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Degradation of Liquid Embolic Polymer - A Pulsatile Flow Model

Degradation of Liquid Embolic Polymer - A Pulsatile Flow Model. BME 440 Design Group 1 October 31, 2005. Overview. Previous Techniques Current Studies Future applications. Aneurysm Background. Aneurysm – Out pouching of a blood vessel Caused by weakened internal elastic lamina

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Degradation of Liquid Embolic Polymer - A Pulsatile Flow Model

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  1. Degradation of Liquid Embolic Polymer- A Pulsatile Flow Model BME 440 Design Group 1 October 31, 2005

  2. Overview • Previous Techniques • Current Studies • Future applications

  3. Aneurysm Background • Aneurysm – Out pouching of a blood vessel • Caused by weakened internal elastic lamina • Clinical • Ruptured or un-ruptured • Rupture causes hemorrhage • Rupture rate 10-25 per 100,000 population • 60,000 annually in the U.S. suffer from aneurysms – Half ruptured, half not. • If the aneurysm ruptures, the damage is as follows: 35% die, 30% suffer severe morbidity, 35% recover • Mechanical degradation of polymer • Embolism

  4. Previous Techniques • Surgery • Removal of Aneurysm • Platinum coil (Gugliemi Coils) • Catheterization • Insertion • Maneuverability

  5. Previous Materials • Liquid acrylics • Glue-like • Ethylene vinyl alcohol • Toxic solvent- DMSO • Alginate • Conflicting evidence • Growth factors

  6. Types of Models • In-vitro • Glass • Polycarbonate • Plexiglass • In-vivo • Porcine • Canine

  7. Polymer Delivery • Catheter Choice • Single line catheter • Concentric catheter • Efficiency • High percentage of polymer deposition • Re-canalization • Side by side catheter • In-vitro (can control flow) • Injection of polymer; no initial flow • In-vivo (constantly flowing) • Injection of polymer; initial flow

  8. Catheter Injection

  9. Injection Against Flow • Minimizing the Effects of Flow • Surgical Clip • Balloon • Stent

  10. Design Implementation • 2D and 3D models • Watertight • 2D – Block geometry with machined aneurysm • Easy to clean • Large gasket • Adaptable • Pressure supplied by clamping mechanism • Bifurcation and Wall Aneurysm • Adaptable 2-in-1 architecture • Removable screw mechanism

  11. Side View End View MS.Paint Schematics of Model Rubber Seal

  12. Gasket Materials • Necessities • Water Tight • Compressible • Durable • Compression Set • Resistance Dow Corning

  13. Flow Mechanism • Flow Pump Options • Diaphragm (Pulsatile) • Peristaltic (Steady) • Important Characteristics • Biological similarity • Variable flow rate • Length of use • Ease of use • Cost

  14. Various Pumps • SP100VC ($159) – Cased Variable Flow Peristaltic Pump • Flow Range: 0.03ml/min to 13ml/min • Control: Knob • SP100VO (OEM) ($59) – Variable Flow Peristaltic Pump • Flow Range: 0.09ml/min to 13ml/min • Control: Vary Voltage • SP200VC ($169) – Cased Variable Flow Peristaltic Pump • Flow Range: 0.06ml/min to 62ml/min • Control: Knob • SP100VOBL ($179) – Brushless DC Variable Flow Peristaltic Pump • Flow Range: 0.09ml/min to 20ml/min • Control: Vary Voltage • Continuous Use – Long Life • PM10.001 ($135) – Miniature Diaphragm Pump. (Pulsatile Flow) • Max Flow: 100ml/min • Control: Vary input voltage APT

  15. Fluid and Pressure Concerns • Desired Fluid Flow • 70-100 cm/min velocity • 1-5 mm tube diameter • Yields a flow range of .55–19.7 ml/min (Q = v*a) • Pressure • Increased flow rate = increased pressure • Pressure range helps find possible system materials (i.e. gaskets, pipes, tubing, etc)

  16. Degradation Monitoring • High Speed Camera • Monitors individual particle loss • Costly • Image distortion due to materials • Software Options • Image differentiation analysis • Computer Aided Speckle Interferometry (CASI) • Fine Mesh Gauze • Downstream collection of particles • Smaller particles can escape • Inhibits flow

  17. Degradation Monitoring (Cont) • Fiber Optic Camera • Evades material distortion • Site specific • Hard to implement without hindering flow • Resolution and speed

  18. Versatility Features • Bifurcation vs. Side Wall • Steady Flow vs. Pulsatile Flow • Open Flow vs. Closed Flow • Flow Rate

  19. Material Choices • Glass • Expensive • Easily destroyed • Primitive • Plexiglass • Cheap • Mechanically Strong • Machinable • Polycarbonate • Very similar to plexiglass. • Slightly more expensive, but is better in most categories

  20. Conclusion • Polymer to be tested: Chitosan • Model Structure Material • Polycarbonate • Gasket Material • Silicon Rubber • Pump choice

  21. Acknowledgements • Professor Chen • Professor Strey • Lester-machine shop • Professor Bluestein

  22. References • Soga et al. Neurosurgery, 55(6):1401-1409, 2004.All figures, unless otherwise noted, are referenced from this paper. • APT Instruments. Flow Pumps and Accessories.http://www.aptinstruments.com/ • Dow Corning. Rubber Applications and Markets.http://www.dowcorning.com/content/rubber/rubberapps/app_gasket.asp?WT.srch=1

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