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Redesign of a Distal Protection Filter for Carotid Artery Stenting

University of Pittsburgh Senior Design – BioE 1160/1161. Redesign of a Distal Protection Filter for Carotid Artery Stenting. Sandeep Devabhakthuni Chenara Johnson Daphne Kontos Perry Tiberio April 18, 2005 Mentor: Ender Finol, PhD. Arterial Stenosis.

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Redesign of a Distal Protection Filter for Carotid Artery Stenting

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  1. University of Pittsburgh Senior Design – BioE 1160/1161 Redesign of a Distal Protection Filter for Carotid Artery Stenting Sandeep Devabhakthuni Chenara Johnson Daphne Kontos Perry Tiberio April 18, 2005 Mentor: Ender Finol, PhD

  2. Arterial Stenosis • Narrowing of carotid arterial walls due to plaque build-up • Considered 3rd leading cause of death - Stroke • New, less invasive treatment: • Carotid Artery Angioplasty and Stenting • Problem: Possible embolization to the brain resulting in a stroke. • Solution: Embolic Protection Devices

  3. Background

  4. Filter Properties • Neuroprotection (distal protection) filter • Polyurethane material for the basket • Nitinol tubing • Nitinol • Stainless steel • 80-140µm pore size

  5. Problem Statement • Predicate devices include the FilterWire EX, AccuNet and Angioguard • These filters are 80-90% efficient • The goal of our design is to maximize emboli capture efficiency FilterWire EX AccuNet Angioguard

  6. Design Requirements • 99% capture efficiency • Lay flush with vessel lumen • Biocompatible • Durable • Collapsible • For insertion and retrieval

  7. Economic Considerations and FDA Regulation • Market Size: • $752M worldwide http://www.menet.umn.edu/~shayden/Neuro_report.pdf • Distribution • Medical Supply Companies • FDA Classification • Class II – Cardiovascular Diagnostic Device

  8. Quality System Considerations • Manufacturability • Simple Design • Materials already used for other medical purposes • Human Factors • Easy to use for trained interventional cardiologists • To be determined through survey • Biocompatible

  9. Initial Design Considerations • Incorporate the best features/materials from all current designs into our filter • Implement a novel feature to improve design

  10. Proposed Solution • Ring • Three struts • Polyurethane basket • 70-80µm pore size • Skirt

  11. Final Design • Ring • One Strut • Extra Struts don’t assist in securing filter • Stainless steel wire • Nylon filter basket • Nylon due to material restrictions • Polyimide tubing to enforce nitinol ring • Pore size of 70-80µm • Captures smaller particles • Nylon skirt

  12. Prototype Fabrication Shape nitinol into ring and reinforce with polyimide tubing Attach stainless steel wire guidewire

  13. Prototype Fabrication Dimensions of filter Basket Outline filter on nylon sheet Cut out pattern and put together with polycyanoacrylate

  14. Final Prototype

  15. Intended Method of Use • Collapse filter by pulling strut • Insert percutaneously • Deploy filter by releasing strut • Pre-shaped to align 20° to vessel wall • After procedure, retrieve into retrieval sheath

  16. Experimental Methods Used to Test Device Performance • Glycerin-water solution (9:16) in flow loop • Insert filter into loop • Set peristaltic flow to 150 mL/min • Inject embolic beads • Run for 5 minutes • Weigh beads passed and collected by filter

  17. Peristaltic Flow Pump Reservoir Glycerin/Water solution (9:16) Inline filter Point of Filter Deployment Length = 20 cm Insertion Point of particles Schematic of Flow Loop Insertion Point of Filter (one-way valve)

  18. Data Analysis • Embolic capture efficiency determined by: • ezANOVA • Between- and In-group comparison • Student’s Paired t-test

  19. Experimental Results Trial 1: 98% capture efficiency!

  20. Experimental Results (cont.)

  21. Filter Comparison Chart *The modified capture efficiency data is presented here

  22. Discussion • Nitinol ring cracked during trial 2 • Bottom of filter tore during trial 6 • Filters are designed for one time use only • Poor results due to: • Placement of filter • Retrieval mechanism

  23. Competitive Analysis for Prototype I • Strengths • Reduced pore size • 74 microns compared to 80 – 120 micron range of filters currently on the market • Skirt • Assists in maximizing capture efficiency • Deeper basket • Prevent loss during retrieval of filter

  24. Competitive Analysis for Prototype I • Weaknesses • Non-collapsible filter • Non functional delivery or retrieval method • Not a 1:1 scale

  25. Future • Redesign flow loop to include: • Pressure Transducers • Latex Tubing • Redesign a second prototype to include: • Develop a deployment/retrieval mechanism • Use polyurethane as the filter basket material • Use nitinol tubing

  26. Acknowledgements • Dr. Ender Finol • Sanna Gaspard • Mark Gartner • Special thanks to Drs. Hal Wrigley and Linda Baker whose generous gift made this project work possible • University of Pittsburgh, Department of Bioengineering • Carnegie Mellon University

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