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Minimally InvasiveCompressional Assist Device
Erika Brown, Caryl Brzymialkiewicz, and Mark Carlson
Advisor: Dr. Drew Gaffney, M.D.Professor of Medicine, VUMC
Project Definition
To design a cardiac assist device, implantablewith minimally invasive surgery that aids inpumping, and in the case of a hypertrophic
heart, also improves function over time.
Cardiac Indications
• Systolic Ejection Fraction= Stroke volume _
End Diastolic Volume• Hypertrophic heart
(e.g. Chagas disease)– sarcomeres expand and
lose contraction efficiency
– self-perpetuating positive feedback system Frank-Starling Curve
What is currently available?
OPTIONS• Extracorporeal assist
devices• Heart transplants• Total Artificial Hearts• Ventricular Assist Devices • Batista’s wedge
resectioning surgery• Various drug treatments (ie
- digitalis)
PROBLEMS• Invasiveness
– Cost– Mortality– Discomfort
• Length of use• Aid in pumping or
healing, but not both• Recipient limitations
Project Overview
• Brainstorming until end of January• Research until mid-February• In vitro model design and testing through
mid-March• Evaluation of in vitro results and adaptation
into a prototype clinical design by end of the semester
What have we done so far?
• Web page is up and running• Patent search• Located pertinent cardiology and
instrumentation resources• Began in depth review of current technologies• Brainstormed wants and needs, possible
design options, potential problems
What are we currently doing?
• Continuing review of current technologies/devices
• Biomaterials research• Re-evaluating our problem and looking for
alternative solutions• Trying to set up viewing of cardiac surgery
Current questions...
• How much pressure should be applied to help the heart pump effectively?
• What is the most effective triggering mechanism?• Quantitatively, how much pressure is needed over
what length of time to help heal a hypertrophic heart?
• What are the anatomical constraints in implanting a device sub-xyphoidally?
What will we do next?
• Make a evaluation matrix of potential solutions
• Focus brainstorms on best solution and develop concepts for in vitro model
• Specify design parameters • Develop tests for in vitro model • Research Batista’s wedge resection surgery
Resources
• Sherwood, L. (1997) Human Physiology: From Cells to Systems, 3rd Ed. Wadsworth Publishing Co.: Belmont, CA.
• Quall, S.J., ed. (1993) Cardiac Mechanical Assistance Beyond Balloon Pumping. Mosby Year-Book, Inc.: St. Louis, MO.