P10021 – Miniaturization Team The Miniaturized System System Architecture LVAD Concepts Case Research Circuitry Research Microcontroller Research 10/2/2009 Evan Sax Lowell Smoger Christine Stone Mike Calve

The Miniaturized System Overall electronics package size with currently used components can be reduced to approximately 8 x 6.5 x 2.5 inches (130 ci) Using miniaturized components and removing unnecessary shows an estimated package size of 6.5 x 5 x 2 inches (65 ci) Device can be distributed into multiple cases Potential for certain cases to be implanted

Estimations on Allowable Implant Dimensions Abdominal x-ray provides components sizes estimates (referenced to pelvic dimensions): Electronics package dimensions: 4 x 4 inches Heart pump dimensions: 3.5 x 4.5 inches Coronal (front) plane dimension immeasurable Studies provide empirical date for allowable intrathoracic dimensions[1]: Model size seemed to be constrained to: 17.5 x 10.5 x 3.8 cm 42.61 cubic inches Current pump volume: 2 x 2 x 4 inches 16 cubic inches Figure from Book: Heart Replacement: Artificial Heart 7

Concept 1: Centralized Electronics Package w/ External & Separate Battery Example Single Case Size: 6.5 x 5 x 2 inches (65 ci) Pros Minimal outer body components Increased Maneuverability and QOL Decreased risk of device damage due to impact & particle ingress Cons Serviceability: Components not easily replaced/updated Data acquisition and programmability Depending on requirements for microcontroller interaction Size constraints in body Limitations on feasible size Space consumed by LVAD decreases usable space May be overcome with proper distribution (concept 2) Heat generation Cost Biocompatible materials Cost of size reduction Conclusion: Not within scope of project May be too big to implant in one particular place New lines out for user Interface

Concept 2: Multi-case Electronics Package with Partial Implant; Battery External & Separate Case 1 (External): Micro-controller, USB port, Converter(s), Relay(s) Approximate Size: 5.5 x 5 x 3 inches (82.5 ci) Marginal Case 2 (Internal): PWM Amps, Motor Controller, Differential Amps Approximate Size: 5.5 x 2.5 x 1.5 inches (20.6 ci) Ideal Pros Increased maneuverability compared to completely external (concept 3) Potential for fewer wires through body (wireless transmission) Battery can be included in external case Serviceable/Updateable external components No limit on external case size means easier to design and increased likelihood of success Cons Items outside are easier to damage Items in body more difficult to service Limited Space in Body Discomfort with internal components Conclusion Research shows within acceptable implant limits Benefits patient Within scope of project Concerns with part life inside body Potential need for larger than expected components could make infeasible

Concept 3: Centralized External Electronics Package; Battery External & Separate Example Single Case Size: 6.5 x 5 x 2 inches (65 ci) Pros Reduces case size No internal component issues (i.e. part failures) Ease of design Easier component changeability/upgrade/maintenance No bio-compatibility issues No internal health issues (i.e. case leaks) Cons Slightly more Impedance More wires through the body; greater risk of infection Greater risk for component damage Perceived weight is greater Wire connecting battery to controller Conclusion This option can be a backup for concept 2

Concept 4: Centralized External Electronics Package; Battery Included Example Single Case Size: 6.5 x 5 x 2 inches (65 ci) Pros (compared to Concept 3) None/shorter connecting wire Protected Battery Cons (compared to Concept 3) Larger case size Weight not as balanced on body Overall Size Conclusion If it is found that all components need to be in the same case, then this option will become more appropriate.

System Architecture – Diagram Signal Power System Architecture – Diagram Current Subsystem MICROCONTROLLER USER INTERFACE A/D Converters PWM Signal Gen Speed/Power Control Battery Meter FUNCTIONAL OR PHYSICAL ELEMENTS INTERMEDIATE ELECTRONICS POWER SUPPLY PWM Amps Diff Amps Converters Motor Controller Relays Battery OUT TO PUMP IN FROM PUMP

Bibliography [1] T. Mussivand, et al., "Critical Anatomic Dimensions for Intrathoracic Circulatory Assist Devices %J Artificial Organs," vol. 16, pp. 281-285, 1992. [2] P. J. Hendry, et al., "The HeartSaver left ventricular assist device: an update," The Annals of Thoracic Surgery, vol. 71, pp. S166-S170, 2001. [3] L. K. Fujimoto, et al., "Anatomical Considerations in the Design of a Long-Term Implantable Human Left Ventricle Assist System. J Artificial Organs," vol. 9, pp. 361-374, 1985. [4] T. V. Mussivand, R. G. Masters, P. J. Hendry, and W. J. Keon, "Totally implantable intrathoracic ventricular assist device," The Annals of Thoracic Surgery, vol. 61, pp. 444-447, 1996. [5] T. Mussivand, P. J. Hendry, R. G. Masters, M. King, K. S. Holmes, and W. J. Keon, "Progress with the HeartSaver ventricular assist device," The Annals of Thoracic Surgery, vol. 68, pp. 785-789, 1999. [6] R. D. Dowling, A. S. Ghaly, and L. A. Gray, "Creation of a diaphragm patch to facilitate placement of the AbioCor implantable replacement heart," The Annals of Thoracic Surgery, vol. 77, pp. 1849-1850, 2004.