Transcript Concept 1: Electronics are all internal except for power supply

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The Miniaturized System
System Architecture
LVAD Concepts
Case Research
Circuitry Research
Microcontroller Research
10/2/2009
Evan Sax
Lowell Smoger
Christine Stone
Mike Calve
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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)
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Device can be distributed into multiple cases
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Potential for certain cases to be implanted
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•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
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Example Single Case Size: 6.5 x 5 x 2 inches (65 ci)
Pros
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Minimal outer body components
◦ Increased Maneuverability and QOL
Decreased risk of device damage due to impact & particle
ingress
Cons
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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
◦ May be overcome with proper distribution (concept 2)
Cost
◦ Biocompatible materials
Conclusion:
Not within scope of project
May be too big to implant in one particular
place
New lines out for user Interface
Cost of size reduction
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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
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Increased maneuverability compared to completely external
(concept 3)
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Potential for fewer wires through body (wireless transmission)
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Battery can be included in external case
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Serviceable/Updateable external components
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No limit on external case size means easier to design and
increased likelihood of success
Cons
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Items outside are easier to damage
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Items in body more difficult to service
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Limited Space in Body
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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
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Example Single Case Size: 6.5 x 5 x 2 inches (65 ci)
Pros
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Reduces case size
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No internal component issues (i.e. part failures)
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Ease of design
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Easier component changeability/upgrade/maintenance
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No bio-compatibility issues
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No internal health issues (i.e. case leaks)
Cons
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Slightly more Impedance
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More wires through the body; greater risk of infection
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Greater risk for component damage
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Perceived weight is greater
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Wire connecting battery to controller
Conclusion
This option can be a backup
for concept 2
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Example Single Case Size: 6.5 x 5 x 2 inches (65 ci)
Pros (compared to Concept 3)
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None/shorter connecting wire
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Protected Battery
Cons (compared to Concept 3)
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Larger case size
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Weight not as balanced on body
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Overall Size
Conclusion
If it is found that all components need
to be in the same case, then this
option will become more appropriate.
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Signal
Power
Current
MICROCONTROLLER
A/D
PWM
Converte
Signal
rs
Gen
INTERMEDIATE ELECTRONICS
USER INTERFACE
Speed/Pow
er Control
Battery
Meter
POWER SUPPLY
PWM
Amps
Diff
Amps
Converte
rs
Motor
Controlle
r
Relays
Battery
OUT TO PUMP
IN FROM PUMP
Subsystem
FUNCTION
AL OR
PHYSICAL
ELEMENTS
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[1] T. Mussivand, et al., "Critical Anatomic Dimensions for Intrathoracic Circulatory
Assist Devices %J Artificial Organs," vol. 16, pp. 281-285, 1992.
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[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.
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[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.
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