April 13, 2004

Design of a Prenatal Perfusion System

PROJECT PROPOSAL

Timothy BachmanGarrett GrindleLeigh McClureScott Morley

Bioengineering 1160/61April 13, 2004

April 13, 2004

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 100’s of cases per year.

April 13, 2004

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

April 13, 2004

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

April 13, 2004

Market and Competition• Research Competitors

– Stanford/UCSF group (one case w/ J&J’s pump)• Commercial Competitors

– Blood pump companies: J&J, Medtronic, Cobe, etc– No competing commercial products at this time

• Strengths and Weaknesses vs. Stanford/UCSF’s Group

– Stanford has not published their work. Our competitive advantage or disadvantage has not yet been determined.

• Catheter-based solutions (Verimetra)

April 13, 2004

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)

Nimbus Centrifugal Pump

April 13, 2004

Design

Solidworks Model (exploded view)

• 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

April 13, 2004

MaterialsChamber: Acrylic stockBladder: Medical grade PUCannulae/Tubing: Off the shelf (Medtronic/Tygon)Valves: Check valves – not medical grade

April 13, 2004

April 13, 2004

Mock Loop

April 13, 2004

Preliminary Results - Prenatal Perfusion System

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April 13, 2004

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: 4/6/04

Rev.: 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

April 13, 2004

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

April 13, 2004

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

April 13, 2004

Regulatory Strategy:Humanitarian 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

April 13, 2004

Team ResponsibilitiesAction 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

April 13, 2004

Acknowledgements

• Frank Pigula, M.D.Pediatric Cardiothoracic Surgeon, Boston Children’s Hospital

• William Federspiel, Ph.D.Director Artificial Lung Lab, MIRM

• Brian FrankowskiDesigner, Artificial Lung Lab, MIRM

• Heidi EashLab Manager, Artificial Lung Lab, MIRM

April 13, 2004