1. Minimally Invasive Compressional Assist Device Erika Brown, Caryl Brzymialkiewicz, and Mark Carlson Advisor: Dr. Drew Gaffney, M.D. Professor of Medicine, VUMC

2. Project Definition To design a cardiac assist device, implantable with minimally invasive surgery that aids in pumping, and in the case of a hypertrophic heart, also improves function over time.

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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?

9. 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

10. 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.