF BLOOD FLOW IN BASILAR ARTERY WITH 3D LASER DOPPLER ANEMOMETER Sergey Frolov, Tambov State Technical University, Russia Sergey Sindeev, Tambov State Technical University, Russia Dieter Liepsch, Munich University of Applied Sciences, Germany Andrea Balasso, Technical University of Munich, Germany Sergey Proskurin, Tambov State Technical University, Russia Anton Potlov, Tambov State Technical University, Russia Biomedical Engineering

  2. Topicality Актуальность Brain aneurysm suffers 3-5 % of adult population More then60 % die from ruptured aneurysm (stroke) Biomedical Engineering

  3. Aneurysm Protrusion of the arterial wall due to its stretching or thinning Кафедра «Биомедицинская техника» Biomedical Engineering

  4. Current state Causes of aneurysm development and growth are not fully studied Researchers suggest that key role in aneurysm development play violation of local and global hemodynamics Biomedical Engineering

  5. Flow-diverters Problem of choice Biomedical Engineering

  6. Morphology «classic» ≈ 35-40 % cases deviations Biomedical Engineering

  7. Multiscale model of basilar artery hemodynamics Biomedical Engineering

  8. Multiscale model of basilar artery hemodynamics Biomedical Engineering

  9. Compartments of cardiovascular system Cardiovascular system is a set of compartments (elastic chambers) Every chamber is characterized by blood volumein it and pressure Link between chambers is characterized by blood flow Biomedical Engineering

  10. 0D model • 14 chamber model • Pulsating heart • Heart as a source of pressure • Valves with backflow • Flow inertia Biomedical Engineering

  11. System of global hemodynamics simulation(bmt.tstu.ru/cvs) Biomedical Engineering

  12. Link «Left ventricle – aorta» Biomedical Engineering

  13. Multiscale model of basilar artery hemodynamics Biomedical Engineering

  14. 1D model Biomedical Engineering

  15. Approach Arterial tree is a set of elementary regions Number of elementary regions may beN>48 Number of equations is 3*N Biomedical Engineering

  16. Approach i+2 i+1 i-2 i-1 i i – elementary region; Blood flow; [sm3/s]; [mmHg]; Functions Volume; [sm3]; Pressure; Festdaten Parameters Stiffness Elasticity; [mmHg/ sm3]; Inertia; [mmHg*s2 / sm2]; Conductivity; Resistance; [Тоrr*s / sm2]; Length; Unstrained volume; [sm3]; Cross sectional area Biomedical Engineering 12

  17. Multiscale model of basilar artery hemodynamics Biomedical Engineering

  18. 3D model Navier-Stokes equations Initial conditions Continuity equation Boundary conditions Biomedical Engineering

  19. Parallel computing Computational mesh spits on N parts. Every part is computed by it’s own thread Technology: MPI + OpenMP Programming language: С++ Libraries: Intel MKL, Trilinos, LifeV Solver: GMRES Preconditioner: Domain Decomposition Timestep: 0.0001 s. Precision: 1e-10 Domain Decomposition 8parts Problem of choice of numberN*, that T min Biomedical Engineering

  20. 3D model of bifurcations Geometrical model Biomedical Engineering

  21. Experimental setup 3D Laser Doppler Anemometer measure blood velocity in elastic vessel model.It gives opportunity to estimatestent influenceon blood flow Biomedical Engineering

  22. Principle of LDA Photomultiplier LaserHeNe Flow Signal conditioner Signal Processing unit: PC Biomedical Engineering

  23. Measurements • The flow velocity is measured with a 1-component laser Doppler anemometer system equipped with a 5mW He-Ne laser with a wavelength of 632.8nm. The laser Doppler anemometer does not disturb the flow and is not affected by temperature, pressure or fluid density. It offers a high spatial (focus point less than 70 µm) and temporal (1ms) resolution. • Velocity measurements are performed in the model at different cross sections allowing a 2D or a 3D-flow-reconstruction. Biomedical Engineering

  24. Measurements Blood cannot be used as a fluid for LDA measurements, because the laser light is absorbed by the red cells. The model fluid have a similar flow behavior as blood, a refraction index of n =1.41 to match the refraction index of the silicon rubber model wall. The fluid and the model wall have to be transparent so that the laser beam can pass undisturbed the medium. A 58% aqueous glycerol mixture with Separan AP45 and Separan AP302 (a macromolecular polyacrylamide) with a dynamic viscosity of 8mPas is used. The mixture shows viscoelastic flow behavior similar to the non-Newtonian characteristics of blood. Biomedical Engineering

  25. Realistic vessel model Biomedical Engineering

  26. Scheme of experimental setup • An overflow chamber (3) filled with the perfusion mixture gives the constant inflow pressure to the model (10). • A computer-controlled piston pump (1) superimposes a dynamic pressure gradient needed to obtain systolic and diastolic pressures in the inflow section of 80 mmHg and 145 mmHg respectively. • Pressure transducers (9) monitor the amplitude and frequency of the pulse wave. The outflow of the model is connected to a reservoir of variable height (11) to allow control of the flow volume. Biomedical Engineering

  27. Thanks for attention Biomedical Engineering

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