Design of a Prenatal Perfusion System

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Design of a Prenatal Perfusion System PROJECT
PROPOSAL Timothy BachmanGarrett GrindleLeigh
McClureScott Morley Bioengineering 1160/61April
13, 2004
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Overview

• The practice of fetal heart surgery to correct
  congenital heart defects has been limited by the
  lack of a fetal CPB system.
• It is believed that if congenital heart defects
  are corrected early, that blood flow patterns can
  be restored and the heart will develop normally.
• 2001 Mortality CHD 4109
• There is an extremely small demand for a fetal
  CPB system probably 100s of cases per year.

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Overview (cont)

• This group has designed, constructed, and tested
  a prototype prenatal perfusion system comprised
  of
• Pump
• Venous and arterial cannulas
• Controller
• Existing pumps were evaluated and deemed
  inappropriate for the application
• We have developed a novel, pulsatile pump

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Project Objectives

• Design a cardiac perfusion system capable of
  providing ex utero fetal cardiac support for up
  to 2 hours
• Variable, pulsatile flow
• 300 1000 mL/min
• 120 180 BPM
• Mean arterial pressure 40 50 mmHg
• Minimal priming volume
• Less than 15 mL

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Market and Competition

• Research Competitors
• Stanford/UCSF group (one case w/ JJs pump)
• Commercial Competitors
• Blood pump companies JJ, Medtronic, Cobe, etc
• No competing commercial products at this time
• Strengths and Weaknesses vs. Stanford/UCSFs
  Group
• Stanford has not published their work. Our
  competitive advantage or disadvantage has not yet
  been determined.
• Catheter-based solutions (Verimetra)

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Design Concepts Considered

• Existing pumps Nimbus Centrifugal Pump
• New Pump Design
• Rotary or centrifugal (design too difficult,
  pulsatility likely difficult to achieve)
• Positive displacement pumps
• Imitates ventricle behavior
• Inherent pulsatility
• Ease of design/construction
• Availability of resources (materials and
  controller)

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Design

• Pneumatically driven positive displacement pump
• One-way valves direct flow
• 6 mL stroke volume
• Compatible with IMO controller
• Modular design for valve and bladder testing

Solidworks Model (exploded view)
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MaterialsChamber Acrylic stockBladder Medical
grade PUCannulae/Tubing Off the shelf
(Medtronic/Tygon)Valves Check valves not
medical grade
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Mock Loop
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Project Mgmt Schedule and Milestones

• Conceptual Design Complete Actual 1/17/04
• Choose pump
• Cannula size and insertion sites
• Determine console requirements and electrical
  safe guards
• Primary Design Complete 2/21/04 Actual
  2/15/04
• Apply engineering model to determine dimensions
• Determine Specific Components
• Preliminary drawing and parts list

• Design Refinement Complete 3/13/04
• Integrate components
• Manufacturing protocol
• Final drawings, parts list, and testing protocol
• Prototype Fabricated Org 4/6/04Rev. 3/21/04
  Actual 4/2/04
• Testing Complete Org. 4/12/04Rev. 4/2/04
  Actual 4/09/04
• Business Plan SBIR Complete Org. 4/14/04
  Actual 4/20/04

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Future Design Work

• Complete pressure/flow characterization in a
  physiologic mock loop
• Valve evaluations or new valve design
• Evaluate bladder design for flow optimization
• Redesign pump with integrated valves
• Design/build drive system for this specific
  application

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Considerations for Future Development

• Economic
• Good project for university level development
• Projected market size is very small ? not
  commercially attractive
• Manufacturability
• Current product design is relatively simple to
  manufacture
• Future designs should use medical grade products
  and be evaluated for durability and sterilization
  compatibility
• Final manufacturing (for human use) would require
  a cleanroom
• Human Factors
• Console design, setting of use (OR)
• Regulatory Issues
• HDE qualification would simplify approval process

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Regulatory StrategyHumanitarian Device
Exemption (HDE)

• Similar to a pre-market approval (PMA)
• Exempt from effectiveness requirements
• intended to benefit patients in the treatment or
  diagnosis of diseases or conditions that affect
  fewer than 4,000 individuals per year in the
  United States - CDRH

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Team Responsibilities
Action Item Bachman Grindle McClure Morley
Pump Design Lead
Current pump evaluations X X X X
Solid modeling X
CFD if req. if req.
Cannula Design Lead
Evaluation of available cannulas X X X X
Console Development X
Regulatory and QS X
Mock Loop and Experimental Protocol Design X
HFE X X
Fabrication and Procurement
Pump X X
Cannulas X
Console X
Prototype Evaluation X X X X
SBIR X
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Acknowledgements

• Frank Pigula, M.D.Pediatric Cardiothoracic
  Surgeon, Boston Childrens Hospital
• William Federspiel, Ph.D.Director Artificial
  Lung Lab, MIRM
• Brian FrankowskiDesigner, Artificial Lung Lab,
  MIRM
• Heidi EashLab Manager, Artificial Lung Lab, MIRM

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