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Slide 1 University of Pittsburgh (PowerPoint)

VIEWS: 6 PAGES: 24

									In Vitro Experiments and Redesign of a
 Distal Protection Filter Used in Carotid
    Angioplasty Stenting Procedures

                  Erdrin Azemi
                  Heather Gray
                  Emily Miner
     Project Advisor: Ender A. Finol, Ph.D.
     Project Director: Mark H. Wholey, M.D.
                    Senior Design
                      BioE1160
            Overview
• Distal protection filters are used
during angioplasty stenting
procedures to reduce the risk of
stroke

• These filters are used in high risk
patients where angioplasty with
stenting is the only viable solution
     Objective and Goals

• To perform in vitro flow motion
  analysis of several distal
  protection filters currently
  available in the market
  • Angioguard ™, Accunett™, and FilterWire EX™

• Redesign a filter based on the
  results obtained from the in vitro
  experiments
                                           Background

                                                          •Stroke is the 3rd
                                                          leading cause of
                                                          death in the U.S.

                                                          •Dislodging of
                                                          atherosclerotic
                                                          plaque increases
                                                          the risk of stroke

              Schematic of Plaque in the Carotid Artery
www.besthealth.com/surgery/ CarotidArterySurgery_4.html
Angioplasty Stenting Procedure
                                                                      Filter


    Stent and
    Balloon




                                          Trapped Plaque
                               Atherosclerotic
                               plaque
                             Retrieval
                             Sheath                                            3
                                                                                   2
                                                                                   1
            www.besthealth.com/surgery/ CarotidArterySurgery_4.html
 Current Filters



Nitinol Ring
Deepest basket




  Shorter basket
  Longer wire                                                 Deeper basket
  8 Struts                                                    4 Struts
    www.besthealth.com/surgery/ CarotidArterySurgery_4.html
            Current Filters
Problems with current designs
• Possibility of missing small particles
  (low efficiency)
• Difficulties in crossing tight and/or
  tortuous lesions (high profile)
• Somewhat cumbersome procedure (need
  to keep the wire extremely stable during
  catheter exchange)
• Potential to cause spasm
                                   Methodology
                                    Pump and Controller

                 Experimentation                                 Pressure Transducer


          • In vitro flow loop was used to test
             the efficiency of the three filters
 In - Reservoir
                                                                                  Flow Transducer




                     Split Point            5 mm ID tube                     Insertion of Filter


In-line filter
A-B
                                                               Hemostatic Valve

 Out- Reservoir                        Injection Point of Particles
      Experimental Design
•A general procedure protocol was decided
                                      Broad
                                Apex- Acute
 based on literature and experience
•Blinded/Randomized Experiments
•To mimic the curvature of the carotid arteries
   we used 3 different configurations:
   •Apex-Acute                  Proximal -
                                Broad
   •Apex-Broad
   •Proximal-Broad10 cm Tape
          Tape
                   8 cm
   •15 experiments were performed for each
   filter Tape             Tape

                                     Not to scale
        Experimental Results
Efficiency of the three filters expressed in percent

               Angioguard AccuNett       FilterWire
 Proximal-     96.81±4.78 97.73±3.94 90.86±12.57
  Broad
Apex-Broad     90.69±12.15 99.2±1.09     98.69±2.93


Apex-Acute      98.7±2.24       100          100
        Experimental Results
    Efficiency of the three filters after retrieval
               expressed in percent
              Angioguard      AccuNett      FilterWire
 Proximal-     79±14.79     76.32±28.86     96.69±5.11
  Broad
Apex-Broad 62.99±39.28 98.94±1.54          90.77±10.41


Apex-Acute 63.27±19.02           100       84.72±19.67
                    *             *
        Design Alternatives
• Redesign a device based on FilterWire
  EX™ from information in literature
• Alternative design of deployment and
  retrieval sheaths
• The most efficient components of each
  filter were incorporated into our redesign
  • This approach was chosen based on
    extensive usage of each filter and the
    results of the in vitro experiments
The Redesign


                 Deeper,
                 pointed sack
Easier                          Low profile
conformability



                      120 µm pore size


  Smooth transition
Redesign: Features & Benefits
    Features              User Benefits
• Deeper basket:        • Lowers the risk of
  captures plaque         stroke
  more efficiently
                        • Easier to keep the
• Shorter wire 190        wire stable, less
  cm                      cumbersome
                          procedure
• Optimization of
  Nitinol ring          • Reduces spasm and
  diameter for use in     vessel damage
  3.5-5.5 mm vessel
                        • Increases Nitinol
  size
                          ring stability
• Redesign of struts
           Technology

Engineering Modeling
  •SolidWorksTM modeling was used
  to develop our redesign
  •PhotoWorks used to visualize
  appropriate materials
        Competitive Analysis
Competitors
• Currently, there are several distal protection filters on
  the market. In our research, we tested the three filters
  previously mentioned. We considered these filters to be
  our direct competitors
Strengths
• Relative to other competitors, our redesign pieced
  together the most efficient components of each of the
  filters tested

Weaknesses
• No in vitro tests were performed to assure proper
  function or efficiency of redesign. The redesign is
  assumed to be effective based on predicate devices
  experimental results
 Economics of Redesign

•Angioplasty stenting procedure with
use of a distal protection filter shows
50% reduction in stroke rate
•By the year 2010 it is estimated that
270,000 angioplasty stenting
procedures will be performed using
distal protection filters in the U.S
alone
                    Constraints
Regulatory
  • Class II medical device intended for one time use
  • Over 20 predicate devices
  • To bring device to market:
     • 510(k) required
     • Prototype
     • Quality systems analysis
     • Engineering analysis
     • Feasibility study in animals
     • Since predicate devices exist a 50 patient feasibility study
       would need to be performed to prove the following:
            • Conformability to vessel
            • Ease of passage
            • Efficiency of filter
 Quality System Considerations
Manufacturability
Materials
  •Nitinol ring and struts with dynamic sizing in the 3.5
  to 5.5 mm range
  •Polyurethane filter membrane composed of 120
  micron pores
  • 190 cm PTFE coated stainless steel wire

Methods
  •Materials will be bought from suppliers
  •Assembly will occur in-house
  •Production will be in mass quantities
    Project Management
Fall 2003 Goals
• Design History File
• Meet with advisors
• Literature Research
• Prepare Presentation
• Perform Preliminary Tests
• Filter Redesign
    Project Management
Spring 2004 Goals
• Meet with advisors on regular basis
• Perform experiments and analyze data
• Send out a Physician Survey
• Filter Redesign
• Finish Design History File
• Final Paper and Presentation
• Continue testing to finalize a
  manuscript
                   Team Chores
Erdrin A.            Heather G. Emily M.
“Quality Control     “Surgeon” of         “Countess of
Manager”             experiments          Beads”
Analyzed the data    Solid Works          Experimental
                     Modeling             document control
Introduction         Methods              Results and
                                          Discussion

Survey handling      Updated Design       Wrote PDS and
and monitoring       History file         510(k) application

Put together final   Put together final   Put together final
presentation         paper                paper
    Acknowledgements
Thank You:
• Christine Scotti
• Mark Wholey, MD
• Ender Finol, PhD
• Mark Gartner
• Bioengineering Department,
  University of Pittsburgh
• Carnegie Mellon University

								
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