Question/Thesis - JAKE Can a user interface be created on a
computer that can link and affect different aspects of a heart
simulator? The user will input a heart rate and/or blood pressure.
This input will then cause a sample heart to beat at that rate and
simulate an ECG that will display the blood pressure and heart
rate. The point of this simulation is to mimic real problems that
may be observed in the operating room and train students to react
accordingly. 2
Slide 3
Engineering Requirements The simulator must be controlled by a
computer software package. The software must drive a physical
heartbeat in a porcine heart based on the user provided heart rate
data. The software must also produce an ECG display that
corresponds to the user provided data. The simulated heartbeat must
be dynamically alterable The physical palpitation of the porcine
heart must mimic real- life motion. 3
Slide 4
Jonathan C. Nesbitt - JAKE Graduated from University of
Virginia with a BA in Biology Attended the Georgetown University
School of Medicine in 1981 Completed postgraduate training at
Vanderbilt in 1986 Was a surgeon on the USNS Comfort during
operation Desert Storm/Shield Joined department of thoracic surgery
at Vanderbilt University Medical Center in 2008 Specializes in the
treatment of esophageal cancer, lung cancer, thymoma and thymic
carcinoma 4
Slide 5
Background - ME Current System in use by Dr. Nesbitt Utilizes a
bicycle pump which cyclically pumps a plastic bellows. Air lines
connected to party balloons placed in right and left ventricles.
Does not allow for variable BPM or real time control Does not
produce a simulated ECG display Does not displace enough air to
accurately represent the magnitude of contraction in a healthy
heart 5
Slide 6
Methods - NICOLE We have segmented our design process into
three main steps: 1.Produce a beating heart 2.Computer control of
heart 3.Simultaneous ECG output 6
Slide 7
Developing a Beating Heart - NIKKI We plan on using an actuator
to regulate the flow of compressed air into balloons placed in each
ventricle. Image courtesy of
http://www.yourheartvalve.com/heartbasics/heartanatomy.htmhttp://www.yourheartvalve.com/heartbasics/heartanatomy.htm
7
Slide 8
Developing a Beating Heart - NIKKI We plan on controlling the
actuator with a square wave input At rising edges the signal will
produce a digital logic 1, allowing air to flow into the balloons
At falling edges the signal will produce a digital logic 0 and cut
off the air supply. Images by Judy Jowers from
http://www.flickr.com/photos/judyjowers/4391452125/http://www.flickr.com/photos/judyjowers/4391452125/
8
Slide 9
Developing A Beating Heart - Niki We are currently looking at
means of driving the movement of air into the balloons We are
considering two main options A solenoid driven pneumatic control
valve A servo motor driven pump or bellows system 9
Slide 10
Three Way Solenoid Pneumatic Control Valve Solenoid pneumatic
valves are relatively cheap at around $100 and incredibly reliable.
These are capable of controlling the pressure we need at rates of
under 20 milliseconds. 10 Image courtesy of
http://www.omega.com/ppt/pptsc.asp?ref=SV4100_SV4300&ttID=SV4100_SV4300&Nav=http://www.omega.com/ppt/pptsc.asp?ref=SV4100_SV4300&ttID=SV4100_SV4300&Nav=
Slide 11
Three Way Solenoid Pneumatic Control Valve The arduino will
control the pneumatic valve to alternate between compressed air and
the vacuum pump to produce the physical heartbeat. Balloon Vacuum
Pump Arduino Air Compressor 11 Control Valve
Slide 12
Servo Motor Driven Pump 12 Alternatively, we have considered
using a servo motor to drive a piston or bellows system that will
force air into the balloons This option is advantageous because it
is significantly cheaper than using a pneumatic control valve.
Unfortunately, the motor system is less mechanically reliable and
offers less control over the movement. Image courtesy of
http://www.galilmc.com/products/servo-motor.phphttp://www.galilmc.com/products/servo-motor.php
Slide 13
Servo Motor Driven Pump The motor system would work by driving
a piston in a vacuum tube. As the motor rotates the piston would
oscillate between forcing air into the balloons and sucking air
from them, thereby eliminating the need for a vacuum system. piston
air balloon to motor 13
Slide 14
Computer Interface - JAKE We will develop a computer program
that will enable the user to dynamically alter the heart rate
during simulated surgery. Ultimately this software will both
produce the ECG display and program the Arduino microcontroller in
order to control the motion of the heart. Input Heart Rate 14 Image
courtesy of
http://mc202.com/synthesizers/arduino-glitch-box-machinedrum/ and
of
http://www.yourheartvalve.com/heartbasics/heartanatomy.htmhttp://mc202.com/synthesizers/arduino-glitch-box-machinedrum/http://www.yourheartvalve.com/heartbasics/heartanatomy.htm
Slide 15
Simulator Pump DriverECG Driver USB Port Computer Program (C++)
1.Pump Driver input -> Pin 1 2.ECG Driver input -> Pin 2
Arduino Program (C++) Output to Pump Output to ECG Classes
Singleton Stores heart rate and arrhythmia values Allows for
dynamic access to variables Ensures single instance of class
(Singleton GoF Pattern) Pump Driver Operates within unique thread
Accesses heart rate value from Simulator class Outputs instructions
to pump through Arduino board ECG Driver Operates within unique
thread Accesses heart rate and arrhythmia values from Simulator
class Outputs instructions to EKG through Arduino board 15
Slide 16
Simultaneous ECG Output - ME We plan on recording different ECG
rhythms as.wav files. Once completed, these.wav files can be freely
manipulated and accessed through the use of C++. The ECG output and
beating heart prototype will operate simultaneously but completely
independently of one another. Image from:
http://www.swharden.com/blog/images/simple_ecg_circuit_output.pnghttp://www.swharden.com/blog/images/simple_ecg_circuit_output.png
16
Slide 17
Simultaneous ECG Output - ME Currently, a program is being
licensed that displays variable and adjustable ECG signals. We are
considering using this program as an alternative to manipulating
sample recordings of the various waveforms when displaying the ECG.
17
Slide 18
Additional Goals - ME Once we have developed a successful
prototype we will contemplate endowing the system with additional
capabilities to increase functionality. These include: Plot of
arterial pressure Simulation of the effects of anesthesia
Simulation of common arrhythmias 18
Slide 19
Status/Results - NIKKI We have met with the faculty sponsor,
Jonathan Nesbitt, and been informed of the details of the project.
Dr. Nesbitt also showed the current heart pump. We are acquiring an
ECG generating program that allows for variability. A skeleton
program has been developed in C++. We are researching various types
of mechanical control devices to drive the heart. Scheduled the
first meeting with Dr. Nesbitt for the new year, during which we
will present different potential devices and determine budgetary
constraints. 19
Slide 20
Conclusion - JAKE Our goal is to develop a prototype for a
cardiac surgery simulator that will permit dynamic alteration of
variables during surgery. We are planning to meet with Dr. Nesbitt
consistently throughout the semester. We will be ordering raw
materials within the next month and continue developing the
program. 20
