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Transcript 
ECE 640: Intro to
Biomedical Engineering
-Guruprasad A. Giridharan
Human Circulatory System
The Heart
Natural Control
Nervous
Humoral
Local
Failing Heart
Why it
happens?
Effects
Why Model?
Learning tool
Inexpensive research tool
First step of device design
Predict effects and deepen understanding
Play GOD !! (idealizations, assumption,
know true values)
Modeling:
Human Circulatory System
Utah Circulation Model (UCM)
Modeling Assumptions
Physical parameters are linear and
lumpable
Blood flow is influenced only by pressure,
resistance and compliance
Blood is a Newtonian fluid
Ideal valves
Resistance and compliance remains
constant for any block (except heart)
Modeling:
Active and Passive blocks
P= Pressure, V= Volume, C= Compliance, F= Flow rate,
R=Resistance
Modeling:
Human Circulatory System
Modeling:
Valves
Modeling:
Failing LH, during rest
Modeling:
Failing LH, during exercise
Ventricular Assist Device
What is a VAD
Axial & Centrifugal
Flow VADs
How does it help?
©2000 MicroMed Technology, Inc
VAD Control
Objectives
Adequate
perfusion
Avoiding Suction
Low rpm
oscillations
Sensor Issues
©2000 MicroMed Technology, Inc
The DeBakey/NASA VAD
Modeling:
Ventricular Assist Device
VAD Model
Equations & Assumptions
RPM
Torque
Flow
Modeling:
Ventricular Assist Device
J= Inertia of the rotor, Te= Motor Torque, Tp= Load Torque,
= rpm, I= Amplitude of phase current, Fp= Pump Flow rate
Modeling:
Model Integration
Modeling: Axial Flow VAD
Model Integration
Modeling:
Model Integration
Modeling:
Model Integration
Control
Control Objective
RPM constraint
Why P setpoint ?
Equations
PI VAD controller
Simulation Results
Control:
Constraints and Objective function
Control:
Control Schematic with 3 sensors
VAD Control:
Weak LH, Centrifugal VAD, at rest
No VAD:
Weak LH, during rest
Performance of the PI VAD
Controller
Sensor Issues
Required 3 sensors (2 pressure, 1 rpm)
Pressure sensors unreliable
Data Noise
Estimate pressure using rpm and current
Extended Kalman filter for estimation
1 Sensor (rpm sensor only)
Weak LH with VAD, during rest
1 Sensor (rpm sensor only)
Weak LH with VAD, during rest
Performance of the PI VAD
Controller with P Estimator
Artificial Vasculature
Device (AVD)
Conceptual recovery directed device.
No damage to the left ventricle.
Ability to alter the impedence seen by the
LV.
Increase coronary perfusion by counterpulsation.
Design and In-vivo setup
Inlet
Valve
Filling
Outlet
Valve
Transonic
Inflow Probe
From
Aorta
Inlet
Valve
Emptying
Transonic
Outflow Probe
Outflow Cannula
Outlet
Valve Return
to Aorta
Transonic
Coronary Artery
Flow Probe
Intramyocardial
Pressure Transducer
Artificial Vasculature
Concept Device
Linear Actuator
To Power Supply
and Controller
LV Pressure/Volume
Catheter
Inflow Cannula
Artificial Vasculature
Concept Device
Artificial Vasculature
Device (AVD)
Aortic
Valve
Artificial
Valve
Left Heart
Aorta
F
S
F
S
P
S
Flow
Sensor
P
S
AVD
Rref
Pressure
Sensor
Ract
Filter
e
S.V
Controller
Modeling of the AVD
Reduce resistance and
increase cardiac output
Reducing Resistance
Controller action
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