Thermal Analysis Assumptions Body Temperature Environment is 37C

Thermal Analysis Assumptions: • Body Temperature (Environment) is 37˚C • Heat distribution on outside of device will be modeled via FEA • Heat transfer method inside body is conduction • All energy inefficiencies result in heat generation • Device is surrounded my muscle tissue which is at equilibrium between perfusion and heat generation

Additional 1 -D Assumptions 1 dimension normal to the skin Uniform heat generation Constant Properties Body is at equilibrium (neglect heat generation effects) • Steady State • •

Data • Reference Temperatures[C]: • Body Temp= 37 C • Ambient Air Temp= 25 C • • • Conduction Coefficients : Internal Organs and Muscle = 0. 500 W/m*K Skin and Fat=0. 300 W/m*K Titanium=19. 000 W/m*K (P 13022 only) Clothing=0. 029 W/m*K • Convection Coefficients [W/m*K]: • Air=10. 000

Critical Values The purpose of our thermal model is to ensure this device will not harm the patient. With a factor of safety of 2, our maximum heat flux through the tissue is 40 m. W/cm 2

1 -D Analysis Model

Results

Engineering Model Boundary Temp: 37˚C Device Conduction Internal Environment (Abdomen Muscle) • The Device will be implanted in abdomen muscle • Assuming a worst case scenario, the device will be surrounded by muscle tissue in all directions for an “infinite” thickness. • An ANSYS model which includes the boundary temperature of 37˚C and all muscle properties will show worst case temperature and flux conditions

Summary • For the given area of 64 cm 2 , 0. 3 W (4. 67 m. W/cm 2) of heat generation will be dissipated before exceeding 40 o. C. • For a surface area of 340 cm 2 we should be allowed to generate up to 13. 6 W of heat energy within the device. • Expected worst case heat generation = 2 W.

Conclusion • The Internal Battery Storage Device is not likely to harm the body through heat generation based upon the of energy flux through the total surface area. • Further analysis will be conducted (in ANSYS) to confirm the results. • Due to the extreme difficulty of finding a relatively accurate model for the body in relation to the LVAD system, the 1 -D analysis is only useful for worst case results and only provide limited useful data. • Further analysis in ANSYS should provide more reliable results. • Development of the P 13022 device should continue with minimal design change.