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Multi-Disciplinary Senior Design Conference
Kate Gleason College of Engineering
Rochester Institute of Technology
Rochester, New York 14623
Project Number: P09021
LVAD TEST LOOP
Jonathan Klein / Project Manager
Kyle Menges / Lead Engineer
Priyadarshini Narasimhan / Electrical Engineer
Christopher Stein / Mechanical Engineer
Julie Coggshall / Industrial Engineer
Christine Lowry / Mechanical Engineer
ABSTRACT
INTRODUCTION
The primary goal of the LVAD Test Loop project
was to design and build a biocompatible test loop to
aid in the development of a magnetically levitated,
axial flow Left Ventricular Assist Device (LVAD) by
characterizing the pressures and flows associated with
the device and determining the pump’s impact on
blood. The final product is a modular, biocompatible,
quick-connect, single tank design with test specific
tank lids, and is capable of testing the LVAD under
both steady and dynamic states, simulating the
physiological conditions of the human body. This
paper will describe the design, fabrication, and control
of the LVAD Test Loop, as well as the testing
processes and results.
According to the American Heart Association, in
the United States alone, one in three adults have a
cardiovascular disease, resulting in approximately one
death every 37 seconds [1]. Recognizing this high
occurrence rate, the medical device market has
targeted several products aimed at helping those with
heart disease. One such medical device is the Left
Ventricular Assist Device (LVAD); a surgically
implanted pump that is designed to assist the left
ventricle of the heart which is solely responsible for
pumping blood out of the heart and through the aorta
to the rest of the body. If the left ventricle becomes too
weak to pump the blood on its own, a heart transplant
may be the only option for survival. However, the
waiting list for a heart transplant can range from
several weeks to several months, and therefore the
LVAD can be used as a temporary solution to
preventing any further deterioration of the heart until a
donor organ can be obtained.
The Rochester Institute of Technology (RIT)
currently has a research team dedicated to the
development and testing of a magnetically levitated
axial flow LVAD under the guidance of Dr. Steven
Day, Assistant Professor of the Mechanical
Engineering Department, in collaboration with the
University of Virginia and private consultants on an
National Institutes of Health (NIH) funded project lead
by Dr. Donald Olsen at the Utah Artificial Heart
Institute [2]. To assist the team with their
development, a previous senior design team designed
CARNA, a durability test machine for the LVAD
under project P08025. The CARNA test machine was
intended to provide realistic conditions for LVAD
NOMENCLATURE
CO – Cardiac Output
CVD – Cardiovascular Disease
DAQ – Data Acquisition Device
HDPE – High Density Polyethylene
LVAD – Left Ventricular Assist Device
MAP – Mean Arterial Pressure
MVP – Mean Venous Pressure
NIH – National Institutes of Health
PVS – Pulsatile Ventricular Simulator
RIT – Rochester Institute of Technology
SVR – Systemic Vascular Resistance
VI – Virtual Instrument (LabVIEW)
biocompatibility – component will not directly cause
clotting or inflammatory response of blood due to the
material composition
Copyright © 2008 Rochester Institute of Technology
testing over long duration testing (approximately 2
years), but did not include the physiological
simulation of the human circulatory system. Since
then, the LVAD research team created an additional
test loop, primarily built out of PVC tubing, to be used
to generate performance curves for the device. The
current test loop is capable of running at steady-state
and allowing for pressure variation through an external
clamp to create flow restriction, however the data must
be manually recorded.
The purpose of this project, P09021, is to provide
a biocompatible test loop capable of evaluating the
damage to blood associated with the LVAD using
bovine blood as a test fluid as well as simulating the
physiological conditions within the human circulatory
system through the use of a PVS in order to further
characterize the performance of the device. The data
collection during testing is to be automated, and used
in a proposal for an Investigational Device Exemption
(IDE), allowing the device to be used in clinical trials
before premarket approval can be obtained from the
FDA. The project was carried out in two phases
consisting of an initial concept design and selection
stage followed by the fabrication and implementation
of the approved design.
be minimized. It should be easy and safe to fill and
drain the system using either blood or water-glycerin
mixture that simulates the properties of blood.
With regards to the physical system, Dr. Day
required that the test loop should be able to run both
with and without the PVS, and that the system
temperature should be monitored and controlled to
simulate the physiological properties of the human
circulatory system (i.e., temperature, resistance, and
compliance).
To ensure the success of the design phase of the
project, the team interpreted the needs of the customer
to create design specifications. These specifications
and their respective units of measure and ideal values
are summarized below in table (1). Although the
specifications were derived by the project team, the
ideal values were established to meet or surpass the
current testing parameters achieved by the previous
test loop devices.
DESIGN PROCESS
Specifications
System Leakage
Portability
System LxWxH
Arterial
Compliance
Systemic Vascular
Resistance
Specifications
Sample Extraction
In order to clearly define the objectives of this
project, Dr. Day provided specific criteria throughout
the design phase. Imperative to the design was that the
test loop needed to be self contained and portable, as
space within the research lab is limited, and testing
with blood can only be performed in specific rooms
within the building.
Dr. Day also indicated that the test loop needed to
be capable of automatically collecting data and
generating pressure and flow curves for LVAD
performance through a user-friendly software
interface. Currently, the pressure and flow data for the
test loop being used by the research team has to be
manually recorded and analyzed meaning the test has
to be constantly monitored by a technician.
Automating this process will allow for longer duration
tests as well as real-time performance curves.
For blood testing, it was required that the test loop
consist of biocompatible components to minimize any
damage to the blood other than that associated with the
LVAD. Also, when running the blood damage test,
samples of the blood need to be extracted quickly and
in a safe manner at various times throughout testing.
Although a licensed butcher has willingly donated
bovine blood, many impurities exist within the blood
and therefore, purified blood may need to be
purchased in the future. Based on the desire for a
compact system, the volume of fluid required to run
either the physiological or blood system tests should
Blood Damage
Fill Time
Drain Time
Portability
Cost
Viscosity
Density
Pressure
Pressure Accuracy
Flow Rate
Flow Accuracy
Temperature
Temp. Accuracy
Data
Processing/Output
Units
# leak locations
minutes
inches
Ideal Value
0
45
48x36x30
mL/mmHg
2
mmHg·min/L
13
seconds
mL
g Hgb/100mL
minutes
minutes
minutes
$
N·s/m2
kg/m3
mmHg
mmHg
L/min
L/min
degrees F
degrees F
30
4
16
20
15
45
3000
0.002
1150
101
0.2
6
0.05
98.6
0.1
Seconds
10
Table (1) Engineering Specifications
Concept
Through the use of Pugh Charts and a series of
technical design reviews, the concept selection process
resulted in a modular test loop system design. The
reason for selecting the modular loop concept was that
specific customer needs associated with the blood test
and physiological test could best be achieved by using
separate loops for each test. However, there were
many needs that the tests had in common, such as
minimizing the footprint of the loop, and therefore a
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Proceedings of the Multi-Disciplinary Senior Design Conference
modular loop allowed both the individual and shared
customer needs to be met. In addition, using the PVS
in the physiological loop introduces a level of
complexity that could potentially cause damage when
using blood, and therefore any components to be
shared by both tests need to be biocompatible to
reduce this risk. Also, as the necessary sensors were
the most costly system components, using a modular
loop allowed the sensors to be positioned in such a
way that the desired information could be obtained for
both tests. The two figures below show both the
shared components, and those required for each
specific test.
Fig. 1 - Blood Loop
various studies and similar projects provide examples
and methods for obtaining such biological properties,
the values are largely dependent upon the overall
system design. Aside from the biological aspects of
the project, some other critical design areas included
material selection, fluids analysis and air bubble
dissipation.
Resistance
As blood is pumped through the circulatory
system, systemic vascular resistance to the blood flow
that is provided by the peripheral blood vessels of the
circulatory system must be overcome. Within the
body, arteries have thicker walls and are more elastic
than veins, and help drive the flow of the blood
throughout the body as they expand and contract with
each heart beat. Veins on the other hand, being thinwalled and much less elastic than arteries, do not
provide any assistance to the flow of blood back to the
heart.
The equation below was used to approximate the
level of resistance needed to simulate the systemic
vascular resistance of the body. The difference
between the mean arterial pressure (MAP) and mean
venous pressure (MVP) is divided by the total cardiac
output (CO) to determine the level of vascular
resistance. As these characteristics vary as a person
performs different levels of activity, or has a
cardiovascular disease, there are a wide variety of
published values acceptable for modeling the human
circulatory system. In agreement with a similar mock
circulatory loop project created by the University of
Virginia [4], the desired systemic vascular resistance
was determined to range from 0 to 15 mmHg·min/L
(based on a MAP of 100 mmHg, a MVP of 10 mmHg
and a CO of 6 L/min), to allow for flexibility during
testing.
R
Fig. 2 - Physiological Loop
PHYSICAL LOOP DESIGN
One of the most challenging tasks associated with
this project was designing the components of the test
loop to simulate the physiological conditions of the
human circulatory system. While the PVS is used to
emulate the dynamic conditions of the heart, there are
many other biological factors, such as the resistance
and compliance of the blood vessels as blood is
pumped throughout the body, which needed to be
included in the design of the test loop. Although
Pr essure MAPmmHg   MVPmmHg 

Flow
CO L
min


(1)
In order to prevent unnecessary disruption to the
flow in the test loop, it was decided that the ideal
design would be an external form of variable
resistance. As a result, a linear actuator controlled by a
stepper motor was selected to provide the resistance
within the loop. The benefit of choosing this method is
not only that the resistance is external to the system,
unlike a globe or needle valve design, but also that the
same LabVIEW program used to collect the test loop
data could be used to control the amount and rate of
resistance desired by the user. This resistance method
is also crucial during the performance curve
generation, as the pressure within the system can then
be adjusted at a desired flow rate.
Copyright © 2009 Rochester Institute of Technology
compliance tank (Fig. 3) and one without the venous
compliance tank (Fig. 4) as seen below.
Compliance
Consequently, in addition to the systemic
resistance within the circulatory system, a certain level
of compliance is necessary to model the physiological
conditions that exist within the human body. As blood
is pumped through the arteries and veins of the body,
the vessel walls expand and contract causing a
fluctuation in volume as the pressure on the walls
varies. To mimic these changes in volume, a
compliance chamber is needed to simulate the
deformation and distension experienced by the vessel
walls [5]. Published values for the appropriate level of
compliance to mimic the human body were taken from
the human circulatory system model created by the
University of Virginia.
The equation below was used to achieve the
compliance values necessary to simulate the actual
compliance that exists within the human body.
Through the use of an air-tight sealed tank, the system
compliance is equal to the volume of air (Vair) within
the tank divided by the air pressure within the tank
(Pair). The volume of air in the tank is adjusted by
varying the volume of fluid (volume of the tank (V tank)
minus the area of the tank (Atank) multiplied by the
height of the fluid (hfluid)) in the tank along with the air
pressure (pressure of the fluid (P fluid) minus the density
(ρ) multiplied by gravity (g) and the height of the
fluid) within the tank.
C
Vtan k  Atan k h fluid
Pfluid  gh fluid

Vair
Pair
Fig. 3 - System model with both an arterial and venous
compliance tank
(2)
As the intent of the test loop design is to provide
realistic conditions that the LVAD will experience
when implanted in the body, the need for both an
arterial and venous compliance tank was evaluated
using an electrical equivalent model. The LVAD and
PVS were modeled using a square wave with a 1V
base voltage representing the LVAD, and a 100V
maximum voltage to mimic the pulsating of the PVS.
The pulse width was assumed to be 360 ms to best
represent the duration of a single heart beat, and the
period was set for 60 beats per minute. The arterial
and venous compliance were modeled using 2 mF and
50 mF capacitors respectively, as the desired value for
the arterial compliance is 2 ml/mmHg and the venous
compliance value is 50 ml/mmHg. The resistance of
the tubing is represented by resistors (R1-R4) with a
value of 0.51 Ω (actual units of mmHg/L/min) based
on an assumed tubing length of 1m. In addition, the
variable systemic vascular resistance was modeled
using a resistor (R5) with a value of 13 Ω to simulate a
differential pressure of 90 mmHg across the LVAD
with a flow rate of 6 L/min. Two simulations were
run, one containing both the arterial and venous
Fig. 4 - System model with an arterial compliance tank
As a result of modeling the system both with and
without the venous compliance tank, it was determined
that a venous compliance tank was not necessary to
include in the test loop design. The table below
summarizes the results of the equivalent model with
voltages at the nodes near the arterial and venous
capacitance. For the simulations, voltage (V)
represents the pressure (mmHg) within the system,
and current (A) represents the flow rate (L/min).
Analyzing the results, the fact that the voltage and rise
time for the arterial capacitor remains fairly consistent
in both simulations indicated that the contributions of
the venous compliance tank to the system were almost
negligible.
Proceedings of the Multi-Disciplinary Senior Design Conference
Arterial
Capacitor
(V)
Venous
Capacitor
(V)
Current
(A)
With Venous
96.61
3.41
6.64
Capacitor
Without Venous
96.36
0
7.13
Capacitor
Table (2) Electrical Equivalent Model Results
Rise Time
of Arterial
Capacitor
(s)
Rise Time
of Venous
Capacitor
(s)
With Venous
0.0403
0.0727
Capacitor
Without Venous
0.0403
0
Capacitor
Table (3) Rise Time Comparison
From the range of published compliance values,
the University of Virginia’s circulatory model was
used as a guideline in selecting a systemic arterial
compliance of approximately 2 mL/mmHg. Many of
the established values used by other research projects
and medical studies indicate that a value ranging from
1 to 2.2 mL/mmHg is acceptable to mimic the actual
conditions of the human circulatory system.
Design Feasibility
To determine the feasibility of the test loop
design, the approximate head losses throughout the
system as well as the differential pressure across the
LVAD were calculated based on assumed lengths of
tubing and diameter changes at a flow rate of 6 L/min.
Another important preliminary calculation was
determining whether or not the heat loss from the
reservoir or tubing would be significant enough that a
heat source would need to be incorporated into the
system, as keeping the blood temperature from
fluctuating during testing is extremely important to
ensure good test results. Additionally, as with any
hydraulic test loop, being able to purge the system free
of air is also necessary. To prevent air bubbles from
being trapped in the system, the amount of time
required for several different sized bubbles was
calculated to determine the minimum reservoir length
required to provide enough time for trapped air to
escape from the system.
Materials Selection
With the intent of this test loop being capable of
handling blood as a test fluid, careful considerations
were made to ensure that all components that could
potentially come in contact with blood were
biocompatible to prevent any unnecessary damage.
Purchased components that were made of High
Density Polypropylene (HDPE), Polysulfone or
Page 5
Nylon, and preferably those meeting the USP VI
qualification were chosen to prevent negative
hemolytic effects due to component composition.
Biocompatible quick-connects with valves
distributed by Colder (HFCD17839M male,
HFCD22839M female) were used at multiple
locations along the test loop to decrease the amount of
time it would take to fill and drain the system, as well
as to provide points at which the loop could be
disconnected without spilling liquid. Another
advantage to having the quick-connects in the system
was to allow for changeovers between different tests in
a timely manner.
CAD Design Conception
The system layout and component design of the
LVAD test loop was first created in SolidWorks©
(SolidWorks Corporation, MA). The 3-D modeling
software allowed the team to experiment and
systematically organize the dimensions and layout the
test loop prior to fabricating the items necessary to the
design implementation.
To achieve the goals established by this project, it
was necessary to design and manufacture five critical
components. One of the parts designed by the team
was the stepper motor holder. As previously described,
the external method of resistance selected was a linear
actuated stepper motor which required a square “U”
bracket in order to mount it to the cart. Also designed
by the team were stainless steel custom LVAD fittings
with pressure taps for 1/16 inch Tygon© (SaintGobain, Courbevoie, France) tubing to connect the
pressure sensor measuring the differential pressure
across the LVAD. Additionally, the test specific
reservoir tank lids were modeled.
Component & System Fabrication
Using the band saw, mill and lathe available
within the RIT machine shop, the conceptually
designed components were fabricated. The test
specific reservoir lids were cut using a 3-axis end mill,
and the holes were added using a hand drill. The 3axis end mill was also used to cut the stepper motor
holder out of HDPE rectangular bar stock. Custom
spacers attached to the test specific lids as well as the
end cap for the stepper motor were both made from
HDPE round stock, and cut using a lathe. A ban saw
was used to trim the different pieces of bar stock down
to an approximate size for the component being made.
A combination of an end mill and lathe was used to
machine the stainless steel custom LVAD connectors
with a precise surface finish and within a specific
tolerance to minimize damage to the blood and ensure
that leaks would not occur.
Copyright © 2009 Rochester Institute of Technology
CONTROL SYSTEM & INSTRUMENTATION
DESIGN
Essential to meeting the customer needs defined
by Dr. Day was the selection of the sensors, data
acquisition unit (DAQ), and software controls. The
control system was configured using LabVIEW©
(National Instruments, TX) in order to provide a userfriendly control program by means of a graphical user
interface. The control system was designed to record
the information gathered from the various sensors, as
well as to automate the adjustable resistance provided
by the stepper motor. Within the program, the
algorithm allows the user to input the number of
samples desired and at what rate the samples are to be
taken, as well as controlling the number of steps to
increase the resistance. Based on the user input, live
output plots of temperature vs. time, pressure vs. time
and flow vs. time are updated, as both the raw data and
an average set of data are recorded to the file name
required to start the program.
The DAQ that was chosen for this application was
the USB-2416 made by Measurement Computing,
with 32 analog inputs dedicated to reading the signals
from the required sensors, and an additional 8 digital
input/output channels capable of sending and receiving
up to a 5V signal. The reason for selecting this DAQ
over the more common National Instrument (NI)
devices that do not require additional virtual
instrument (VI) blocks was that all of the various
voltage and current requirements for the different
types of sensors and stepper motor could be handled
using this single unit. The other more expensive option
was to use a NI DAQ for the stepper motor, pressure
and flow sensor, and to purchase a separate DAQ for
the thermocouples. The fact that there are 32 analog
inputs also allows for flexibility for future expansion,
as multiple sensors can be used at the same time.
The types of measurements required for this
project included temperature, pressure and flow rate.
Because sensors with the appropriate accuracy are
costly, Dr. Day agreed to share some of the existing
equipment that the LVAD research team uses to
collect data with the existing system. An emtec flow
meter that was not currently being used by the team
was provided to measure the flow rate within the
system. The ultrasonic flow meter requires a straight
section of at least 6 inches of ½ inch diameter, 3/32
inch wall thickness Tygon tubing on either side of the
sensor. The choice was also made to purchase the
same DP15-34 Validyne differential pressure sensor to
measure the pressure drop across the LVAD as the
research team was familiar with this sensor and could
use it with their existing system if so desired with
minimal software changes. Type “T” thermocouples
were purchased from Omega as they were determined
to have the desired accuracy required for the project.
DESIGN TESTING & VALIDATION
After a preliminary trial run using water with the
LVAD it was determined that the Colder quickconnects had a large pressure drop associated with
them as they were intended for low flow, high pressure
applications. In order to quantify the pressure drop
associated with these components, the Biomedicus
was used to generate a plot of the pressure drop over
the normal range of flow rates that the LVAD is run at.
As a means for testing the amount of blood
damage the test loop causes, a comparison between the
percent of hemolysis in the blood was made between
our test loop design and a more simplistic loop
previously tested by the LVAD research team using
both the industry standard Biomedicus pump and the
LVAD. First, each loop is run at a constant flow rate
and pressure that can be achieved by both the LVAD
and the Biomedicus. Multiple blood samples are
extracted from the reservoir at different intervals
throughout the three hour test while the temperature of
the blood, the pressure across the pump and the flow
rate are held constant. Maintaining the blood at
approximately 37ºC is necessary to reduce the amount
of damage to the blood due to temperature
fluctuations, as is a constant pressure and flow rate.
After running with the Biomedicus, the loop is then
connected to the LVAD and the procedure is repeated
at the same pressure and flow rate.
Another important test was to determine if the
compliance value could be achieved using the LVAD
and PVS with the physiological test loop. The outside
of the reservoir tank was labeled in milliliter
increments so that the volume of air inside the tank
could be found by subtracting the volume of water
from the total volume. With the aid of the
physiological test lid, the tank can be pressurized and
measured using a modified sphygmomanometer pump,
and the compliance can then be calculated. Testing the
tank and lid sub-system for leaks and being able to
pressurize the tank up to 160 mmHg will ensure that
the compliance is achievable based on the loop design.
The PVS itself will most likely play a limiting factor if
the back pressure becomes too great, causing the PVS
not function properly.
To validate that the LabVIEW program generates
automated flow curves by varying the resistance
through increasing or decreasing the travel of the
stepper motor, the pressure across the pump in the
system as well as the flow rate of the system need to
be recorded at several points.
RESULTS AND DISCUSSION
Although our final test loop design follows our
initial conceptual modular design, some modifications
were necessary over the course of the production and
validation phases. The following figures (Fig. 5 and
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Proceedings of the Multi-Disciplinary Senior Design Conference
Fig. 6) show the assembled blood and physiological
loops.
Fig. 7 – Pressure drop across quick-connect
Fig. 5 – Blood test loop (Biomedicus attached)
Automated performance curves were generated
using the Biomedicus in place of the LVAD for four
different rotational speeds as seen below in Fig. 8.
Although the data points for our test loop (X’s and
diamonds) correspond with the data points from the
LVAD research team (dashed lines), the pressure loss
due to the quick connect can be seen as the flow
increases along the curve. Also, moving along the
curve towards the y-axis, our data points do not extend
as far due to the fact that the cap on the stepper motor
is not wide enough to completely close the tubing.
Biomedicus Performance Curve
250
Pressure - mmHg
200
150
100
50
Fig. 6 – Physiological test loop (LVAD not connected)
0
The results of the pressure drop measurement
across the Colder quick-connects indicate that there is
an exponential relationship between pressure drop and
increase in flow rate. The plot below (Fig. 7) shows
the relationship between flow and pressure drop across
the quick-connects. Because of this significant drop in
pressure, all but one of the quick-connects in the
system was removed to reduce the pressure losses of
the loop for pump performance testing. The reason for
keeping one quick-connect in the system was to ensure
that during blood testing there would be one point that
could be disconnected without spilling blood for
drainage and air bubble removal.
0
2
4
6
Flow - Lpm
8
500 rpm
1000 rpm
1500 rpm
2000 rpm
500 rpm SD
1000 rpm SD
1500 rpm SD
2000 rpm SD
Fig. 8 – Automated performance curve using the
Biomedicus
Even though the quick-connects introduce a
significant pressure drop into the system, they do not
affect the results of hemolysis testing. After two three
hour hemolysis test using both the LVAD and
Biomedicus, the percent hemolysis for our test loop
was slightly lower than that of the LVAD research
team’s simplistic loop. This indicates that the loop
itself does not have a significant effect on hemolysis.
Copyright © 2009 Rochester Institute of Technology
10
The results of the hemolysis testing are shown in the
figures below.
Fig. 9 – Biomedicus %Hemolysis comparison results
temperature control, especially cooling, when
performing blood tests. Verification that the 2
mmHg/mL arterial compliance value can be reached
should be performed. Automating the compliance tank
pressurization system would be beneficial to the
technicians running the test by removing the need to
constantly monitor and pressurize the tank by hand
while testing. Additional verification and progress on
the LabVIEW program to ensure compatibility with
multiple pressure sensors and flow meters and
verifying the effect of the pressure drop using a quickconnect during LVAD performance characterization
would also further validate the capability of the test
loop.
A few physical improvements to the test loop
would be to increase the range of the automated test
curves by improving the stepper motor cap so that the
tubing is completely closed will allow for more data to
be collected. Continuous improvements on reducing
the test loop footprint and the fill and drain system to
reduce set-up and tear-down time would also benefit
the constraints of the lab as well as being able to
extend the amount of testing time by shortening the
preparation before and after testing.
REFERENCES
Fig. 10 – LVAD %Hemolysis comparison results
The LVAD Test Loop successfully fulfilled all of
the customer needs, but only met 15 out of 20
engineering specifications, including the budget. The
arterial compliance and temperature control were not
verified and the performance curves using the glycerin
mixture to simulate blood were not obtained as the
team was behind schedule. The accuracy of the
temperature and flow rate measurements were not well
defined during the initial development of the
specifications, however they did meet the customer’s
needs.
CONCLUSIONS AND RECOMMENDATIONS
Overall, the project can be considered a limited
success, as not all of the initial specifications were
met. However, if more time was available for further
testing, the remaining specifications could most likely
be achieved.
Continuation of this project should begin with
further investigation of the need for automated
[1] American Heart Association. “Heart disease and
stroke statistics – 2009 update.” Dallas, Texas:
American Heart Association; 2009.
[2] Day, S.W., “Research”,
<http://www.people.rit.edu/swdeme/research.html>
[3] P08025 CARNA Project
<https://edge.rit.edu/content/P08025/public/Home >
[4] Yingjie L., Wood, H., Allaire, P., Olsen, D., 2005,
“Design and Initial Testing of a Mock Human
Circulatory Loop for Left Ventricular Assist Device
Performance Testing,” Artificial organs, vol. 29, pp.
341-345.
[5] Noodergraaf, A., 1978, “Circulatory System
Dynamics,” Academic Press, NY. pp. 255-286.
ACKNOWLEDGMENTS
The team would like to express its appreciation
and gratitude to those who made a contribution to this
project. Special thanks to Dr. Steven Day for his
guidance and support, and Ivan Farber from Oetiker
Inc., for his generous donation of components and
installation tools. Additionally, the team would like to
thank Dr. Richard Doolittle, Dr. Daniel Phillips, Mr.
John Wellin, Mr. David Hathaway, Mr. Robert
Kraynik, Mr. Steven Kosciol, Dr. Mark Olles, Dr.
ShanBao Cheng, Dave Gomez, Jim Cezo, Jessica
Watkins, Steve Snyder and the entire LVAD Research
Team for their assistance, patience, cooperation and
constructive criticism.